Improperly Sized HVAC Equipment
Besides putting ducts in the attic, the next biggest mistake builders in hot climates make is allowing HVAC contractors to install oversized air conditioning units. Air conditioners that are too large for a home don’t run long enough to provide dehumidification, which can lead to a damp and moldy house, according to this Energy Vanguard article. The issue is a problem in well-insulated homes especially, Seville says, because a tighter interiors don’t require as much cooling.
“I’ve had arguments with engineers insisting that they were putting way too large AC systems in,” says Seville. “You have to make sure the home is tied into an air conditioner that’s not too large to dehumidify.”
To prevent this
problem, builders should make sure their trade partners are using Manual J
calculations for heating and cooling loads. This article talks about how to avoid common errors in the
calculations. But even if the system is perfectly matched to the total load,
there’s another concern to look out for: a mismatch between the supply and the
return sides of the system. This can make individual rooms too hot or too cold,
and it can cause leakage of conditioned air to the attic or the outdoors. So here’s
some advice on the final step in HVAC design: balancing the system.
