In this video, david richardson from nci is speaking at the second annual hvacr symposium on the topic of combustion error and specifically, a lot of the myths that technicians believe about combustion air. I know these videos are a little longer, but you will definitely learn something if you watch this video big thanks to david at nci, for allowing us to share this with you on youtube. So here we go david richardson talking about combustion, air myths. Please join me in welcoming david richardson he's a trainer with nci and he loves hvac so give a round of applause to david, hey guys! Good morning i was uh.

I was being social, so sorry about that. Sometimes i i drift - and i start talking so we're going to be talking about combustion air this morning - we're going to talk about some of the myths that go along with those and also how we can debunk those. So let me ask you guys a question. I'm going to address some sometimes they're, uncomfortable things.

It's like you pick up a rock and you find something real nasty and scary underneath it, and instead of addressing you want to throw the rock back down real quick. So when we start talking about combustion, air, i'm gon na bring up some uncomfortable facts, and what i want you to do is don't take my word for it. What i want you to do is go out and measure and test and prove it to yourself. Does that sound like a plan? Is that fair enough, because without measurements all we have are opinions, so i want to make sure you guys are measuring.

So that's my challenge and also my opportunity that i want to present you guys with is to measure this stuff. Now, if you don't test you're, just guessing as john ellis was pointed out yesterday as he was presenting, i was sitting in the back and i see a lot of his slides and i'm going i'm going to talk about that. I'm going to talk about that. Oh crap, i'm going to talk about that.

So what you're going to hear is probably stuff that you already know now. I have the curse of being an sob. Is anybody else in here? In sob i was the son of boss. I was the kid that got stuck pushing on the pull door for about 10 minutes before i finally figure out.

Oh, it goes the wrong way whoops. So i found out that the two types of boss's sons - i was the one that took a little bit of struggle and a little bit of work to learn something. So i present things from a very simplified standpoint. The way that i had to learn them.

I wasn't blessed with the gift of intelligence. It takes me a lot of struggle, a lot of effort to learn something. So what i my effort to do in this presentation is to break things down very simple. So if i insult anybody by breaking it down that simple i want to take, i want to take it now to apologize to you.

So i don't get super detailed on some things, so we find out sometimes in our industry we suffer. What's called the curse of knowledge. We forget where we came from and we talk and you use a whole lot of terms that are familiar with us, but everybody else looks at us just like we. You know we understand what you're saying, because they don't so i will try to break things down at a very simple level now before i do get started guys.

The undertaking that brian orr and his team have put together here is incredible. If you haven't taken an opportunity to thank them, i would encourage you to do that. His staff, the event to put on an event like this is incredible, and if the past year that we've had we needed this, our industry needed this, and my hat's off to brian and his team for putting this together he's got a little gal works for him. Named danielle, i got to tell you i appreciate what she does.

She kept me in line on getting things in on time and gave me the butt kicking that i needed a lot of times to get that information in so daniel wherever you are. Thank you for that, and also the sponsors they've made a significant investment for us to be here to improve ourselves. So with what we're going to talk about this morning, here's my encouragement to you take one thing: take one thing out of this conference and do something with it immediately. This is an investment not only in your time, but also in your education.

Take something and do something with it pick something and set a deadline for what you're going to do with this now onto combustion air. A lot of the things that i'm going to talk about you already know. What i want to do is take the topic and i want to shift it about 90 degrees, and i want you to look at it through a different set of lenses. And then i want you to measure to verify that combustion air is actually working, because air is the key word in combustion, air.

It is air and once you understand the principles of air and then you start to tie it in with the principles combustion, it makes a world of difference and we make a lot of assumptions. Those of you that are in here now. How are you verifying that? There's enough combustion air. What do you use what tools i heard a combustion analyzer, you rock whoever said that, because that's your number one tool, most of our industry, uses a tape measure and a calculator combined with a code book we're going to talk about some assumptions that are made with That and then how you guys can test to see if those assumptions are working or not we're going to see some of the things that go along with that.

So let's get into a preview. What we're going to talk about so i didn't put numbers on this. So i apologize so sometimes it may be a little hard to follow, but just as a preview of what we're going to discuss we're going to talk about some code, references first we're going to talk about where they came from that sort of thing. Some of the actual references i'll give you the code numbers if you want to refer to them - and i referred to this out of the 2015 international fuel gas code.

After that, i want to talk about a research project that some engineers did for ashrae. Some of their findings are very interesting. They should cause all of us to ask why and then to measure to figure out. Why then we're going to talk about what influences combustion air there's a couple of different things, and i'm hoping at this point you guys are going.

Oh, oh yeah, we're getting this now. Not only are we going to talk about the influencers we're going to talk about how they affect the most common combustion air installations that you guys may see beyond that. We're also going to talk about how to diagnose it. The test instruments that you need.

