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What should I do about improper installation of an air exchanger?

Wats068 | Posted in General Questions on

A year and 4 days ago, we moved into a brand new house. Installed already was a Venmar AVS air exchanger. Immediately we found that the house always felt cold. Being a newly constructed house, and our first winter in the house, we thought that we just needed to ‘let the house warm up’ and remove the humidity. We left the air exchanger on the setting that was recommended by the installer. We found that the house, and basement especially always felt cold. The windows constantly have condensation on them, and it is difficult to breathe. We asked many questions and had technicians in to be sure everything was working properly. During the summer months, we found the opposite. The house always felt too hot and our AC could not keep up with cooling the house. Again, we had it inspected and they determined that our AC unit was the correct size for our one-story bungalow and that we should have no problems. Now this winter, we have been feeling the same coolness throughout the house. Upon closer inspection by my husband, he found that the ‘Fresh’ air pipe that comes from the air exchanger was not connected to ANYTHING. It is blowing cold air from outside directly into our basement. The company has a technician coming to the house tomorrow, and I want to be educated before he comes. Any thoughts? Could this lack of fresh air being distributed in an air-tight house also be the problem that has been causing my son and I to be sick so often?

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  1. GBA Editor
    Martin Holladay | | #1

    C Wat,
    I'm sorry to hear about the disconnected duct. If the HRV has been "blowing cold air from outside directly into our basement," your house has probably been getting plenty of fresh air. But it's hard to know without visiting your house and measuring the air flow through the duct.

  2. Wats068 | | #2

    Is the fresh air in the basement being distributed throughout the house when the furnace turns on then? How would this have passed an inspection by both the installer and the municipality since it was a new build?

  3. Expert Member
    ARMANDO COBO | | #3

    This could be several different things, or maybe not just the air exchanger, but a combination of issues. How tight is your building envelope, any testing done? What are your wall and roof/ceiling assemblies? What type of insulations you have and quality of installation? What’s your climate zone? When you say the AC was inspected and sized correctly, who inspect it? The same guys that designed and installed the system? Must HVAC systems are grossly oversized and underperforming! Have you thought about getting an Energy Rater involved?

  4. davidmeiland | | #4

    I'm confused. It sounds like your HRV was not connected correctly, and was blowing outdoor air directly into the house. That would explain it being too cold in winter and being too hot in summer, but why do you write "it is difficult to breathe"? You also state that you and your son have been sick often. Do you think that excess fresh air is the problem, or is it being cold, or what? There are a lot of potential irritants in a new house (or in any house) and the ventilation equipment could be part of the cause, or it could be unrelated.

    I would also like the information Armando has asked for above, and would like to restate his suggestion that you involve an Energy Rater, although I would suggest that you are looking for a BPI-certified energy auditor, a highly skilled home inspector, or someone similar who can evaluate the entire home and identify the issues.

    I doubt you can get a proper solution directly from the HVAC contractor, and I KNOW you can't rely on the code inspector to make sure every single thing is done right.

  5. mrgregpittman | | #5

    The fresh air comes in the basement hows it distributed to your room? Also as im not sure what could be the exact problem. I suggest follow what David said.

