Programming an ERV to regulate balanced air pressure?
Izzza
| Posted in General Questions on
I don’t understand why depressurization has not been solved yet. When it comes to ERVs – can they not be programmed to respond to air pressure or at least programmed to be adjustable?
It would be great if I could hit a switch beside the stove in the kitchen to put the ERV into an unbalanced mode providing more supply air than exhaust air. Then, while using the hood exhaust the depressurization could be reduced or eliminated.
This is the ERV we have, it says the balance is electronic which leads me to believe it is possible to mess with it – https://broan-nutone.com/en-ca/product/freshairsystems/g3000ee
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There is nothing to solve, this is not how erv work. Erv recover energy from the exhausted air and transfer it to incoming air. If you are exhausting air not through the heat exchanger, then there is nothing to recover. If you want a switch in the kitchen you flip for makeup air, then install an intake fan on a switch ducted to near your stove. Or you can install a fan tech unit coupled to your hood. Or you can install and air scape automatic makeup air system. Or you can install a passive system with the broan pressure sensing damper.
Make up air has been solved. The reason there are no erv hood ranges is that what you are exhausting is grease and it would gum up the exchanger in no time.
Yes but realistically I don’t think too many people actually install make up air systems for numerous reasons, so I don’t have the impression that it is a very good solution. Sure, there might be solutions but none of them are good ones and that is why very few people do it.
There are very good solutions, the are just expensive. Here is the fantech: https://hvacquick.com/products/residential/Makeup-Air/Residential-Makeup-Air-Fans/Fantech-MUAS-Residential-Makeup-Air-Systems
Without heating the air it costs almost $2k. You are going to be spending more than that to have it installed. Then if you want to heat the air that's another expense.
So the only thing I would say is that we are in need of a less expensive makeup air system that targets less powerful exhaust fans. Let us know what you find. The thing is though that 99% of people aren't going to bother buying it unless code requires it or they have a backdrafting or gas leakage issue.
People building code compliant houses do, as it’s required for all appliances that exhaust more than 400 cfm. Your cfm discrepancy between the erv and hood make it a bad solution, just because it has an air intake does not mean it is designed for that. A simple inline fan with an intake and ducting is not a very onerous barrier considering everything else in a house. Even a passive air inlet, properly sized is probably a better option than making a combo makeup air erv, as 90% of the time the erv fan would be horribly oversized, and you would probably have freezing issues.
"People building code compliant houses do, as it’s required for all appliances that exhaust more than 400 cfm. "
It's only required in houses that also have combustion appliances that rely on gravity for exhaust.
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To add to that: if you make the ERV supply only it will recover n0 energy. So then you have a very expensive fan that can only move a fraction of the CFM to where it’s needed. That is if you positively pressurize the entire house a little bit it will still be de pressurized locally at the fan and locally still have some of the depressurization issues.
You can setup a kitchen exhaust for the ERV away from the range (far enough to avoid grease) and run that through the ERV- that will lessen the need to run the exhaust fan- mostly when the cooking is done, not necessarily much during it when you are running a more powerful exhaust fan that can handle grease exposure.
OK well I will continue to remain unimpressed with the available options 🙃 I know an ERV has too low CFM, I think ours is only 220 CFM but that still seems better than nothing. Though you have good points about why it is not a good idea! I still think some genius is going to come up with a range hood that actually works and possibly one that has energy recovery and a way to integrate make up air.
Yes, we are building a code compliant house but MUA is not required. When I talked to the engineer he said if we are sticking to the 400 CFM hood it’s not the end of the world to skip the MUA system. Passive seems pointless to me, I’d rather just crack the window that is like 3 feet away from the stove. With no filter and no heat, it’s not a great solution either way. Also good point, we did put ERV exhaust with grease filter in the kitchen between the stove and the toaster oven area so I guess using boost mode after cooking means we can minimize using the hood.
I might ask about the Fantech option but I have low expectations, especially since we no longer have the spot for it to fit. I have a hard time believing it would cost the same here, not sure where you’re located. In southern Ontario, HVAC costs are very very high for reasons I cannot explain.
