Best HVAC System? My Universal Layout: High Performance Ventilation System for IAQ Control

Added: 2026-05-18

[00:00:00]I've been asked recently on the channel what the perfect HVAC system looks like so that cuz if we can try anything, let's just aim for what we're aiming for. I've been talking recently about this new mixing room method distribution. In my opinion, that's not a perfect system. It solves some very interesting issues and you can see more of it in the video that I talk about, you know, what that kind of solves. I will have more stuff about how that is exactly done, but this is a system that I have in my own home and this is a more conventional system that you're going to have be a lot more available to you.

[00:00:34]It's a lot less creative thinking and this is just if you want the kind of plug and play universal performance layout for HVAC and I call this the performance ventilation layout because um the the secret sauce here is that we're we're uh plugging all of our ventilation accessory systems that handle the five factors of ventilation, which are circulation, capture and filtration, humidity control, dilution or pressure relief, into our main river of air.

[00:01:02]So, what you'll see here, the gray, is on this side as the air is being pushed into it, called the supply ductwork.

[00:01:09]This is the supply trunk.

[00:01:11]And then the branches come off of it just like a tree. Each of these branches or the little run-outs goes to a grill and those are delivering to every single room that has a load and you should be careful about loadless rooms. Loadless rooms would be a room in the middle of your house that's over conditioned space, under conditioned space, and surrounded by conditioned space on all sides. That room should not get one of these room supplies from the heating and cooling system. So, in that case, we need to do a little trick, which is to just move air generally, not to eject air or throw the air in that room away with an ERV extract, which you can see down here, but just to have a fan, a transfer fan, that's kind of taking a uh a step towards that mixing room method distribution using bath fans for moving air, not for exhausting air to outside.

[00:01:58]Anyway, rooms are going to get supplies, most of them. And in those supplies is not just going to be heating and cool heating heated and cooled air, which is coming from our heat pump, which heat pumps work in almost all climates at this point. Um they don't work for all sizes. You need to run the D rating calculator, which I think you D rate a heat pump by about 3% per thousand square feet or excuse me, a thousand feet of elevation.

[00:02:23]I had a client yesterday who was at 5800 elevation and so I had to D rate his heat pump by 18% almost to figure out what it actually will be able to kick out and that's because of the density of air.

[00:02:34]This could be a furnace uh and AC combo. This could be a geothermal blah blah. It doesn't even matter what it this is. So, let's just step to the side on this. This is your heating and cooling system which has an air handler built into it and that's one of the problems with this distribution in residential is that the air handler is tied is built next to the heating and cooling system. And so, the smaller your heating and cooling system gets, the smaller your fan gets. And that's when we start using ceiling fans for mixing air around high performance homes because you're just not going to get very much air out of this thing. That being said, in my house, this thing is a two ton.

[00:03:15]And that means it moves about uh 700 CFM.

[00:03:20]So, I can use this 700 CFM and plug smaller equipment, which for example, this dehumidifier. Let's get to this first since it's at the very top.

[00:03:30]This gets plugged into the supply. That way, both the cooling coil and the dehumidifier are able to dry the air in the house. At the same time, when the air is wet enough that it needs extra drying, we've got both of these machines really doing their job.

[00:03:44]If you plug this dry air here into the return, that means you're feeding this air handler not just dry air, but also hotter air.

[00:03:53]Um which interestingly does make the air conditioning coil a little bit more efficient for cooling, but it also takes away the ability for this thing to dry it all because the air that you're feeding it is this is going to heat the air somewhere between like 15 to 20° above the air that it's coming into.

[00:04:10]This right here is a dedicated return into this dehumidifier. That's the best way to keep the pressure low because we're pushing into something that's being pushed into by a bigger something.

[00:04:19]There's a fight going on there. If I pull this from something that's being pulled on by the bigger something also, then I'm just I'm fighting on both sides. This is an easy way to just have no fight on your return. That way you save all the fight for your supply. And almost any of these pieces of equipment are going to tell you what the airflow is going to be at certain static pressures. And the static pressure is like blood pressure. It's the measure of that fight that's going on to be able to push the air or pull the air from where it's trying to uh go to or come from.

[00:04:50]So, it's dedicated return here. You also on a ventilating dehumidifier, which there are a couple brands that do this.

[00:04:55]Uh incidentally, I'll just mention and there's all these little nuggets inside of these videos that uh Aprilaire and Santa Fe are both owned by the same company now. And Broan is also owned by that same company. So, FYI, it's like same corporate deal that's always going on is that like there's just two two few people controlling too much.

