New three story ICF construction / Andersen Series A windows, blown insulated attic in coastal area of Delaware. (No basement)
Geothermal HVAC - Two independent ducted zones
Zone 1: Ground Floor + 1st Floor (total square foot = 2,400)
Zone 2: 2nd (top) Floor (total square foot = 3,000)
Floors are connected by 4 foot stairwell "tower" with landings on each floor.
This is a very tight house and needs ventilation.
Builder forgot to install ERV (in spec) until after home was 99% complete, drywall, trim, paint, etc.
Builder/HVAC contractor who installed the Water Furnaces need to retrofit ERV into the home and are recommending that a single ERV be installed and tied into the Zone 1 only. Room Air from ERV would be tied to Return of furnace. Fresh Air from ERV would tied to Supply of furnace. They say the ERV blower may be operated separate from the Furnace Blower.
1) Will one ERV be sufficient to provide adequate air exchange to 2nd floor? They tell me there will be sufficient "mixing" of fresh air via the single stairwell.
2) I've read that it's best to have completely separate ducted ERV system from HVAC, but since this would not be costly, the builder/contractor are recommending to use existing duct. Is this a valid design?
The design recommended is documented n the RenewAire Installation and Operation Manual for Models EV70, 130, 200, 300 in schematic "D" - title: "Furnace Return Air Into Furnace Supply Air".
Thanks in advance for any input on this issue.