Air quality: HRV/ERV/Filter
LNCO
| Posted in General Questions on
Hello, we are in the proceess of replacing our 17 year old HRV and seek/need direction.
Our little guy has bad seasonal alergies, including to mold and dust. Windows are closed all year long. We want the new system to filter allergens/dust. We’re unsure if filters on newer HRV/ERV are efficient and sufficient or if they need help from an air filter.
With this in mind, are there brands we should pay more attention to? We live in Canada if that helps. We have a gaz furnace with ducts. Don’t mind changing the furnace if it can help improve the air quality.
Last, have you heard of the brand Greentek from Canada?
with thanks
Helene
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Replies
I run a Fantech FB inline filter box on my ERV for similar reasons. Some better units do come with hepa filters but these are quite small and fairly expensive to replace. The MERV 13 ones for the FB are a couple of dollars each in a 3 pack and a filter is usually good for a year.
Replacing the furnace is not needed, but if it has a filter box that takes 1" filters, replacing it with one that takes 4" ones would be worth it. The 4" filters have a larger surface area which means you can run a finer filter (such as MERV 11) and not choke the blower. The 4" units are also better sealed so less bypass.
During ragweed season, I also run my ERV unbalanced to slightly pressurize the house. This mostly works well in a tight house as it ensure that all the air that comes in goes through the ERV+filter. DON'T DO THIS IN THE WINTER TIME, positive pressure pushes interior air into your walls and can create issues with condensation.
Getting an air quality meter with a PM2.5 readout is a good way to see how things are running now and to dial in the new setup. PM2.5 is much finer than pollen, but anything that lowers Pm2.5 also removes pollen/mold.
Akos, have you ever checked the pressure drop on your Fantech filter box vs cfm? I've been looking at this model as it is the right form factor and filtration I am looking for. The spec sheet shows a higher than expected pressure drop vs a typical filter only spec. It may be that there is a big penalty from the filter tilted over that far. I am curious what the actual is performance is?
https://www.hvacquick.com/catalog_files/Fantech_FB_Filter_Box_Catalog.pdf
These are another option, but hey seem more difficult to insulate, which is important.
https://www.hvacquick.com/products/residential/Air-Filters/Inline-Filter-Boxes/HVACQuick-CFB-Series-MERV-13-Inline-Filter-Boxes
For the OP, the Pansonic FV-10VE1 has an option for a Merv-13 internal filter.
https://na.panasonic.com/us/home-and-building-solutions/ventilation-indoor-air-quality/energy-recovery-ventilators/intelli-0
The filters are more expensive than I like, but that is more a pet peeve of mine than a deal breaker.
My ERV has no problems pushing 95cfm on boost through the filter. The drop is around 0.1", the filter is not original though.
Outdoor air is usually cleaner than indoor air (an interesting fact), so you might want to check to be sure the things you’re trying to keep out aren’t actually coming from INSIDE your house.
MERV 13 is about the best normal air filter rating you can get. Aprilaire has some MERV 16 filters available now, and some with activated carbon in them, but they’re expensive and only available for their furnace filter units.
My mom has had chronic allergy issues for decades. She’s used an electrostatic air filter for a long time. Electrostatic filters can be washed, so they are essentially reusable forever, and they can get very fine particulates. The downside is they are expensive and only available in a few sizes so probably not for an HRV. An electrostatic air filter after a MERV 13 pleated filter would probably be the best possible filtration option for you if you have family members with chronic issues or extreme sensitivities.
Bill
Thank you for your replies, much appreciated.
Akos: our furnace uses 1inch filter. We've started using hepa filters but can hear the furnace work harder. Hubby was also discussing measuring the air quality. We'll look into that. Will also look into Fantech.
Matt: will review your links.
Zephyr7: yes! Good to be reminded. We are planning to have testing done before the allergy season kicks in. We'll look into your suggestions.
Thank you again.
If you have enough space modify your filter slot to handle a 4” pleated filter, you’ll see much less back pressure even with a HEPA filter.
1” filters just don’t have enough filter media to be able to offer low back pressures in the higher efficiency (better filtration) filter ratings.
Bill
What Zephr7 said.
The 4" & 6" pleated filters don't have to be replaced more than about once per year too.
Interesting. I didn’t know we could modify the filter slot. Definitely worth trying.
I was researching the Fantech product line and found out it is owned by Systemair who also bought Greentek. Small world.
I have enough info to continue my research. Thanks everyone for your valuable feedback.
Helene