Thank you everybody for joining us! We are here with our second live stream uh with an esteemed guest Ty Branaman as well as Adam Muich and Matthew Bruner Um and today our topic is going to be uh, covering 90% furnaces. And for anybody who knows me, you know that I don't know much about 90% furnaces. so I'm not going to talk much on this one. I'm going to let the guys who actually work on this stuff, um, talk and uh, kind of cover the topic.

We're going to start by just talking about uh, some basics of 90% just the basic concept, why they work the way they do and then we're going to jump into Diagnostics It's worth mentioning that Michael House was uh, going to join us and he is, uh, ill this evening so thoughts and prayers with him uh as he's recovering from that. but I'm sure he'll be I'm sure he'll be just fine. He's a hearty, hearty fellow. so with that I'm GNA turn it over to Adam to kind of lead the lead off the discussion.

Hello everybody! good evening! So uh I think like probably a good place to start would be to talk about like what is the difference between an 80% and 90% furnace? the uh, the inner workings? Um so um, if if you look at the the slide on the screen you see it's kind of a little bit difficult to see. but you have a secondary heat exchanger that is on an UPF flow furnace. um just right below the primary. uh, heat exchanger.

Um, so that's kind of it. You do not have traditional metal venting. You have a PVC vent and a lot of times you'll have a PVC intake as well too. Um so uh yeah, he's talking about like what's the like Why yeah so I wanted to I I Kind of wanted to to talk to Ty about that.

like what is what happens in a condensing furnace? Like why I kind of spoiled it I Guess a little bit, but it's a a 90% furnace. What is the magic behind a 90% furnace tie? Well, let's go back a little bit. When I first started, we had a lot of standing pilots and 80% was new. It's like oh, these 80% furnaces and I was asking well, how do we get so much more energy out of that gas for that 80% furnace and they were said well, we just added more heat exchangers.

We had more heat transfer thermodynamics so we have more room to have more of that hot gas, touch, more of the air. and then so I said okay, well now are we going to have 90% I said yeah. but that Sff just far into future? Well it wasn't that far in the future because it's all around us and it's been around for a while. So the catch is we want to get that extra heat out.

Well, the problem that we have with the gas furnace. if we take heat out of that gas, we start to condense and we start moisture. There's actually been people in their basements where they've tried to put you know, extra pieces of metal around that flu pipe trying to get that extra heat out of that flu gas instead of it just going out the top. But the problem is the moisture in it condenses.

So every time we have combustion or a fire, a byproduct is water vapor and we don't see it because it's a vapor. The problem is that water vapor. Once it cools off too much, it changes state from a vapor over here to a liquid. and that's latent heat that's condensation now in an 80% furnace.

That's bad. You start having this run down that flu pipe and it eats away at the aluminum and all those parts inside of there and starts eating away the heat exchanger. And everything's bad, right? Because it's also very acidic. but how can we utilize that? So I Said Well, let's take that flu pipe and let's run it through a secondary heat exchanger and that's going to be less heat than the rest of the Furnace We got to put it through that air first.

so the air from the house has to touch that secondary heat exchanger first. So we're getting two winds. one that extra heat that we were just exhausting out through that flu pipe. We're able to put it through more metal, more surface area, better heat transfer, but also as we take that moisture from combustion that leftover, uh, water vapor and we make it change state from a vapor back to a liquid, we gain heat out of that just like we do with the condenser, which we're rejecting heat.

So 9 70 B2 of heat energy come out of one pound of water, changing state from a vapor back to a liquid of course. Then we have some other challenges: how we going to deal with the water, manage the water, and those are things we'll talk about today. but simply, we just took that extra heat that we're sending out the flu pipe, and we put through a secondary heat exchanger. and then we took that water vapor left over from combustion made it condense back into a liquid.

We got latent heat out of it, so it's pretty awesome how that happens. I Think So what are some of the challenges that you could run into in a condensing furnace with the water management? Like what do you normally run into problems in the field? So we have. We have some big ones. Anytime we have combustion and we have that water, it's going to be acidic so we have to think about that drain water.

We can't just put that in the regular Plumbing pipes because if it's metal pipes, it'll It'll eat a hole of them. So that's going to be one of the big issues. And I've seen that firsthand where somebody piped it into that and uh, it was a big issue. I've also seen firsthand where people thought well let's just drain it outside like like we normally do.

Like the problem is in the winter time, what happens when you Drain Liquid H2O outside to where it's less heated. Yeah, that that water is going to turn to a solid and uh, it's going to back up inside the furnace. and then our third one's going to be where we have those those flu pipes. Um, we have to have the proper drainage because that that moisture level is going to be wanting to drain back and we got to make sure we manage that so it doesn't clog up that heat exchanger.

So water management is going to be one of the biggest issues and that's why that secondary heat exchanger is usually stainless steel. That's why we have those PVC or plastic types of a composite material for those inducer fan motors because the metal ones would simply rust away. Now ideally stainless still works good. Um, there's a lot of Manufacturers tried different things and some of them worked better than others.

There's been some recalls in the past, but essentially that's why the instruction manuals got to be so very important because what there other considerations that we never had with the older furnaces. So making sure that that that water management is going to drain someplace that's going to be either acid neutralized before it go goes in the drain or it's not going to drain simply outside where it clogs up and then our vent pipes where we have the proper drainage so it doesn't uh, doesn't cause a problem I Want to touch on something too I Know you were saying like water management let's get the the water out of the pipes and Out of the Furnace um one thing that I always try to do um is pitch the furnace slightly forward in order to you know you're ensuring the water is actually draining out of the front of the secondary heat exchanger and Out of the Furnace um sometimes you can get if you have the furnace you know back pitched slightly. you'll have water actually collecting and sitting in the back of the secondary. and like you said that is acidic water and you could actually deteriorate the heat exchanger.

