Hey thanks for watching in this video, jim bergman is speaking at the second annual hvacr symposium here in beautiful claremont florida talking about furnace commissioning. This is one of my very favorite talks that jim gives and he has a lot of excellent insights on furnace commissioning. I know it's long, but it is jim bergman, so i'm sure you'll get a lot out of it. Big thanks to jim all of our sponsors and speakers, especially measure quick and diversitec for sponsoring the event and making it possible, as well as emerson for doing the online virtual presentation.

The reason we have this video is because of the generosity of all of our speakers and sponsors for making it possible again big thanks to jim. If you want to find out more about his excellent tool for diagnostics and commissioning, it's called measure quick go to measurequick.com thanks for watching, probably the uh. The the most important thing - and this is um you know with gas heating - is - is to take your blinders off and become a master of the obvious. I don't know if you guys have ever seen horse blinders before, but the whole idea behind horse blinders is everything's gone in their peripheral vision.

All they see is straight ahead right and that's the whole problem with our industry is everybody looks straight ahead. We've got what we call appliance fixation everybody's fixated on the appliance right and they don't look beyond the box to actually see what's wrong right when somebody says i'm going out to do work on a gas furnace, this is literally what autotexts think think is they're working On a gas furnace - and that's the only thing they see in the basement is the gas furnace, and i was watching dave richardson's seminar a little bit this morning and i'm like yeah. He gets it you're, not just looking at the gas furnace, because everything interacts with everything you know when you're looking at that furnace, it's not just a furnace. It's a it's a system, it's a system and it's tied to a lot of sub-systems in your home right.

I mean, if you look at, that, we got a control system right, we got a thermostat, we got an air distribution system, that's taking the furnace and moving the air through the house. We got our air filtration system, that's filtering! The air. We've got our condensate drain system. We got our indoor equipment, our vending system, our make up air system right.

Then we got components like the heat exchanger on there, the fuel delivery system right, and so, when you, let's start looking at all these subsystems - and you start thinking of gas heating as a system instead of and even the house is the biggest system it interacts with. That's what dave was talking about this morning right when you start looking at that as a system? That's when you're going to really understand how to make gas heating operate safely. You know, and i think it's interesting in our industry when we talk about you, know everybody's always fixated on heat exchanger. You know failures and things like that and it's just like dave was saying: it's not the heat exchanger.

That's really. The issue in in 99 of co poisonings - it's actually that there's the furnace, if, if, if it comes from your furnace at all, which is highly unlikely if it comes from your furnace at all, it's because it's produced by your furnace and there's a path to get It back into your house right and that's what we're talking about here. This is a a classic venting system problem right you can see on there. Those those those rings are are warped up right people look at this stuff, all the time, there's guys looking to go.

Wow, those rings must be defective right, can't believe the manufacturer didn't make them high temperature rings right now, it's hard to figure out why it's happening on the cold side too, and it's like it's a venting. It's a flue gas spillage, that's causing that thing to lurk and it's like just be a master of the obvious right, don't be fixated on the furnace, because the furnace is not like the problem. It's everything that's attached to the furnace that you got to look at. It's that when we always talk about you know the 80 plus furnace ago 80.

Pluses are great because there's no draft to it anymore. Well, it's hooked to the draft hood on the hot water tank and you got to look at that. You got to consider everything. That's attached to it right so check in for sizing when we're looking at the vent system - and this is this - is crazy stuff, because we don't think about it all the time too many guys in this industry they get so fixated on the appliance that they don't Look at things like the vending system.

Is it the proper size? Is it the proper pitch? Is it the properly supported? You know, pvc pipe? Is it supported every four foot? Does it have a proper termination bill spun and i went out? Oh gosh, it's got to be five or six years ago now, on a co poisoning. We got called in as expert witnesses for a company up in cleveland. The lady got co poisoning she got brain damage right. They pulled out a comfort maker furnace because the comfort maker furnace had a crack in it right, maybe a small crack and they said it was making co.

So they tagged it shut it off. They come out and they put a brand new linux furnace in there and the linux furnace when they tested it. The technician actually wrote down them, it was not working properly and i think it was producing high co and he they used the standard of care. What's called a standard of care and we're going to talk about this a little bit in our industry, but there there are documentations in our industry of what would a would a reasonable person do under that circum under that circumstance right.

So if you ever get called on the court, you do have something happen to you, they're, going to look and say: what's the standard of care for your industry, if it's making 17 000 parts of 17 000 parts per million of co, what should the technician do? Right and did you do that right, it's the same thing. We do to doctors right, it's it's called mouth. This is what we're trying to avoid. Is malpractice? Okay, so are you looking at these things when you're when you're, when you're there and what bill? What we found was the technician did not shut down that furnace, so he said: hey cracked heat, exchanger freaking out got to shut it off right, sell our new furnace puts the new furnace in making high co, doesn't shut it off right now the installer came out.

They went from a single stage to a two stage: furnace okay, lennox, in their directions. They have very specific directions. They had a four inch flue pipe that knew new one had a four inch flue pipe old one had a four inch four plate perfect. I don't have to spend any time changing the flue pipe cuts it off hooks it up, re-pipes it in walks away on the end of the flue pipe.

