Heat Pump Mystery

[tinknocker service tech]

yes your units are to close and it does have an affect on the. I also agree with you second contractor that moving the unit apart isnt going to resolve you real problem
at best it will help the units effiency but you from what you have said have other concerns going on there
make sure the systems are sized correctly and the ductwork is also sized properly this can also cause the units to not operate properly and run you bill up
before moving them and the expense of it find out the real problem fix it and then move the units

[timebuilder]

sorry clicked the wrong one.....

there are alot more factors too. I have a customer that has 2 units side by side, with manufacturer's clearances supported.....But he built two 6 ft privacy fences to hide them on either side (front is open). On a 85 degree day, its about 114 degrees down by the condensers.

Last summer, a church member told me we were having problems with the AC.

Before choir, I walked around the side and saw the problem. Nine CU's, all enclosed by a privacy fence. Several feet of clearance, but it created a heat island with the fence on one side, and the building enclosing the other three sides.

The fence is gone this year. Bingo, all's well.

[wer525]

I found a copy of the engineering data for my model and it states that there must be 24" between multiple units. I'm getting a lot of mixed input. On my poll, 9 have selected "Yes, multiple units installed too close together does effect their efficiency" and only one selected "no". Hoping to get the contractor who installed them to move one of the units about 4 feet to the left (have to accommodate my crawlspace door). Thanks for your input.

[wer525]

Last summer, a church member told me we were having problems with the AC.

Before choir, I walked around the side and saw the problem. Nine CU's, all enclosed by a privacy fence. Several feet of clearance, but it created a heat island with the fence on one side, and the building enclosing the other three sides.

The fence is gone this year. Bingo, all's well.

timebuilder, thanks for sharing that example. Your scenario seems pretty close to what
I'm dealing with - but I don't have fencing around the units or any major obstructions apart from the units being only 8" apart. Not sure if that alone is enough to effect their performance. I spoke to yet another HVAC contractor today and he suggested getting both units running and feel the air expelled from the top of each one. Then, take a sheet of cardboard and insert it between the units while running and see if I can tell a difference in the temperature of the expelled air.

[timebuilder]

timebuilder, thanks for sharing that example. Your scenario seems pretty close to what
I'm dealing with - but I don't have fencing around the units or any major obstructions apart from the units being only 8" apart. Not sure if that alone is enough to effect their performance. I spoke to yet another HVAC contractor today and he suggested getting both units running and feel the air expelled from the top of each one. Then, take a sheet of cardboard and insert it between the units while running and see if I can tell a difference in the temperature of the expelled air.

Have your contractor measure the "delta T" across the coils. That is also key, because if it is high, the air will tend to spill out the end of the fan blades, which can encourage the air to be drawn back in through the coils for another heating.

High delta T will mean a good coil cleaning is in order.

BUT, I feel you root issues are elsewhere, as already mentioned here by others.

[pacnw]

1st, I did not read all the replies, so if this was said ignore it.

I think your question and the answers are a bit backwards/misleading.


"Do multiple Heat Pumps installed too close together work properly?

Yes - does effect performance and efficiency

No - doesn't effect performance or efficiency"

I think the "YES" and "NO" should be reversed, correct?

[skippedover]

I think you've struck on a valid issue but I also think you're spinning your wheels on a red herring. You need to have a highly qualified tech actually come out to your home and evaluate the system. This tech must know about the effects of airflow on system capacity and he must know how to properly charge a system using superheat and/or subcooling. He must be able to spot a dirty condensing unit as well as a dirty indoor coil, dirty blower wheel and closed or obstructed dampers. If he/she is lacking any of these skills, you're wasting your money to have him visit your home. I hate to admit it but you stand about a 1 in 50 chance at best of finding that individual in your area. I wish you success.