That's that's exactly right. um I've I think the installation manual says they want it to be a level furnace but you know a slight pitch forward to where we're getting that water out of that heat exchanger. I have found to be very uh very effective and you got to think about where that furnace going to be located as see somebody take a 80% furnace out in the attic and they put the new 90% in the attic and the attic is not in conditions so that drain line freezes, cracks, the cracks, the drain and also the flu pipe needs to be insulated so those there's some very key insulation component so we have to follow. You'll see someone says if you're in a climb up below, say 40 degrees, they want you to have that, uh, the attic insulated on a flu pipe or the drain lines insulated.

or in some cases, you have to actually add heat tape to the drain lines and that flu gas to make sure that we keep it in liquid form. Which isn't a bad thing, it's just those little details like that can make the difference of a long working gas furnace or one that has lots of problems. One thing I want to mention quickly I Said I Wasn't going to talk much, but um, one of the big advantages of 90% that's actually beyond the efficiency side is the sealed combustion versus open combustion. And our Market We have to deal a lot with combustion air and where we position the furnace because we're actually bringing that combustion air through the front.

and one of the really big advantages of 90% which is sort of unintended. It's not really a uh, it's not really a direct factor with 90% but you tend to get that sealed combustion where you're bringing in that uh, air from Outdoors which is advantageous because now you don't have to worry about issues in that combustion. Air Zone Yeah, I'm really glad you mentioned that because if we're going to burn one cubic foot of natural gas okay, that my cubic foot is betterer, My camera is here. one cubic foot of natural gas.

It's going to take at least 10 to 15 cubic foot of air to burn that 1 cubic foot of natural gas. So all of that gas that's going through there needs a lot of air too. So if we're taking air out of the house, for every one cubic foot of air we're pulling out of the home exhausting outside, that's another cubic foot of air that has to replace the air inside the house. So if we have a high performance home and it's sealed up really well, we got to be thinking, hey, let's take the air from outside and not have it affect the air in the house at all.

So that's a great point and a lot of people do Overlook that that and that's why I kind of cringe when I see people that never install the air intake from outside because you're losing a big advantage to that gas furnace because this one cubic foot every minute one. CFM going through there. that's air that we have to replace back into the house. Nice.

Um I wanted to touch on the intake. Um, if I can for a second I Not, you know one thing I've noticed I I run into a lot of uplo furnaces I'm in the midwest the Chicagoland area so all the furnaces that I work on are upflow in a basement, right? Uh, when you work on a 90% efficient furnace, you have a an exhaust and an intake. So one issue that I see commonly is in the offseason like right in in the cooling cycle. Um, you have the cool air in the basement and you have the hot air outside and what ends up happening is you have air transfer from inside to outside through the intake and you'll actually start um, producing a slight bit of condensation that will run back on the intake and you can, um, actually get water to drip on top of the burners and or the gas.

Val That's a common thing, so sometimes you have to actually have some sort of water management on the intake as well to dependent where it's tied into the furnace. I 100% agree. And it's interesting how not all the manufacturers have the same literature. One will say they want it pitched away from the furnace while another manufacturer will want pitch towards the furnace and some of them will even have where they want an extra drain pipe in there or certain distance.

So it's important to read that installation manual and follow what that manufacturer says because if you do everything like the manufacture says it doesn't work, then you know it's easy to say hey, I did this You know I need you to send somebody out here and help me because I did this exactly how you said to do it and it still doesn't work. It's when we take stuff on our own. That's the way you know. I've say I've installed York furnaces and now I'm installing a carrier.

Some of those slight differences will really be detrimental to how that furnace works. and I think one of the biggest things I see is just people not um, you know, not knowing. You know that not realizing how important some of those steps are in that installation manual. And remember these manuals are being updated and changed constantly and it's just like we have with.

You know, in the old days we had carburetors. which people, you know, a lot of people loved working on carburators. Now we have fuel injection. We know that fuel injection works well, but there's a lot more little details involved and that's what we do.

We're professionals and we have to learn and we have to adapt because time keeps marching on. I'm going to take a minute and address this particular question because I think it kind of ties into, uh, ties into what we're talking about right now. and the question is because the liquid condensing in the heat exchanger and also potentially in the exhaust, you often see deterioration and discoloration of PVC from the acids. Also, what's your take on a drain attached to the exhaust with a trap? So um, the official answer is your PVC drain Or your PVC exhaust is supposed to be a special type of PVC and there's one company I know that makes it Adam if you remember um I've I've ran exhaust issue but officially there is a computer that makes an actual rated PVC for that exhaust I just can't remember off top of my head and it supposed to handle that a lot better I've never had the acids affect PVC Personally not saying that it's not ever an issue as far as the Uh drain attached to the exhaust.

um to a P trap. I've had some installations that I could solve the issue with the correct pitch of the Trap without costing the customer more money than they had and I have done that before even though sometimes it goes against the installation guide. sometimes in the field we have to come up with Solutions and I've I've done that before, whether it's the right thing you know, um, it depends what the manufacturer says. but I have done that to solve some problems before.

so I'm I'm not against it. But officially I will say follow what the installation manual says: I know a lot of people um there's Supply hous in the Chicagoland area that they sell predominantly cellular core you know, 2 inch and 3inch PVC uh for venting but you know most manufacturers I think require a minimum of schedule 40 PVC So like back to what Tai what you were saying. uh I think you always should reference the manual like what type of materials you should be using for whatever situation you're involved with. Um so so I live in Uh Dallas and I don't see a ton of 90% furnaces.

One question that I've always had is like why are there like multiple pre Are there multiple pressure switches? Sometimes there's multiple pressure switch lines. Can you guys just talk a little bit about how the pressure switches are different on a 90% versus an 80? Yes Um, there's several answers that so we have different types. We have single speed furnaces which are you know it's not a whole lot of difference between a 90% And 80% As far as the operation, you got your single pressure switch, but then we have two speed furnaces so you have to have a pressure switch for each one of those. And now of course we have modulating pressure switches.

