Heat-Pump Woes.

[lightedcontrols]

Here's the scoop

After speaking to the engineering dept at TRANE, here's what he said about testing the old heating unit. Please note that my advice was quite sound and the way they test old units as well as new ones. (select ''emergency heat'' on the thermostat and see if the heat comes on. This should cut out the compressor and only energize the resistance heat. IF it doesn't come on, locate the relay. Usually you can (with an insulated screwdriver) manually press the relay down and see if the heater strips energize. If they do energize, then it's the controlers. Ie. boards. If they don't, then check for resistance in the heaters) If there IS a coil to ground, it will simply trip the breaker or burn out the fuse. PLEASE NOTE that the TRANE company has NEVER had a tech blinded by any explosions or flashes checking heating/ac equiptment this way. I was also told that there may be a small spark when the contacts connected, but relays DO NOT EXPLODE nor blind. There will also be NO ''metal bits and plastic shards out at you,'' Lord, where do you people come up with some of this stuff? Mark

 

[toggleswitch]

Thank you for your efforts!

 

[toggleswitch]

and no hair on my palms either!

Well that other thing that is supposed to make a man blind hasn't kicked-in yet, I may have to risk it and press the relay!

 

[tolivac]

Exploding relay---This incident happened at where I work-thank goodness no one did get hurt-but it HAPPENED-and all who saw it were surprized-The relay in question was part of a blower motor controller in one of our transmitters.It involves a two speed blower that is supposed to work automatically-it switches speeds according to temparature sensed from the coolant in the transmitter-as the coolant gets hotter the blower is supposed to switch to higher speed-as it cools goes to lower speed.The blower motor is a 3ph induction motor with two windings-one for hi and the other low.The blower wasn't running at all and a tech pressed the run relay to see if it would start-thats when the relay EXPLODED from a short caused by another relay-whose contacts were welded.The panel the relays are in has 3 ph 380V in it at 200A.the breaker for the panel DID NOT TRIP from the fault.Again I would not manually move relays in a faulted circuit!!After seeing this-I was standing a distance away-two people had the peices fly in their faces and the flash did temp blind and disorient them.Yes, this DID happen.It shows electricity can do strange and unexpected things!!be careful out there!

 

[sudsmaster]

Anything can happen, for sure, but there might be a significant difference between the relay circuits for a 3-phase commerical transmitter site and that for a single phase residential heat pump.

If I were going to push down on a live relay, I might use a clean, dry plastic chopstick.

 

[tolivac]

Other thoughts before moving relays by hand in a circuit--does the relay have an auxillary contact?Aux contacts are put there to prevent just what happened in that blower controller-a relay from being closed on a fault.The bad relay was out of sequence-its aux contact was then OPENED to prevent the start relay from closing.HVAC relays may have these too.Best to get the schematic for your unit in this instance.study the schematic and note how the relays work and their operating sequences before moving them by hand.Yes-the 120-220V feeder to your home can be a high energy source as well.Best treat it as such instead of getting hurt or further damaging equipment.In the times I have worked on HVAC systems in the homes I have been in-the main blower relay had aux contacts to prevent the Heating element or AC compressor from starting unless the main blower relay was closed and supposedly the blower running.fortunately in most household HVAC systems the schematics are right inside the covers on the unit.Makes them easy to see.In the relay incident at the transmitter-3 relays had to be replaced to get the outdoor heat exchanger blower going again.the start relay that was pushed and blew up-nothing left of it but its base in the box-the relay whose contacts were welded closed and another that was burned from the activated relay exploding.Now the blower system is fine.And yes if you do have to move the relay by hand use an insulated tool and try to do it a distance from the relay and its circuit.You never know?In another one of our transmitters-again involving an outdoor heat exchanger-this one has two blowers-one blower runs all the time the Tx is on-the other is supposed to start as the coolant heats up-sometimes this blower has to be started by hand.We have an insulated tool to push the relay in to start it-and there is a panel with a hole in it for the tool to fit thru.So if the relay did rupture say from a faulted motor-the parts won't fly into your face.This relay doesn't have aux contacts on it.It just activates or stops the second fan motor.

 

[toggleswitch]

I love a man in uniform........

