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-   -   Heat pump circuit breaker pbms (http://www.diychatroom.com/f17/heat-pump-circuit-breaker-pbms-33626/)

pinkertonpv 12-12-2008 10:49 AM

Heat pump circuit breaker pbms
 
About 8 years ago I installed a 6 ton heat pump at my house in north Alabama. A friend with an HVAC license helped me with the technical part. I installed the appropriate out door circuit breakers for the amperage with the appropriate wiring. I did not replace the circuit breaker in the house breaker box. The house is approximately 35 years old. The inside circuit breaker is a 60 amp to the HVAC side with a separate 60 amp circuit breaker to the heat strip side of the heat pump. I also installed a digital computerized thermostat. My friend wired and programed the thermostat. Everything worked perfectly for the next 7 years.

This past year I have been experiencing times when the inside circuit breaker to the HVAC side will trip. It usually occurs every 2 or 3 weeks and usually during moderately cold weather. The CB shuts off the thermostat. Heat pump of course will not work until the CB is reset. Thermostat and heat pump work perfectly when CB is reset. Thermostat seems to work perfectly all the time.

I believe the problem is in the CB or the thermostat. I first plan to replace the CB and see. I am a little worried about leaving the house when cold weather is coming. N Alabama is generally mild during the winters but sometimes can go into the teens for a few days. If the CB trips while I am gone, pipes may burst.

If the CB change out doesn't work then I guess I will call a technician. My frien has moved to N Carolina.

Any Ideas?

sammy37 12-12-2008 11:33 AM

If the stat goes off when the breaker trips, then that is the breaker to your air handler, that is also the breaker that runs your aux heat. You say it trips when it is real cold out? That would be when your aux heat is running at maximum.

You may have a weak breaker, or you may have a problem with your strip heaters. I guess starting with the breaker is the easiest part and if it does it again, you'll have to investigate a problem in the air handler. How many KW of strip heat do you have? Also, it has to be a 5 ton unit, anything bigger than that would be 3 phase commercial.

hvaclover 12-12-2008 02:32 PM

5 ton HP?

New one on me, to the best of my knowledge 5 ton is as big as they come.

How big is the home?

pinkertonpv 12-12-2008 03:31 PM

Sammy37; you are right, it is a 5 ton instead of a 6 ton. The breaker to the air handler and the Thermostat is a 60 amp breaker. The in house circuit breaker to the auxiliary heat is 100 amp breaker with a 60 and 30 amp breaker outside. I can trip the inside breaker to the heat side and no aux heat will come on. There are two aux heaters, each with its own outside breaker, one a 60 amp and one a 30 amp. Both connect to the 100 amp inside breaker. One set of heat strips came with the Unit and an additional set of heat strips we added. This a Heil unit by the way.

There are 3 sets of heavy wire in conduit running to the unit from the two out side boxes. One to the air handler and two to the auxilairy heat. Inside the unit are additional sets of circuit breakers on the heat side, 2 30 amp and 2 60 amp.

I believe their are 15 KW and 30 KW Strip heaters. I have the installation book for the Aux strip heaters but nothing is available for the one with the unit. I believe the aux was 15 KW and I think the unit was 30KW.

I'm trying to remember bit it was 8 years ago and I have slept several times since then. I may have misplaced one or more of the factory manuals.

Anyway I will start with the CB replacement and let you know how it goes.

sammy37 12-12-2008 06:12 PM

You talk about all these inside and outside circuit breakers, I guess I should ask. Is this a package (all in one unit) or a split system (air handler indoors and conndensing unit outdoors)?

NYCtinman 12-12-2008 11:46 PM

Question - have you had any other electrical work done or added any other appliances that may over draw/exceed your panel ?

pinkertonpv 12-13-2008 08:46 AM

Sammy37;
Sorry for any confusion. Just trying to get as much info out as possible. Sometime it confuses more. The Heil package I have is one self contained unit. I installed circuit breakers outside the house so any service could be done to the unit with out shutting off the breakers inside the house at the main breaker box. Also so the two aux heat strips could each be on their own breaker instead of the 100 amp breaker at the inside house breaker box. The replaced unit was a GE self contained unit with the heat strip side wired directly to the 100 amp breaker at the inside house breaker box.

No additional electrical appliances have been added to the system wiring or breakers since installation. The airhandling cooling is on its own 60 amp circuit.

If this wiring system is confusing, it seemed right at the time, very similar to the older unit I replaced. The only new wiring put in were the outside breakers and wiring going to the unit.

System worked fine up to this last year.

pinkertonpv 12-13-2008 08:50 AM

Sammy37
To make sure I answered you question, the unit is not split. No part of the system is inside except of course the ducting and the stat.

You guys are a lot smarter than I am on this stuff. Sorry again for any confusion.

sammy37 12-13-2008 10:58 AM

O.k. it is a package unit, that makes more sense.

If the stat goes off when the breaker trips, as per your original post, then that would be an issue with the unit itself, not the heat strips.

In a situation like this, if changing the breaker doesnt help, then you'll need to have a technician come out and see whats up with the unit, measure amp draw etc.

SKIP4661 12-13-2008 11:09 AM

I suggest looking for a loose wiring connection in that circuit as this would cause an excessive amp draw.

pinkertonpv 12-13-2008 12:45 PM

Thanks to everyone that commented. I will change out the breaker and see what happens next. I will update the post and new events occur.

pinkertonpv 02-18-2009 10:47 AM

Well its been several weeks since I changed out the circuit breaker and no shut offs have occurred since then. Seems to have fixed the problem.

Thanks to everyone for their comments and advice.


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