  6. Wats068 | | #6

    Thank you for your comments. I'm not quite sure how to answer your questions, but I will try.
    How tight is the building envelope? If I understand 'building envelope', I guess it's quite tight. We have a poured concrete foundation insulated with the pink insulation and a vapour barrier over everything with a black adhesive at all edges. There was condensation under the plastic barrier for most of the summer and the builder insisted this was fine and that it would eventually go away. We kept an eye on it, and it did eventually 'go away'. Where to? I'm not sure.
    We have had no testing done. Any time anything was inspected, it was either the municipality or the contractors themselves.
    Wall and roof/ceiling assemblies? We are an end unit of a town house with three outside walls insulated with the regular pink insulation. For soundproofing, the wall joining our neighbour is cinder block to the highest point. Our ceilings are 9ft upstairs with unfinished ceilings in the basement. Our builder informed us that we have a higher than normal grade roof assembly, but I can't remember what he said it was.
    Climate Zone? Eastern Ontario. Hot summers and very cold, long winters.
    We have not yet thought of having an Energy Rater come in. I'm not even sure the process of doing so and who I would contact in my area. I will google this.
    Referring to 'it is difficult to breathe', I was more referring to when the air exchanger is on. I have controlled asthma and while the unit is on, I find my breathing laboured. I have no idea what the change is, it just is.
    As for my son and I being sick more often, you are certainly right that it could be unrelated, but we were fine in our old house and have been sick much more often here. We live in the same city, so that part is constant. I suspect it could be the moisture on the windows, or elsewhere in the house potentially causing mold, or because we have been compensating for the cold air by turning up the furnace. I really am not sure.
    Since finding this problem, we have not run the air exchanger, and our windows have significantly condensed. We have 3-4 inches of condensation rising from the bottom of our windows, and we have not boiled water for cooking, or anything. Even showers have been short.
    Lastly, to answer Greg's question about the fresh air in the basement being distributed, it's not. The 'fresh air' pipe leads nowhere. It blows into the basement, and I assume that it is distributed throughout the basement purely by diffusion. It it gets distributed to the main floor at all, it's because it comes up the open stair case. (There is a half-wall in the middle of our house that the stairs go behind to reach the basement. It is completely open. I'm not sure if this makes a difference.)

    Thank you again for your replies! The HVAC technician is supposed to be here this afternoon. I will post again and relay the information I get from him.

  7. GBA Editor
    Martin Holladay | | #7

    C Wat,
    Well, that explains the condensation... it's happening because you turned off the HRV.

    Maybe all that is necessary is that the HRV needs to be properly ducted -- and it needs to be turned on, occasionally, whenever you notice that your windows have condensation.

  8. Wats068 | | #8

    It does explain the condensation. However, we had been running the HRV at the recommended level, and set to the correct outside temperature for the past year, and we still can't seem to keep the windows dry. When we run the unit on Maximum for 4 or 5 days, the windows eventually clear up, but the furnace runs almost non-stop and it still feels cool and drafty.
    After speaking with our neighbours (in the same town house unit, two doors down), I realized that they have the same 'open' fresh air pipe in their basement as well. I have been researching online and have even called the manufacturer about proper installation and it seems that the unit was installed incorrectly. I do hope that I get answers today that proper ducting will allow us to run the HRV and clear the windows and have fresh air circulating.
    I guess when we purchased this brand new house we may have set our expectations too high in hoping for fewer problems than in an older house.
    Thank you.

  9. GBA Editor
    Martin Holladay | | #9

    C Wat,
    I don't know what you mean by an 'open' fresh air pipe. An HRV has 4 ducts: one brings outdoor air to the unit; one distributes fresh air to open grilles in your house (or conceivably, your basement, if the designer saw a reason to deliver fresh air there); one pulls stale air from bathrooms or other locations in your home; and one sends exhaust air out of the house.

    If you have a disconnected duct, that would explain why your ventilation system isn't working well. If all of your ducts are properly connected, remember that you don't have to operate your HRV for 24 hours a day if you don't want to. It's your house. Just run it as many minutes or hours as you want to.

  10. Wats068 | | #10

    One of the four ducts from the HRV that has handwriting on it that says "fresh" is not connected to anything. Two of the four have insulation around them and they lead outside. I assume that one is to bring air in and the other is to exhaust stale air. A third duct is connected to the bathroom and kitchen (to pull stale air). And the fourth is connected to the unit, turns up toward the ceiling, crosses the top of the unit, turns a very small corner, and ends. It is not connected. The end is unfinished with no grill and is at the very top of the ceiling pointed toward a floor joist. it is not pointed in any direction that would indicate this was done on purpose to distribute air in the basement. If it was, it was poorly done and I see no point in distributing air in the basement when we live on the main floor and that is where the fresh air is needed. The technician should be here soon. I will see what he says and comment later.

    I'm sorry for making things seem so confusing. I think that there are a few factors at play here and I am trying to understand them myself. Thank you for taking the time to continue helping me.