It was supposed to neck down from three inch to two inch. Anybody know why we do that exhaust accelerator right so now the furnace is making it's running and it's a two-stage furnace. Now it's running in first stage: it's making 17 000 parts per million of co, but hey it's all exhausting outside, but it has no accelerator on there. So guess what it's doing! It's pooling by the house right now.

You guys have all seen these fireplaces people build under their homes. You know they and they extend this the floor joists out, so they can support the fireplace and then they put you know soffit, underneath there ventilate it soften the insulate and all kinds of stuff. Well, that extension of of underneath the fireplace was actually now a pathway for that co to go up to that ventilated, soffit and back into her house now. The other thing they didn't think about was what steve rogers was just talking about, which was zonal, depressurization right you're, talking about having a micro manometer in there to actually see what's happening in the basement.

So bottom of the furnace has a open base pan on it. That nobody's screwed down and they have a pretty restrictive filter. So when the furnace comes on the base pan is lifting up because nobody screwed the base pan down. So now we're depressurizing the basement.

So now now i've got a furnace. That's making co, i'm not exhausting the co away from the house. I've got a path back into the house and literally all we did was take and - and you could literally take on this furnace and take a theatrical, fogger and shoot it out. The house, you know through the vent motor and you could watch it, pull right back in right into the house.

Uh fill in her home with co, and this lady's got permanent brain damage. Okay, now you got to ask yourself: is that the kind of thing that you want to happen? These don't happen very often, but they do happen and it's because the technician focused on the furnace instead of focusing on the system right, the odds of a co poisoning are about the odds of an electrocution right. So i don't think that they're going to happen. In fact, your car in your garage is more likely to give you a co poison or your fireplace running in your house and then smoldering out is more likely to give you co poisoning in your furnaces, but it can happen and when it does happen, it's usually Catastrophic we've had probably how many do you think we had about 12 14 co deaths in this this year, right so yeah.

So when we do, we do have them, but on an ice storm believe it or not. People are killed by their generators right. They lose their power, they bring a generator into home they're, using charcoal to try and keep warm right. It's not the furnace, that's killing people, but it can happen in this case.

Believe it or not. It was an improperly installed condensate trap right. The condensate disposal system. Well, how can that happen? Well, air sucking backwards up.

The condensate drain was not allowing the secondary heat exchanger to drain out, as it filled with water right as a secondary filled with water. It couldn't bring secondary air in for complete combustion bill stone, and i sat and watched this thing run. It would fire up, and jim davis will tell you he was probably the first one to be aware of. This is rising.

Co right he's always real big on rising co, and i just thought he was a little flaky for a few years until i saw rising co for the first time right and what will happen is it'll start off at one or two parts per million, and it's Like a literally like it goes up a straight wall, it'll hit 30 40 50 and then it goes to you know, maybe 400, and when it hits somewhere around 600, it might go to 14 000 or 17 000 parts per million. Because all of a sudden, you get to a point where there's not enough air to support combustion, we're talking parts per million here right i mean so as soon as you don't have enough air to support combustion. Co goes up to the roof, so that furnace, when the technician where it would run fine for about 20 minutes until it got enough water in a secondary heat exchanger to actually start backing up once it started backing up, then it started making co. Now you got a two-stage furnace guess what i have a two-stage furnace in my house.

It ran 320 hours last month, which is about 10 hours a day, okay, 30 days about 10 hours a day, 300 some hours. That's why that furnace was such a was such a death trap, because it's making high co and it's running an extremely long time, because it and you know all those things coming together what's causing the problem, you know we all time we walk into the furnace room And uh dave was talking again about carbonic, acid, and - and this is also these are different acids. These are from dryer chemicals and things that go happen when you see corrosion and pitting of heat exchangers like that, that's not because the furnace is a piece of crap right carrier doesn't make crappy heating. I see this all the time these carrier heat exchangers are horrible.

No, the environments that we put them in are horrible right. So when you have that bounce dryer sheets in there, you have four paints, you have solvents in there. You have bleach in there right. Look at this is a classic.

This is a oops. I shuddered myself here this is a classic laundry room right again goes back to what dave was saying this morning right if you, everyone's cfm in you've, got to have a cfm out, i'm going to steal that from you for this presentation all right - and here we Got a dryer, that's definitely exhausting cf amount and we have a wonderful two-pipe furnace that they did a one-pipe installation in right. Why would you do this? I mean we got a perfect one, cfm1 cfm out and it's it's engineer solution and somebody decides to save seven dollars and fittings and another twenty dollars in pipe and maybe another twenty dollars in labor to not install that second line on that furnace and they're pulling In we're in a laundry room, all those chemicals all that bleach all that stuff is now getting pulled in the combustion air and that's what's going to cause problems in the furnace right again. Looking at the venting system, i went out just this just this year.

