Multiple Reversing Valve Failures

[lonboy]

OK, here's the scenario... 10 yr old 20Ton Carrier package heatpump, 2 stage cool/heat, 2 compressors, cap tube system.

On circuit 2, reversing valve failed for 3rd time in 10 yrs - stuck in Cooling position. Circuit 1 has gone thru 2 RV's in lifespan. No compressor failures in history - don't suspect contamination. What a PITA to change - you have to be a contortionist!

So, any ideas on why these RV's are failing every few years? Could it be a piping design flaw? The RV's are very close to the compressor discharge valve. They are factory mounted in a horizontal position. These are pilot operated valves - could a low discharge pressure prevent the actuation? When checked it was runnning 175psi.
Thanks for your input!
lb

[berg2666]

OK, here's the scenario... 10 yr old 20Ton Carrier package heatpump, 2 stage cool/heat, 2 compressors, cap tube system.

On circuit 2, reversing valve failed for 3rd time in 10 yrs - stuck in Cooling position. Circuit 1 has gone thru 2 RV's in lifespan. No compressor failures in history - don't suspect contamination. What a PITA to change - you have to be a contortionist!

So, any ideas on why these RV's are failing every few years? Could it be a piping design flaw? The RV's are very close to the compressor discharge valve. They are factory mounted in a horizontal position. These are pilot operated valves - could a low discharge pressure prevent the actuation? When checked it was runnning 175psi.
Thanks for your input!
lb

What was your suction pressure?

[jogas]

1.) Check with Carrier tech support for any service bulletins on the unit.
2.) Can you cut out the bad 3-way valve (no heat) and take it apart (cut it if you have to) to try and identify if some contamination/corrosion/acid is affecting the slide valve or solenoid porting?
jogas

[Mrfixit39]

double check the circuit before ur final answer.

[freonguy]

Lonboy:

Reversing valves are notoriously prone to failure from contamination.

IF they are a PITA to get at, did they get a little too hot when sweated back in. The scale on the copper from brazing is enough to cause grief as well - purging with nitrogen is the answer, but difficult if not impossible because shuttling the valve during brazing is a PITA as well.

Some of the other boys might have more help - perhaps a generic question on the Residential Forum will bear fruit - some of the boys there deal with alot of heat pumps and if you can weed through the DIYs, well, just a thought.:confused:

[william antley]

Almost all of the reversing valves I've had to replace for being stuck have been because they were overheated during installation, the rest were due to contamination roughing up the slide and teflon seal.. I found this out because I have a habit of cutting them open to find out why they failed when I have to replace them. I do that with TEV's as well, I like to find out the "why" so maybe I can prevent a recurrence.

[dieselairman]

I have come across valves that have just disintegrated. No sign of heat, Suction was always ok. The Nylon and Bakelight almost act as if age had something to do with it. Then again the first one went in two years. The most recent one made it ten.

[Hrdworkingacguy]

I talked to a Sporlan engineer a few years ago at a class and he told me that reversing valves teflon seals get better with age and shifting them is good for them...I have seen where units that run in cooling with a heat activated RV, the valve goes bad from just sitting there...:eek:

[call-back]

It's hard to believe, and it's amazing how a compressor can sustain damage from slugging and pumping liquid ref. and yet, the reversing valve is the whipping boy from all that hydraulic hammering!---I would imagine the circuits had suc. accumalators, but if they didn't, I would pretty well guess that the culprit would be liquid compression through the RV....Acidic content in the system will usually cause flaking and blockage of the pilot ports; and Ive seen this even in contained burns!...Ranco valves were notorius for slide valve piston ring distortion, and who? Knows? how well the valve was kept from excess heat from brazing; even at the factory! Ever notice how clean and painted those factory joints are when the unit was new!...A little glass fluxing and paint hides the bad burns!...Another factor would be if there was a discharge muffler before the RV...They are prone to breaking up and chipping up deposits in the slide mechanisms too!..Just my thoughts and memories with HP agony! Ha! Heaven was changing a RV with rotalock or bolt on RV's...and they were far and few in between!

[lonboy]

Thanks for all your comments and suggestions. Case is now closed

Installed the new Ranco RV after carefully cutting out the old one. What a pain - but success - all working well now and no leaks!
Went down to the shop and used a porta-band saw to cut open the old valve to see what might have caused the issue.

To our surprise after cutting open the end of the valve - the problem was obvious. One of the screws that holds down the disc was completely out of it's hole and the disc was wedged sideways in the cylinder. It looks like someone at the factory in China didn't tighten the disc screws down enough. When one backed out, the disc turned and got stuck.

I wonder how many other components in AC systems these days are made by low paid and low skilled workers - Rank-Oh lives up to it's name.
Cheers,
lb

[call-back]

Thanks for all your comments and suggestions. Case is now closed

Installed the new Ranco RV after carefully cutting out the old one. What a pain - but success - all working well now and no leaks!
Went down to the shop and used a porta-band saw to cut open the old valve to see what might have caused the issue.

To our surprise after cutting open the end of the valve - the problem was obvious. One of the screws that holds down the disc was completely out of it's hole and the disc was wedged sideways in the cylinder. It looks like someone at the factory in China didn't tighten the disc screws down enough. When one backed out, the disc turned and got stuck.

I wonder how many other components in AC systems these days are made by low paid and low skilled workers - Rank-Oh lives up to it's name.
Cheers,
lb
[COLOR="DarkRed"]Thanks for cutting it open and doing an autopsey on it! Great learning experience!
Nice to know there was a Screw Loose in that whacko valve!......Probably, the little 7 year old kid that put the valve together, was hungry cause he didn't put 100 valves out in a hour, and he was a little weak! And so it goes on and on and on! /COLOR]

[jogas]

I worked for one supermarket refrigeration shop that refused to use the ranco LPC's. Now I know the Reversing Valves are junk also.
jogas