We already kind of let one of them out of the bag with a combustion analyzer there's a couple, others that you're going to need and you'll be able to determine if combustion air is performing, and i'm going to show you how to do that through test results. Now, once you find the combustion air problem, you also need to be able to fix it, so i will cover some very common solutions that you guys can use to fix combustion air problems, because once you understand how air works, once you understand how combustion works, you Can use those principles to fix some of these problems and you're going to find out that the most complicated problems typically boil down to four rules that you can measure, but you have to understand them before you can take advantage of them after we get through with Those solutions, we'll wrap it up with questions and comments, as we continue on now. The word debunk is kind of a funny word you don't you don't hear it a lot. It has to be from the south, because bunk is one of those words.

That means nonsense. Something that's silly and when you look at how we consider combustion air and what we assume happens, it really is bunk. It's nonsense when you look at it through the lens of what happens with airflow the properties, the physics that it follows and we start to go. That's nonsense, so we got to debunk it.

We debunk that through measurements, not opinions, so i'm going to teach you guys in this session how we're going to expose some of the falsehoods of combustion air and then how to fix them as we go through this. How many of you guys are here with your dads? Anybody here is a father-son excellent that rocks he's watching virtually excellent guys. It was an event just like this that changed the course of my career back in early 2000. I was on my way out of the hvac industry i thought about quitting.

I got sick and tired of getting my butt kicked by low price sound familiar. My dad knew i was getting frustrated. I was young enough that i could get out, get it back into college, finish my degree and figure out something else i wanted to do. He knew i was down.

He said why don't you go to this conference with me? We've gone every year. It's called the energy management conference in louisville kentucky at that conference. I met a gentleman named, rob faulk. He introduced me to something called airflow.

My life changed ever since five months after that i met another fella little did i know that he would also change the course of my career. How many of you guys know these fellows up on the screen? You probably know who the guy in the middle is he's the least important, there's two other guys up there that you need to know. Does anybody know these fellas because they are rich in combustion? History, the guy with the cool haircut on the far right hand, side is jim davis, not the guy that draws garfield, but the daddy of modern day combustion testing jim, actually wrote the original books on combustion testing. Jim is the reason that i'm at nci, when i met jim a lot of people, think, oh you just jumped on the bandwagon.

I thought jim was nuts when i first heard what he had to say. I was like he can't be that bad. He made the same challenge to me that i made to you guys, go test. Prove me right or prove me wrong, see what you find, and here i am 20 years later, helping him write this stuff.

Isn't that odd? So jim is the guy that this also all the stuff that i'm going to talk about comes from. None of this is from me it's just stuff that i've done tested, backed up and it's physics, it's stuff that we know now. The other gentleman up there is rudy leatherman he used to be with bacharach. Rudy is the one that said you need to get into jim's.

Class 2020 was a rough year. We lost rudy in a farming accident. Rudy was the guy that his his heart was as big as his laugh guys. You probably all know somebody like that, and that was rude.

He cared about the industry. He wanted to see it get better. We talked about some of the forefathers of our industry. Yesterday, gentlemen, these and ladies, these are some of the forefathers of combustion, so i don't stand up here alone.

I stand on their shoulders, as i present this stuff to you now they asked they influenced me in some major ways and one of the biggest ways was to ask why: why is something acting up? Why is this doing that, and not just to say because, but to be able to measure it? Because if you don't measure, if you don't have the data you're, just somebody else with an opinion? How many times have you gone in for a second opinion, and somebody says: well, my brother's cousin's roommate said this and he did hvac for two weeks and they'll take their opinion, sound, familiar they're, taking it as an opinion. When you measure you change the game, you provide facts, you get data now you have to take that data and you have to translate it into something that makes sense. I'm a firm believer that, once customers understand the words that are coming out of our mouths, they buy based on value if they don't understand the words that are coming out of our mouth, they buy on price, because that's the one thing that they understand. We gripe that customers always pay for the lowest price.

It's because they don't understand this. It's because we are poor communicators. So, as we go through this and we start to translate some of these combustion air things, you start to find these problems for your customers. Don't scare them present the facts, just like a doctor would now, as we continue on with measurements and with data, it's important to understand that you don't want to walk into some place dangerous.

How many of you guys assumed in here that it was safe to breathe the air? That's in this tent all do right. We don't think we're going to come to an hvac event and get co poison. Is anyone in here measuring ambient co? Good some hands went up because a lot of us are out of town number, one poisoning location. Look there, ty brandon, holding up a low level personal monitor, guys that don't ever assume what you're breathing there have been a lot of guys that have been drugged.

Out of mechanical rooms unconscious because they assumed the air that they were breathing that it was safe. Even though we're in an open, tent, there's vehicles running around there's generators, a lot of us are staying in hotels, hotels are the number one most dangerous location for co. Poisoning events, so, as we talk about combustion air, your safety is number one. Your safety comes first, so monitor the places that you go into monitor the air now with space testing.

You need to be aware of this. A lot of guys will go in they'll, say: oh, you've got x amount of co. This is your problem. You cannot pinpoint a co problem with ambient co testing alone.

Ambient co testing tells you that there's a problem. It doesn't tell you where, if you measure co in a return duct or in a supply duct, it tells you that the blower and the equipment is circulating air flow. It doesn't indicate the source, so ambient cos for your personal protection. Now john ellis went over this yesterday in his session, some of the levels that you guys need to be aware of.

