I thought I would keep this seperate from my mini-split post.

If I go with the ductless mini-splits I want to add in a stand alone HRV, now I`m sure a lot goes into planning this system but is it something I could do myself. I`ve installed my garage furnace and built my entire house so far so I can usually figure things out with a little help.

 The house will be heated by in-floor, Sip construction, spray foam everywhere else, triple pane windows, etc. I`m trying to stick to the details of keeping it tight. I calculated the cubic feet per floor minus about 5-10% for walls:

Upper-13500 ft³
Main- 12100 ft³
Basement- 10450 ft³

I have four bathrooms planned requiring five fans (master is about 150 ft² and 12`foot ceilings).

Does this sound too complicated for a DIY.

Thanks,
Sean

Sean,
Here is a quick calculation to determine the minimum ventilation rate for a house. Total air volume in cubic ft X .35 = minimum exchange rate in Cft/Hr. Most ventilation systems are rate in CFM or cubic feet per minute. so divide the minimum exchange rate by 60 to determine the minimum sizing for the ventilation system. For your house here is the quick calc's.

36,050 X .35 = 12617.5/Hr / 60 = 210.3 this being the minimum exchange needed for you home requirements on a continual basis. 210 CFM of continuious ventilation to meet this requirement. I would double this to meet times when you need additional ventilation. Some people prescribe to ide

Thanks, that seems to make sense from what I've been reading. What is "ide"? So to double this I would probably need two machines I take it as I've only seen them up to 230 CFM. Is there a limit to how many vents are added to each machine? I realize you should add fresh air to any bedroom or living space and take exhaust from the bathrooms and kitchen, is this on top of bathroom vents and kitchen hoods? Thanks again, Sean

sorry hit a wrong button!!

Some people prescribe to the idea of using the bathroom fans to meet the ventilation rate but do not allow for make up air to enter the home. If your house is very tight then the natural air leakage for this to work will not be available. A blower door test can help to determine if the house leaks enough to allow this to work. To aire on the side of caution I would install two seperate systems one to handle the basement and one to handle the first and second floor. dedicated duck work sized to meet the air flow required and balanced return ducks are needed. Not complicated if you know how to properly size and install duct work. allowing for loss of flow factors for corners and length then then you will be able for figure it out. typically 6" returns located in kithen/bath and laundry areas as well as basement. and supplies running to the other areas of the house. They should be sized to handle the air flow requirements for the individual space under the same minimum exchange rate as used to determine total system requirements.
Don't forget that whenever you open your windows the HRV/ERV system does not need to be running, turn it off. In some areas of the country this might be 50% of the time. No need to waste energy on a ventilation system running when nature takes it's course.

Tom Pittsley
[email protected]
www.eebt.org