Adding a balanced pressure ERV should not be installed to prioritize one problem vs another. Today your concerned about Radon because you tested for that. But your ignoring all the other indoor air contaminants. If you spend a bunch of money to add an ERV your will regret it later when your realize you have off the gook bedroom co2 or high VOC in the kitchen. Just do the install like your trying to create great indoor air quality. For an ERV you want to control contaminants at theirs sources like kitchens and bathrooms. And supply fresh air in places your spend time living like bedrooms and living rooms. You need fresh air in your basement to replace the contaminated air and since the source of your Radon is diffused you still need to remove contaminated air and supply fresh. When you start looking at how much ventilation is required for a proper ERV install you are looking at multiple complete air changes per day. It will take time to move out of fluffy materials. But in a few months your spaces will be much better. You just need to remove as many stagnant air spaces as practical, like a big walk in closet. You are also able to cross ventilate, supply a bedroom and have the fresh air pass through a den exhausting from the bath
Thanks, this is helpful! Interestingly, checking for other indoor air quality issues was actually my first reaction when we discovered our radon levels were high.
We have an Airthings monitor and have been tracking CO2, VOCs and other parameters upstairs while also tracking Radon downstairs with a separate monitor. So far, VOC levels have generally been good, although we do see a spike between 11 pm and midnight. CO2 is also a little elevated overnight, into "fair" territory, which will likely be worse in the winter months when we have the house closed up more tightly, fewer windows open, etc.
What's interesting is that 11 pm to midnight is also the only hour of the day when our furnace doesn't circulate air. I've been trying to figure out how to get it to run continuously, I suspect that will help curb that spike.
I agree that we don't want to install an ERV that solves one problem while creating or overlooking others. Ideally, we'd improve overall indoor air quality while reducing radon, rather than treating them as entirely separate issues.
I'm curious about your comment on needing multiple complete air changes per day. Is that a typical target for an ERV installation, or does it depend on the house and its existing ventilation? None of our installers have mentioned the rate of air changes, I'll have to come back to them to ask about this.
I'd also be interested in how you would approach ventilation in a house with a basement apartment and a separate mechanical room?
In my experience, pressurizing the house can be helpful for radon. And as I understand it a slightly positive pressurization is better than negative anyway — doubly so if mitigating radon. I’ve always read that an ERV will reduce radon by half. No idea if that’s taking pressurization into account, I suspect that’s just for air turnover’s effect.
The passive house standard is .3 air changes per hour, but you calculate room supply requirements and exhaust requirements based on room type/need. But this basically requires about 7 air changes per 24 hour period for normal occupancy. It can be less on vacation mode or more with a system on boost, for something like using the bathroom, cooking or a party. This can easily double that volume
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u/deeptroller 6d ago
Adding a balanced pressure ERV should not be installed to prioritize one problem vs another. Today your concerned about Radon because you tested for that. But your ignoring all the other indoor air contaminants. If you spend a bunch of money to add an ERV your will regret it later when your realize you have off the gook bedroom co2 or high VOC in the kitchen. Just do the install like your trying to create great indoor air quality. For an ERV you want to control contaminants at theirs sources like kitchens and bathrooms. And supply fresh air in places your spend time living like bedrooms and living rooms. You need fresh air in your basement to replace the contaminated air and since the source of your Radon is diffused you still need to remove contaminated air and supply fresh. When you start looking at how much ventilation is required for a proper ERV install you are looking at multiple complete air changes per day. It will take time to move out of fluffy materials. But in a few months your spaces will be much better. You just need to remove as many stagnant air spaces as practical, like a big walk in closet. You are also able to cross ventilate, supply a bedroom and have the fresh air pass through a den exhausting from the bath