Help! - We're still in the HVAC planning stage, a 16 seer Trane. (...

HOMEOWNER CRIES FOR HELP...

posted: September 8th, 2008 - 2:04pm

QUESTION:
We're still in the HVAC planning stage, a 16 seer Trane. (2,975 sq. ft. foam insulation, unvented attic, heat load calc. recommendation 5 ton) The installer is recommeneding 2 units. He says we will need 2 energy recovery ventilators (one per unit), plus a ventilation fan in the attic to get rid of the sweating of the unit that goes in there. Does this sound right? Thanks!

ANSWER: One 130-180 CFM ERV (energy recovery ventilator) incorporated into the main HVAC unit is fine. (The air will blend in the house).
If for some reason you did want two, you could go with two smaller ones in the 60-90 CFM range Wouldn't make sense to me though to double the penetrations outside and service required. With regards to the fan in the attic, if you are going with a ridge vent, soffit vents and my recommendation of a solar barrier, adding a fan will disrupt the designed flow and can actually raise the attic temp by short cycling the air from the ridge vent right into the fan.