My system will run for a while, heating nicely, and then suddenly trip the circuit breaker on the furnace. Occasionally it also trips the circuit breaker in the main panel for the heat pump. I have paid almost $300. to have the Heating and AC company check this out, and they cannot find anything wrong. Perhaps I have been asking the wrong folks? It does not due this upon start-up; just seems to heat for a while, and then randomly kick off. The Heating AC folks just wanted to sell me a new system, but it seems to me that if this is all that is the matter, it should be something that can be repaired. The system is getting up there, about 14 years old, but has been very well maintained, and had a new defroster put in last year as well. Can you help? I hate to call someone else, and incur another $100 service charge with no fix! Thanks so much.
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Without looking up the specifications for this heat pump, I cannot be certain, but I expect the operation to provide cooling may require more power than when heating. You probably can find the specifications online for this unit. As you probably know, power is measured in watts and is calculated by voltage times current. This also is likely to be 240 volts operation. If you take the specified power on cooling and divide by voltage (240), that will indicate the current in amperage that will be required to start it. Your circuit breaker is set for current and needs to be a higher current than is required. If that is the problem, you can buy circuit breakers at Home Depot or Lowes. You have to remove the front panel of your breaker box and snap out the circuit breaker. To be safe it would be good to turn off the main breaker switch before you open the front panel and remove the circuit breaker for the heat pump. Should your calculation of current required be less than the rating of the circuit breaker, that implies a malfunction of the heat pump in the cooling mode and would require a service call to the local representative of the heat pump manufacturer.
the breaker may need replaced, I would start there first. I am assuming that it has a dedicated line (meaning only the heat pump is off that circuit), if not then it will need to be wired that way...Good Luck Tim
Hi, yes the thermostat feed does come off the furnace from the transformer. That's where it gets it 24 volt supply, 120 volts is stepped down to 24 volts for the controls. If it trips the main breaker, it may be a matter of the wires that feed the breaker are loose and this will cause the breaker to over heat and trip. Shut it off and tighten the wires.The breaker may also be weak. This is a high voltage problem. So, anything that runs off of this breaker can cause it to trip, like the blower motor may be drawing to much amperage. Make sure there is no lint build up on the motor or in the windings or on the blower wheel also. My guess would be the breaker is burned or wires are loose creating enough heat to trip it at times. This is where you will need to start. Keep me posted. If you have a amprobe you can check the rated amps on the data plate of all motors and see what they are drawing under a load. If not, you will have to see whats getting hot, breaker, motors ect. Keep me updated as you will be able to find the problem. Like I said, my bet would be the breaker is going. You can also kill power and pull the breaker to look for any hot or burned spots on it. Concentrate there first. Best of luck, you should find it quickly. Shastalaker7
Does it trip the breaker when the safety switch is NOT pressed? I am trying to isolate where to look for the short circuit. Is it before the furnace, or after the furnace. If the breaker trips with the safety switch not depressed, the problem is not the furnace, and could be where power enters the furnace, or further upstream from the furnace.
I would suspect you have a problem in the defrost circuit of your heat pump. there are a couple of things you can try. first just run the system on emergency heat and see what happens. you could have a defrost board that is shorting when it kicks into defrost. it sends a signal back to the furnace so it will come on during defrost. if you do not blow a fuse as long as you are running in emergency heat, i would suspect the defrost control board. also you could have a dead short in the wire that runs from the "w" terminal on furnace control board, out to the heat pump. keep in mind that any of the wires could be the cause and i am just tying to give you the most common things. your furnace will still run if you unhook all the low voltage wiring out at the heat pump. if you do this and stop blowing fuses. you know it is something on that wiring. goodl luck.