Heat-Pump Woes.

[toggleswitch]

The heat-pump in question works and defrosts just fine.

A friend's heat-pump has needed to use auxiliary electric resistance coils during the latest cold snap. Problem is they won't come on. He says the house went down to 50*F (10*C).

Now I am assuimng the thermostat is not defective, and that the wiring sends the signal to the air-handler just fine.

The circuit breaker (220 v via two @ 60a) is putting out power and there is indeed power (for the electric coils) in the air handler.
Both hot legs are active/hot (to ground) and to each other (i.e. the hot legs are indeed different "poles" => delivering the requisite 220v.)

So what's the problem?

Defective relay not allowing coil to be energized?
One-time thermal fuse, open?
Heat sequencer not cooperating? I see two of them rated at 5kw each. How do these work? Thermal trigger? Time trigger?
[These are intended to prevent the full load from coming on at one time, which would dip votage and brown-out lights, etc.

Any ideas as to how to "DIY" fix this is appreciated. Friend has that Italian disesase "Fundzarlo"! I'm gonna need to strap on my *COUGH* toolbelt and act like a man.

 

[SactoTeddyBear]

Re: My Experience with a Heat Pump:

Hi! Steve, "Toggles" my problem with my Heat Pump Unit happened when I bought a new house in 1986 and it had a Heat Pump, for all of the houses Built in the area. I was experiencing the same problem, that when the Unit went into a Defrost Cycle, the house was getting way too cold. I finally decided that I wanted some more Storage Space in the house, so I contacted some Heat/AC Companies for some Bids and had a Gas-Pack installed on the Roof. We came to find out that the Company that supplied the Heat Pumps and Installed the System's didn't connect the Strip Heaters on my Unit, so that is why I wasn't getting any extra Heat, when the Unit was Defrosting.

I would strongly suggest that your Friends either open the Heater Unit themselves or have someone come out to open it and check to see if the Strip Heaters did in fact get connected. I would never recommend that Company to anyone to have any Heat/AC or Heat Pumps being Installed by them, even if this was an Isolated thing that happened, who knows how many other people had the same thing happen to them as well, during these Installations?

Good Luck with finding out why the Strip Heaters aren't functioning.

Peace and New Years Cheer, Steve
SactoTeddyBear...

 

[DADoES]

There may also be one or more PC boards involved. My system had a board go bad, which caused one element bank to stay on continuously. The reverse is possible, I'm sure.

Or a burned wire.

Or, grasping a bit, thermostat? Typically it's the thermostat that calls for auxiliary via 2nd stage when the compressor can't keep up.

Strap on your tools and have a look!

Pics please.

Or even better, a VIDEO!!!!! Come on, come on, come on ... do a VIDEO.

 

[sudsmaster]

Well, if I were in your position and had to strap one on (tool belt, that is), I'd probably do the following:

Confirm that the thermostat is sending an on signal to the heating unit. If I had a spare thermostat I'd just swap that in and see what happens.

If thermostat ok and/or swapping it doesn't get the heat on, I'd test the heating coils for resistance (after shutting everything off at the circuit breaker panel, of course. If infinite resistance, then they are probably broken and need to be replaced. If no resistance, I'd suspect they need to be isolated from other components for testing. If some resistance, the coils may be ok.

If possible I'd next try to bypass all the controls and hook the coils up directly to a switched 220 volt power circuit. If the heater coils get hot, they are probably ok.

I'd try to check the relay. Normall they emit an audible click when activated or deactivated. No click, might be a bad relay. One could also measure for 220 volts at the relay output when the thermostat is calling for supplemental heat.

If thermostat, relay, coils all look ok, and still no heat, then maybe it is the delay circuitry or maybe a high temp power cutoff sensor failure (if the system has one). At that point I might call in a HVAC pro, esp if the system has any computerized controls inside. Meanwhile I imagine your friend has some portable electric space heaters running to help heat the home. They won't be any less efficient than the supplemental heating coils in the heat pump.