As promised to all, went to see the suffering heat-pump this weekend.

At 20*F (-7*C) outside it was struggling to maintain 64*F (18*C) inside.

My gut said "hire a professional". So we did

 

[toggleswitch]

Mr. macho was poking around in the unit..........

 

[toggleswitch]

....and started testing it with his multi-meter.

(Some of the ducts are fiberglass.)

 

[toggleswitch]

So you want to see the unit......

 

[toggleswitch]

And such a nice toolbelt it ws.

Things really started getting interesting when he strapped his on..

 

[toggleswitch]

I'm ready for my close-up Mr. DeVille.......

 

[toggleswitch]

Its' getting hot in here, so take off all your clothes..

Now if you ask me the name of the compay should have been renamed "Charred" from "Chard".

I dont know what the service-person did, but the WHOLE house went dark. How he tripped a 125a main breaker instead of the 60a breaker for the heat-strip coils is beyond me.

I'm thinking--> Perhaps you should take off the wedding band. It conducts electrciticy. The main breaker was located outside the house by the meter panel, and repairs continuted.

It was, after all was said and done the sequencer a $30 part.

1&2 terminals are Stage 2 @ 220v electric heat coils
3&4 terminals are Stage 1 @ 220v electric heat coils
5&6 termials are for the 24v contol circuit (yes twenty-four volts). Inside is a bi-meatal heating coil whose purpose is to trigger Stage 1, and then Stage 2 heating. To my surprise the opposite happens when the call for heat ends. Stage 2 temp switch cools first and shuts off that stage, followed by stage 1. So the heating coils are staged "ON" in sequence and staged "OFF" in sequence.

The repairman did not have enough wire to make his loops and jumpers and what-not. So I asked what gauge he was looking for. He said 14. (CAN'T BE; THOSE ARE 30a COILS, each) So I said, "Well 14 gauge handles 15 amps, which I don't have. But there is some 12 guage on-hand which can handle 20 amps). How very quickly he then said the wire has to be able to handle 100*C or some such temperature. So he informed me that he would caniblalize what was there to use suitable wire. I was not thrilled. Why would you want to shorten it if it's nice and long? anyhoo......

In the end, the resitance heaters worked like a charm and the sweet smell of dust and hair burning off the electric coils was evident. It took all of 15 minutes to bring the place up to a comforable room temperature.

Had mr fix-it add some R22 refrigerant(still FREON, IIRC) as needed, which made the condenser coil (which is IN the house in heating mode get much hotter. He add one pound of the stuff which he said is about 15% of the total charge of refrigerant.

For less than $250 all was well. Much more techincal work and far less of a rip-off than $900 to clean the heat/-cooling "coil". There was no charge for the refrigernant per se; perhaps when the lights went out I earned that one for free *LOL*

Thanks all for your support, comments, input and advice!

 

[toggleswitch]

Did I day $900?

I meant $700 for a D&C (dusting and cleaning).

 

[sudsmaster]

I dont know what the service-person did

Maybe he toggled the wrong switch?

Perhaps he wanted to be fumbling around for a toggle switch in the dark?

In any case, congrats on a successful, in the end, servicing of the home's heat producing regions. May Betty's protuberances be warm and toasty forever.

 

[panthera]

I would say:

"All's well that ends well"...but in this situation, I think your friend is very lucky to have had you there.
14guage to handle 100 amps...no wonder that insulation has to be 212F or better. Heck, maybe he was trying to up the resistive heating capacity.
Keep us up to date on what happens next!
Oh, and, thanks for the pics.
I like to watch.

 

[toggleswitch]

Don't you just LOVE souvenirs?

I learned that a heat-pump typically increases the air temp. by 20*F (intake was 60*F, condtioned/heated air out was 80*F)
Reesistance coils in such an application typically raise the temp by 40*F. They did here too.

Mr. repair-tech left his duct thermometer firmly planted in my, well you know.... YAY!

 

[neptunebob]

While a heat pump may not heat the air as much as electric or gas does, that can be an advantage for seniors and people with sensitive skin - Heat pumps are not as drying to the skin as other sources. But most seniors don't like being cold either so they may still be grouchy (especially if they don't get their daily fiber)!