While I understand that technically these MUA systems do exist and they do work… I don’t think they will ultimately be the solution that gets adopted at scale. People don’t have the budget or the space. What I think is far more likely to happen, because it is already happening, is that people either add recirculating hoods and suffer the consequences or they add inadequate low powered hoods to minimize depressurization and suffer the consequences, or of course they add whatever CFM hoods with no concern for make up air especially in renovations where new build rules do not apply. Ultimately, IAQ will suffer.
If I recall you have an induction oven. So between that, the exhaust, and the ERV exhaust I think you are in good shape. I would look closely at the kitchen exhaust hood and get one that captures well. And toasters are just bad news for IAQ- I try to condition people to not using toasters. There's room here for a toaster that somehow guarantees no burnt crumbs.
For the ERV exhaust, I would locate it farther away rather than relying on a grease filter. The problem with ERV boost is that it boosts the entire house rather than your kitchen location. I have seen 2 tricks employed, both of which might void your ERV warranty:
1) add a fan to push air to the ERV. This means the ERV won't be taking air from other exhaust streams. In theory a good solution for temporarily prioritizing just 1 stream
2) Use the Aldes ZRT registers. This is a whole house solution where you would use these everywhere and be able to temporarily boost any one exhaust stream and keep the others limited. Aldes actually sells an ERV with this system and in theory you could use it with a different ERV.
What about toaster ovens, with a cleanable tray? I cannot give it up! How the hell do you expect people to make toast? 😂
We also use the toaster oven to reheat food and make bacon. I had a great idea to put an over the range microwave fan (just recirculating w charcoal) above this area and I kind of regret not doing that now. Oh well. I guess we all die from something and if toast crumb smoke is what does me in, I probably deserve it.
toaster ovens with trays are a lot better. Crumbs still try to go where they shouldn't so you still need frequent diligent cleaning to avoid burned crumbs. I put the toaster in the garage!
I think the energy you lose from spot venting / makeup air is fairly insignificant because I would guess most people only use their range hood for 10 minutes per day or less. I also wouldn't trust a grease filter to use an ERV for this purpose, especially since sometimes things burn on the stove. I do think we need better spot vents though that are insulated and stay closed when not in use, so they don't lose energy when closed, which to me is a bigger issue. I have a design for this but looking for someone with more time / money to develop it.
Interested to hear more about your design! I agree the exterior vent is a problem when not in use, one of the reasons I’m not sure about MUA.
To clarify we wouldn’t be using the ERV instead of the hood, but in addition to it and to pick up remnants in the air that the hood misses. We use the kitchen exhaust about 30 mins a day on average on lower speed and maybe 5 mins or less on high speed.
If you stipulate that depressurization from an exhaust fan is a problem that needs to be solved -- which I'm not convinced of, but I'll play along -- the only way to solve it is to have another fan bringing in an equivalent amount of makeup air.
If the exhaust fan is a kitchen vent fan, you're not going to be able to do energy recovery because the kitchen air has nasty stuff in it that would have to be filtered and collected to keep it from contaminating your ERV. So the outside air you bring in has to be conditioned somehow.
I see three possible ways of doing it:
One is to dump the air unconditioned into the house and try to get it to diffuse so that there aren't spots where the unconditioned air is so concentrated that it causes comfort problems, and let the HVAC control the climate of the house.
The second would be to run it through the intake of an ERV in unbalanced mode and have the ERV deal with conditioning and distributing it, and the third would be to do the same thing but use the HVAC instead.
I don't see how option one is any different from just letting the house be depressurized and letting makeup air come in where it will.
The question of whether option 2 or option 3 is better depends upon what kinds of ERV and HVAC you have and how they're configured. My sense is that in most situations using the HVAC would work better. Note that in commercial buildings it is common for part of the return air for HVAC systems to come from outdoors, to provide ventilation and also a slight positive pressure. Positive pressure in large buildings is believed to improve comfort by preventing the infiltration of unconditioned air, although it's a somewhat controversial subject.
I am intrigued. This was part of the reason we decided to skip burning wood inside, it’s easier for me to accept a bit of depressurization without risk of CO or backdrafting appliances. I also thought the ASHP would be best for pressurizing it but I mentioned this recently and someone mentioned that the heat pump is not bringing in fresh air so my thinking was incorrect.
I recall some of what you previously mentioned about doubting the problem of depressurization from kitchen exhaust, as much as I could understand anyway. Can you explain in simple terms why it might not be a problem? What about driving moisture into walls?
