Folklore or Fact

[Mark P]

Folklore or Fact

An a/c works more efficiently when placed in the shade. I have always heard this, but I have doubts that it is true. One web site stated placing the a/c in the shade will save 10% in electric bills.

Next week I’m having a new heat pump installed. My current unit sits in a nice shady corner that gets almost no sun, but is directly in front of the cloths dryer vent. I’m considering moving the new unit (because of the dryer vent) to the east side of the house that will get full AM sun, but no dryer lint.

Since it is a heat pump I’m thinking the sun will help it during the winter months.

Are there any facts that support where or where not to locate an a/c / heat pump?

[Scottpat]

It will help a conventional A/C. With a heat pump, logic would tell me that it won't make much difference in the heat mode. If it is in the sun, Yes the metal on the unit will get warm but the air is still cool. The HP recovers what heat it can from the air, not the metal around the unit. Air temp is what you are looking at.

The A/C cools itself with the air, so a lower air temp would make a difference for cooling. I don't know how much difference, but I would not spend a great deal of money moving a unit just to put it in the shade or the sun. The cost of running lines, etc might outweigh any gain in efficiency.

[Jim Katen]

Originally posted by AHIS

Folklore or Fact

An a/c works more efficiently when placed in the shade. I have always heard this, but I have doubts that it is true. One web site stated placing the a/c in the shade will save 10% in electric bills.

Next week I’m having a new heat pump installed. My current unit sits in a nice shady corner that gets almost no sun, but is directly in front of the cloths dryer vent. I’m considering moving the new unit (because of the dryer vent) to the east side of the house that will get full AM sun, but no dryer lint.

Since it is a heat pump I’m thinking the sun will help it during the winter months.

Are there any facts that support where or where not to locate an a/c / heat pump?

That's an interesting question. I don't have any facts.

If I had to guess, however, I'd say that it would make a difference. No matter how much air you're drawing through it, there will still be a distinct amount of heat transferred to the coil via incident solar radiation. In the cooling mode, this heat will work against the system and in the heating mode it'll work with the system.

Here in Oregon I have two heat pumps both on the north side of my house and both in permanent shade. I figure this is the best location because in the summer they aren't affected by solar radiation and in the winter, there isn't enough solar radiation to matter anyway.

I couldn't begin to predict how much of a difference shade would make. You'd need to do some very carefully controlled studies to quantify that. It's the sort of experiment that might yield surprising results.

- Jim Katen, Oregon