# furnace tripping breaker



## iron (Mar 29, 2017)

we heated all winter with the fireplace. now, that things are warmer, we switched over to the electric furnace/heat pump. however, we have tripped the breaker several times (never happened in the 2 previous years). 

curious as to what might be causing it. i just replaced the filter and used compressed air to blow out dust. 

the electrical panel is new (replaced about 13 months ago) and i don't recall if we really ran the furnace since it was replaced. 

furnace is on a 70 amp breaker. it also has a 60 amp breaker on the face of the furnace unit (presumably for the heat pump???). i believe the furnace is a 1979 model. heatpump is likely 1980s. we just bought the house in 2014. 

what other things can i easily check?


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## Gotrek (Mar 29, 2017)

Failed sequencers your furnace elements are likely coming on all at once instead of sequenced.  Not expensive and easy to replace.
Assuming you have heating coils additional to the heat pump.  If not I would test the capacitors in the heat pump.


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## iron (Mar 29, 2017)

would this cause the furnace to trip immediately (like in seconds after starting) or would it be a random event after an extended period on?

so far, it's tripped 3 times. once it was on for 2 days with no issues. then, after resetting the breaker, it tripped relatively quickly (10 mins?). today, it tripped after about 3 mins from being turned on (we keep it off at night)


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## Highbeam (Mar 29, 2017)

Are you tripping the 70 amp furnace breaker or the smaller(usually 30) heat pump breaker? 70 amps is a big current. Is it popping right when something turns on? Surge loads from a big pump or motor turning on can be quite high. The 70 amp breaker feeds the furnace blower and the resistance heat strips. Since it has been so warm lately I wonder why your resistance strips are coming on and if they aren't then it would be really hard for the rest of the furnace to trip a 70.

When running, is that 70 breaker warm to the touch?

Breakers go bad. Not usually very expensive to replace. Cheaper than hiring an electrician for sure.  

Final thought is to check your voltage. When voltage is low it takes more amps to power the same heating element and since breakers only look at amps, you can trip the breaker during low voltage events. Expect between 115-125 on each leg.


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## iron (Mar 29, 2017)

i didn't get a chance to feel the breaker to see if it's was warm. i agree that swapping out 70s seems like a simple solution. i will grab some 60s too for the thing on the furnace unit.

the tripping hasn't occurred immediately. the first time was after a few days of using the furnace. the next few times were within minutes of the furnace turning back on for the first time (after not using it during the evening). definitely not seconds, but minutes.


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## Highbeam (Mar 29, 2017)

iron said:


> i didn't get a chance to feel the breaker to see if it's was warm. i agree that swapping out 70s seems like a simple solution. i will grab some 60s too for the thing on the furnace unit.
> 
> the tripping hasn't occurred immediately. the first time was after a few days of using the furnace. the next few times were within minutes of the furnace turning back on for the first time (after not using it during the evening). definitely not seconds, but minutes.



Heat pumps and their complicated thermostats are usually set up so that if the desired temperature is more than a few degrees above the current temperature the electric resistance heat strips come on. Since your furnace blower and outside unit are all coming on and running for a few minutes before tripping the breaker I suspect that it is not until your heat strips kick on that you are tripping the breaker.

The resistance coil is pretty simple with no moving parts but can get dirty and can be damaged to where it may draw too much current and short out which would trip your breaker. You should be able to pull out the filter and look in to see that the resistance coil is clean and that your heat exchanger is clean. I assume you are getting good flow through the registers?

The other thing you can do is prevent the thermostat from calling for aux/emergency heat so it doesn't energize the resistance coils. You don't want that to happen anyway as it is expensive to run them.


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## iron (Mar 29, 2017)

air flow seems good. house heats up from 64 to 69 in about 10 minutes (2300 SF). 

i definitely would not be surprised with a dirty coil with all my remodeling. tried blowing it out, but perhaps not good enough. 

yes, i know the thermostat somehow was on EM heat the 2nd time it tripped. wonder if it happened again somehow.


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## kennyp2339 (Mar 30, 2017)

Check your capacitor outside in your condenser, see if its starting to bulge, these things do go after 15-20 yrs, it looks like a tall cylinder with wires going in and coming out of the top.


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## semipro (Mar 30, 2017)

iron said:


> air flow seems good. house heats up from 64 to 69 in about 10 minutes (2300 SF).


Sounds like your emergency heat (resistance) is being used if you're heating up that fast.  This will make your electric meter spin like a circular saw.  You should make sure and disable "emergency  heat" if you can.  Some thermostats don't provide for that function.  You can disconnect the wire that energizes emergency heat on the thermostat to disable.  I'd leave it disabled if you don't need it.  I will cost much less to use the HP.  At least disabling it will let you isolate the overload a bit.


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## Highbeam (Mar 31, 2017)

kennyp2339 said:


> Check your capacitor outside in your condenser, see if its starting to bulge, these things do go after 15-20 yrs, it looks like a tall cylinder with wires going in and coming out of the top.



Different circuit. The heat pump is on its own 30 amp feed usually. He's tripping the big circuit that feeds the furnace and strip heat.