In my case, we are aiming for 0.6 ACH50 and we will do the first blower door fairly soon. The indoor space is about 3,400 sq ft split nearly evenly among 3 levels. Ceiling heights are about 8ft, 9ft, 9ft. My completely uneducated + unproven theory was that there is enough space so using the kitchen exhaust might not have a huge depressurization impact because there is a decent amount of volume. But moisture is definitely a concern because we don’t have overhangs, and since I learned about inward vapour drive I got concerned about that with the black siding. So the idea of the house essentially inhaling all exterior moisture into the wall assembly seems very bad. But when I think about it - the moisture might get sucked in and then so what? Between the 2x6 studs we have mineral wool batts covered by a smart membrane (Intello) and then latex painted drywall. So if moisture does get sucked into the walls, will it be able to dry out adequately? I can see why it would be an issue with poly inside because the moisture would be trapped. I think ‘graygreen’ had an interesting point about wind drive having a bigger impact… our architect never mentioned anything about wind and we were pretty stupid to forget about the existence of wind when we decide on the site - we built into the top of a hill with wind exposure in all directions and way too many windows. Regardless of the kitchen exhaust, this will be driving moisture inward.
Except for some areas of the deep south with very humid and warm summers, depressurizing the house doesn't bring moisture into the walls. Generally outdoor air dew point (amount of moisture in the air) is lower than typical house dewpoint, so sucking in outside air through the leaks is actually drying the house out. This is especially true in the wintertime in colder places. The only risk of depressurizing the house is combustion appliances, but if you don't have these, there is nothing to worry about.
Pick an exhaust fan with reasonable CFM and use an insert hood with slats. Build this into a larger cabinet inset so you can build a good aperture size and capture volume and call it a day. Some cabinet makers offer an aluminum or stainless veneer on one side so you would end up with a pretty easy to clean surface.
If you really want to do something about makeup air, I like the behind fridge idea posted in here:
https://www.greenbuildingadvisor.com/article/choosing-the-right-range-hood-makeup-air-system
A passive backdraft damper such as a Fantech RSK8 is good for about 600cfm and limits pressure to about 10PA. Mount this inside the wall, add on a largish filter grill to cover and you are still around under 20PA worst case. This is maybe $300 in parts, no need for $8k of MUA with controllers, fans and heaters.
Are you advocating for makeup air with a passive vent?
Perhaps it will be helpful since his house will be tight:
https://www.greenbuildingadvisor.com/article/passive-air-inlets-usually-dont-work
Where is your evidence of "good for 600 CFM"? You can probably get a lot of CFM if right next to the range but then it will probably interfere with exhausting.
The other issue is wind pressure pushing open the damper. I would like to have a passive vent for kitchen/laundry to provide some of the makeup air needed. I think it would need to be normally closed and have an electrical connection so that it would stay closed when there is not exhaust in operation.
And there is the issue of energy loss when the passive vent it is not in use. It would be amazing if there were a normally closed and normally well insulated vent.
I did a quick check of the pressure curve of that passive damper and winter time stack effect is enough to cause a fair bit of leakage.
You can go with a passive damper but needs a higher opening pressure, one of the adjustable barometric dampers would probably the work. The issue is something that won't leak under expect house pressures (stack effect+some wind) will also allow the house to depressurize a fair bit.
A much better option for passive setup is a motorized damper interlocked with the range hood. Make sure the unit has a gasketed damper as typical dampers can leak a fair bit even when closed. These kits are relatively cheap and a simple install.
Wind will drive air in one side of the house and may pull a lot out of the other side. So you want to determine the prevailing wind direction (where the wind comes from most of the time) and plan accordingly. Facing into the prevailing wind needs more overhang and meticulous detail on windows and doors so the wind doesn't drive the rain into the house. I am looking at adding a missing overhang to my house to shelter from the prevailing wind. The doors and windows on that side on the first floor are in bad shape because the only overhang is the roof above the 2nd floor.