Uh, you know for the the furnaces that have the full variable speed inducer fan and you know those are the ones that gets quite expensive and have a little bit more time as far as trying to diagnose. but you'll see a lot of times extra pressure switches on that secondary heat exchanger and what they're looking for is to see if there going to be a pressure drop from the primary to the secondary heat exchangers. It's giving you an idea if we're having a an issue with that secondary heat exchanger ahead of time and I know when you open those up. I Remember the first time when I opened up a 90% furnace and I was just overwhelmed with all of the stuff and I had to call into one of the senior Texs and he's like yeah, look at the schematic on it, see what it says and I did I pulled up the schematic and it had stepbystep testing each one of those and when you break down a component individually, what it does and you can test it, you know what it's supposed to do, do and then what it's actually doing, you can start eliminating it and then it just comes down to is it the switch that's bad or is it what the switch is testing to be bad? Other words, my fuel gauge shows empty Am I out a gas or is it the gauge? Yeah.

So so in short, uh, basically different manufacturers and different model furnaces. You'll have different situations with different amounts of pressure switches. You could have one, you could have two, you could have three lot of times. you'll have one that monitors just the drain.

Um, but yeah, it really depends on the individual furnace and application that you're working with. So should we talk a little bit about the sequence of operation here? Yeah, let's go to. let's go to sequence of operation All right. Um, so it it's It's very similar to an 80% furnace.

Uh, basically you start off with your W call and um your W call from the thermostat you need to provide 24 volts to the W terminal on the circuit board. Um, now the next thing the board is doing is that looking at the pressure switches, you need to make sure the pressure pressure switches are open. It won't start if they're closed it it if it's assuming that something has failed. If a pressure switch is closed without the inducer motor on right.

Um, your inducer fan will start once it proves the pressure switch is open, Uh, your pressure switch will then close as long as you meet the proper pressure set on the switch and then it goes through and checks all the safety devices roll out switches. Main Limit: uh, blower safety. Um, your igniter will start up and then after a certain period of time the gas valve will open, You prove the flame with a flame sensor and then after a time period the blower motor starts and voila, you have heat. Yeah, um one thing I'd really love to to pick both of y'all's or all three of y'all brains about is just like uh, your kind of troubleshooting process in general.

Um Ty Do you want to start off and just kind of tell us like what's what's your big picture When you're walking in doing troubleshooting on a 90% furnace, the first thing I do is I look for anything out of place. so I look for if there's any loose wires, uh, any any kind of connections, thermostat wires I look to see if there's any water built up in that secondary heat exchanger I look to see if there's any debris or anything in that, um, in that burner compartment if I can I try to make sure that, uh, the exhaust and the intake is clean and clear. Sometimes a leaf blower is a great way to do that. I find a lot of times that a bird will like to craw up inside that pipe and clog it up.

and uh, that's one of your big problems. So I follow the uh, the Kiss method. you know, look for anything that's out of place first because it was working and now it's not working. So look for any of those things first and find out what catches my eyes quick.

And then the second thing is after I've eliminated that m we actually have gas I don't know how many times I've been their service calls to where something happened with the customer. they didn't simply, uh, pay their gas bill. There was an issue and they didn't have any gas. so eliminate all of those first.

and then you know your sequence of operations. so everything there is good. you fire it up. You start following your sequence of operation and see what's missing.

Yeah, that's a good point. Um I also I kind of look always visual first. um and one big thing that I always look for is water. You know? um a lot of times you'll have certain water leaks, water drips from all over the place in uh, 90% furnaces.

so uh, just look and see. sometimes you'll get water that can drip down onto the circuit board. um just for look for any signs of water damage whatsoever. and uh.

another thing is if you're having intermittent issues like let's say the furnace is going off on limit or something else. um sometimes you'll have you know a big one with 90% furnaces. When you have a issue with the secondary heat exchanger is the roll out switch will trip right. Um, smells.

Pay attention to your senses. Smells like um I Know you can't smell carbon monoxide, but you can smell a acidic heat exchanger. Um, you it smells like rotten eggs or something like that. So when you smell something off when you're working on a 90% furnace condensing furnace, um my.

my advice would be to watch the video from the last you know two weeks ago and pull out your combustion izer and start testing that furnace gotcha. So would you guys say that like water is typically the Pr like the primary cause of problems with like a 90% furnace, something water related or um yeah, what are you guys typically seeing? Flame sensor is what? I see the most common I would say air flow is huge. Uh, you need a lot of air flow for a high efficiency furnace. Um, you're trying to get rid of the heat right? So you need to have provide more air flow through the furnace than you do on an 80% efficient furnace, right? Um so in our Market we run into undersized filters, undersized return, oversized equipment, and um so it's like a big deal making sure you have the correct air flow gotcha.

Um what? So and does this does a secondary heat exchanger? Does it tend to get like plug like plugged up or things like that? um differently than like a maybe a primary heat exchanger? It shouldn't? I Mean typically you really shouldn't get anything in your secondary heat exchanger. Um, you will get dust and debris in the Trap and whatnot. But like you will have, you know, heat exchangers that will I think they call it the official term is delaminate or something like that where the you actually start eating away at the interior uh the tubes in the heat exchanger and it just plugs everything up. Then you'll start noticing pressure switch or uh not pressure switch.

You can have pressure switch issues. You can have roll out switch switches that will trip and the top of the heat. The top of the Furnace itself will get extremely hot when that something like that happens like it's It's actually difficult to put your hand on the top of the furnace and can you and can you can you talk us through like why? like why is that happening So the roll out switch uh is not making is not making and then you're getting heat, You're feeling a lot of heat Like what does that do to can you kind of talk us through what's going on internally? You want to take this tie. so I I Want to back up on the air flow side.

When we talked about it stopping up One of the the things that heat exchanger is like an evaporator coil. You have a a tube and you have fins on it. so if the customer is not changing their filter which you know we know that never happens right? So that secondary heat exchanger gets clogged up so we don't have the proper air flow. if we don't have the proper air flow, we don't have the proper heat exchange on that so that secondary cool does start to heat up.

So uh, pulling that blower out, inspecting that secondary heat exchanger a lot a lot of times I found that that's an issue. even in the summertime. I'll have technicians that call me and there's an airf flow issue and they say the evapor coil is clean. We found that's a 90% furnace.

I Have them pull that blower out and they see that that secondary heat exchanger which is right there in front of the blower is clogged up. so clogged up with dirt and debris. And that's going to clog up before the evaporator does. So making sure that coil is clean on the external side is going to be super important because if it's clogged up on the external side, you're overheating that on the internal side and nothing's going to work like it's supposed to on the internal side.

