Not recommended. With a return in there and the supply closed off, depending on how much air can get under the door, you are actually creating a negative pressure in the room which can pull in cold air from cracks and around windows, depending on how sealed up the room is.

Even worse, the negative pressure is hard on your blower motor and may lead to premature failure.

There is no "one size fit's all" answer. One way to know the answer is by calculating duct size,diameters,bends and blower capacity. It is far simpler to have a tech make simple tests. What makes you believe ineffecient system performance isn't at fault?

There are conditions that call for auxillary heat. Yes it costs more in operating costs but what is inside comfort worth? I really don't understand the point of this thread.

If you don't want the heat strips to operate, just cut them off at the breaker and sacrifice comfort. Aux heat is usually placed on a separate circuit.

And yes, I am opposed to closing doors and vents particularly that have a cold air return. Now if you have dampers in your supply runs, yes go ahead and adjust but definitely not close.

IMO

This post was edited by tigerdunes on Thu, Jan 8, 15 at 7:15

Thanks.
tigerdunes.......what is the point of this thread? Just what I asked. There's no one living in that room and I'm of the generation that doesn't want to waste heat if it isn't really needed. Just wanted to understand how it would affect things if it has a return vent in that room.

klem......This happened last year during a terribly cold spell too. The tech said it wasn't unusual for a geothermal. We're not uncomfortable.......I was just curious about closing off rooms to help make the ones we're living in more comfy.

If I set the geo to, say, 66, it seems to only be able to heat up to 63 or 64. If I set the temp higher, the aux heat comes on, which I'm trying to avoid.

Our geo installer likes to put in slightly smaller units, so that we don't have a.c. in the summer, but not enough dehumidification with it. Other than this little glitch when temps are -0, we are more than happy with our system.