[00:05:16]6-in outdoor intake is what I was getting to. This is a ventilating dehumidifier. So, you've got an extra intake on it. You can use that as an extra. But, in most houses where you're going to have an ERV, you're going to have to run the ERV uh as the bath fan system. So, the bath exhausts will be handled by the ERV.

[00:05:35]There's one fan in here and we're pulling along this 8-in upsized uh trunk because the collars on the ERVs are 6-in. They're not They should be 8-in. They're not 8-in because if they made them 8-in at the factory, they'd have to make the whole ERV bigger and they really don't want to do that.

[00:05:51]They're already having a hard time selling ERVs to normal people.

[00:05:54]So, you are not a normal people. You know why we need this, which is to get rid of bath fans because they are a liability for very airtight homes. So, each one of these run outs is a 4-in run out. We've got these kind of >> [sighs] >> grills right here that we're using to dial and adjust the airflow on each of these run outs. You just pop it right into that you bring the the round ductwork right up to the drywall, pop this thing in here. These little spring clips hold it in place and then you adjust it with the screw.

[00:06:24]Each one of those then two 4-in combined, they go into a 6-in. You get one more or two more of those 4-in in there, you got to go up to the 8-in and that's going to keep the pressure low.

[00:06:33]The ERV is spilling its fresh air into either the return or the supply and I am a person who has built an independently ducted ERV system into my own home. I installed my ductwork myself if you haven't seen that video. Uh it took a long time, but it was worth it because now I know what it takes to actually install a duct system.

[00:06:52]This was all sheet metal.

[00:06:53]Uh and I would not do an independently ducted ERV again. I would do it this way. Uh so, this way if you take it into the supply, then you don't have to run the air handler. Uh and this is what people will say is I don't want to have to run my air handler on continuous on all the time.

[00:07:12]You want to do that for a couple reasons. Number one, if you buy a nice piece of equipment, this thing is not loud. It's so quiet in fact in my house that I have to touch my heat pump to know if it's running when I'm in the crawl space.

[00:07:24]Uh and it runs 24/7. It hasn't shut off for 6 years.

[00:07:28]A machine would rather run and run and run than start and stop. That's where the generally the wear and tear on the machine it lives is in the starting and stopping. So, running this fan is really not a huge noise concern. It's not a big efficiency concern if you buy a nice piece of equipment, again, don't buy a piece of crap. And they'll be like, "Oh, well, it's so loud I have to use flex duct for the last 3 ft of my supply runs to make sure that I cut down on the noise." Like it should not be noisy.

[00:07:52]Manufacturers need to do a better job.

[00:07:55]They're charging us for it, and they're all like complicit in trying to up the cost of all these things, but they're not doing a better job. I don't know what they're doing exactly, but it's not doing a better job. So, when they actually get their their stuff together, and by the way, just to remind you, we'll be in Spain for the next year, and I'm looking forward to like seeing what kind of equipment they're working with over there um in Europe in general, because um maybe they have different stuff. It turns out that a lot of people have better stuff than we have in uh the States these days. So, hopefully that changes.

[00:08:23]The air handler then combines with this dehumidified air. Boom. It combines with maybe the ERV. I don't like this as much as, and you can see here this either or not both going in here. Because if you go in here, we've got this MERV 8 filter that's built in the ERV. You could upgrade that to a MERV 13. Those things tend to cost about 50 bucks a pop, and you replace them once every 3 months tops. So, that's 200 bucks in just filters. And by the way, there's two filters in this ERV, not just one.

[00:08:51]Uh you don't need a MERV 13 on the outgoing that's going out uh to protect the outside. But, this air comes in, it then immediately hits this MERV 16 filter, best case, which is just shy of HEPA. HEPA starts at MERV 17.

[00:09:03]Uh MERV 13 minimum. MERV MERV 11 is where you start looking at human health.

[00:09:08]If you're not using a MERV 11 minimum, you're not making it healthy for people.

[00:09:12]Um it's good for the equipment to have a filter of any kind in there, but in general, MERV 11 is the beginning. MERV 11 is not going to grab any tiny particles. MERV 13 is where you start to do that.

[00:09:22]So, you can see this either or not both.

[00:09:25]You either want to do insulated supply air, which I generally don't recommend almost ever, with a mechanical damper on it, with a controller for a timer or something like that, or the ERV. And if you're airtight enough, you're either going to use this ventilated dehumidifier as we already mentioned, or this ERV to get away from the bath fans.

[00:09:42]Um and here, you could try to use this thing as a makeup air for a dryer. I've had clients try that, but I it's it's more complicated than it seems.

[00:09:51]I'll just say that.

[00:09:52]Okay. So, on the return side, now that we're talking about this return with the ERV going into it, you could also put insulated makeup air, that's a passive makeup air system, into this.