Really, it comes down to, you know, if you have proper air flow and you have the proper combustion, the proper amount of gas going into that system, that secondary heat exchanger should last the life of that system. Now there's some exceptions. We know that some manufacturers use some different materials. over the years there were some recalls on that, but really, most of the time I found out that those secondary heat exchangers, especially the ones made with stainless steel, if they had the proper drainage and a proper air flow, they really lasted a long time.

I've seen a lot of some of the really old older furnaces that were really surprising, looked really well inside. so I did oh sorry, go ahead I did look up that PVC and it's uh. Ipex Ipex uh that's rated for 90% furnaces PVC temperature rated flu sorry I was distracted I had to look it I had to find the answer I was just getting back to Matt's uh, question about the the roll out switches. Roll out switches are actually manual reset.

There's like a button they click. It's like when you push it right? Um, so what ends up happening? Think of it this way. like the inducer motor is kind of drawing the flame, drawing everything in through the heat exchangers, right through both heat exchangers. and then what ends up happening is when you clog your secondary, you're not able to draw it through.

so the Flames will actually start rolling out and kind of heating it. You know you won't basically get the true the flow of the flame into the heat exchanger so it overheats the combustion chain chamber. gotcha. Okay, so that's why it could be you could see it on the inducer side or you could see it on the rollout switches.

Like just kind of depends how it ends up happening. Yeah, and then also another thing I Want to mention on the um, the pressure switch side is another common thing I Run into frequently is mismatched um. intake and exhaust pipe like sized incorrectly. So every furnace has a vent table right? Um, and every vent table is particular to the individual furnace.

So you might have two furnaces with the same you know size basically same BTUs but uh, same manufacturer but you might have to use differ size. PVC Based on the individual furnace, you just need to check every individual model. That's exactly right. The 80% furnaces a lot of times you get have an oversized exhaust and you still relied on that natural convection for that to draft out.

But in a 90% furnace, you're pulling the air in from outside and then you're forcing that exhaust back outside and you need to be able to pressurize it up. You literally could not pressurize that pipe if it's too large and that's definitely going to affect the airf flow of of that system. so that pressure switch knows hey, that uh, that pipe's either too big we don't have, we don't build up enough pressure that we need or it's too small and it's not moving enough air that it needs. So making sure that that is size to that table is extremely important.

I Know we don't like the read: we don't like look at tables with a 90% furnace I Can't tell you how important that is. that and air flow? Yeah. I've seen people mention online a couple a couple of times that uh, like when they're having problems with the 90% furnace, they'll just they'll pull the door off. um and I know that um Adam you had mentioned that has something to do with um, the venting as well.

could could you talk a little bit about that and kind of what that is indicating? Yeah, so what I've noticed is when you have, let's say you have a furnace that requires 2 and a half or 3 in PVC and you somebody installed it with 2 in Um. For whatever reason, I've noticed that Um furnaces can and will work with undersized PVC For a certain amount of time, but as time goes on, Parts start getting dirty. Um, it's the motor is getting a little bit more tired. Um, over time it just stops working.

Um, so the pressure switch won't make and you'll have a pressure switch air to three four five years down the road. Uh, the customer is confused about it when you have that conversation. why isn't it working? It worked before? Well, if you show them and Blue On is a great app to look up the manuals. you could look up any manual any furnace, pull up the vent table and show it right to the customer.

Uh, pay attention to the number of elbows because on this table that's on the screen right now, it will tell you how many elbows you could have with the total length of the pipe. Certain other tables it might not tell you the number of elbow elbows, but it will tell you um, what the equivalent length is per elbow. So we'll say maybe five foot or six foot per elbow and you just need to do the math. gotcha.

We had a good question about how to keep uh, animals out of the intake. Uh, friendly neighborhood maintenance guy and I tell you that's a, uh, that's the $100,000 question right there. That's a it's a great question and there's not a good answer. Anything that we put over that pipe is going to affect the operation.

I See people constantly screens over the uh the exhaust on the outside to keep the birds out, but that will cause a problem in the winter. as that moist air is coming out of that exhaust, it's going to hit that metal. It's going to turn the ice on. It's going to freeze up faster so we can't put any type of coating on the outside uh to to protect it.

and unfortunately it leaves it open for the animals. I've heard of people trying some homemade remedies that sometimes work, sometimes don't but if you look at the insulation instructions, they'll typically say nothing over that outside edge. Uh, because because it will cause a problem in the middle of winter. So I wish there was an easy answer for that.

I don't know I've also seen kids. they'll put a a ball inside of there and that causes problems before too. So I it's a great question I don't have an answer for that yet I've had some pretty good luck using either. I Know diverse attch I Think makes a flush mount kit that it.

It's kind of oblong shaped and it draws the air from the backside of it. Um, I Haven't had too many issues with that otherwise. just a regular concentric. Which a concentric is basically a pipe inside of a pipe and it blows the exhaust out of the face of it.

And it's a cone and it draws from the back side of it as well too. so you only have one penetration with a concentric. We have another couple questions that I want to just go ahead and answer while we're while we're answering questions. Um, and and they're They're kind of kind of tricky ones, but this one here says is there an appropriate pressure drop on your incoming gas pressure once the gas valve opens up So basically they're saying Inlet pressure versus manifold pressure Is there some sort of appropriate pressure drop that you would see when the gas valve opens? I'm curious, are we talking about I'm assuming he's talking about Inlet pressure? like yeah, he's saying he's saying if you're watching the inlet pressure and the valve opens, would your Inlet pressure change should your Inlet pressure change significantly I mean obviously we know that it shouldn't drop below the rated Inlet pressure.