  11. davidmeiland | | #11

    C Wat, how about taking some photos and posting them here? I would like to see a few of the furnace or other heating and water heating equipment, the "fresh air duct", the HRV itself and at least a few of the various rooms where the ducts go, and so on. Anything and everything mechanical...

    I don't know what the HVAC tech is coming to inspect, but it seems like he should probably perform combustion safety testing (draft, spillage, and CO measurements) on any gas appliances (furnace, water heater, etc). Your description of the "fresh air duct" makes me wonder if you have natural draft gas appliance(s) and the duct is to provide combustion air to them. I'm not sure what's common in Canada.

    Do a Google search for "energy auditor" or "energy rater" or "building performance contractor" using the name of your town, and see what turns up. You want someone who will use a blower door, possibly a duct tester, tools for measuring temperature and humidity, moisture meters for wood and other materials, tools for inspecting gas appliances (combustion analyzer and CO meter), and stuff like that. A HVAC tech might have part of that kit, but is not likely to have all of it. You need someone who can figure out the source(s) of the moisture, determine what if any ventilation is needed and how to get it, determine that the heating equipment is working right, and so on.

    Last thing, a new house is likely to have a lot of low-level pollutants in it. The plywood, the paint, the carpet, the wood and floor finishes, the furniture... it all has chemicals in it that are slowly released into the environment, including inside the house. In an older house, a lot of those chemicals have already dispersed, if they were ever there to begin with. In a new house, you have higher levels, and if you are sensitive, it may be a problem. Do you feel better if you stay out of the house for several hours? Any other changes, such as working in a new office, etc.?

  12. Expert Member
    ARMANDO COBO | | #12

    I hate to be a pessimist on your house, but the more you describe your construction, the more issues come to mind, and the HRV maybe only a small part of your problems.
    From my understanding, it appears you have a “typically” constructed house; leaky, drafty, with “regular pink insulation” batts (?) that is installed wrong 99% of the time, with an HVAC system that is probably grossly oversized and bad installation. As I mentioned before, I would suggest you hire a third party INDEPENDET rater/auditor so they can provide you with an UNBIASED assessment of ALL your problems.

  13. davidmeiland | | #13

    Here's a possible place to look for the right sort of technician...

  14. davidmeiland | | #14

    Your description of the HRV ducting is not clear to me. In your post #10, your first sentence describes a duct "from the HRV" that is "not connected to anything". Is it in fact connected to the HRV? Is it connected to the HRV port that supplies incoming, tempered air to the house? Is it the same duct you describe a bit later as being "pointed toward a floor joist"?

    Pictures would really help.

  15. Wats068 | | #15

    Sorry. In post #10, the duct not connected to anything is the 'fourth' duct that I describe later on in the same post. It is the one connected to the unit, labelled 'fresh', but points toward a floor joist with nothing on the end. No grill, nothing. Just the end of an open duct that I could put my arm into.

    Thank you for the link. I checked and the closest of those listed is two hours from here. I am currently searching the other 'auditors' and such you suggested.

  16. Wats068 | | #16

    I will post photos later today.

  17. Wats068 | | #17

    Here are some pictures. The first is a close-up of the end of the duct labelled 'fresh air'.
    The second is a larger view of where this duct ends. You can see a small portion of the duct above the two running perpendicular to it. There are two wires in front of it.
    The third is our HRV.
    The fourth is our bedroom window this morning. The parts in the corner are ice and frost.

  18. davidmeiland | | #18

    Well, you have a good puzzle there. Maybe the mechanical designer (if any) intended the forced air heating system to distribute fresh air in the house, but I personally have not seen that, I've only seen HRVs installed with their own dedicated ductwork for supply and exhaust. Is there a return air opening for the heating system in the basement?

    It looks like you have a closed combustion furnace, which is good. There should be one or two white plastic caps on the roof or outside wall, with steam coming out at times. Where is the water heater and what does it look like? Photo? What else is using gas in your house, and what other mechanical equipment is there?