[00:10:02]Um each floor gets a return. Now, you don't have to do that. My house has one return, and I essentially have a three-story house. I have a crawl space that's half height, 4 ft. I have a first floor that goes from 10 ft to 16 ft height, and then I've got a second floor that goes from uh 9 ft to 11 ft height. So, that's essentially a three-story building, and I've got one return for my entire living space, 2,200 sq ft.

[00:10:29]And it's in the middle of the dead middle of the house, and it's fine. I have less than 1° of temperature variation between rooms with doors closed. So, it can be done. That being said, and by the way, what I was trying to get to is you don't need room by room returns. Central return works just fine.

[00:10:45]Anybody who says, "No, it doesn't." is just not That's just saying something without having any backup. Manual D, the duct design manual, allows you to use In fact, they encourage you to use door undercuts as a return pathway because there's no friction from the duct There's no friction from the static pressure drop of the grill on the one side or the grill on the other side. If you're using a jumper duct or transfer grill or a ducted return.

[00:11:08]Okay.

[00:11:09]So, we've got these returns coming in.

[00:11:11]Um we also uh So, that that's spells out the total of the return. Going through this MERV 13, MERV 16 filter, this is always oversized. Use the the pressure drop tables from the manufacturer.

[00:11:24]Normally, they don't have this, that's what's why I recommend Aprilaire all day long because they actually have tested the uh has pressure drop at all of the different airflow points for this.

[00:11:33]Over here on the supply, we are can put insulated supply air into the supply.

[00:11:38]And again, to get back to this air handler turning off, if you let your air handler run in auto mode, for most manufacturers, that means that the air handler turns off unless there is a call for cooling or heating.

[00:11:50]In that case, anecdotally, your fan will only run about 20% of the year. At which point are we really doing IAQ? The five factors of ventilation are circulation.

[00:12:00]We're not getting that when the air handler is off.

[00:12:03]Filtration, we're not getting that when the air handler is off.

[00:12:06]Humidity control and fresh air.

[00:12:09]These two things right here, if we're dumping both of these into the supply so that we can turn off our air handler, what that means is that we've got this river of air that is 800 CFM in my case for a two-ton air handler.

[00:12:23]And then, we've got this 300 CFM tops.

[00:12:26]Mine is really only about 250, and we've got here about 150. So, now, if both of these were running at the same time, we've got a combined flow of 400 CFM in an 800 CFM highway.

[00:12:39]And that means that the air can pretty much do whatever it wants. Now, it can turn left and go backwards through the heat exchanger and backwards through the filter and go out here. It probably doesn't want to do that. What it'd rather do is turn right. But then, it's going to come out the first place it possibly can. It is not going to the end of the line.

[00:12:56]And if they're not running at the same time and you only have the ERV running, this is 150 CFM fitting into an 800 CFM highway. So, now, it's definitely coming out the first, and none of it is going to come out later down the road. So, again, keep this air handler running.

[00:13:11]That's the best thing. Steam humidifier, if you need it, there are modulating ones. This is really important.

[00:13:15]Aprilaire makes a modulating one that they keep taking on and off the market that goes from 36 gallons per day down to 25 gallons per day ish. There's a better one that's called the Neptronic that tops out at 14 gallons per day, and I've honestly never seen a house that has an ERV in it that's going to retain half the humidity already.

[00:13:33]Need more than 14 gallons per day. So, that Neptronic is you can find that at HVAC Quick.

[00:13:39]Okay, so that basically spells out the whole thing. This is the ideal system.

[00:13:44]You can see some extra little you know, ifs, ands, and buts up here.

[00:13:48]We've got again, remember this either or not both. This makeup air for the kitchen exhaust. This is really important. I would almost never do this.

[00:13:57]It's better to do the separate because that way it injects as close to the exhaust as possible for minimal mixing.

[00:14:03]You do not want this river of air that's outdoor air coming across the kitchen and then going up the exhaust hood to be long because then you have to recondition and re-humidify all that air or re-dehumidify it.

[00:14:17]So, I hope that this helps. This is a free download on the front page of our site which is buildingperformanceworkshop.com.

[00:14:23]I'm giving a link in the notes below. I don't want your email address in exchange for this. Just download it and just use it. So, if you have any notes on this, I've shown this to a bunch of people including Positive Energy who does all my Matt Risinger's clients mechanical designs to Ross Trethewey.

[00:14:38]None of us really can find much wrong with this. This is essentially what the standard of like kind of best practices as far as I understand it across the board. With that being said, if you have any improvements for it, please let me know.

[00:14:48]Add your comments, add questions, things like that. You can also book consults with me on my website which is again this buildingperformanceworkshop.com.

[00:14:56]Thanks for watching. Tune in next time.