 

[panthera]

Steve,

I can't add much to the above except your suspicion it might be tied into the delay circuit is probably a good place to look for a problem.
Given that the split-phase (oh, I just love that term) is doing, have you checked for an open neutral somewhere. Much of that system could well be 120V and that would explain the failures.
Depending on the age of the system, the relais could also be 24V, powered by the same transformer as the thermostat.
So that would be worth checking into, too.
If the elements show resistance, there is no open neutral, no hi-temp limiter has blown, etc., then it is possible that the device - mechanical, electrical or logic driven, which decides when to switch from heat pump to resistive heating has failed.
You should be able to override it without too much difficulty unless the logic for the rest of the furnace is tied into it.
Gosh, I hate to profit from other's problems, but pics would be groovy.

 

[lightedcontrols]

a few thoughts...

***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 themselves. Mark

 

[retroguy]

Everytime I have had that same problem.....

It was the sequencers. It didn't help that the ones my system use are made by Klix-on and are rather hard to find.

 

[retroguy]

and....

sequencers are on a time delay. My HVAC unit has four of them. But I have 2 sets of coils.

 

[toggleswitch]

~Open the heater unit...... and check to see if the strip heaters did in fact get connected.
I verified that the strip heaters are connected when I checked for incoming power.

~There may also be one or more PC boards involved.
This unit is 25+/- y.o. and I did not see any in the air handler, nor were any indicated on the wiring diagram. Will double-check. Will not energize coil either of its own accord with 2nd stage "Call" cor heat or when switched to "EM.HEAT [Emergency heat]

~Or, grasping a bit, thermostat?
It looked OK, But I may have to cross the proper wires to simulate thermostat's "call" for backup heat.

~Or a burned wire. Visibly (and to the nose) they were fine. Need to get my buddy to buy me volt-ohm-meter so I can get busy!

~Pics please. Or even better, a VIDEO!!!!!
Sure thing. Can't get there till Jan-19. Being "engaged" and all I won't be starring in any videos. oh oh I'd be BEHIND the camera; silly me.

~If I had a spare thermostat I'd just swap.
I do have one and great idea! Will do.

Rich for your MAAAHVELOUS suggestions which are too numeuos to acknowledge individually, will attempt all.

~Meanwhile I imagine your friend has some portable electric space heaters running to help heat the home.
Oh honey don't start me up. I put in a 125a sub-panel and ran 9 (yes 9) new circuits. Why you ask? Becausee amoung other electrical inadequacies, his basement space heater was blowing circuits, un-ashamedly and constantly. (*SLUT* of a heater!). Do you think he might have fired even ONE up in his time of need? uh, no. RRRRRRRRRRRRRR

~Have you checked for an open neutral somewhere?
I ddin't relly check for continuity in that it sits capped off in the air-handler, unused by any component. Therefore all components of the air-handler are indeed 220v.

~The relays could also be 24V, powered by the same transformer as the thermostat. Yup and yep. So I assume they have low voltage avaialble in that the heat pump itself runs.
The transformer also is suppled by 220v.

~Gosh, I hate to profit from others' problems, but pics would be groovy.
Toggle and ye shall receive. Will do; but can't get there for about 2 weeks.

I already copied the wiring diagram. But it is in the next state. Will ask GadgetBoy to scan it in for us.
So can anyone confirm (not to be pushy or anything)if the sequencer is thermal or time-based?
Thank you everyone for your kind input and concern.

BTW my friend got screwed royally (BY THE HVAC COMPANY!!!)He paid upward of $700 to get his fan and coil cleaned. The air handler started leaking condensate water this summer, when the inside coil, of course, was acting as the evaporator.

I don't trust him to get it fixed. They see the terror and fear (and probably his "light-in-the-loafers" qualitites) in him and pounce. I, on the other hand ain't intimidated by no unbathed, unkempt, ungroomed burly bear-like country bumpkin in overalls and a flannel shirt.