We see this a lot right, vent systems rotting from the inside out. This means that you have chemicals, you have acids in your flue pipe that are eating and attacking the flu pipe and eating it from the inside out and this you would never see this unless you walked around the back side of the vent system against the wall. Where it was touching a brick wall to see that there was not only a cold spot where it caused condensation, but then also corrosion and people. Look at this stuff, all the time and they're so fixated on the furnace that they forget to actually look at the appliance above right.

I'm in a a at an installation a couple months ago and we're looking at everything and b vent has one inch clearance right. I'm standing and looking well there's a there's, a big enough hole there for one inch clearance, but when the roofer roofed the pipe, he pulled it against the side. And now the clearance is gone right and this becomes again a master of the obvious. Here's a lovely chimney liner right.

Did you guys know that part of the fuel and gas code? I think it's appendix maybe appendix a requires you to actually disconnect the venting system and look inside the venting system to see if the vetting system is intact. There was a pile of aluminum that you could have filled the shop back with from this chimney liner. It was completely gone completely disintegrated because again acids uh, uninsulated liner right. This is very popular in ohio where we put liners and we don't insulate them right.

These things happen and you got to become again a master of the obvious right vent terminations. I cannot stress enough to consult the manufacturer's vending tables on sizing number of elbows the length right. It's pretty cool we're talking about the large vacuum hoses yesterday, when you go to a three inch when you go to a three inch line is to reduce friction right. So, as you go to a longer vent system, you have to upsize the pipe.

So you have less friction in the system, but you may have to neck it back down again, so you minimize all the friction for the long length but then neck it down again to get the exhaust gases away from your home right. This is a induced draft heat exchanger inspection. It was published by ahri, okay first, i thought this was you know i looked at the standard. I thought it was a pretty crappy standard, but the more i thought about it.

The more i thought well. This is actually very significant to our industry, because it's one of the only standards for testing heat exchangers back in 1989, we had the five part or the four four part heat exchanger inspection, which was a flame disturbance. It was uh visual inspection for cracks. It was uh using a chemical method to um to uh check for seo.

You remember what the fifth one was. Fourth, one was dave, tracer gas method. Yes, since it yeah and it was very expensive and it was also um. It was also very inaccurate because it picked up all almost all heat exchangers leak: okay, they're, not hermetically sealed if you were to take a heat exchanger and fill it with water.

It's gon na it's gon na drip water out and that's that's just part of the way it's designed. In fact, when you guys are, are picking up cracks on a furnace and you swap out the front and you're you're so fixated on the crack you're completely fixated on the wrong thing. What you need to be fixated on is: why did it crack? Not that it cracked, because when you're going to take that new furnace and you're going to put it in on the existing duct system, with that existing venting with those existing registers and that and it's and you're going to use the existing size right, you go. Oh, it's 100 000.

Let's just put another hundred thousand back in. It, worked fine for the last four months right and you change it out again: you're not addressing the root cause. Now. What was interesting is this new ahri heat exchanger inspection.

This is, what's called the standard of care. This is a document you need to be very aware of, because if you get involved in a co poisoning somebody's going to come back like a smart guy like me or bill spohn right sorry to be kind or conceited - i don't mean to be, but then i'm The guy they're going to call - and i'm going to just say: hey - are you aware of the uh the 2008 guideline? I think it's 2000.. They don't have the glasses on here for for reduced draft heat, exchanger inspection and you're going to look at me, you're going to go uh. No, i'm going to say really.

So how did you test the heat exchanger right or how did you test the system? Because this is a guideline for all furnaces that have induced draft appliances, so you're going to be expected to did you watch for flame disturbances right? Did you measure co in the airstream, both supply and return? Did you measure co in the stack? Did you verify the installation was correct right? Did you inspect the? Did you get the owner's manual out and look at the venting requirements for that appliance? Did you physically inspect the heat exchanger? If all these other systems failed? Okay - and this is this - is extremely important for 4.1 of that guide. Look for flame disturbances, 4.2 measure, co levels, 4.3 measure seal levels in the stack 4.4 verify proper installation, 4.5 visually inspect the heat exchanger by removal. If you can't see the the damage from the inside, you can just go right online and pull this inspection down right. So, if you're working in this industry today, you can do it on a cheap, like nate, does with a multimeter or you can be a real man and buy a combustion analyzer and and actually have much more fun in this industry because who doesn't want to play With fire right, it's it's it's much better than electricity is right.

Nate yeah she's knocking his head, so i don't number one you know uh. I do a lot of work with accutools and i questions i don't care what combustion analyzer you buy. Just please. If you work on gas appliances own one, because now you're aware that there's a standard that you really need to have one all analyzers, whether you're talking testo bacharach, blue flame, they're, they're, all this they're, all basically the same okay, they're gon na they're gon na have Three cells in them they have two cells: three, if you're in california, they have an o2 cell, a co cell and they have a draft gauge uh built in uh, and they have temperature right.

So there's there's four measurements: a combustion analyzer makes they all basically do exactly the same thing and what they do is they keep you out of harm's way and to keep your customers out of harm's way. Okay, you've got to have one if you're going to work on gas appliances. The the first thing you want to do with a the combustion analyzer, your ambient seal and people don't realize this is not just for combustion analysis. First of all, okay, that's what i, when i thought, when i first bought this tool, i'm thinking! Oh, it's! Just a combustion analyzer! It's got one function! It's measure combustion.