    The picture of the frost and ice is impressive. There is far too much humidity in the house, and/or too much air leakage around your windows. If I had to take a guess at this point, I would look for moisture coming from the concrete floor and walls in the basement, and from the concrete block wall separating the units, as well as from the other construction materials that might have been wet during/after installation (framing lumber). The condensation trapped behind the vapor barrier may be contributing, or it may have gone away. That should be checked, unfortunately by drilling some inspection holes.

    This is all assuming the HRV is working somewhat correctly, in spite of the goofy supply duct in the basement. Someone needs to confirm that the exhaust inlets are in fact pulling air and moving it outside, and that there is no source of moisture getting inside the ducts. At this time of year, the HRV should easily be drying the indoor air, if it's working right. In your climate, it will need to periodically defrost, is it doing this and where is the drain going? Maybe you can get a Venmar tech rep to visit your house and independently check the installation.

    Let us know what the HVAC guy has to say.

  19. GBA Editor
    Martin Holladay | | #19

    The condensation isn't so puzzling if you read what C. Wat wrote in Comment #6: "Since finding this problem, we have not run the air exchanger, and our windows have significantly condensed."

  20. Wats068 | | #20

    The windows were full of condensation before we stopped running the HRV. We only stopped on the advice of the company whose technician is coming today to see if the duct should in fact be left open as it is, or if it should have been connected to the furnace to re-distribute the air throughout the house. It is a constant battle with the HRV and the humidity in the house. Even running the HRV at its max, we experience condensation on the windows. They very rarely dry up. If they do, it is because the HRV has been running on MAX for nearly a week.
    Here is another picture of the basement set up. I have no others on my computer at this time and will wait until the technician comes.
    Thanks again.

  21. davidmeiland | | #21

    Martin, don't forget, I live in a wimpy 5200 HDD climate. We don't get ice on our windows, so I'm not used to seeing what's in the pic. It sounds like there was excess humidity even with the HRV running (although probably running too much), and then there's the difficulty breathing mentioned.

  22. Wats068 | | #22

    The only things using gas in the house are the furnace and water heater.

    There is a return air-opening in the basement. We have two sets of grills in both bedrooms - one under the window and another on the opposite side of the bedroom. I believe they are cold-air returns. There is another cold-air return in the main living room at the top of the basement stairs. They all lead to the same duct in the basement.

    The unit does not seem to be iced up. There are two clear drain hoses attached to the underside of the unit and they lead to a hole in our basement floor.

  23. GBA Editor
    Martin Holladay | | #23

    C. Wat,
    More bad news: if the HRV is in your basement, then the basement wall in the background was insulated wrong.

    First of all, the batts shouldn't be covered with polyethylene.

    Second, you don't want to have any batts on a basement wall -- unless of course there is a 2-inch layer of rigid foam between the studs and the cold concrete wall. I hope the foam is there!

  24. davidmeiland | | #24

    Yikes, Martin is right about the walls.

    With the HRV set up as it is, it's moving basement air up into the house whenever it runs. That can't be helping.

  25. Wats068 | | #25

    The technician came and it turns out that the 'fresh air' duct is connected to the furnace, but a significant proportion of the fresh air is blown into the basement instead of the small 'T' connection that goes to the furnace. He set our HRV to what he thought was correct and said he would return on Monday to see if it has improved our condensation problem. He said that we should leave it as is and possibly run a humidifier in our bedrooms at night to compensate for the dryness. To me, this seems contradictory to what the HRV is supposed to do. I am unsure as to how I will find a balance between keeping the windows dry and not my throat.
    I suppose now I will look into the basement walls. Hahaha. Thanks, guys. (What I was told by the builder is that the plastic surrounding the insulation in the basement is a 'new code' they have to follow. It is wrapped around the three outside walls leaving the shared wall open. It is behind this vapour barrier that we found a TON of condensation last summer.)

  26. davidmeiland | | #26

    I wouldn't run a humidifier unless you can absolutely confirm that the air in the house is already very dry. Did the technician take an temperature/humidity readings? I would be more inclined to run a DEhumidifier in the basement, based on information you've given.

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