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## iron (Apr 1, 2017)

so i had an HVAC guy come out from a local company. he saw my furnace and right away knew the issue. he ID'd the heating elements as the issue as the rheem furnace is 19 years old and at the end of its life. he said he's dealt with 20-30 of these models and it's the same thing everytime. 

now, having said that, i wasn't super convinced by his response. i looked at the heating elements. he said they are a little wavy (horizontal) - and i agree - and that the waves is what's causing the trip. basically, when they heat up, they deform a bit and then trip. he said this rheem model RBHA-17 J14SUAA was one of the only ones to use these types of heating elements and that they've been found to cause fires when damaged/dying. the guy wasn't a salesman, just a tech, but seemed to be pushing hard for a replacement option. 

if his assessment is correct, one option is for me to replace the heating elements. he said i can find them online for about $35 each (4 total), but that his company doesn't do that kind of work. i have been unable (so far) to find these exact heating elements, so if anyone knows a good way to find them, please let me know.

what he ended up doing was disconnecting two wires so that only the heat pump runs when the thermostat calls for heat. seems to work fine enough for now. he also said that the heat pump would need to be replaced if the furnace is replaced due to compatibility. 

so: any recommendations for 3 ton systems (heat pump + air handler)? he gave me some #s for lennox models, but my initial research shows the low end stuff is junk. 

thanks for any help you can offer.


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## Highbeam (Apr 1, 2017)

iron said:


> so i had an HVAC guy come out from a local company. he saw my furnace and right away knew the issue. he ID'd the heating elements as the issue as the rheem furnace is 19 years old and at the end of its life. he said he's dealt with 20-30 of these models and it's the same thing everytime.
> 
> now, having said that, i wasn't super convinced by his response. i looked at the heating elements. he said they are a little wavy (horizontal) - and i agree - and that the waves is what's causing the trip. basically, when they heat up, they deform a bit and then trip. he said this rheem model RBHA-17 J14SUAA was one of the only ones to use these types of heating elements and that they've been found to cause fires when damaged/dying. the guy wasn't a salesman, just a tech, but seemed to be pushing hard for a replacement option.
> 
> ...



I'm on a heat pump kick. The new ones are almost as good as minisplits in their efficiency and ability to maintain full output way down into the teens. In our climate that means you wouldn't need those heat strips but I would install them anyways. The improvements have really accelerated in just the last couple of years but only in the good brands. Not the goodmans.


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## iron (Apr 1, 2017)

Highbeam said:


> I'm on a heat pump kick. The new ones are almost as good as minisplits in their efficiency and ability to maintain full output way down into the teens. In our climate that means you wouldn't need those heat strips but I would install them anyways. The improvements have really accelerated in just the last couple of years but only in the good brands. Not the goodmans.



HB: do you have any links to products you could recommend for the heat pump? i have 2300 SF on two levels (upstairs is 1500 with r13 walls, air sealed, r54 in the attic, and my fireplace; downstairs is 800SF with r15 foam on concrete + r13 in cripple walls, air sealed). when using the furnace/heat pump, the whole house heats pretty uniformly.

are you saying that my air handler would serve mostly as an electrical connection for the heat pump, and that the heat strips would only come on when triggered by the heat pump (if it's too cold)? i'm a heat pump rookie.


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## Highbeam (Apr 2, 2017)

iron said:


> HB: do you have any links to products you could recommend for the heat pump? i have 2300 SF on two levels (upstairs is 1500 with r13 walls, air sealed, r54 in the attic, and my fireplace; downstairs is 800SF with r15 foam on concrete + r13 in cripple walls, air sealed). when using the furnace/heat pump, the whole house heats pretty uniformly.
> 
> are you saying that my air handler would serve mostly as an electrical connection for the heat pump, and that the heat strips would only come on when triggered by the heat pump (if it's too cold)? i'm a heat pump rookie.



I'd have to research for sure but think trane, carrier, American standard. Not the budget lines. To size the heat pump there should be a load calc. I think they call it a "manual j" and not just replacing what was there or the tech eye balling it. 

The system will look and be built just like what you have except the fan speed of both indoor and outdoor units are variable so quieter plus the heat pump will carry the load in just about all of our weather conditions. During defrost or if you demand a big temperature increase the resistance strips will kick in.


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## semipro (Apr 2, 2017)

iron said:


> so i had an HVAC guy come out from a local company. he saw my furnace and right away knew the issue. he ID'd the heating elements as the issue as the rheem furnace is 19 years old and at the end of its life. he said he's dealt with 20-30 of these models and it's the same thing everytime.
> 
> now, having said that, i wasn't super convinced by his response. i looked at the heating elements. he said they are a little wavy (horizontal) - and i agree - and that the waves is what's causing the trip. basically, when they heat up, they deform a bit and then trip. he said this rheem model RBHA-17 J14SUAA was one of the only ones to use these types of heating elements and that they've been found to cause fires when damaged/dying. the guy wasn't a salesman, just a tech, but seemed to be pushing hard for a replacement option.
> 
> ...


 
I'm having a hard time understanding how electrical resistance elements can fail where they pull excessive current unless they are warping so much under heat that they are contacting each other and shorting out.  Heating elements of any kind typically fail in an open circuit mode where they pull little or no current.  

You can typically but a whole resisitive heat unit box that is not furnace-specific. Its just the metal box with heating elements, wiring, and contactors.   If you have another backup source of heat why even worry about it. Use the heat pump and when it can't keep up crank up the wood heater.  If your heat pump is operating properly you will be pleasantly surprised  with your power bill.


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## iron (Apr 3, 2017)

semipro said:


> I'm having a hard time understanding how electrical resistance elements can fail where they pull excessive current unless they are warping so much under heat that they are contacting each other and shorting out



yeah, i struggled with that concept too. they did not appear to be contacting each other or anything else. the tech wasn't terribly reassuring. might need a second opinion.


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## fbelec (Apr 9, 2017)

i wired a few york affinity's nice unit. a couple were dual fuel heat pump and if it could not keep up it would switch to 99% eff gas variable speed compressor and air handler and modulating gas fire. only used as much power or gas as needed controlled by thermometer at the compressor.


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