It's actually got an ambient co testing. So you can walk the home. You can test the ambient air for co, which is something that you should do before you before. You do any testing it's got in.

You can use it for setting your incoming gas pressure. You can use it for setting your manifold pressure. You can use it for doing your temperature rise. You can use it for total external static pressure.

You can use it for pressure drop across filters. You can use it for combustion testing, your furnace, your hot water, your stove, your dryer. You can use it for cavs testing and draft testing in some cases, depending on the on the accuracy and resolution of the manometer. After using the text pneumatometer the it's, i think it's the uh, the eight.

I can't remember the exact model - number dg8, you don't own. One of those i'd highly suggest you look at one of those, because that is one slick instrument, because it constantly auto zeros right when you have a high high accuracy, high resolution manometer they tend to drift. So the one in your combustion analyzer is good for short-term testing um what uh, what what what dave was showing you earlier with the um with dwyer 760 air meters? That's that's the number for that right, yeah, dwyer draft gauge! I think it's they call it! The 760 air meters, the the full name for it, but it's that is probably one of the best visual indicators for continuous measurement of draft uh. I've used one of those things for years.

In fact, i think i met jim davis at a supply house on a moral control in akron and he looks exactly the same today as he did back in 1989. He has not changed exactly the same and am i wrong yeah. He is like dick clark all right, so let's talk a little bit about ambience co testing ambiencio can be checked and recorded with a combustion analyzer. It should be.

I highly recommend you carry a personal co meter with you, whether it's a testo sense it. They will save you from co exposure at some point, i'm not going to say they're going to save your life, but they'll definitely save you from a migraine. Okay, they'll. Definitely save you from a flu-like symptoms, um, they'll, definitely and especially like here in florida, go huh.

Who would need a co tester here? Well guess what i'm? My house that we're in has got a lovely pool, heater right, powered by natural gas pool heaters are notorious for making co, especially when they put them in a small room and attach them to the house, and they have a pathway for getting co into the into The home right, so you you need to make sure no matter what climate zone you're in no matter where you're at i have had co meters go off in my van when i'm driving a van, because i had exhaust leaking into the van and a co meter. You, if here's the whole thing unless you're aware of what the problem is unless you've made a measurement, unless you know you, don't you can't make any corrective action, that's the whole thing that kills me with our industry. Is we have people that don't measure everything you need to measure, so you can at least know when you have a problem all right. Their typical alarm levels are 35 to 50 ppm and a typical stop work is around 75 ppm or higher is is on there.

You want to zero your analyzer in fresh air. Okay, all these analyzers are make a relative measurement. So if we're like in new york city and it's middle of the day, it's going to be six ppm, a ceo in the ambient air. If you were to go to upstate new york, zero, your sienna, co, analyzer and drive down back to new york, uh city you'd be reading six ppm in the air right.

That's a baseline co! What we're concerned about is co above the baseline, so we always need to make sure that we're zeroing the analyzer in fresh air and we test in the ambient air that you're walking around and you're testing about chest level. And you should test on every floor because uh again stack effect in homes. We don't want to just test in the basement next to the furnace and there's there's other possible sources of seal, we'll talk about in a minute. Next thing you want to do.

Is you want to test in the airstream now how many of you guys are staying out here in a in a like a airbnb house and while you're here or staying at home? How many guys have noticed where they put the furnace at you know in the garage right they put them in the garage. Now guess what the garage is a major source of it's, a major source of co people back their cars in their garages. People start their cars in the garages and luckily, here in calif in florida they don't warm them up too often in garages. But if you start your car in the garage and you back out and you close the garage door and we had any wind blowing towards a garage, you can guarantee you've got a garage full of chemicals in there that are going to end up in your furnace.

Through duct leakage and through the return air leakage and the appliance, so you want to make sure you're testing in the airstream you want to test in the supply and test and to return. Okay, you want to test also for co levels in the stack now the the the standard that ahri has in there is 200 ppm or less. We typically strive for 100 ppm or less and there's typically, no reason you actually can't get appliance down to zero. We actually provide excess air to an appliance so that it doesn't produce co.

Okay. Over 100 people under 100 ppm is advisable over 400 ppm. I'd. Advise you to lock the appliance out right.

This is all measured. Steel wear free, so here's uh, because we're because we're in in in florida and all you guys can can understand this. Okay, it's dilution is um. If, if you had your kid pee in the pool right, he had a bottle of pea there and he dumped it into the he had a bottle.

There's there's so many there's so much pee in the bottle right, it's one! It's one! Quart of now we dumped that in the pool the amount of p didn't change. We just diluted it right. Nobody wants to go swimming in that in that pool. Once you dump that pee in there, i guarantee you, nobody will go in the pool and it's the same thing here when we're making a measurement.