Ideally, we should breathe zero parts per million of co depending on the equipment that's inside the building, especially if you're dealing with gas ovens. You may measure some ambient co so at zero to nine parts per million. It's okay to test you're, not in harm's way yet, but you need to find out why. Why is there co inside that space continue to test figure out where it's at it may be? The oven that's been running and you just need ventilation, or there may be a more deeper problem that you need to look into, such as we're going to talk about this morning with combustion air.

Now, as you dig a little bit deeper and you get into 10 to 35, at that point, you need to start squirming a little bit start figuring out. Why zero parts per million is the only acceptable level from vented appliances. You should never have co in the space from a vented piece of equipment, because if you do it's spilling and you guys are going to see, sometimes it can turn from a situation that may not look very bad into something. That is extremely dangerous, like that, and i never believed it when i first went through my first combustion class over 20 years ago, and then i saw it happen i'll share that with you shortly anything over 35.

Anybody in here with the fire department, any fire departments. What do you do over 35 parts per million john test, you're - probably sticking something over your face. Aren't you you've already got it okay, so different fire departments have different different standards. Usually 35 self-contained breathing apparatuses go on so at that point in time you need to start taking action ventilate that space get the air out.

How many guys in here on blower doors, anybody there's a great alternative use for a blower door, ventilate co out of the space clear it out, then you can go back in and test and you need to test each appliance one at a time to figure out Where the problem is at we're going to get into equipment testing here shortly once you find it out, either shut it down and repair it. So you don't turn everything on all at once. You don't want to put yourself in harm's way anything over 70 parts per million. At that point in time you need to leave.

You need to evacuate, don't go in the house, don't be a hero, turn the equipment off open anything that you can turn the gas meter off. If you have to, or the propane tank get the customers out, you may need to call 9-1-1 at this point depending on, if anybody's, showing any types of symptoms or anything, but before you do any type of testing. This is what you need to do, and this isn't guys this isn't just on equipment with fuel fired equipment in it. This isn't on homes that just had gas or oil.

This is any home because if you've got an all-electric home, what are some of the other potential sources that we may have to deal with? That could make this an issue i'll give you a hint everybody drove over here in one cars, guys i'm from central kentucky. We just had a massive ice storm that went through shut off power for a whole lot of people. There were a whole lot of generators running. They are also at the top of the list.

A lot of times we get seal poison. We don't expect it. We go into survival mode. Things happen so make sure that you're monitoring don't get complacent as you walk in and you start to do these tests so there's some health instances that you can look at that are sometimes we mistake, such as allergies.

Chronic fatigue dig deeper whenever you see any of these lists. The most common misdiagnosed symptom of co poisoning is fever. There have been people that have had fevers gone to the doctor, been misdiagnosed sent home. They died that night because they got poisoned again.

So fever is the most misdiagnosed symptom of co poisoning and if you look at the list, if you guys want it, you can email me. My contact information should be available i'll. Send you the whole list, it's like a page long and when you read it you're gon na like describes everybody. I know.

That's me more than like all of us have been poisoned at some point in time. Any smokers in here. It's okay, if you admit it, ceo get! This co actually increases your memory, so hot box, one and you'll be smarter. Now, on the flip side of that flip side of that, how many of you, if you were spoken young, remember the first time you smoked too much! You got real sick failing! You got co poisoned after about four hours, or so you start feeling a little bit better.

Co has a half-life of about four hours in your bloodstream. The carb, the hemoglobin in your blood, is a junkie for carbon monoxide. It bonds carbon monoxide bonds with hemoglobin 250 times easier than oxygen. So basically you are fixated from the inside out.

That's the danger of it. John mentioned yesterday: the dangers of long-term low-level poisoning. That is why it is so deadly because you're being poisoned consistently and you don't know it sometimes it's environmental. You may feel great when you go into a location you leave and all of a sudden you're feeling worse.

So sometimes it's not that you hate your house or you hate going to work, maybe that you're being poisoned while you're there. So if you're not measuring you're, just guessing. So as we get into this, i wanted to take a little bit of knowledge up front and help you guys just emphasize again re-emphasize the importance of combustion air now the standards for our industry. When we look at fuel gas codes, i took all this information that i'm going to present you guys for this.

First little little bit out of the 2015 international fuel gas code, i made up a table of all the different uh listings of stuff, and i also want to talk about a ashrae journal report from over 20 years ago, and you guys can download this on the Internet these guys found some very interesting results as they went through it now. As far as code goes, there's numbers we've got to consider where the location for the air for combustion is coming. Now, where should combustion air go if you've got fuel fired equipment? Let's just say: we've got a standard water, heater and furnace installation. Where does the combustion air need to go? What needs the combustion air? I know this sounds super simple, the flame, the burner the burner needs oxygen.

