Looking for ERV recommendations for a new two level ICF residence located at 6800 ft elevation with 6001 HDD base 65 and 0 CDD base 50. Radiant floor heating only. Conditioned living space is 20,000 cf per level plus small amount of conditioned attic due to foaming the roof deck. Lower level is walkout on one side and buried on three. Upper level has garage attached on one side only.
Using total volume * 0.35 ach / 60 min/hour = ~120 cfm flow per level. There are two baths and laundry per level and two bedrooms and great area on each level. Plan on drawing from baths and laundry and supply bedrooms and great area.
Looking for easy to install and maintain system with auto dehumidification boost capability for the bathrooms. Will install in storage room on lower level and conditioned attic space on upper. Prefer side pipes due to limited height in attic space. House as gas fireplaces on each level that vent to the exterior, though currently drawing from the house. Also, large range hood over island stove top with no makeup air. Considering making the house slightly positive pressure.
What do you find that works in the dry southwest at altitude? Remote area with limited HVAC technicians to rely on! Any design considerations we should keep in mind?
Thank you in advance for sharing your knowledge.
I've used the CAR II regulators before. They work, but obviously it's more mechanical moving parts that might fail overtime. I've had good success using simple adjustable diffusers. Diffusers closest to the ERV will be more "closed" and ones farther from the ERV will be more open.
If you give old school HVAC contractors a good ERV strategy outlining duct sizes and locations, they shouldn't have a problem. ERV/HRV systems can be as simple or as complicated as you want to make them. In your strategy (60-120 cfm per floor) I would use 6" trunks off the ERV and 4" branches to 2-3 locations.
ERV-1 operating at 60 cfm continuous and 120 cfm in boost.
Supply: 6" trunk off ERV, 4" branch to bed1, 4" branch to bed2, 4" branch to great room.
Exhaust 6" trunk off ERV, 4" branch to bath1, 4" branch to bath2. Boost timers wired from bathrooms to ERV for increased flow rate.
Two 6" insulated trunks routed to the exterior 6" hoods -- hoods located minimum of 6 ft a part and preferably 4 ft above the exterior ground.
4" adjustable round diffusers (SEIHO) installed at the termination of each branch duct in ceiling. Adjustable to achieve the desired continuous flow rate in that location.
Hard to make a full strategy without seeing the actual floor plans. But this is a pretty standard set up for an ERV in an ICF house. Balanced approach.