I think we will be in bad shape regardless, we have no overhangs anywhere. Though 2 of 4 doors are covered. I’m looking forward to seeing what happens with the fully exposed sliding doors! Not to be bitter, totally bitter, but below is an early email excerpt with my architect during the early design phase. This was in response to seeing the roof design, my text is black and the architect’s responses are in blue. I don’t know how much of what I was told is true, but it seems to differ from what I’ve read on Buildingscience.com and everything else I’ve read. At the end of the day, I’m just a ‘girl’ and had to trust the self-proclaimed experts with decades of professional experience. 🤷♀️
Seems fairly obvious to me that we have made many errors in design, but it’ll still be good enough. I think the maintenance costs will be astronomical, so many windows and doors. It’s seriously not even possible to clean the windows they are so high up.
I don’t want to add a passive air vent, that option is off the table for me. It’s down to doing nothing or waiting and seeing if we have a problem and try to figure out active MUA after the fact. Normally my line is that “hope is not a strategy” but I’m starting to wonder if it is in fact the best strategy and I might just have to try it out with our kitchen ventilation 😅
I don't think your architect is wrong (assuming you don't have wood siding). The problem though is that it requires the builders to be meticulous in their installation of windows and doors without any real margin of safety. So you probably need to get involved in those installation details now. Any exposed wood without an overhang and not on the south side is going to be at risk of rotting. The side with the most prevailing wind is going to have it the worst. The wood around my door, particularly at the bottom corners is rotting now. I saw someone else's door installation under similar conditions but they had aluminum (painted white it looks the same as wood) on top of any exposed wood around the door so there wasn't rot. They also had a sill plate that had 2 back walls (lower and upper section) to prevent the rain from driving in.
graygreen,
"The problem though is that it requires the builders to be meticulous in their installation of windows and doors without any real margin of safety. "
And there is the rub. All sorts of building assemblies work fine as long as they are perfectly installed and stay that way throughout the life of the house. You could make the same argument for walls without rain-screens, or vented low-slope roofs. There may be nothing wrong with specifying higher risk assemblies for aesthetic reasons - if you are clear on why you are doing that. What I'm not keen on is designers dismissing practical concerns with suspect justifications.
>Can you explain in simple terms why it might not be a problem? What about driving moisture into walls?
I guess I would turn the question around and ask why you assume it would be any more of a problem than the normal levels of air infiltration that occur without depressurization?
But I'll try to answer. As Akos notes, during heating season the dew point is always going to be lower outside, and outside air entering the house is going to tend to dry things out. If the vapor barrier is on the inside of the wall, the air entering the wall is going to be at the same absolute humidity (dew point) as the air it replaces. And the vapor drive is all toward the outside. However, in heating season there is a concern that you not create surfaces that are exposed to indoor air that are below the dew point of that air. Typically that's something you worry about if the vapor barrier is on the outside of the wall. So a small leak that gets cooled by infiltrating air could get chilled to the point that condensation happens when warm, humid indoor air touches it. I haven't experienced it myself but I've seen pictures of drywall with surface mold spots, and when it was opened up it turned out there was no insulation in those spots. I've even heard stories of wall outlets icing over in extreme climates. The question is, if those conditions exist, does occasional negative pressure make them worse?
In cooling season, the concern is reversed: it's that warm, humid air from the outside comes in contact with something cool enough on the inside to condense. Keep in mind that it has to be really hot and humid for this to happen. If your house is at 75F, the dewpoint outside has to be 75F or higher, that would be equivalent to 92F and 60% RH. Those are tropical conditions not found in most of the US. Just as the infiltrating air tends to cool the wall in winter, in summer it warms the wall and makes condensation less likely. If the vapor barrier is on the inside of the wall, air flowing through it isn't going to change the moisture content, it's already exposed to outside air. If the vapor barrier is to the exterior then infiltration will increase the humidity inside the wall. But in that situation all of the vapor drive is to the interior, if the wall can dry to the interior the moisture should be driven through and removed by the HVAC. If the wall can't dry to the interior you'll have bigger problems.
So I don't see any theoretical reason why depressurization would cause any more problems than just normal infiltration.
Look at CERV2 from Building Equinox. They have the use case for balancing a cooktop. The documentation shows the configuration of the function block library. It also identifies the sensors you need to install.