We know that. um, but he's saying you know if you see a drop, how much drop is too much drop and I think he's just saying like in terms of gas piping and just ensuring that you have that proper Inlet pressure so it will drop. You want to make sure it's not dropping enough to affect your output pressure. What I like to do is I'll test the furnace, especially if I'm having a problem that it's intermittent like.

sometimes it happens and sometimes it doesn't I'll check the incoming pressure and then I'll go turn on the gas stove I'll start running hot water I'll start making sure other gas appliances are running and at that point, if I see that incoming pressures drop lower than what my output pressure is going to be, then I know that there's an issue with the piping and so at that point for me, uh, where I'm at, that's a plumber issue. So I hand that off to the plumber. I Know that some municipalities allow for the HVAC person to handle the gas sizing thank goodness. I don't have to do that because threading pipe's not a big joy for me, but that's one of the things I like to do is simply run the other appliances I don't do it every single call.

But if I'm having one of those intermittent issues or I think I'm I suspect that's going to be a problem, run those other appliances and then see if your Inlet pressure starts to drop. But really, I'm not too worried about the inlet pressure as long as my outlet pressure stays in the range that I need and again, combustion analysis is keing yeah and also just ensuring that your Inlet pressure stays within the range that's on the data tag, right? I mean it's going to tell you what your designed Inlet pressure is for that Appliance Um, another question here is um and and I and I Know this is kind of a common issue, but that the inducer motor won't let let the condensate run down. Uh, it sounds like we have a situation where the condensate is filling into the inducer motor for some reason. um, causing the Uh causing it to rise on.

Co When this happens, would you see an increase in exhaust pressure? The inducer motor won't let? um Adam uh I am not sure to be honest with you I I've never measured that. Yeah, I haven't either. So I was I Was wondering if maybe you guys had I probably should have. They always say that you should not try to answer a question if you don't already know if you know the answer.

So I broke the I broke the first rule of uh of live streams here I Think it's a great question and I'm going to write this down and I'm going to go find that answer because you know I've never thought about that so thank you for that question. It's a great question. Yeah, that's one of the advantages of having a uh having a smart audience. You know they sometimes ask ask really good things that we haven't haven't me mentioned at all? Um, one of the one of the things that I want to ask you guys um that just came up in the last uh and and I've just recently kind of become aware of this um is the whole uh X protocol from Ahri standard X I think is what they call it um, it is guideline X is what it is um and it is available for free on the HR website.

Um, are you guys familiar with that and uh because it does sort of just talk through how we assess Co problems and specifically when to actually look for crack heed exchangers because the whole cracked heed exchanger thing. whenever we're talking about anything related to furnaces, this isn't 90 plus specific um, but that's a really big heated debate. and their protocol their their. Their guideline basically says you're not even really looking for crack heed exchangers unless you see um CEO in that Supply a uh which in the past was something that I remember being told that that wasn't something that we do but now that is the that is part of that guideline.

I'm not familiar with that that particular guideline but I do know that checking for Co I keep in my mind separate from checking to furnace I do want to check every house for Co but it doesn't mean a lot of people say they see Co and they immediately go to the furnace. So my thing is if I see Co in the system I Want to eliminate the furnace from being an issue but my thought is look at the whole entire house as an envelope. you know where is that Co coming from is it the water heater? Which a lot of times it is and you can simply look for melted plastic around that that water heater and uh, is the the garage attached? Do they have a fireplace? Uh, is there a gas stove vending outside? I even had one house where they were extremely heavy smokers and I was having like six parts from million Co just from the the cigarette smoke I eliminated everything else and that was the issue. So I like to look at Co issues separate from just the heat exchanger because they get a bad WP on that.

But yeah, definitely want to check the heat exchanger. but I'm not only focused on just that, that's a good point. I Uh posted I'm not sure if this is what you were talking about Brian but I posted a link to the Ahri uh furnace heat exchanger inspection sheet in the chat. Yeah, I Also posted the actual link straight to the HRI site so people can look at that.

But basically and I'll just I'll just cover it really quickly because I think it's there's a lot of good here whether or not people practice it every time or not. But you know. Number one: look for: PL Flame disturbances. Um, number two.

uh, let me pull it up here. Number two: measure Co levels in the Airstream So they're saying look at it in the return in the supply. um, uh, measure Co levels in the flu pipe making sure that uh and and their standard is below 200 PPM A lot of the standards say below 400, but like Jim Bergman said, you can actually generally get below 100 PPM in the flu, verify proper installation and disassemble uh as needed and verify heat exchanger only if um, you have situations where uh, uh, where you're showing that uh, increased Co in your supply duct in comparison to your return. um, but I think kind of going back to what Tai was saying I think it's really critical that we're using our personal protective uh Co monitors throughout the entire process when we're in the structure, when we're in the mechanical room, and we're generally going to have a pretty good sense if we're seeing some coo there.

Whether or not we have a significant issue like that, nobody else is talking. for some reason. what happened? Break everyone just. you're on point.

You had it, You covered it. That's reading the coms. Yeah, I was reading comments too. I can't multitask? Yeah, um yeah.

I UND I Understood the guidance from from the from the HRI as saying you measure the you measure it in the in the you know ambient H like in the house Supply versus return and then you also check check it in the flu and if it's over 200 in the flu then then you also start to look for something so not so. That was kind of how I read it Brian was not just in the house, but also if you check it in the flu and it's over 200, then yes, you are correct and you did. No, you did read it correctly I was the one who, uh, read it correctly because what what the note basically says is uh and and it's really fun reading live on a live stream here, but it says um, but it says here uh that make corrections as needed than recheck Co in the flu gas sample. If the Co is still at 2 PPM or higher in the flu gas, that's when you proceed to section 4.5 But also when you're when you're also seeing um SE levels in the Uh in the supply, Airstream then it's also giving you a guideline of kind of what to do next um, and uh and going from there.

So it's um. basically they're saying whenever you're seeing any of any issues, then that's when you would start to disassemble and look more carefully inspect for for leaks. Anyway, Regardless, it's a good standard. It's got some good stuff in there and I know it's 200 parts per million is the limit, but that's pretty freaking.