We want to know how much p is in the pool right. So that's what seal air free is it's just simply how much p's in the pool. We can tell you exactly because we're taking out the effect of dilution. So if we know how much water is in the pool - and we can measure the the p and ppm, we can tell you, okay, here's the co or the p, here's the pool, p free right and that's what we're trying to do is we're just trying to Take out and take out the effect of dilution right on there.

So when you want to know how much, because, because the furnace, if we, if we just said hey, it's making high co, just keep adding dilution error right, that's what we would do is just keep adding dilution area. It would look like there's less and less and less, but in fact, if we want to apples to apples measurement, we have to make a seo or free characteristics of carbon monoxide. It's obviously colonless odorless tasteless mixes well in the air. It really doesn't stratify.

It does follow convective air currents in there and it's obviously highly poisonous. If we get exposed to it, it's going to get persistent headaches, dizziness fatigue right. You can have long-term damage from that. There are uh uh guidelines for health exposure yeah, so the nine parts per million in the u.s is the maximum eight hour exposure limit.

They wan na see and there's all kinds you can reference on there. But again, when you walk in that, you can't just focus on the furnace. There are so many other sources of co that are not the furnace and that's most likely your true source of co. It's going to be your stove! It's going to be your your gas! Your your gas log fireplace it's going to be your dryer.

It's going to be the auto that's running in the car right, it's going to be the believe it or not. I think the most the the thing that i've seen produce the most co consistently in a home is the hot water tank. The hot water tank is a large enough appliance, it's you know, usually around 40 50 000 btus. It runs a lot depending on your household.

Look at brian or brian orr has 10 kids. I don't think his hot water tank would ever shut off. It's got to run continuously right. How do you have a family that big he's probably got? I mean i'm sure he uses a hot water, a heat pump, hot water tank because he's not a real man.

But but if, if he used a gas hot water heater right, he would he would have a pretty potential large source of flue gas in his house. Right so don't get fixated on the furnace. That's the the big takeaway here draft and spillage right. Most people don't understand what the actual function of the draft hood was.

The draft hood was actually designed to prevent fires right because what? If you ever, anybody ever see the movie backdraft right. So what happens? If we can't, if we can't get air in and the fire starts to smolder, when we open it up, it's going to fly out the front the flame will is going to look for oxygen. It's always going to look for air and the draft hood separates the appliance from the draft. So it goes back to what dave was saying earlier.

What's the most powerful force, it's it's, the convective heat, that's rising up to the appliance and what's cool? Is this process called entrainment, so it's going to pull as the air rises up, it's actually going to pull air in behind it to replace it. It goes back to the one cfm end is one cfm out and what's cool with natural draft is, if they design the appliance perfectly and it it the the the design of the heat exchanger is going to control the airflow through the heat exchanger. At the precise rate that they get the exact fuel and air mixture, in fact, if you look at a lot of natural draft appliances, they'll run around 20 percent excess air. I always thought when i first started this, that the natural draft appliances would be running really really high excess air levels and in fact they typically run very low access air levels because they can so carefully control the draft.

So it's the design here is it separates. If you look at that, drawing i have up there, it physically is separating the appliance from the draft and it keeps the burner. It keeps the the the the heat exchanger, the air, from being drawn too quickly through the fire box, because it's physically separated, if you've ever ever, bought a straw at sonic right and you go to drink your shake and it's got a little crack in it. And you go and you can't get anything up the straw, because air takes the path and least resistance.

So it's going to go through the crack in the straw much easier than it's going to pull through the to the heat exchanger. When we separate the appliance from the draft right, that's what's going to happen. So it's going to pull in the air at exactly the right rate as the flue gases rise to the heat exchanger and it's going to you're going to get the the amount of primary and secondary primary air always goes through your burner. Secondary air goes around the the heat exchanger package.

We need both and if you were to take, for example - and you put a bird in the flue right and what's going to happen, is we're going to get spillage now? What's cool with this is on a natural draft appliance is if it's burning properly it's just gon na it's gon na emit carbon dioxide, water, vapor and heat right now. The reason that we don't you know you guys think about ohio, we're pretty we're pretty crazy. Almost as bad as kentucky, but not quite we don't marry our cousins so, but we we have non-vented appliances in our homes, so we have space heaters, we put on our front porch and we just burn gas just in the open air. It's really cool right, no venting on them and and people have used them for years.

I think they're starting to we're starting to see fewer and fewer of them. Blue flame heaters, infrared heaters, all kinds of different heaters, and so, as they're burning this gas in here, if it's burning right, all it emits is carbon dioxide, water, vapor and heat, and the reason we don't vent. Large appliances like that in our home is because the tremendous amount of water vapor that they make now in this case here when we, when we block that chimney with a bird in there what's happening, is because that draft hood is separating the appliance from the draft. It's not going to create a fire right.

This is why, if you, if you, if you do, modify a draft hood and you were to cap, it off, you'd need to have a spill switch so that you could shut the appliance off so the fire when the fire comes out the front you're not going To cause a problem, so when we get that spillage in there, it's going to be simply carbon dioxide, water, vapor and heat. Now that's if everything's working correctly in a lot of cases, we also have that unburned fuel right and if we have a recirculation of flue gas. This is where it primarily happens. We're also going to get that that carbon monoxide, but you can have an appliance spilling in your home - i've seen literally appliances spilling in your home for years.