It doesn't need the nitrogen, the nitrogen's actually useless in the combustion process. It needs oxygen so with the assumptions that are being made here, is that if we do this, the equipment's going to get the oxygen that it needs now, as you look at this table - and i just made something up in word for indoors - you have to look At the conditioned space, you have to see what the amount of cubic feet or volume that you have per thousand btus of the equipment. Of course, you've got the corresponding code references up there, we've also got to con. Consider where are we taking the air from? If it's from indoors how many openings, typically for combustion here, one or two, typically, it's two you can get away with one and canadians like one for some reason, but we're gon na find we're making some assumptions with that.

But you can see. We've got all kinds of different numbers up here: one square inch per thousand btus all the way up to one square inch per 4, 000 btus, depending on the location. Now, how do we know this works? There's a hard question: how do we know that these actually work? A group of engineers got together and they asked that same question. They said how do we know this works? Something smells fishy, we're calling bunk on this.

So they started digging. They started doing some questions. They could find no technical basis for these recommendations according to code and that's what we hang our hat on in our industry. We consider this as the gospel.

However, measurements prove that sometimes they work. Sometimes they don't. Let's take a look at what the engineers found. They asked why, if you guys want this, a quick google search will pull it up.

There's also a 200 page research paper on this. It's called ashrae research project 735. If you want to look it up, this is only eight pages. It's it's a lot easier to read, i'm all about simple guys.

If you're really interested you want to go nuts into it, you can go. Read the 200 page document: it's really cool, but if you're, if you like that stuff - but here in a nutshell, is what they found as they went through this they tested coat approved installations. They had dampers on them. Sometimes, we've run into combustion air installations that are interlocked.

The equipment comes on dampers, open up right, they tested it both ways, multiple configurations they tested this. They ran it from top to bottom. They heated the combustion air. They checked with different pressures.

They checked at different outdoor conditions, barometric pressures, wind conditions and they documented everything. Here's what they found. All these configurations had different ventilation rates, and none of them were consistent. The installation that they put in based off of what we just looked at should have provided those guys.

70 cfm under all conditions, makes sense right, because if we install a combustion air, duct air's supposed to go through it right. How does the air know that? How does the air know as we get into air basics? We're going to look at? There are some principles that drive air flow that you guys know we're just going to take it 90 degree shift check at that variation. Guys 15 to 1 was the variation on their air flows and, as the combustion air changed, your air flows changed. Now we talk about a combustion triangle.

What are the three things that we need on that combustion triangle? Fuel oxygen, which is air and a source of ignition those three provide heat. Do we do a good job of controlling the fuel source? We've got gas regulators, gas valves, adjustments right. We we regulate that we control it. What about the ignition source? We control the ignition source right i mean.

Sometimes we've got it down to a 30 second of an inch in distance timing down to a second for how long it should be on and then kick off now here's a hard question: do we control combustion air? Maybe we're going to take we're going to see about that we're going to see how much the flu design has an impact on that, because that's the other part of the equation and the germans call this. The goes into goes out to the combustion air in the german, that's the that's the gosinta and the flues that goes out there. So we got to make sure that they they do. What they're supposed to we're gon na talk about that guys.

That's unacceptable! A 15 to one variation: sometimes it worked. Sometimes it worked too much mother nature, controlled combustion air. In these instances, i'm going to teach you guys how to control it. Now what these engineers found was that mechanical systems, they proved reliable, consistent and they could repeat the results every single time so using a fan, we're all airheads right airheads in this tent's, a good thing, we're airheads guys we can control air.

So i'm going to walk you through how to do that. Now, when we look at some influencers on combustion air, we run ducts vertically or horizontally, and we assume the air direction right that pipe that's coming through the ceiling. There is wide open. What do we assume that that's going to do? We assume it's bringing in outside air right and guys we're clever? Sometimes we will actually put labels on there or we'll write it in a sharpie combustion air and then we'll put an arrow like the air goes.

Oh, i got ta go down that one. I can't go down the other one. Air can't read a code book air can't read labels. We have to direct it because, if there's some things that drive it so we're going to look at a function of draft, and this is where we're going to start talking about flues a little bit, what drives flues and what causes them.

I want you to look at things, we're going to tie everything back to air, so i want you to look at them a little bit differently. What's crazy, is you start to look at combustion air? It's the same physics that drive a duct system, there's nothing different! There's no difference in how we do this, so we're going to talk about draft. What its function is, what it does it's roll and it's really important and we're going to talk about buildings. Buildings are actually part of a duct system.

There's two sides we're going to talk about and we're going to look at the difference and then we're going to see what we're assuming happens. Once we start punching holes in the walls or through the ceiling to see what happens, then we're going to get into some very fundamental elements of pressure and airflow and we're going to tie every single one of these into combustion air. So you can see what's influencing these and then i'll give you guys some visual clues to look for you've probably been seeing this stuff all along and been going. Oh, that's! What's causing that so i'm hoping that there's some big aha moments as we go through this section.

So let's talk about flues. Everybody say this with me: a flu is a duct flu's, a duct. It's an opening between the indoors and the outdoors and just like a duct system, it's dependent on pressure, difference now, there's two driving forces on a flu temperature and pressure. Now we assume that the flu is going to remove the flue gases notice, i said, assume, that's the intention draft.

