Best Ventilation Strategy for Improving Indoor Air Quality?
Hi There,
My wife and I want to retrofit a ventilation system for an old house to help with allergies.
Our options seem to be 1) HRV or ERV 2) connected to furnace and existing duct work (not ideal from IAQ perspective) or 3) Lunos. We don’t prefer mini-split because of the mold that can build up—we don’t want to have to be vigilant about cleaning them. Also nixed spot ERV because we’d like more air flow and it doesn’t seem useful without mini-splits.
Our questions:
1. We figured out ASHRAE recommendations, but how would a blower-door test fit in to those calculations to really nail down what we need for her and her husband?
2. The house is located in St. Louis County, Minnesota (Duluth region, climate zone 7). HVAC people install HRVs up there, but it seems like you recommend ERVs with moisture sensors—is that right?
3. Ventilation options
a.) HRV/ERV
Is there any recent solution to make tying an ERV (or HRV) into the furnace less of an energy waster and more robust? It’s a small, 995-square-foot house, but there are two floors. Given how she is in different environments, she seems to also be affected by CO and formaldehyde.
b.) If we go the route of new, dedicated ducting…
i.) We are pretty limited in space and think bulkheads/soffits wouldn’t look right. We could deploy exposed supply ductwork (for an industrial look) in the kitchen, the largest room on the first floor, puncturing through one wall to split into the dining room and another to split into the living room and then up the ceiling into a chute in one room, which would then puncture through the other bedroom. That’s a lot of ducting for a small house in the finished spaces, so we’re wondering if it would be imbalanced if we put the supply duct in one bedroom? And could the return duct go in the bathroom floor or is it better to have it run into the wall so it’s up higher?
ii.) We have read that doing a good job of installing exposed duct can be hard for DIY. Is that pretty true? What professional would we hire that could make it look nice? Do HVAC generalists typically have the skill for exposed ductwork or do we find a finished carpenter who also understand ducts?
c.) Last options are the Lunose2 with a Lunos Ego in bathroom. We saw that 475, supplier of Lunos, has a contact form, so we will write to them about specifics. We’re more wondering if this seems like a good idea, and if anyone in our zone has experience with these in-wall products. Also, because we have two floors and we’re aging, we would like someone to install them but we haven’t found HVAC contractors with experience. If we go with this, do we contact electricians, since it involves electrical?
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Replies
Ken,
A blower door test would give you a reference point for making energy performance improvements. For example, your relative's allergies may be aggravated by dust and pollutants leaking into the house. There is a lot of value in having a strategy to air sealing the structure.
If you are considering minisplits or some other HVAC upgrades, you will want to hire an independent engineer to complete a Manual J (and possibly some other calculations). Alternatively, you can probably come up with your own parameters if you have the time and inclination. Don't rely on the HVAC contractor to properly size the system.
On the ventilation issue, you need to consider filtration. If your relative has allergies and you plan to introduce outside air (a good thing), you will want to capture as many allergens as possible by placing a high-quality filter at the air intake.
FWIW. I would start will the blower door test and air sealing the structure.