What's crazy is the hot water tank's over here spilling continuously and this guy is going there's a microscopic crack in your heat exchanger, your whole family is going to die and he's tearing out the furnace and putting in the new furnace and he's and he's, and he Didn't cr, he didn't fix a single problem in that home, except for the cracked heat exchanger and he completely fixated on the furnace missed the hot water tank, and this goes back to you've got to think systems when you're when you're. Looking at these appliances or you're gon na create problems, and it goes back to you know - there's been guys. I i bust nate's chops all the time, but he's made me aware of of things on on the on the blower door side in his quest to actually make electric work in homes right. He had to eliminate all of that lovely infiltration air that we get to.

Actually make that thing work yeah, he thought the house it does have to breathe, but there's two things we want to talk about. One is infiltration, one is ventilation and by the way, it's very important understand that difference, but ventilation is controlled with the fan. Infiltration is not right, and so we want to eliminate infiltration because we can't control it and it doesn't always do what we want it to do. Right, that's what dave was saying this morning and but if we always use a fan, we can control it precisely all right.

So the draft hood must establish draft within within five minutes. Now, when you start an appliance, it can have a cold, it can have a cold chimney, but once that is warm once it should, it should stay warm and what we're? I think. One thing that i'd like to clarify is listening to dave's presentation, which i thought was excellent by the way the what we're concerned with is the air has a very low specific heat value. It takes a very small number of btus to take the heat from the from the flue gases and cool them back down and there's two things we want to be concerned with.

The reason we want to have a warm stack is not primarily the draft, but it's more the condensation right. We don't want to. We don't want to condense inside there, but once we get that stack, warm, it's going to tend to stay warm, but there are standards for drafting. It must establish draft within five minutes.

You've got to make sure you're checking all the way across when, whenever you look at a furnace, if it shows any evidence of rust on the draft hood something's wrong, that appliance most likely needs replaced. In fact, today i tell you: if you have a natural draft appliance, it probably needs replaced they're just to a point where we don't need them in homes, anymore, right, induced draft and and 90 plus furnaces with steel combustion are really the way to go. We still have things like boilers that are going to be a natural draft. I'm sure you can still buy them out there, but they're they're things that i would.

I would avoid the um oops i blanked myself again, all right. So will you typically use a wind, pencil or smoke indicator? Look for evidence, rusting danger, spillage right, do not ignore the hot water tank. That's most likely your source of co because the homeowner went down to to a home depot and they bought themselves a hot water tank and they put it in and they torqued the burner when they were putting it in and it's impinging on the bottom. And it's making massive amounts of co um and you got to make sure that you're that you're testing that again same way all the way around the hood.

Whenever you see those melted plugs like i showed an earlier sign, that's not an indication of cheap plugs! That's an indication of spillage right and that needs to be addressed. If you walk in any home, that's got a gas appliance. You need to look at all the appliances in the house when i was a high school teacher. One of the things i used to do is i would i would have my students go out.

I had a. I had a furnace and a hot water tank that were common vented like this right. I give my kids a combustion analyzer, give them everything and hook it all up and being kids. You know they'd measure the draft and it would read them wrong.

It would read positive instead of negative, so they just would fix the problem. Real quick by just putting the hose on the other port, because of course it can't be positive pressure in the stack. It's always negative so to just move the hose over and get a negative reading on their combustion analyzer and they come back and they say that bergman everything's right clocked. The meter got this got this got this right.

This and i said super. Let's come over here. You just killed your customer. What no you just killed your customer.

How could i kill my customer walk over and i had a? I had just had a damper in the flue pipe it just closed off and the top of the hot water tank's wet and it's hot the plugs are melted. I said two two things wrong number: one is you you did not when you, when you got a screw reading on your draft gauge, you didn't take a look and see what was causing that you didn't use a smoke pencil to verify. Is it blowing in or sucking out, right, visual? There is nothing that beats visual inspection use your eyes use your senses. Your instruments will fool you and you have to when you get fooled by your instruments.

Take the next step and do something simple. Like light a lighter in front of the flue pipe and see if there's if those gases are sucking in or sucking out, get a smoke pencil, that's sucking in or sucking out do something simple to verify. What's going on before you dismiss it, we dismiss way too many things. Don't tell me, you guys haven't seen something in your career where you you look at something and it intrigues you but you're so busy with everything else.

You've got to do when you're dispatchers, calling you and everybody else, and you get home at about three o'clock in the morning. You wake up and you start thinking about what was causing that problem right and you're sort of in that twilight of sleep, and you go back to bed and you wonder, you know, did what the hell did you just leave that you should have been that you Should have seen - and it happens to all of us - so you just got ta call you got ta, slow down and and uh make sure you're doing that right. Any questions up to this point by the way, all right so common vetting, is a huge problem. Setting the manifold pressure on an appliance all right, um, one of the things that that uh - and i don't know if i got the slide in order brian - had to ship these to them a week ahead of time.