This was really important if you guys are taking notes. I need you to write this one down. There's very few things i'm going to recommend you write down. This is one that you need to write down.

Draft is the force that controls combustion air. It's a second bullet point up. There draft is the force that controls combustion air as we start to look at these influencers, we're going to see how they influence draft because, as draft changes, so does combustion air, that's a relationship. I want you guys to take out of this.

As draft goes up. More combustion error draft goes down less combustion air, so, as draft is constantly moving up and down our combustion, air is changing. That's what the engineers in that ashrae study were measuring as draft changed. They saw the combustion air rates that they were measuring through flow stations change, sometimes drastically.

We want to start narrowing that down and fine-tune that range to something that's going to be acceptable. Now of the two that control draft temperature difference and pressure, difference which do you think, has more of an effect temperature or pressure, everybody says pressure. If pressure is what affected draft the most we'd all be dead, if we ever stopped in a mechanical room, we would be dead. Temperature is the number one driver on draft.

The heat of the flue gases is what creates that flow. Those are familiar. We'll talk about stack effect in a little bit stack effect is an old school term for flu, so you could also think of stack effect as flu effect, and this is where we start to tie the building as being part of a duct system in temperature. Is a big driver when it comes to flu drop, so this is why it's so important that the equipment that you guys install is fired correctly.

If we under fire it flue gases, are really cool. We don't get a lot of draft now. Cavs is a term. We see thrown around a lot, that's an abbreviation.

What is a cavs, the area that our it's basically mechanical room, that is, the combustion appliance zone that any vented equipment's located in so anytime. You see that little term cavs up there we're talking about a combustion appliance zone, any area that has vented equipment in it. So that's what we're going to be referencing if you guys see that term floating around as we go through this now flues are ducks that connect indoor outdoors, you guys ever looked at them like that before i'm ashamed to say i never did. I was like.

Oh, that's: a flu flu gases are going out. We assume all this stuff. At least i did. Maybe you guys are more advanced than i am, and the combustion air duct.

Oh air comes down that one, but there's some driving forces that affect that now. Buildings are ducks when you look at this. We've got just a nice standard building furnace up in an attic we're going to assume it's a perfect duct system, everything's, sealed airflow's balanced. All the air that's going into the duct system is coming out all the air.

That's being delivered into the building is coming out. We've got nice solid flow moving through there now. How many guys have ever considered this before that the building is actually a duct system. There's two different sides of the duct system that we have to deal with.

Sometimes we deal with them unintentionally and when we deal with combustion air, we have to understand that second side of that duct system, the first side of the duct system is the traditional side. The traditional side is what we deal with that's the sheet metal. That's the ducts flex, sealant balancing dampers, makes sense so far registers grills anything that affects air movement. That's the traditional side of the duct system.

Now the building side of the duct system is what makes the connection from the supply air coming out of the supply registers. In that illustration, back to the return grill now for a duct system to work right, what are some of the aspects that it has to have ducts need to be leaky or tight, got to be tight right. You can't control air unless you can contain it. Well, what about balancing dampers? Is it a good idea to have dampers to control airflow yeah? What about insulation got to have insulation? Yes, please got ta, have insulation because we're trying to reduce what heat heat loss or gain heat flow we're trying to reduce that through thermal resistance and insulation.

So, as we look at these, those are the principles that we need on a duct system right. Those same principles apply to a building. It needs to be tight, a lot of times. Builders say well, the hou.

The house needs to breathe great. Where would you like me to knock the holes? You can't control air until you can. Until you contain it, you got to seal it. It's the same thing with trying to balance a duct system.

That's leaking like crazy. You can't do it. You can't control ventilation. You can't control air changes in a building until you control the leakage rates, so those of you that are getting into building science.

It ties in to combustion error as well. There is a direct correlation. As a matter of fact, some of the terms like stack effect come from that market, so notice that we've got a continuous flow here. The building is what provides the connection from the supply air to the return air.

Now, one of the things that we do, if everything's perfect great, no pressure difference now what we do is we start sticking ducts inside this building part of the duct system. We stick fuel-fired equipment in it, we'll take another duct and we'll stick it through the roof. That's wide open and we'll assume air is going to come down it and because it's thought, according to code, we go everything's working great guys, we're the only industry. That's crazy enough to start fires in somebody's house and not test them to prove them and make sure that they're safe.

Is that a fair assessment, or is that a little brutal? I'm not saying you guys our industry in general as we test, we can make sure that both the building side and the traditional side work so consider all the components. Buildings are really sandwiches of stuff, as you start to break it down. We looked at kind of that big picture before when you look at the different mechanical systems, the different pieces and parts of that you start to add indoors a roof, the hvac system, ventilation systems, all these different components notice. I can't go with the laser, so you guys will have to bear with me i'll try to walk you through this notice.

The duct system, as it goes through and penetrates the ceiling. It becomes a part of that building. At that point, any penetration through that drywall becomes part of the building. So we have to account for how that pressure difference is going to change, because if it does - and it will it's going to affect combustion air, how it's entering sometimes it'll work great other times, not so good.

