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-   -   Copeland scroll running backwards. I am not kidding. (http://www.diychatroom.com/f17/copeland-scroll-running-backwards-i-am-not-kidding-184411/)

viper 07-28-2013 06:19 PM

Copeland scroll running backwards. I am not kidding.
 
This pump is from about 1993. I have seen it do this before when we lost power for a second and it reversed the pump. However, I recently returned home to hear only a slightly "different" hiss from the A coil than I was used it. I touched the line set and determined the liquid was cold and suction was hot.

So I shut down for a bit and restarted. It is still doing it!! I am really confused now. Could this be the capacitor? Usually a cap start motor will not start with no cap and the pump fires right up and does not sound too bad other than running backwards.

This is a heat pump BUT I cut the reverse valve out myself so I know it no longer exists so no way that could be it.

Help!

UPDATE: I did verify that the run capacitor is perfect. I can find no other issues. I started it direct on the compressor with the contactor and it seems to start perfect and really does not make any loud racket but is still running backwards.

HVAC1000 07-28-2013 08:45 PM

Quote:

Originally Posted by viper
This pump is from about 1993. I have seen it do this before when we lost power for a second and it reversed the pump. However, I recently returned home to hear only a slightly "different" hiss from the A coil than I was used it. I touched the line set and determined the liquid was cold and suction was hot.

So I shut down for a bit and restarted. It is still doing it!! I am really confused now. Could this be the capacitor? Usually a cap start motor will not start with no cap and the pump fires right up and does not sound too bad other than running backwards.

This is a heat pump BUT I cut the reverse valve out myself so I know it no longer exists so no way that could be it.

Help!

UPDATE: I did verify that the run capacitor is perfect. I can find no other issues. I started it direct on the compressor with the contactor and it seems to start perfect and really does not make any loud racket but is still running backwards.

I know yurt will have something to say about this

viper 07-28-2013 09:04 PM

I hope yurt chimes in because as of now, I can find so joy here. I have not put gauges on yet but I can guarantee that a cool liquid line and warm suction ain't right but as I said, I can also guarantee that there are no heat pump guts left so no way it is reversing flow without reversing the pump. The pump also sounds different.

HVAC1000 07-28-2013 09:06 PM

Quote:

Originally Posted by viper
I hope yurt chimes in because as of now, I can find so joy here. I have not put gauges on yet but I can guarantee that a cool liquid line and warm suction ain't right but as I said, I can also guarantee that there are no heat pump guts left so no way it is reversing flow without reversing the pump. The pump also sounds different.

I'm sorry I meant Yuri. Darn autocorrect

beenthere 07-28-2013 09:23 PM

A scroll running backwards won't pump refrigerant.

Is there a liquid line filter drier in the cabinet. if so, it may be restricted, and causing your cool liquid line.

Put gauges on it.

viper 07-28-2013 09:35 PM

We installed an after market filter drier just outside the condenser.

I am not sure how we would get a noticeably warmer suction line though. I understand the thoughts on restriction but that should trip out the pump overload in short order should it not?

Regarding running backwards. I have seen this same thing last summer with a momentary power outage. Sounded odd and verified line set temps were reversed. I stopped the system and restarted, worked fine. This is my basis for thinking it is running in reverse right now. I think it can do it. The pump is older, before they started putting reverse protection in them.

hvactech126 07-28-2013 09:46 PM

Again, a scroll compressor running in reverse will NOT pump and therefore there would not be a pressure differential to provide for the refrigeration cycle to take place.

beenthere 07-28-2013 09:48 PM

Scrolls can't pump if they run in reverse rotation. Its due to the design of a scroll compressor. Not something they thought of intentionally though. The compressor will just make a grinding noise, as he inner scroll's edge/edges rub against the outer scroll.

Did you leave the metering device in the outdoor unit, when you took out the reversing valve. Something may be restricting it, if you removed the filer drier from inside the cabinet that it can't be restricted.

A restriction won't necessarily shut down the compressor on low pressure, nor the compressors over load real quick.

beenthere 07-28-2013 09:52 PM

A restriction in the cabinet, or the outdoor units metering device would tend to make the suction line colder then the liquid line. Cause the refrigerant going to the indoor coil has to much flash gas in it. So the vapor warms up/absorbs the heat, instead of the liquid absorbing it and boiling off to vapor, so little to no latent heat exchange in the refrigerant.

viper 07-28-2013 09:54 PM

Near as I can tell, the system make have run an hour or two like this. It has run perfect all summer long. I keep an eye on it being so old. It runs about an 18* dt across the A coil pretty consistently.

I can go along with a restriction since that is possible but it has done this before over a year ago and then just ran perfect.

No, there are no metering devices left in the condenser. I cut the entire thing out and fabbed up new plumbing. Still have the valve.

beenthere 07-28-2013 10:01 PM

If the scroll is running backwards. Then the liquid line being cooler then the vapor line would be from the gas on the vapor side heating up from the compressor getting hot. The liquid line would be at outdoor temp.

Remember, since you took out the outdoor metering device. If the scroll could pump backwards. The gas/liquid coming back from the indoor coil would still be hot(no metering device to have a pressure change). So the liquid line would not be cool.

beenthere 07-28-2013 10:03 PM

Gonna need to put on gauge to find out what is really happening.

An old scroll can run backwards because of a weak capacitor, or a weak start winding. Then again, so can a new scroll.

viper 07-28-2013 10:46 PM

Uh, no need for gauges... I starting thinking a bit and if there is any restriction at all between the comp and A coil (filter/drier), that would probably vaporize the liquid line with the suction side sucking on it.

Anyway, went to just test a port on the condenser. there ain't jack squat in that system!! I mean it dumped out quick! It was working earlier this morning. There was no hint of pressure. I am really hoping the A coil is not it but I would think I would smell that 22 in the house, no? I mean refrigerant is pretty obvious in odor. I guess I did hint at some sort of almost burnt wiring smell in the back room but that could have been many things and probably my sniffer on the high and up.

COLDIRON 07-29-2013 06:23 AM

WHaaaaaaaaaat?

yuri 07-29-2013 08:44 AM

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Sounds like a story from the zone.:):yes::laughing:


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