So hopefully i got this in order here, but setting your manifold pressure is not the key everybody wants to say, i'm going to set it at three and a half inches, there's actually an acceptable range of management. 10 minutes 10 minutes for what you're going to take a break. So all right now i got ta talk fast, all right how much air is required. The key thing is that for every cubic foot of natural gas there's ten foot of air required all right.

Additional five cubic feet of excess air and 15 foot of dilution - air. If you have a draft hood on there, so you need 15 to 30 cubic feet of air. What people don't often tell you is that natural gas comes with different heat contents, so you and they're pretty consistent for your region, but you have to set it for your region, and these are average heat content, meaning the the heat content is going to go up And the heat content is going to go down. If you went to csa labs, they actually track the heat content and it will go from 900 btus to 1050 btus in a day, but the average heat content is x and they tell you the average heat content, because we supply this really cool thing to a Furnace called excess air, so we supply it with enough air that, as the heat content changes, we have enough excess air to assure complete combustion.

The key thing here is that, when you're setting the manifold pressure, there's a range of manifold pressures from about 3.2 to 3.8 inches, now you're going up, never seen that in a manual in my entire life, the manufacturer has 3.5 stamped on there. Well, what you need to do is actually research. Just look at go to carrier's website and research, converting appliance from propane to natural gas and for some odd reason, and there they tell you, there's a range of gas pressures that are acceptable and you want to the meter right. So we're going to and here's what we typically do is i'll set the meter at a at a at three and a half inches of pressure, and then what i'll do is i'll go out and i'll the meter and i'll see if that fuel pressure has to Go up or down to get the fuel pressure correctly, so these charts that you're looking at notices clock the meter chart here.

These charts that you're looking at are all based upon a heat content of a thousand btus per cubic foot of gas. You may be in an area with 950. You may be an area with 10.75 and you're going to have to adjust that and after you get the, if, once you clock the meter, if you're, if you need the fuel pressure below 3.2 or above 3.8 right, then you're going to have to change the orifices. If required, now everybody's going, oh you're modifying the furnace.

Well guess what? If you read the dang directions right it'll tell you right in there that you can change the orifices in the appliance. Now i'm not a big advocate of drilling or for some guys like to drill the orifices they're a little tricky to drill to drill straight, not a big advocate of that and you have to have a what's called a burnishing tool. There's it's a science and some people they they'll do it, but i'm just telling you don't go out the harbor freight and buy a number drill, set and decide you're going to use your hand, drill and try and drill over this ain't going to work. You're going to have problems right and then it's much better to just go to the manufacturer and ask them for the right, orifices and guess what we're in a we're in a place in florida, where these guys have been changing, orifices their entire career.

They convert appliances from natural gas to propane right every single furnace out there you can convert over to propane with a propane kit. There's no reason we can't adjust an orifice on there supplier. This is just a little chart on on on calculating the input based upon different heat contents on there, because you know caleb's going to throw me off the stage, because i talked too long, blah blah blah measure quick. We actually will do this for you.

So when you clock them, you put the fuel pressure in you clock the meter. It'll tell you whether you need to upsize the orifice downsize, the orifice or where you need to set your fuel pressure. It does all the math for you automatically all right. Yes, sir altitude comes into play as far as the um, the primarily your your meter.

There can be, and you do have to de-rate your appliance, because the o2 content drops in the in the air there's two things you got to look at temperature compensated meter. I was going to get confusing myself for just a second which happens periodically my age, so when you're talking about altitude right, what we're talking about is and, and again your your gas appliance - will tell you in the directions that you need to derate it for the Altitude, it's because the density of the air changes every, but one of the most important things people need to understand. Is we don't move cubic feet of air? We move pounds of air, it's all everything we do is mass flow rate, 100 percent mass flow rate. That is one of the most important concepts to understand.

So we're talking about air conditioning right in a cubic foot of airways point: zero, seven, five pounds per cubic foot times; four hundred, that's 30 pounds per minute per ton, so five ton air conditioners moving 150 pounds of air a minute right. So if you could take that air and crush it into a tank, it's 150 pounds when we go up to altitude now and the density drops down that 150 pounds might go to 100 pounds. So now we've got to take that air flow from 400 up to 450 or 575 to get the same amount of air across the across the heat exchanger. And then we also have to de-rate the appliance, because the air densities drop down, because we don't have enough oxygen to support complete combustion and those get into some pretty complex things that you need to talk to your to your manufacturer about.

But this again, when people are get poisoning, five minutes go away all right. So these things, these things are things you that you need to take into account so uh temperature testing right once we get the once we get the the the manifold pressure. The input correct right manifold pressure within the acceptable range. This is one one of the most important steps.

By far is making sure we have the correct airflow across the heat exchanger right now. I always recommend close the supply register and return near the furnace. I do not, i see guys all the time drilling holes in the ductwork and putting the probe above. That is completely the wrong spot to measure your temperature rise, get six to ten feet away from the furnace, where the air has time to turn and mix on there and if you're going a wide branch you may want to use even two supplier probes measure quickly.