We take all these materials, we start to smash them together. We start to crunch them down and we start to make them fit so with that is the building air tight. We building submarines and refrigerators. Yet we're not there we're getting there, but not yet so with that.

There's field installation variables that we have to account for, and you cannot account for them until you measure so measurement is going to be key with this there's one variable that we can't measure for and that we have to allow for though, and that's the occupants. People start living inside the duct system and when they do, they start changing damper positions and i'm not talking about dampers in the ducts. I'm talking about conditioned space manual dampers, we call them doors, they start opening closing doors. What happens to airflow and pressures inside the building, as people start to open and close doors? It's a moving target.

Isn't it it changes all over the place. People living inside the building can actually change combustion air just by changing door positions. So we're going to look at some solutions on how you guys can fix that so buildings are ducks any questions or comments so far kind of gone through this a little quick. Yes, you made a point earlier um about the showing the slide about the 15 to one ratio, and i've got an issue that i've been dealing with where excellent.

So the question that was the comment that was made was uh luke's running into a situation where you've got a you believe, you're running into a negative pressure situation in the building. Looking at the 15 to 1 ratio and you're sound, like you had an aha moment when you encountered that, but he thinks that 15 to 1 may be what he's dealing with his combustion air is changing you're going to like the end of this, because we're going To talk about how to fix that, depending on your installation, all these people, that's putting these big kitchens in anymore. You know they went from a standard fan and they put it in this thing's taking six or seven hundred cfm's out. Well then, it's got to get better here from somewhere, that's right, and then you will start pulling down excellent.

So the comment was made on combustion air we're putting six seven hundred, sometimes up to sixteen hundred cfm exhaust hoods in residential appliances. That air has to come back in from somewhere. That's an excellent point for those of you who do kitchens, restaurants and stuff that make up bears coming right down on the kitchen. I'm sorry i'm from arizona.

So in the winter time it gets cold. You know 60 degrees and they'll turn off the makeup air. It starts pulling makeup there from bathroom events, so the question was made in arizona when it's in their winter, which all of us just we it's hard for us to sympathize with you jake their winner, that they have in arizona that you know when it gets warmer. They start to shut off the makeup air and that makeup air is coming in from somewhere.

You guys make it some excellent points, because that's air air doing what it does so fantastic points. Thank you for that. Your winter's awesome man. I love your winter in phoenix.

Yeah, so it's awesome, i told you guys, you know, take some notes, here's why i'd recommend you take some more. I encourage you. The next couple of slides, take some notes on these. Here's my promise to you the most complicated combustion air issues that you run into will boil down to one of five topics.

I'm getting ready to talk about. It will typically fall into one of those five buckets. Sometimes it's multiple buckets, but if you understand what i'm going to talk about on the next two slides, i could pretty much sit down and we can end this presentation. I won't but you'll have it in a nutshell.

What's going on now, the first cause you got you're going to go dave. This is too simple. We know this stuff and that's right. You do know this stuff, but once again it's that 90 degree shift to look at things a little bit differently through a different set of lenses from a different angle and apply what we know to combustion air.

So how many of you guys know this? If you have an opening, it takes a pressure difference for flow to move through that that's one of the most basic principles of airflow. Everybody in this room knows that right. So whichever side has the higher pressure difference, it will drive air to the other. Mother.

Nature loves balance, she will rot a building and she will kill a family to get it pressures like to be neutral balance. It's one of those universal things, the higher the pressure difference, the higher the flow higher, the pressure difference, the higher the flow. So, as you look at this, we've got an opening if there's no pressure difference across that opening, there's no flow. If you've got a little pressure difference across that opening, i'm looking at the bottom middle, a little pressure difference you get a little flow.

If there's a big pressure difference get a big flow across it all right. We like big flows, not for combustion. Air too much flow is not good, so we get this right. There's has to be something that creates flow across an opening.

Now, here's something i would encourage you to do. We got a little breezy yesterday, phil awesome. I want you to watch this side of the tent this afternoon. If the breeze kicks back up and see if it's always blowing out you're going to see something you're going to watch it go out and you're going to watch it come in you're going to watch it go out and you're going to watch it come in, and I want you to think about this.

What if there was a combustion air grill in that wall, even though it's fabric, it would do the same thing. You guys have any aha moments yet, as the wind changes, that's actually one of the drivers that affects pressure difference and you can't account for it. I recommend you either take a photo of these write them down. This is your super complicated diagnostics rules to follow these four rules, guys most complicated things you run into on combustion.

Air are going to boil back down to these. Typically that first rule and some you know some guys may switch these up. That's cool just i just want you to remember them and know how they apply to what we're getting ready to talk about. First rule air takes the path of everybody can say it at once: path of least resistance.