High You know, like even a 100 I would say is pretty high I Think it's pretty easy to get combustion down below 50, sometimes even below 20 parts per million anybody? No. I I Agree I Think that the combustion analysis its own topic I Think it's it's not done enough I compare combustion Al like superheat and sub cooling I Think it's so important and people think it's this new thing. but my old equipment actually have the chemicals. We had the mix with it which was toxic and bad.

but you actually mix these chemicals together. do your combustion analysis. You had these math charts so now we have these really cool instruments that we can plug in and we can get these numbers for us on the fly. So if if don't be afraid of it, like start learning it, start practicing it.

and then the more you hear about it, the more classes. There's stuff that's free. There's stuff that's paid, but the more that you hear, the easier it comes comes to you and that's going to make a huge difference. And then you start to be able to read these numbers.

You start seeing things that are out of a line and you start thinking oh, that's not normal and you go to groups and start asking questions and you you learn. So Flu Gas Co is different than House Co So want to make sure that the audience knows there's a difference when you're talking about the carbon monoxide and the flu pipe, which is an allowable amount versus we really don't want any in the house because it builds up in your body in your bloodstream over time. And while we're talking about that, let's go ahead and bring up just quickly: Low-level carbon monoxide alarms go out. look up the difference, make sure you have yourself a personal low-level Co Monitor And then instead of just putting in an alarm in somebody's house thinking you're protecting people, look at low-level monitors.

Especially if you have elderly people or young people because that carbon dioxide builds up in the lungs or builds up in the bloodstream. And if you look at an alarm, then the ratings in those are incredibly high. It's like, oh, it sounds for 30 part million after like 30 days, you know, and that's building up in your bloodstream. So just you know I challenge everybody to start looking at that and it's a big.

It's a lot to take in. There's a lot of science that goes into that, but it just simply starts giving you time to notice. Hey, this isn't a great condition ahead of time. I even had it this uh, two summers ago.

went off while I was working in a walk-in cooler. I had it with me all the time started going off. somebody closed the door. while I was brazing inside, the alarm went off.

not told me that there was an issue and um, that was the middle of summary. Like, who would have thought that would have been an issue. So I can't recommend that enough. One of the things that um, you see a lot and again, this isn't necessarily specifically to 90% but where people will, um, they they'll assume that a pressure switch is failing or failed.

Uh, when? actually it's something else. One of the more common things that we've talked about. talk about that just a little bit. like the testing of pressure switches uh, and ensuring that you know we're not just swapping apart basically.

So yeah, pressure switches are are pretty cool. It's just a it's just a little diaphragm inside and if you have a pressure difference between one side and the other, the 80% usually had only one tube on it. So it's super simple. and 90% lot of times have two tubes because they're measuring between two locations, is just measuring the pressure difference between two locations and it's a cool little part.

if the pressure exceeds. uh, whatever it its set point is that it closes contacts or opens a contact. So a lot of people get you know, overwhelmed because they see all these wires and switches in there. But if you break, come down, look at it.

The wiring schematic. See what? when does it open, when does it close and then use some kind of a instrumentation to see is it getting that pressure? So if it's supposed to close at three inches of water column first, Am I getting 3 inches of water column to that, and if I'm not getting 3 in of water column, well I don't need to look at my pressure switch. Why am I not getting that? It's just like my fuel gauge shows empty. Is there gas in the car or not? I Don't just blame the gauge.

So we start looking at what's happening. So having some kind of instrumentation I know. Back in my day we had the the Magna Helix was keying and now we have the digital stuff that either way hook it up and see what you're getting. What is it pulling down to and you''ll be surprised.

It doesn't mean if there's some big scary problem a lot of times, just that hose will have a crack in it or there's just a little bit of rust or a little bit of debris or condensation in that hose. And by either cleaning that hose out or replacing the hose, you can a lot of times solve the problem. and then if it is in that heat exchanger and you're not getting it, uh, you you can start investigating more. Start opening up the drains and seeing what else is causing it.

so don't be afraid of the pressure switch, start going through and seeing what it does. and when you're doing other maintenance, check them when they're good. So that way when you have one that's bad, you can see the difference. Yeah and uh yeah.

Tim Rob Just stole my thunder here because I was just I was literally just going to mention this and I don't remember the model I'm a really really really bad marketer here. Uh, but I have the field piece uh, monometer that actually has a pump in it so that you can actually actually test the pressure switch by actually applying pressure to it. which is really nice if you're suspecting that maybe there's some sort of intermittent problem or maybe it's not making or breaking at the exactly right level. If you actually look on the switches, it will tell you um, where where the make and break point is for those switches, which is really, really handy.

and again, that's more kind of. It's nerd stuff. It's not really necessary, but it is. It is a lot of fun, Just just don't suck on them.

I'll see a lot of people like to to put it in M They suck on it and the problem is you can have too much of a pressure difference and it can actually damage that diaphragm inside. So you can have a good pressure switch and by you know, sucking or blowing on it. Whatever you call it, it's it's going to damage it. So make sure you're actually using instrumentation and checking it.

And like that field piece meter. Actually, you can control what you're uh, how much pressure you're using on it to see when it opens and closes. But yeah, don't don't over pressurize you don't want to damage them. One of the other questions that was asked and I and I'm having a hard time finding it here, but the the basic question was um oh, here it is about the uh, actual normal combustion analysis readings and and the question is about whether you see something different on on High versus low stage I'm not aware that that is the case to me.

I Would think that they would be pretty similar, but you guys obviously have done a lot more of this. Do you see that where you get, uh, a big change in readings on High versus low stage I think normally I would say that you wouldn't expect to see a big variation whatsoever between first and second stage. I Usually check on high stage just because I don't want to have to go back have the thermostat cycle off on me. But um, when I do check low stage, especially for gas pressure, it's it's been fairly the same.

I mean that they design it so it's pulling the right amount of air as the gas pressure is lower. It's also pulling less air through that inducer fan motor. so it's it's balancing out. and that's why we have the pressure switches for each stage.

So as you have a low stage, your inducer fan motor slows down so you're you're keeping the air fuel mixture the same and then you have the pressure switch that confirms terms that were moving that right amount of air through there. So um, it's it's really going to be pretty close to the same. I'm going to go ahead and plug quickly um, the article that Emily put together. Uh, and by the way, for those of you who haven't noticed, uh Emily is like, incredible how quickly she produces this stuff.

