heat pump vs. straight cool compressors

[JWB]

What are the significant differences? Had a customer I suspect bought a compressor off ebay and had a 'friend' install it in a heatpump. wondered if it may have failed because it wasn't correct. That got me thinking, what if any are the differences between heat pump and strait cool compressors?

[hvacvegas]

What are the significant differences? Had a customer I suspect bought a compressor off ebay and had a 'friend' install it in a heatpump. wondered if it may have failed because it wasn't correct. That got me thinking, what if any are the differences between heat pump and strait cool compressors?

Alot of heat pump compressors come with sump heaters, while alot of AC don't.

Different ports, that kind stuff. (shooting in the dark here.)

You look for the obvious? Like unit says "copeland scoll" and it's got a recip in it?

[cjpwalker]

No differences that I can think of... a heat pump compressor doesn't do anything that an AC compressor does - it pumps cool, low pressure superheated vapor into high temperature, hi pressure superheated vapor regardless of heating or cooling. The other components of the system make it a heat pump.

Now, that being said, every heat pump is engineered for a specific compressor, and if a different compressor is used - the wrong size, for example, and if that compressor is put installed improperly then there are a lot of reasons as to why that compressor could fail. If the cause of the original compressor's failure was not corrected then the new one will likely fail as well.

[karsthuntr]

If the cause of the original compressor's failure was not corrected then the new one will likely fail as well.


This is why 90% of replacement compressors fail.

[JWB]

wow, my manager at work said they were different.
could you add a rev valve and defrost board and oriface to a sc carrier and make it a hp? just askin' i am only 4.5 years into this job. so i really don't know.....

[hvacvegas]

wow, my manager at work said they were different.
could you add a rev valve and defrost board and oriface to a sc carrier and make it a hp? just askin' i am only 4.5 years into this job. so i really don't know.....

Might need a different evap to get a "match".
Anyone remember those goodman AC only coils?

Don't forget a receiver, and a crackcase heater.

[John Markl]

IIRC, back in the 70's and 80's, Copeland compressors were different for the two applications. Seems the model numbers were different.

But, I've slept since then. :Faint:

[JWB]

John- Maybe that is what he (my field suppervisor) was thinking of. He is usually right or admits when he doesn't know. We have a bunch of demo/display straight cool 1.5 tons sitting around our shop, and I just happen to have a 1.5 ton heat pump cooling my upstairs, it went out in January. I replaced it with a Trane from a friends shop, but it's about a 1999. I just wanted to mess around and try to make a sc a hp......sounds like I could do it.

[ChaseAir]

This is why 90% of replacement compressors fail.

Not scrolls. They can take some serious abuse compared to recips. Saw one that was flooding for ten years because the evap could not get enough airflow. That is above and beyond the call of duty.

The above unit someone put a 5 ton where a 4 ton was and there was no way to enlarge the return. It was a piston also so superheat was 0 no matter what. Airflow was on high. Static was over 1.3"