DIY heat recovery and ventilation question
Ok..so it’s been a while. We completely destroyed and then rebuilt our 1800s house and aside from some trim and exterior improvements…we have been comfortably living in it now for over a year with many thanks from this site. We used the cut and cobble insulation system combined with blow in with a mooney wall to keep our house very energy efficient. Even in the deep cold of winter our heat bills are below 100 bucks in a 1400 square foot house built over 135 years ago.
The problem is the basement. I’ve insulated and air sealed and have a dehumidifier going constantly but the occasional heavy rain brings some water in and the whole house smells musty coming up from the basement when the house is closed and the AC is on. The house is pretty tight and I have no air exchanger.
I’ve been looking into a fan tech unit and recently been looking into some DIY solutions..one using a length of PVC and some soda cans (i’m sure it can be done better with a small aluminum pipe spaced out inside a larger pvc section).
I’m working on the water intrusion issue but still feel some fresh air would be nice. I didn’t have this problem last year before I replaced all my old original leaky basement windows with glass block and sealed it up.
Does anyone have any experience with the DIY HRV or ERV units? Thanks much
G
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Replies
I may add we live in Northern Wisconsin and have a fieldstone basement.
Geoffrey,
I've heard of several attempts to build a home-made HRV, and they all ended in failure. The main reason these devices don't work is that tinkerers fail to properly handle condensation -- everything ends up soaking wet -- and fail to anticipate freeze-up problems. (You need a defrost cycle or an electric heater to handle cold temperatures.)
No one makes a homemade refrigerator, although you could try if you wanted. Why bother? Buy one at the store. It's the same with HRVs.
Here is a link to an article that you probably want to read: Fixing a Wet Basement.
Every tight house needs a mechanical ventilation system. For more information, see Designing a Good Ventilation System.
Ok...I don't have the time to rip my house apart again to install duct work for an HRV at the moment. Would installing one in the basement with just basement intake and exhaust work for now to ventilate the basement area? I could tie into my bathroom fan duct work, which is running off one fan but is only 4" duct. Would connecting the HRV to the 4" bathroom ducts (which draw from the 1st and 2nd floor baths) cause any issues? I could then fresh air vent to the basement and 1st floor. I have forced air heat. thanks
Geoffrey
If your basement seems damp, you should do everything you can to limit moisture entry into your basement. This article describes what you need to do: Fixing a Wet Basement.
Assuming that you have at least taken a stab a reducing water entry, you may want to install a ventilation system. It's worth pointing out, however, that operating a ventilation system during the summer is likely to increase, not decrease, the amount of moisture in your basement. (During the summer, if your goal is to reduce indoor moisture levels, operating a dehumidifier makes more sense than operating a ventilation system.)
During the winter, on the other hand, operating a ventilation system can lower indoor humidity levels.
I'm working on the water intrusion now..but the house is so tight that without the windows open upstairs it gets noticeably stale. This house is completely air sealed with modern windows..the entire envelope walls and ceiling is spray foamed tight. The final straw for air sealing was replacing the old basement windows with glass block last fall and after that..the winter was splendid and we had to add humidity..this summer has been awful with standing water in the basement even with two humidifiers running..I'm sure getting the water away from the building will help greatly but the air stuffy issue may or may not go away. One side of my house does not have gutters and the water runs directly down the side of the house (where it's wet in the basement)..I'm fixing that this weekend. I have a line on a builder grade HRV for dirt cheap and that's why the urgency :) Thanks for all your help again!!
Geoffrey,
Every tight house needs a mechanical ventilation system. For more information on your options, see this article: Designing a Good Ventilation System.
Gutters and grading will help keep the moisture away from the foundation. My house does not have gutters per se. For aesthetic reasons, I used "in-ground gutters" similar to the example in this article.
Also... Have you considered installing a sump in your basement to remove bulk water?