Thanks DC! I will have to read your explanation another 10 times to fully understand it but this is helpful! I also can’t think of any theoretical reason why depressurization would cause problems in our scenario 😂
Thanks graygreen & Malcolm, I have told myself the lack of overhangs is not the end of the world because we have a good builder. Our goal was to avoid unnecessary risk and I’d say a modern aesthetic roof that looks good, say in an architect’s portfolio, doesn’t really fit our priorities. However, it does look good and our builder was careful with exterior detailing. Good does not = perfect though so only time will tell. We have mostly steel siding but wood wrapping around the southwest section on level 1 as well as wood accents between windows on all sides. The design included the wood window accents be inset, reducing exterior insulation and creating water risk, so the builder eliminated this which is probably a good call with no overhangs. I’m not sure how much you can tell from this photo but you can see the detailing around windows and the basement door. However, there are details I noticed after the fact like it appeared they put horizontal furring above and below windows which I just saw in a Steve Baczek video is not good. I don’t know exactly how they did it so I might have missed something though.
The trouble with everything building-related seems to be that it is SO incredibly complex and the slightest error or issue in one tiny area can have massive unforeseen catastrophic consequences. Since building science is still evolving, and nobody has 100% perfect knowledge or perfect execution of every single detail every single time, I think it seems generally best to try to be more conservative and err on the side of caution and eliminate risk at every opportunity.
"The trouble with everything building-related seems to be that it is SO incredibly complex and the slightest error or issue in one tiny area can have massive unforeseen catastrophic consequences. "
I'd argue it's because houses are designed one at a time. Imagine if you decided you wanted a new car you had to have it designed and built. First step was to go to your local government and seek approval for your design...
I know people have been talking about building houses in factories for 100 years or more but it seems that in the age of computers the process could be better.
I’d like to see more designers and builders putting their minds together to design housing that is more scalable and more reliable. I see how custom projects are very high risk. You have a good point, I’m glad the car manufacturers have tested everything so rigorously and I wouldn’t want to drive a special vehicle nobody has ever driven before.
To quote the father of permaculture:
“Architecture and architects are the largest out-of-control experiment ever inflicted on mankind (except for mobile phones).” - Bill Mollison
DC,
I think a reasonable middle ground between the entirely bespoke and the factory built might be only using two or three assemblies in each climate zone that we know work.
I also htink houses shoudl eb more generic, and that variations are best made to adapt to their site and surrounding, not the individual preferences of the first owner. Considering that the average American moves every five to seven years, a lot of the discussion around both ROI and customization of houses makes little sense to me.
With everything clad in metal seems like you won't have too many issues with rotting wood! I would be worried about the wood accents, but just keep inspecting them. A lot of home problems happen because they go unnoticed for years.
I think the problem is that we won’t be able to inspect most of the windows, they are too high off the ground. It is built into a hillside so it would be hard to use a ladder. They had to use like 3 ladder extensions while building, and then a lot of scaffolding. Seems like one more thing people should consider during design! The ability to inspect and maintain the home, clean windows, etc.
That being said we want to buy a drone so maybe we can do drone inspections. How to crash a drone 101.
Visual inspection from outside with binoculars should work for major issues. Windows can be inspected from inside- particularly if they can open. It's nice to be able to physically press on wood although by the point that tells you something there is usually another visual sign as well.
@Izzza, I do pretty much exactly what you're looking for but with a Hubitat hub and automation that controls both HRV ECM fans, as well as the kitchen exhaust. IAQ data is pulled from sensors in the basement, 1st floor and 2nd floor every 2 minutes. The HRV has temp sensors on the four air streams, and 1 after the heater array. This is more or less the setup, which works exceptionally well:
1. Kitchen exhaust (inline ECM fan) is triggered and then speed controlled by power use of the induction cooktop. Fan speed is controlled in increments from 0-100 based on power use by the cook top.
2. If Kitchen exhaust is in use, then the HRV runs asymetrically, providing about 90 CFM more air in, that is going out. HRV efficiency drops to about 55%. I also use this asysmetric mode when loading our high efficiency fireplace to stop smoke puffing back (with the door open) into the house while loading it.
3. The HRV is run at 50,60,75,80,100, or 110 CFM (balanced profiles) controlled by the Hubitat hub. Ramping between those balanced air flow profiles is based on average Co2 levels across the 3 sensors. High VOC or Radon levels trigger the 110 CFM profile.
4. Heat is provided (after the exchanger) by two PTC heaters that vary wattage and operation dynamically using feedback from the temp sensors. Automation turns them off during defrost cycles, or when delivered temps are over 65F. This works shockingly well.