We know this stuff, the path of least resistance, always air's lazy. We have to direct it rule number two, any air, that's leaving a building, it's trying to come back in from someplace else, one cfm out one cfm in that's the exhaust fan that you guys were talking about kitchen exhaust hoods. That's the principle that they operate off of the third rule, higher pressure, lower pressure. You guys see these are things that we know, but we're going to take them we're going to plug them into combustion, air and then rule number four.

Although it's super simplified hot air rises, cooler, air falls and displaces it, and we're going to look at how this ties in to combustion air ducts, because, as those principles are happening, those rules are going on. They create both infiltration and exfiltration. Now we understand how these apply to comfort issues john explained to us yesterday how they apply to iaq issues. Now, let's talk about how they apply to combustion air, if you have infiltration what's combustion air doing think of the first two letters in combustion.

Air is going in through infiltration. If you have x filtration, what's combustion air doing think of the first two letters and then add i t to it exit it's leaving the building, so we either have air coming in or going out. This is always happening. Remember rule number two.

If you've got one cfm going going out, you've got one cfm coming in from someplace else to replace it, and sometimes it's coming from places that we don't want it to. So. As we look at this, there has to be a driving force. As we said earlier, buildings are sandwiches and material.

There has to be a driving force. So, as we look at these there's, some things to consider wind is the first. It's the unknown variable that you can't account for, as we talked yesterday, you're going to see air moving in and out of this building, and you can liken that to combustion air it's changing drastically now, if we have fuel-fired equipment in this building, we're wide open to The outdoors you're not going to run out of combustion air right. You would think so.

You shouldn't, i was teaching in a class in dallas a few years ago and we did our hands-on training at a vocational school out there. There were two doors: approximately this size, probably 20, of a 20 wide open for carpentry students. The hvac equipment was on the opposite end of the building. As we walk up to it.

The doors were off the two 80 percent furnaces. There was also a natural draft boiler that was there guess, which way the inducers were spinning. They were going backwards. Every heat exchanger has a pressure drop to it so for air to come down the flue overcome the pressure drop of the heat exchanger and then go out the burner openings.

That's a lot of depressurization and it can happen now with two 20 by 20 openings shouldn't that have been enough combustion air. You would think so, but for whatever reason, wind the air wanted to come down. What do you think happened when i went down and talked to the carpenter guys? I said you care if we close those doors for a couple of seconds. What do you think happened to the inducers going backwards? You think they kept on going.

They stopped. We stopped the path because air takes the path of least resistance, those 20 by 20 doors or the path of least resistance. So here's what was happening on that illustration that you guys can see those arrows - and this is a very, very simplified illustration of what happens with wind wind - does all kinds of funky stuff on a building as you're, seeing the air arrows moving from left to right. What you're seeing is the windward side of the building, if you have combustion air ducts on that side, air will push into those grills and that will cause infiltration when the wind's blowing.

Now you guys tell me, what's going to happen on the opposite side, if that wind's still blowing that same direction and it's coming out the right hand, side it'll, be exiting those combustion. Air grills will actually act as exhaust grills because of pressure difference. Anybody having any old crap moments yet because the air is doing what it naturally does. We can't assume it.

You can have properly sized openings in a wall, and this will still happen. Isn't that interesting wind can cause this. It can also cause some goofy stuff. That happens if you take the ducts vertical, if the wind is the only driving force that we have, if there's no wind, what happens to combustion air, no combustion air, you have to have an opening.

You have to have a pressure difference across it now. The second way that we talked about combustion air - we talked about the stack or the building being a duct when we talk about stack effect, what we're talking about is the building acting as the flu hot air rises, and it goes out any openings in the upper Part of that building it enters in the lower part. So what you're, seeing with those blue arrows in that illustration, is infiltration air coming in at the lower parts and you're seeing exfiltration at the upper parts now in between that you've got a center spot and it constantly moves. It's what's called a neutral pressure plane and it constantly changes depending on out outsource outside and indoor temperature differences.

So, as you see that change these exfiltration and infiltration points, stop have you guys ever wondered why co poisonings go up so drastically in the winter time? What typically gets the blame furnace right? Cracked heat exchangers, causing all those co poisonings, cracked heat exchangers - are a defect absolutely, but here's what i would submit to you we're fighting a building problem. More than we're fighting a cracked heat exchanger problem. The building is becoming the chimney and guys we're trying to fight it with equipment. You ever think about that air changes directions in the summertime.

This is why we don't see it why it's more prevalent those arrows they flip in the summer. You have hot warm air. Coming in through the upper spots, cool air leaves down low those of you that are in cooling, dominated climates that have multi-story homes. If you can hang meat on the first floor, but it feels and smells like the attic on the second floor, you're fighting a leaking building, it's bringing probably 10 tons of load in through the attic to a system that may only be designed to handle three or Four tons you can't counteract that with hvac.

This type of an effect affects combustion error. Now what causes stack effect? What's the driving force that creates stack effect temperature? Now, let me ask you guys a question, because this is a common misconception in our industry. Do you have to heat up the walls of a house to create stack effect? What are you heating? The air you're heating, the air? That's what creates the stack? That's what creates the draft in the building common misconception, our industries? We have to heat the flu to create the flow we don't have to heat the flu. We have to heat the temperature of the air inside of it a lot of guys say i got a cold flu if you have a cold flu you're fighting a building problem.