TE HE HE HE I know of two; one in TX and one in OH that have an increased pulse just about now. (ducks and runs)

*MUAH* to all.

 

[toggleswitch]

~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

FABULOUS.
I should have remebered this.
Thank you !

 

[Cybrvanr]

Your heat pump thermostat has several wires. Here are the most common ones...unfortunatley, color may vary depending on your make/model and the technician's preference at the time of install:

Hot: 24 volts from low-voltage transformer
Ground: just like it says
AC: Most heatpump reversing valves default to heat mode. Applying power on this lead activates the valve to cooling mode.
FAN: turns on the air handler fan
COMPRESSOR: starts the heat pump compressor outside (and it's fan)
AUX HEAT: activates the heat strips...jumper 24 volt lead to this and see if the heat strips come on
DEFROST: A return line from the outdoor unit. It gets 24 volts on it when the compressor goes into defrost mode (switches to AC). Your thermostat crosses over this line to the AUX HEAT line, so your home doesn't get cold while defrosting.

 

[andrewinorlando]

Is the heat strip burned out? Did you check for continuity through the heat strips? 25 years is old and they don't last forever.

 

[toggleswitch]

I need to simply stick the tip of my finger on that little t

...and keep that thing (relay) pressed in to see if it does indeed get hot.

Thanks Douglas for stating "time" rather than temp. on the sequencers. Missed that the first go-around!

Thanks Steven!

~DEFROST: A return line from the outdoor unit.......
YUP...defrosting is simpy air-conditiong mode with the outside unit's fan "OFF"

I was wondering how aux. heat is triggered during defrost.
Here is an interesting tid-bit: Should the thermostat stop calling from heat during a defrost cycle, the system will stop. Upon the NEXT call for heat the defrost cycle will start all over again. My understanding is (@ least with a Carrier brand system) the unit will defrost 'til the outside coil reaches 80*F (27*)o for 10 full minutes whichever comes first.

 

[toggleswitch]

~Usually you can (with an insulated screwdriver) manually press.......

Actually, I see myself using a gloved finger. Much less dangerous.

 

[toggleswitch]

~Most heatpump reversing valves default to heat mode. Applying power on this lead activates the valve to cooling mode.

This makes sense. Should the valve fail you'd get heating which is more crucial to survival than cooling is. Well, in most parts of this country........

(Nearly) nothing in life is a "always" or "never".

 

[toggleswitch]

~Is the heat strip burned out? Did you check for continuity through the heat strips?
Maybe bunt-out. No, need to buy volt-ohm-meter. There are two coils in the unit in question, sequenced.

Even the FAN won't run in EM.HEAT mode. Smells more like a relay issue don't it? I am assuming that the fan is relay-triggered (instant on), rather than temp.-triggered (time dealy) as one sees in a gas furnace.

I guess I need to witness a defrost cycle. Supplemental resistance-coil heat "ON" during defrost steers me to thermostat/wiring issue. "OFF" screams relay, IMHO.

 

[toggleswitch]

~Well, if I were in your position and had to strap one on (tool belt, that is), I'd probably do the following:

~the ones my system use are made by Klix-on and are rather hard to find.

Klix-on or Snap-on, either way I'd still be in a really bad mood; probably permanently. Then I'd stop feeling sorry for myself and get a little blue vitaimin "V".

My neon electircal tester is rated 80 to 500v AC/DC. Can I find one easily that will work on 24v?

 

[dalangdon]

I have to deal with heat pumps at work, and they confound and confuse me. If they are over three tons, their start-up can wreak havoc with distribution transformers, and now there are regulations about how noisy they can be. They're a real pain in the behind.

But anything beyond walking over to the thermostat and turning it on confuses me, so good luck

 

[gadgetgary]

Wiring Diagram

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