Nothing fancy there for automation. Just a $150 Hubitat hub, and zwave/zigbee off the shelf bits. More on the techy side here: https://community.hubitat.com/t/success-0-10-volt-control-of-ac-infinity-or-any-ec-fan-motor-using-leviton-zs057-d0z-zigbee-dimmer-or-zooz-zen54-zwave-0-10v-dimmer/104450
Been running now for 2 years with no issues. Our house is old, but heavily retrofitted. It's pretty easy to pull .4 in w.g. with a bath exhaust and the kitchen exhaust fan (160 CFM, max, measured with full ducting/hoods/silencer etc.) at full tilt. Is this a big deal? With the fireplace on, sure, but otherwise, no.
The automation true value (IMHO) is that it ramps up or down to provide "healthy" IAQ 24/7, but minimizes throwing BTU's out the door if no one is home, occupancy is low, or on a windy day. In other words, CO2/VOC/Radon levels are actively managed, while power use and BTU loss is minimized at all times.
Wow! Someone actually mentioned Hubitat on here in the past, maybe it was you, I looked into it and it looks incredible. Though it sounds like your cost was low to do this, it requires a massive brain. I don’t think I have anywhere near the ability to set up something like this. Are you an engineer or programmer? I just like the IDEA of this kind of stuff, coming from UX background, but I don’t actually have any clue how to do it.
There is a huge market gap in the area of home automation. While I’d looove to learn this myself, I don’t want to screw up the house so I’d much rather have a professional handle it. My thinking is very similar though - it makes no sense to just run our ERV 24/7. We are building a decent size house (~3,400 sq ft total) and right now there are only two of us as we don’t have kids yet. I think we’ll be doing a lot of manual adjustments depending on what we’re doing/if we have guests/etc.
Is the hubitat setup you have something that can be easily added later or would it need to be done during construction while we have the walls open? I’d like to wait until we move in and then dig into it to see what I can figure out as I’ll have more free time. We are starting drywall fairly soon so there is not much time to add wiring.
My HVAC guy recommended Altra – Aidoo Pro by Airzone if we want wi-fi control over our system. We just installed a Mitsu ducted ASHP and Venmar/VanEE ERV. Fully automated is ideal but at minimum it seems like we should be able to control the HVAC from our phones. I understand that to some this seems unnecessary, but in 2024 it seems odd to build houses without smart controls.
Which VanEE ERV? The AI series capabilities give a lot of ability for it to automate some controls and also to control it manually from a separate LCD screen.
Gold series. I wish we had been given a choice I would have also chosen the AI but I only saw it after it was too late.
Doesn't defrost mode ruin your setup? Have you considered pre-heating the air rather than post-heating? Would you be better off now with a RenewAire with no defrost cycle?
Defrost mode just diverts some of the required energy from resistance heat, to the homes HVAC (currently gas heat) which is far less expensive. We could do preheat but the required watts to avoid defrost cycles is quite high at -35C. The more efficient way to do this would likely be an air to water heat pump with a coil in the intake…but much more expensive.
Doesn't defrost mode mean there is no makeup air from outside for the range and that you can still have backdrafting of your stove?
Defrost mode does “break” asymmetric supply, however defrost mode is dynamically calculated based on outside temp, every 30 minutes. It’s only an issue at very cold temps, and only for a short time. The fireplace has outside air for combustion, so back puffing is only an issue (if house pressure is negative) while loading..2-3,times a day if using the fireplace. You are 100% correct in that redoing the system with an oversized ERV core from RenewAire Premium L (about $1200) would reduce any kind of defrost cycling to near zero, and be more efficient too. I’m just being mindful to minimize my material consumption here, and I have some very tight space limitations.
Sounds interesting. Does Hubitat allow you to create your own sensors and devices? I'm a bit of a nerd and I have devices that I created around the house, I'm trying to figure out a way to tie them all together into an interface that someone other than a mad scientist can use.
You could probably do this with homebridge, I dont know what sensors you have but if there is not a plugin for it on homebridge you can create one that is easily controllable through that
There are a couple reviews on this channel from someone that built a Passive House: https://www.youtube.com/watch?v=YDVD523ZUEE&t=624s
You can probably do what you want with Hubitat. Do a search for your devices first on Hubitat forums.
You can write your own device drivers, yes. That’s above my pay grade though.