Air comes down through depressurization. This is where we start to talk about. Some of these influences - these are just natural influences. You can't control air in a leaky building.

What about mechanical influences? You start to put a fan behind these things. That's just mother nature controlling in the previous slides. Now we're actually putting fans behind this up to four times more of an influence than mother nature and they're consistent supply, duct leakage - and you start to look at this. If you've got combustion, equipment located inside the condition space and you have supply duct leakage to the unconditioned space you're, pulling that space into a vacuum and it's trying to get air from wherever it can get it now time back to those four rules that we talked About air takes the path of least resistance, and for every one cfm that is being lost.

One cfm is coming back in to replace it if you're losing supply air into a crawl space or an attic where where's the rest of the air coming from it's coming from the conditioned space right so any time that blower runs. If you've got this situation, you can depressurize that space it essentially starts to suck those walls in and you're trying to get air from wherever you can get it kitchen exhaust hoods same thing. We just talked we're about north carolina, we'll have a lot of crawl spaces that only have one fight right on the crawl space, because the moisture problems and everything when we go over there, no combustion gotcha, so excellent point mark. So the comment that was made was crawl.

Space encapsulation you've got equipment, that's one pipe in a crawl space, it's dependent on air coming from the outdoors, and if you seal off those openings, you can't get the air to it. So how do you handle that? Well, this is where we're going to talk about using a fan to bring in air, that's repeatable, and it's consistent as you start to bring this back now on the flip side of duct leakage, we've got supply side leakage about return side leakage with return side leakage. It's exact opposite now: you're blowing air into the space, but you may be pulling it from someplace else. So as we control we look at air, we have to consider how it influences the system, how it influences any combustion piece of equipment.

That's located inside that space. Any questions or comments so far appreciate your comments now duck leakage is pretty simple. Now anybody in here doing duck sealing. No, i would hope everything will go up.

So here's something to keep in mind with duck sealant. Do you just randomly start grabbing pookie and slapping it on the ducks? You need to do one thing: if you don't, if you do nothing else, one thing before you start sealing ducts, just measure total external static pressure and compare it to the rated nameplate, see where it's at. If total external static pressure is high, those ducts may not need to be sealed. You need to dig a little bit deeper, find out why the static pressure is high, because if you seal an undersized leaky duct system, what's going to happen to the total external static, it's going to go up.

You're going to sign the death sentence on the equipment. Then the heat exchanger will crack for sure. You may have signed the death sentence on it, trying to do something good, so that's a pre-qualifier for any duck sailing. Sometimes it's something simple other times you got to dig a little bit deeper.

Sometimes it gets into some issues that you got to take some additional measurements that we may not have on a service truck when we get into air balancing issues, and this is where we have either too much or not enough air being delivered into a space. So, as we start to deal with air balancing issues, you have to measure at the registers and at the grills to be able to define if these situations are going on and once again, these tie back down to some of the most basic air flow issues that We've talked about because they're taking the path of least resistance and also us being able to control it, you shut the damper off. You start to shut those those conditions that down now what about duck design. This look like a standard house that some of you guys have to deal with.

Let's say that you've got just a standard. This is just a ranch. It could be on a slab central return. Water heater is located in a closet there.

On the left hand, side with a louvered door, pretty standard install right, so with all the doors open and guys, this could be a perfectly tight duct system. Everything's great on this thing, it's it's balanced. The system is running, pretty close to laboratory rated capacity. You've done a rocking job, but something's something's variable here something can change.

What is it? We've got doors or condition space manual. Dampers customers come home, they start living in the duct system. They start to change these damper positions, and things happen when you close a door to a room that has a supply register only to it or that has air balancing issues you're going to change the pressure, because now you have cut off any communication with the rest Of the building and air always takes a path of least resistance, so if you're pressurizing those bedrooms that only have supply registers only in them, what's it doing to the main body of that house, where there's a fireplace and a water heater, it's depressurizing it right pulling It into a vacuum and air takes the path of least resistance, so it's going to pull air from wherever it can get it. What are the two paths of least resistance in the house that we're looking at here i'll give you a hint? We got a fireplace and we got a water heater.

They will pull the air right out of the flue. Now you may say well what's to keep it from coming out of the combustion air duct, it may pull out of the combustion air. Duct too. We don't know because, what's on top of that water heater, that allows it to communicate with the house and any pressure changes that it has a draft to it that water heater's got a draft hood on it.

It is not a sealed system, it communicates with any pressure change inside that house. Now what's interesting, i mentioned the 2015 fuel gas code earlier. If you look at the definition of a draft hood in the definition of a relief opening they're the exact same, try looking it up see what the definition is. You'll go.

Oh, i didn't know, that's what it was. So as we look at this as pressure changes. Air starts to flow one direction or the other, and it can either go up a flu or it can go down a flu. Now i mentioned the fireplace and you guys ever had issues with fireplaces getting them to start.

They smoke up the house.