Dudes two wireless probes will average the temperature on there because sometimes you'll get convective air currents taking heat one way or the other, and you might have to get a second measurement to get an accurate measurement you want to. You want to be out of line inside the heat exchanger you want to allow that to stabilize so the important thing to remember when we're talking about steady state which jim davis will tell you he's never seen, study state i've seen it right and study. State just means that that and here's what you got to understand is your stack. Temperature is going to continually rise because your return, air temperature is continually rising, so stack temperature is going to never stabilize it's going to creep up as return air temperature creeps up.

What we're looking for is stabilization of the delta t across the heat exchanger right, so when it stabilizes at 40. That's what we consider study state. What jim's always talking about is steady state of combustion and that combustion is always changing, because the dynamics are always changing and nothing's ever stable and he's correct about that. But when it comes to temperature rise, we can actually tell when it's stable worst case.

Draft uh testing on here it's not the furnace. We need to be concerned with it's the dang hot water tank, and you look here. This is my basement. I'm standing there and behind me is a door and when i open up that door, that's right there guess what it covers up.

The hot water tank right and in that room is a dryer. I have like the worst combustion air zone. You can have known demand because i've got a dryer in there. I've got a small room in there.

I had to put provisions for combustion air in there, but it's the hot water tank. That's the the draft, hooded appliance that we have to test. That's the danger in that room: it's not the 90 plus furnace that is vented in and vented out. That's necessarily going to cause the problem in the home combustion testing right then we have the whole combustion guide.

You can do this, but the whole idea behind this is we're getting the correct amount of fuel, the correct amount of air and that's going to give us the optimal combustion on there. This is what we're looking for. You notice that purple line at a stack temperature continuously increasing this is what we're looking for right here right. So the the o2 got stable.

Look at that co. It went down it lit and it went right down to zero. Our efficiency stable, everything's stable. This is what it looks like when we don't have stable combustion, and this is what happens when we have issues in our combustion air zone.

This was actually an apartment building at amha building that an elevator was causing depressurization as it went up. It was acting like a giant plunger in the room when it went all the way to the top floor. It sucked all the air out of the out of the boiler room and as soon as it stuck the air to the boiling room and all of a sudden hit a threshold where it went from zero parts per million to co. Up to, i want to say it's 3 500 ppm right.

This is when you're looking at a combustion, analyzer you're looking at things stable. This is exactly this is the exact reason that nate said he likes pictures instead of data, because when you're looking at a combustion analyzer, it spits so much data that you don't see. The big picture and trending is probably one of the most powerful things we've done on instrumentation in a long time right measure, quick gas, heating. It'll do all these types of things.

For you, then, there's a whole bunch of specific testing of compliance, because i know that caleb's over there with his finger right over the mic, he's just going to shut me off at my at my end of time, i was just informed that lunch food has not Yet arrived, so you feel free to go back there. Are you sure? Yes i'll, let you know i'll yell at you? No there. There is a question going back to the cast testing, though there was a couple of questions online um about what type of manometer you would recommend. People have a lot of the you know the field piece, job link, probes, uh and we we need to probably clarify what type of manometer you would suggest.

Uh tony did an awesome job with the job link probes. They are probably one of the most stable probes that i've seen when it comes to static pressure testing, but it's not the right probe for caz testing. There's two things we need is range and resolution and if you want the proper gauge for that is actually the dg8 or blower door. Dg8 is about a 500 draft gauge right and it's it's expensive, but it constantly re-zeros and it's going to give you the accuracy and the resolution and the repeatability that you need to start solving some of these building science problems.

So that's about the only gauge i mean i would not testo's got. You know, draft gauges built into their into their um into their combustion. Analyzers, blue flame back rack, they're all high accuracy gauges, but they don't take good long term measurements and for a lot of the work that we do, we can't rely on that gauge not to drift enough. Over time.

We've tried pushing the field piece gauges out. An extra decimal place as long as they're kept at a reasonable temperature. You know you don't change. Temperature dramatically, they'll hold the zero and they probably hold zero better than anything out there.

In the market there. By far for a low cost manometer there there's there they got, they got it licked right now. I think they're really good, but it's not a draft gauge any other questions. Caleb nope, not right now, um, i think, there's a question over here.

Yes, sir nate yeah, so well, we don't even measure external static and and there's 28 inches per in there's 28. Is it 28 inches of water column per psi, and anybody know how many pascals per psi it escapes me: 250 pascals yeah, so you're a pascal's about like a net fart right. It's it's a very, very small amount of pressure. Okay.

So if you get a net, you can capture them and you hold them up to your face. You might fill up that's a pascal, roughly okay, so you need a very, very accurate gauge. Well, it's actually again. It goes back to there's three terms that often get confused, there's accuracy, resolution or accuracy, let's say accuracy, resolution and um precision; okay, so we're talking about accuracy, that's an absolute thing, it's how closest to the actual measure.

So it's it's. What it's against our reference! Pascal right is it that's, that's and, and then there's uh resolution was how much, how much change can we resolve and then there's precision, which is: how often can we hit the same spot? So you can be very precise and you can throw at a dartboard.