@Izzza, not an engineer or particularly smart guy myself, ha. Jack of all trades, master of none. University degrees in biology, education, but life so far has been business and IT. I'm just a curious person who likes to solve problems.
Is there a market? Hard to say, but I did run a business for 13 years with up to 16 staff that started accidentally, playing around in my garage to get more "filmic" footage of my kids. If you look at general interest in my setup from the pros here, I'd say it's pretty low, at least in the rather "raw" form that it's in now. That said, it would not be all that hard to package this stuff up, call it open source HVAC. However, HVAC guys would not like it as their business model is to show up, set everything up in the shortest possible time, collect the cash and walk away. The other thing is that every manufacturer then wants to collect revenue beyond the hardware sale by collecting $$$ monthly to manage their system on your phone. I get it.
The reason I'm using Hubitat ($180) is that we're in a 100 + year old house and changes are not easy. Everything is wireless these days with home automation, Zigbee or zWave chips at the core of it. It seems like a lot of complexity but as you step into it, it gets easier and easier. In the commercial world I'd still want to run low voltage wire and use something a bit older school like Bacnet for closer to 100% reliability. But to answer your question, the stuff I'm doing is easy to add on.
Automation is not as complicated as it sounds. You have an automation hub (I'm using Hubitat, but there are quite a few options out there) that you "register" your lights, sensors etc. to when you first set them up. I'm using 0-10V dimmers, the Zooz Zen54 (about $35) that connect to each of the EC fans in my setup. The HRV has two fans/dimmers, and the kitchen exhaust has the third inline fan/dimmer. Each of those dimmers is registered to the hub and communicates with it wirelessly. The 0-10V dimmer can be located right at the fan..no need for a switch unless you want manual control as well.
You create rules so the hub knows what to do with the bits it's talking to. You don't need to learn how to program to create rules. Hubitat lets you create them using a web browser and more or less guide you through rule creation. There is a learning curve, but it's not that hard.
You have full control of the system via your phone remotely, and it's free.
For future proofing, you may just want to have CAT6 network cable run from your HVAC system, bath fans, and kitchen hood back to low voltage boxes in your utility room, just label them and leave them.
Now, based on all the data I've gathered over a decade and a few buildings (commercial and residential), if you just set your equipment up at ASHRAE recommended levels and leave it, you're most of the way there, anyway :-) Pick up an IAQ monitor (AirThings View Plus works fine) and mount it centrally to keep an eye on things. If you are able, buy a hood and induction cook top that talk to each other. Do that, and let your VanEE sort out balance. I'm not sure what the stats are exactly, but many studies correlate on the fact that many, many folks just don't switch on the exhaust hood when cooking (my family, never did!). This really spikes PM2.5 and VOC inside. My approach is quite inexpensive (about $300, including the fan) but you can buy units now (Samsung and I'm sure others) that do this. This is my setup: https://www.garagejournal.com/forum/threads/automate-kitchen-exhaust-hood-fan-using-inline-ecm-fan-turbocharge-yer-exhaust.491330/
Interesting! Well maybe there is hope I can figure something out down the road.
I was planning to use AirThings monitors so I’ll start with that. The range will be Bosch, it probably has modern features like wi-fi. Someone on here recently recommended an exhaust hood that also has wi-fi. Normally I would not want appliances with internet, like what is the point I’m not operating the oven from an app, but it will be interesting if this allows automation like you’ve described connecting the cooktop to the exhaust.
Dennis,
" If you look at general interest in my setup from the pros here, I'd say it's pretty low, at least in the rather "raw" form that it's in now. "
I think it's great. Any apparent low interest probably stems from the difficulties in how to adopt it in new builds for clients. Who sets it all up? Who maintains it later?
Malcolm, yes, very good points. I can see Broan pushing to this, but the challenges to fully integrated reactive “plug and play” HVAC are significant.
The kitchen inline fan connected to any old 240 volt cooktop is an easy one, providing you have a hub already :-) An inline 6" ECM Terrabloom fan with a metal case (code require here) is all of $110 USD. Then you just need a Zen54 0-10V dimmer ($36) and Aeotech 240V switch ($110) inline with the cook top wiring.