She works on our team as our technical writer and she did a sort of a summary of the last live stream that we did on combustion analysis and in that we actually share a uh a table from the ACU Tools combustion Quick Start guide which is one of the kind of the simplest, um, kind of quick tables uh, that you can look at and it actually talks through the entire process. but again, the most one of the most critical things you're measuring uh is in the Uh is in the Flu and because it's been mentioned a couple times depending on the appliance, um, there's sort of this unacceptable uh level. And we're talking about 400 PPM Co airfree, which is where you kind of recalculate so that you're not just uh, uh, you're not just taking into account excess air dilution and and thinking that you're okay because you're diluting a lot with excess air. Um, that's that sort of worst case scenario.

A lot of people have gone down and said 200 PPM But back to what Adam said. you can generally get well below 100 and that really should be our goal and we pretty much have consensus about that nowadays that, um, that we can achieve below 100 PPM in the flu and that should be um, what we're shooting to to try to achieve. Yeah, so we mostly do 80s here in Dallas and I just have like a screenshot of what the normal combustion readings are for an 80% furnace. so that I have something to reference.

um and I think that's from the I think that's from ACU tools. So yeah, that's that. That's that Blue Flame guide and you can still. Even though Blue Flame I don't think is really, um, active on the market anymore, that guide is still out there and it really is a great.

It's a great guide on combustion, but again, that's all available on the most recent Tech tip if you want to if you want to look that up. The name of the tech tip is practical uses of combustion analysis. So Ty I wanted to ask you can we talk a little bit about the importance of properly grounding a a 90% furnace. Yeah, I mean it.

They sure they absolutely have to be grounded, especially because we're using flame rectification. So it's going to actually sense uh, that flame signal. the electricity is actually flowing through the gas through the flame closing the switch. That's why you only have one wire in that flame sensor so it's having a pulsating.

DC F DC signal back to the control board as well as the micro amps. So if your if your polarity is backwards uh or it's not grounded correctly, you're going to have an issue with that flame rectification. I've even seen people try to run it on an extension cord and they cut that little grounding rod off of there the grounding prod prong and uh, it doesn't work right and so that grounding is essential for the operation of that 80% furnace, especially for the flame sensing. I've had them before where it ran fine in air conditioning and he said, well, now it doesn't work in Heating and it's almost always a grounding issue.

So making sure it's grounded from the burner set, to the uh, the cabinet, from the cabinet, to the board, and also to the the plug on the furnace. now in. Texas A lot of times we had just the the pigtail that plugs into the wall. In other states, it's obviously not allowed, but either way, whether it's a switch that's hardwired or if it's actually a plug hooked up I See those ground issues all the time.

So pull that plug apart, inspect it. Um, and you'll see a lot of times it's corroded, it's cracked, it's uh, it's broken, It's not a good connection, or sometimes it was never grounded. The old standing pilot didn't care if it had a ground or not. They put in that new furnace and hey, this isn't working.

Can you come fix it and it's a grounding issue? Um so I have a question for for for Ty and Adam Just what are some? Maybe some tools or uh, maybe some parts that you would keep on the truck specifically for 90% furnaces? Are you like? Are you keeping like some some extra rubber couplings? Um, you know what? What are some good things to have? Uh, you know for you for for service number One thing you need to have, you're most important is your phone. You need to be able to get the installation manual and service manual for that equipment and you'll be surprised. Like how many times somebody will call me for tech support. I Get the model and seal number I Pull up the service manual for it and it has a Diagnostics chart that goes through step by step with yes or no what's happening and I can solve the problem for them.

The second thing is second most important tool is you're going to need some way to measure pressure. You're going to need to check those pressure switches. So whether it's the filled piece tool or an Old School Magna Helix Whatever you're using, you got to know what the pressure is and some way of checking airf flow. whether you're using it the mathematical way or the new true flow grid which is super awesome.

Like whatever doing, being able to know how much air flow. Those are your big things and also a level to know uh, which way your drain is pitching so and then your eyes. You know being able to check stuff it's overwhelming when you see something that's new and people come out time. I Got this furnishes all these parts of where.

Let's just start with the basics and you start with those Basics and next thing you know it's not so scary anymore. Uh so how would you check it the old math way as you as you said ah well. they have uh like had with electric furnaces, we could simply do the temperature rise with the gas furnace. We have to know what our input is and then if it's whatever percentage is so it's a 95% furnace.

We do that with 95% and it it's We start talking about numbers and math. I We're going to lose a temperature rise and an understanding or blower chart assuming it's clean and it's the original blower. The blower charts will work um most of the time I I The true flow grids is so fast it's like I was like I'm never gonna pay that for it. Then you start using it.

you're like oh my gosh this I should have bought this first. but yeah checking airf flow is it's um it was hard before. Now we have it. It's expensive but it's You know it's easy now with the with the proper tools.

but yeah checking air flow is I Get people say the airf flow is good. how many CF like oh no it feels good like well that's that's cool but uh I need a number something to work with? yeah and on a furnace I mean you do have the temperature rise um which is also I mean it's not. It's not measuring air flow, but it's it's something. Um, so even if you just start there um Adam has uh Adam has the Adam has the uh official True Flow grid sticker I mean it's an amazing tool, it really is and uh, not not no sponsor relationship there, just knowing and using what they've built.

The other great thing about the also get the Dg8, which is, uh, a really incredible monometer that you can do a lot of great things with as well. So there's a lot a lot of good that can be done with that. and and and especially with furnaces where um, setting airf flow can be a little trickier in some cases because you have such a big variation between heating and cooling air flow. Um, a lot of people who are used to heat pumps like me when you start working on furnaces, it's like man, this is.

this is quite a bit trickier. um than heat pumps because in heat pumps, um, it's kind of all built into one thing and it's manufactured into the cabinet where with the furnace you have a separate coil and some variation there. so setting it can be can be a little bit more tricky. um I Did want to mention quickly before we because we're coming up on the end here.

