Old Trane Unit won't shutt off

D107

AC Trane Model# TWH739E150CO Installed 4/90 with XV1 500 Variable speed heat pump Refrig 22 1/2HP 4 amps AC Space Gard Hi Eff AR cleaner model 2200. 3 ton unit.

On the annual servicing, very experienced tech first found unit unable to start, then could only shut if off manually. Spent alot of time attempting to diagnose electronic problem. His analysis--from my quickly scribbled layman's notes:



<span style="color:#000000">Problem is with electronics. T-stat is digital output, sends msg to control center in air

handler which sends to outside unit. Breakdown somewhere in communication.

</span><span style="color:#000000">This is a complete variable speed system--both units. 0 to 3600 rpm., 4HP. First couldn’t get it to stay on, then would only go off manually.</span>

<span style="color:#000000">Feels that even if he could diagnose problem, hard-to-find-parts and labor could amount to hundreds of dollars on a 21 year old unit.These units are particularly troublesome to troubleshoot.

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<span style="color:#000000">He proposes new outside unit comes dry-shipped with no refrigerant then they'll filter and fill new R22 into system, keeping existing air handler. </span><span style="color:#000000">Replacement seems like the smart thing to do, eh? This is a small, trusted LI company, the tech personally installed the system years ago and has maintained it ever since. When Trane calls them to service some of these old units, they generally decline.

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<span style="color:#000000">Thanks.

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Techman

Stuck unit

I think you would be better off replacing the indoor/outdoor units.Trying to match some other brand of heat pump outdoor unit w/ "electronic controls "  to the indoor unit is "iffy" at best. But ,"trust " is earned, so listen to your AC guy.

D107

Trane

Thanks, yeah I was thinking both units too, though the tech was going to install an outside unit without a heat pump to save on cost. Heat pump does not seem worth it given the house has a new Buderus HW system and I don't know what is saved if anything by using the heat pump late September through mid-October.



Warranty will be for five years; house may be sold by then so a new handler/condenser after 21 years seems reasonable. I guess it's goodbye R-22 and hello R410A.

tim smith

Re: Trane Vs heat pump

This does not sound like a big fix. I agree that it is older heat pump but it also sounds like it has had fairly light use. I would have been inclined to call tech support for Trane while on site and could have figured out the communication error and either fixed due to wire problem or maybe just a thermistor problem. Then you can take your sweet time figuring out how and when you want to fix  the problem. just my .02

D107

Trane

Thanks Tim for the sage advice; yeah since I wasn't there--the family house not mine--I only know he troubleshot it for about an hour. Since he deals almost exclusively with Trane equipment, I figure he went through everything methodically--though if he didn't call Trane he probably should have.



Just to make it clear if I didn't before, it's not the heat pump that's the problem as far as i understand what he said; said he couldn't get the unit (AC) to turn off once on. So it's the functioning of the AC that would be the problem--the heat pump gets very little use and we don't need it.



The dilemma becomes (assuming we've given up on troubleshooting):

1-If we add just a new R-22 compressor outside, then we'll continue to have a system that the tech claims only two companies that he knows on LI still services. (he's one of them, and as the company owner he says he's looking to retire in a few years.)

2-Though the house may be sold in five years, as 2020 approaches, an R22 system becomes less and less of a selling point real-estate wise, and probably more expensive to service.

Eugene_Silberstein

Passing it along... to TRANE

I am alerting the long island area manager at Trane to this post. Maybe he can shed some light on the situation.

D107

Thanks

Thanks Eugene, though in the interim I decided to just go with a new condenser unit. Turned out there was already quite a few hours of troubleshooting, and the tech's rationale --and I agree-- is that more time/labor troubleshooting on a 20 year unit just wasn't worth it. Seemed like the most common sense solution--and he wasn't pushing a full inside/outside unit replacement. Thanks again.

RHalley

It's Hard to Stop a Trane

After 21 years of useful life it's time to make a difficult call, fix or replace. 

Before putting too much time into this unit there are a couple of things to consider. I don't know the geographic location (proximity to ocean/corrosive environment) but even in good conditions I think you should be looking at replacing the condenser after 25 years (+/-)

I also think you should consider the advancements in efficiency and technology as data in your decision process. The unit you are working on is probably 10 SEER at the most. Plus the PT ratio of R-22 only gives you usable heat down to about 30/32 deg F.

Compare this to a newer 410a unit you can now get something in the 19 SEER range and with the higher PT ratios you can get real heating all the way down to 0 Deg F.  You can do a simple cost comparison of the savings in energy over the life of the product an your decision may be made.  Good Luck

Eugene_Silberstein

Thanks Rich!

Thanks for your input Rich!

D107

Thanks

I appreciate your input; ultimately we decided just to replace the outside unit. Given that the house will likely be sold in a few years had something to do with the decision--new owners often put on additions that require new systems. It is nice to know that the new heat pumps can provide heating in really cold weather, but we would never want to trade in comfortable hydronic heating (new Buderus, outdoor reset, indirect hwh) for forced hot air.



The Trane unit --properly maintained--has worked wonderfully for over 20 years, and last summer in particular was a life-saver.