You can also do a few things that even the most expensive setup won't allow. I'm using Broan Eco-vent hoods which have a foam ball that slides back with gravity to seal the opening. Well, at -30C they freeze up a bit. My setup runs the fan at 100% speed for 90 seconds (but only if temps outside are below freezing) which works quite nicely to pop the ball..otherwise it stays frozen in place. After the "pop cycle", the system reverts to ramping with power use. Aside from helping with negative pressure, the ramping also keeps noise down very low with typical use (1 pot/pan on the cooktop), which definitely helps with the wife acceptance factor :-)
True automation nerds will also have wall mounted tablets etc. to monitor/tweak on things...but I have none of those. The attached pic is the Hubitat Dashboard that I can access from my phone remotely etc. to keep tabs on things. It just lets me know at a glance if all is working correctly, where air quality is at etc.
Fun thread. But old fashioned controls/software engineer here. I really dislike the standalone controls used in In HVAC today. Everything is standalone and nothing is integrated. Boiler controls overshoot, floor heating is not localized, ventilation occurs whether it is needed or not, and kitchens have 1200 CFM fan hoods for people boiling water for spaghetti. Where is the Home PLC that has self tuning PID loops?
I hear you 100%, but I also get why the type of system integration you would want is a hard target for a plug and play system. That said, if I hack like me can do it, then why can't a manufacturer provide a hub that you add components to, and then have it manage them with even a simple set of rules? I'm setting defrost cycles in very cold weather dynamically based on outside temps, where every system I've seen so far uses a basic table. Why do this when you can reduce non-ventilation times, and full speed fan power use considerably by doing it dynamically. The list goes on. None of what I'm doing is rocket science by any stretch. Maybe the HVAC industry in NA is just a bit slow to adopt new tech.
There’s also concerns of reliability. The more integrated a system is the more potential for failure modes. HVAC equipment is mostly dumb but reliable.
An integrated system done well has the potential to enhance monitoring and improve reliability.
I am under the impression that commercial BacNet integrations can be sophisticated. Seems like that needs to be scaled down to residential.
On the other side, I recently checked over the wiring for an HRV in a larger home with 5 remote boost switches etc. The wiring for both the wall control and boost switches was done incorectly at installation, some 15 years ago. The system had never worked properly (or at all) since new! The equipment was dumb, and the home owner had no idea it was not working correctly, other than observation that the house seemed "stuffy". That comment got me looking at things.
To your point of monitoring, when you integrate, issues that a home owner might never be aware of can be identified. For example, during a really cold week where temps were in the -40C range, the exhaust hood frosted over in my setup. This was a cumulative thing that took a few days. This showed up as very low efficiency (exhaust air flow over the core was quite low) which I noticed in the dashboard. To address this, I added a rule that runs the system in exhaust only mode at 80% speed at 2pm for 10 minutes if temps are below -20C. This makes sure that the exhaust port is kept clear of accumulating frost. Works like a charm.
On reliability, there is no question that an integrated system adds complexity every time you bring a system/sensors into the collection. Keeping things separate and dumb from a manufacturer's point of view makes total sense. However, as IAQ education increases and we become increasingly comfortable (good or bad) with complexity, consumer acceptance also increases.
I think I at once totally agree but also have no idea what you’re saying Bill 😉
From a UX perspective, it makes no sense to me why everything is not integrated. Some of the worst product and interface design I’ve ever seen… this equipment is not cheap but the companies have spent no money trying to make the systems more functional for users.
Fill me in… home PLC and PID loops?!
PLC (programable logic controller) is basically a programmable system, a simpler version of say my Hubitat hub. A PID loop is essentially control logic that actively adjusts a parameter to get to a desired set point. I do this with my heating setup for example. Sensors at the HRV report the temperature of air after the exchanger, and the current CFM setting on the fans. The Hubitat hub evaluates this every time there is a temperature change, then uses a simple equation (watts required to achieve the desired temp vs actual temp at a given air flow) to set the heaters to the correct wattage. Another example of a PID loop would be to sample CO2 levels, then set both exhaust and intake fans to maintain a desired Co2 level set point. This is not so different from a modulating EC gas furnace that can vary the BTU output and fan behaviour based on demand. An auto balancing ERV/HRV uses a PID loop to balance air flow after the desired ventilation rate is set by monitoring power to the fans, and comparing that to an internal lookup table of fan power vs CFM, then adjusting power to match that CFM setting for both supply and exhaust fans.