If anybody has any questions, feel free to throw them in the chat before we wrap up. But the uh, the ubiquitous question about cleaning flame rods? Um, do we clean? Do we replace? Uh, where are cases where they need cleaning? Uh, you know, is there some magic to them? Uh, any comments on that? Well I I clean them I do not use sandpaper I use um, you know, like either like a still wool or a type of Brill pad U Gosh, it's G to get people so worked up. but I clean most of the time I find out that it works well. but I've also seen where people you know damaged them with, you know, grinding them down with I've even seen somebody use a grinder to to grind one down I sit where the combustion analysis wasn't working right and uh, they actually had.

they were overfiring, it, actually melted or burnt part of the flame. Rod So yeah, there's times we're gonna have to change them. and now with the universal kits like it's you know it's a lot easier. but I you know I still clean them and if it's not getting a good flame signal after I clean it, you know I start looking for other problems and that's my opinion.

I usually I usually measure it before I clean it. Um, so that's a I try not to clean it if it doesn't need to be cleaned. um and I kind of use just like a rule of thumb I Know different manufacturers have different numbers, but like you know, I I would expect to see a reading of three. um if it's if you have a flame s, you know three or above.

If it's if it's good, good working order. Um, one and a half or below is probably GNA have an issue in the near future and you know sometimes you'll see that a rest of up. um, a rusted up burner, the inshot burner on the backside. especially if it's a humid climate pulling in that moisture.

if that is Rusted up right there. that'll give you an improper flame because I had people put in New Flame sensors and they say hey I'm still getting a poor flame signal and uh, it's will make sure that grounding and you know taking um, a wire brush and cleaning up those those burners make a huge difference. That's a good point on the burners too, because if you have dirty burners, rusted burners on the face will CA cause uh, carbon mon oide and the combustion. Yeah, it's worth mentioning.

Again, like when you're looking at microamps on your flame on your flame. Rod Um, there's there's several components there, right? There's the flame Rod itself, There's the connecting wire and connector. and then there's the actual grounding of the not just the furnace, but the burner assembly itself. We work on a lot of pool heaters and uh, if you've seen my recent videos on that, we talk about this like the entire burner tray will be like corroded and falling apart and we're like, like, well, why isn't it? You know, why isn't the flame Rod working.

It's like because the whole thing's ungrounded at this point. So um, you have to think about that. A lot of this stuff is very obvious. One thing that a lot of people also point out is, um, that you do tend to see, uh, a lot more issues with LP So when you have LP for whatever reason, flame rods tend to foul more quickly and potentially cases of, um, certain chemicals in the combustion.

Air Zone So of course, on 90s if you're bring it in from outside, you're probably not going to have that problem. But there's still a lot of people who don't bring it in from outside even on a 90. and certain chemicals, laundry chemicals, that sort of thing in the combustion Air Zone can cause some issues. Have have you guys ever run into that? Jim Bergman Talks about that a little bit.

Uh, from time to time? Absolutely. Um I've I have all the time where I see them install a 90% furnace and then they just have the air intake right there. especially near a laundry room. Oh my gosh, it has has a lot of problems I Understand in the North West there's a condition called Hor Frost that uh, it's a unique condition and they they like to have their vent pipe open.

but what they found is if they cut the vent pipe where it's coming down and then they have the pipe next to it allows enough heat coming in that'll still work correctly. but you definitely want to be bringing that air from outside as as much as possible because I've had laundry detergent things like that uh mess up the heat exchanger cause a lot of soot built up in there as well as uh, we had one that was in a garage and they had a lot of chemicals and they were refinishing stuff whether I think it was some type of wood shop and whatever chemical they were using was causing damage on the heat exchanger and the SE readings are off the wall. So yeah, 90% solves a lot of that because you're bringing that air from outside in to whereas an 80% furnace it's it's destined. We've actually solved problems that had 80% furnaces.

We replaced it with a 90 just because it was bringing that air from outside made A and yes, bleach. Ray You mentioned bleach. but yeah. Bleach.

Kitty litter. A Kitty litter. Interesting, all right. So I'm about to wrap up here guys.

Any other final things that you want to make sure that we cover before we, uh, before we start to close? Don't be afraid of it. Start, Uh, start working with it. Looking at it, it's going to be different. It's going to be harder to get to some of the stuff than an 80.

But don't be afraid of it. It's it's here. Whether you like it or not, it's here. Learn about it.

Move forward. Yeah, and we've had done so much content on this recently. Obviously you have to have the right tools. You have to have that personal protective Co monitor.

You have to have a combustible gas leak detector. You have to have a good quality monometer. Um, you should have a combustion analyzer. Um, you need to.

you need to have. You should be suggesting low-level Co monitoring to your clients in their homes. Um, so there's some basic things that should just be part of your process. but then from there, once you have those baselines, you should have the confidence to get in there and start working.

Um, one thing that I want to just throw up on the screen here because it's I don't We don't have the answer to this I Don't think you guys can comment if you do have the answer to this. Uh, we do know about B vent. We talked about that in the last. um in the last.

uh, live stream where there is the approved manufacturer method for sealing B vent. but on these new um sort of venting systems that we're seeing as as you know becoming more and more common I don't know the answer to this? Do any of you know, it? It depends on your municipality and what they're looking for. Uh, so some placees will allow you to drill a hole, you can tap it and put an actual plug in there. Some people want, some want a an actual brass plug, some allow it just to be a like a type of rubber stopper which I'm not a fan of because I'm worried about that popping out.

uh, but others I've heard of people saying that the inspector wouldn't allow any type of hole put in that vent pipe whatsoever. So under those conditions I don't I don't have an answer I haven't ran into that. so I don't know. Yeah, so the reason I'm putting it up here is because uh, I'm gonna uh as I often do I'm gonna give Emily the chore to reach out to these manufacturers and and see if we can get an official uh answer to this so we can have that for for future content.

Um, the other thing that I want to mention just just briefly. um is that uh, you know we do. A lot of you know this is sponsored content so this is sponsored stuff but white Rogers Copeland does make a lot of really neat Universal parts that I've been working with lately. They igniters their flame rods, their modules, they integrated circuit boards for furnaces, and they do have a lot of really nice features and uh, we've been testing them out.

Obviously I'm n