Filtration and humidification with mini-split systems
Terry121
| Posted in Mechanicals on
I have a customer with allergies. Her existing GFA furnace has a high efficiency filter and a humidifier.
In the new (air sealed and super insulated) home we are designing for her, we are planning to use Fujitsu mini-splits for heating and cooling and a Honeywell ERV for ventilation. Specs for these units indicate a washable filter but no MERV rating.
I will talk her out of the humidification because it should not be necessary and will only cause problems. But what about air filtration? I am not aware of any high-efficiency filters for these units. How are others handling this? We are in zone 5.
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Replies
Terry,
Check out this thread on the topic:
https://www.greenbuildingadvisor.com/community/forum/mechanicals/26830/erv-filter-merv-13-or-greater
Terry,
More relevant links:
Venmar - MERV 8:
http://www.venmar.ca/DATA/DOCUMENT/71_3_us.pdf
Venmar - MERV 8:
http://www.master.ca/documents/Specs_sheet_vanee_THSF_104.pdf
Venmar - MERV 12:
http://www.venmar.ca/214-accessories-pleated-filter-kit-merv-12.html#!prettyPhoto
Why not use a Room air purifier that uses a hepa filter. Austin air makes room air purifiers that have a lot more chemical absorbing charcoal along with the HEPA filter. I think the small unit has about 7.5 lbs and 15 lbs in the larger unit of charcoal. Filter life is 5 years so the lifetime cost of the units are better than you think. We sell them and people have been happy with them.
I know the US government has them in some offices around here.
http://austinair.com/
I would be happy to answer any questions about them
Your can get a MERV 13 filter with a Zehnder HRV. If the Honeywell unit doesn't have good enough filtration, she needs a different HRV. If her allergies are significant, spending more money on cleaner air would seem a logically high priority.
Thanks Martin and Robert,
I was looking at Venmar's website. They have an HRV with HEPA filtration and MERV 12 filtration available for some models but the nearest dealer is almost 3 hours away from us.
My larger question though is this; Will a good filter on an H/ERV be adequate to filter air for the whole house? Obviously it will filter what is coming in from the outside. With an ERV we are only exhausting air from 3 locations as opposed to a conventional forced air system pulling return air from almost every room and using a much more powerful fan.
I'm just wondering if anyone has had experience with these types of systems (mini-splits plus H/ERVs) and people with allergies?
Have they been happy with them or have they needed to add stand alone filters like Robert is talking about?
Terry
the hrv is going to be filtering the air coming into the house but not recirculating air. A room air purifier will recirculate the air in the house.
HEPA filters will filter the particulates out of the air. But there are gases to from building products, cleaners, furniture, etc. For that you need a charcoal filter. The Austin has the largest charcoal filter that I know of.
The units have 3 fan speeds and have air flows of 31/63/125 CFM or 47/125/250CFM depending on fan speed and unit size. Watts are 25/41/80 or 56/83/135 again depending on fan speed. Under most circumstances you would have it running on the low to med fan.
A good thing about a tighter house is that it keeps the filtered air inside. The smaller unit coverage is 750 sf and the larger is 1500sf. On a tighter house you might increase the coverage as the filtered air is being retained.
Let me know if you have any questions.