Compressor Noise During Low Ambient Cooling

[LibertyTree]

I went on a call where a customer was having compressor noise issues with his York 18 SEER heat pump in cooling mode at low outdoor temperatures. I haven't had much experience with cooling at low ambient, I seemed to be able to reduced the noise a bit by raising the head pressure. If low temps are indeed the cause of the noise, is there an easy way to boost head pressure? I tried to install a low ambient kit a while back to slow fan speed but was either too stupid to make it work, or the equipment might not have been compatible.

[ckartson]

Was it a scroll compressor and 410a refrigerant? They do get louder with low head.

[54regcab]

Customer is concerned about high energy bills so he buys a 18 seer AC. Wont open windows on a cool day....

[LibertyTree]

Yes it is a scroll with 410a. Opening windows won't do. He works for the university and does some sort of plant research. He's got a space with some pretty decent heat load from high powered lights that run year round (and no it's not weed haha). Any help for me guys?

[LibertyTree]

Double post

[beenthere]

That unit is not designed to be used with any type of head control. It says that in the install instructions.

Sounds like you are getting flood back. Might want to see if you can increase the indoor blower speed to evaporate more of the refrigerant.

[Core_d]

could installing a crank case heater help this problem?

[Rob_in_WV]

Would putting a heater on the accumulator(if equipped) be an option to speed up the boiling off of excess refrigerant? Just have one on the compressor that energizes on contactor open and one on the accumulator that energizes when the contactor closes.

[SBKold]

Don't think liquid flood is the issue here. I hope you have a txv indoors. Even then with low ambient the valve should be wide open and still have higher than design SH due to ultra low head.

[jim bergmann]

I have heard a pinging noise/rattle when there is not enough pressure difference across the compressor. The scrolls will start to separate. Happens when the head is to low and the indoor air temp to high. The high efficiency of the coil becomes to high. The equipment might be outside of its design specifications.

[LibertyTree]

This unit has a factory installed crankcase heater. There is also an indoor TXV. Beenthere, I will try to increase blower speed, its certainly worth a shot. Ron, thats an interesting idea. Do they even make such a heater? Jim, I'm afraid you're probably right. At this point I'm just trying to figure out a way to raise the head pressure without getting too ghetto... Thanks for the replies fellas

[VTP99]

What type of low ambient did you try ?

[terpfan_]

A common fan cycle switch would work to control head pressure. Johnson sells a bunch of models compatiable with 410a. A hot gas bypass could also help problem with solenoid to close bypass in heating mode. A combination of both might help as well.

[OldSchoolMech]

For the Ghetto landlords I just put a fan cycle control on the fan to cycle it off and on to controlhead preasure. I had one last 6 Years on a CPU room till it started screaming and people complained. Scroll compressor also.

If they don't wanna pay to do it right just make sure they know what they are getting upfront.

[Rob_in_WV]

This unit has a factory installed crankcase heater. There is also an indoor TXV. Beenthere, I will try to increase blower speed, its certainly worth a shot. Ron, thats an interesting idea. Do they even make such a heater? Jim, I'm afraid you're probably right. At this point I'm just trying to figure out a way to raise the head pressure without getting too ghetto... Thanks for the replies fellas

I was thinking about one of those external crank case heaters that wrap around the compressor and tighten up like a hose clamp. Instead of being used on a compressor install it on the accumulator and set to energize when the contactor closes. Also include a temperature sensor to keep it from coming on when ambient temperatures are close to design specs.

[wogpa67]

I would use a manufacturer specd low ambient kit only. if not maybe use an economizer control.

[LibertyTree]

Thanks for the tips guys. I think I might try a fan cycle switch. I'll call up Johnstone tomorrow and see what they have. So what does it do, do you run the hot from the fan through this switch and hook up some kind of shraeder tee to the liquid line service port and it cuts power to the fan when the head pressure is too low and turns on the fan when it gets up to the proper range?

[qwerty hvac]

Thanks for the tips guys. I think I might try a fan cycle switch. I'll call up Johnstone tomorrow and see what they have. So what does it do, do you run the hot from the fan through this switch and hook up some kind of shraeder tee to the liquid line service port and it cuts power to the fan when the head pressure is too low and turns on the fan when it gets up to the proper range?

They have those the cut in and out. You could also get one that slows down the fan motor. ICM makes a few off them. They are easy to install since you do not have to mess with refrigerant connections.


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[SBKold]

That unit have a fancy motor on it? Not ecm is it?

[Rob_in_WV]

That unit have a fancy motor on it? Not ecm is it?

Good question, I've seen some low ambient kits that specify they are for use on ball bearing motors only.