Forum Discussion

Andy-RV1's avatar
Andy-RV1
Explorer
Oct 18, 2020

Suburban Furnace has 2 Amp Phantom Load when off

Folks,
Just took a trip in my fifth wheel. 2003 Cougar with suburban furnace. It had been off the road for about 20 months so I checked out all the subsystems.
AC, Fridge, Furnace, Water Pump, Hot Water Heater all seemed to work fine.
My generator is not working so I was dry camping.
Found that I could not get through my second night without a low battery setting off the CO/Propane detector. That will wake you up!
Was able to run the tow vehicle intermittently to keep things running, but clearly had some unexpected power usage.
Back home I was able to identify that the furnace circuit is drawing 2 amps with the thermostat in the off position.
So my current assumption is that there is some short in the furnace or some circuit is energized which should not be.

Anyone experience anything similar on a suburban furnace? It is an SF model, I think the SF30F, but I am not sure.

I pulled the furnace fuse for now, so I dont have that drain, but would like to track done the issue.

Has anyone experienced anything similar?

Any help is appreciated.
Thanks
Andy
  • Dusty_R's avatar
    Dusty_R
    Explorer
    Oct 18, 2020
    Most gas furnaces will drain the battery in one night or less.

    Dusty
  • Andy-RV1's avatar
    Andy-RV1
    Explorer
    Oct 18, 2020
    Even when they are OFF? I mean like the thermostat is set to OFF, the temp is set to very cold. The only draw should be the thermostat it self. Hmmm. Now thats a thought. I will check that next.
  • dougrainer's avatar
    dougrainer
    Nomad
    Oct 18, 2020
    Is it a RVP or Dometic tstat? Is the furnace controlled by the same Tstat as the roof AC? Or, do you have an aftermarket wall tstat that is programmable. A 2 amp draw on a GOOD fully charged battery will not drain overnight. Doug
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Oct 18, 2020
    “My generator is not working so I was dry camping.”

    Generators are not considered a “hookup.” Consider solar.
  • time2roll's avatar
    time2roll
    Nomad
    Oct 18, 2020
    I would be following the current with my DC clamp-on ammeter. Make sure that power is actually getting just to the furnace and then see what is warm in the unit.
  • BFL13's avatar
    BFL13
    Explorer II
    Oct 18, 2020
    Is there another circuit on the same fuse as the furnace? Follow the wires. Or does something else not work too that is easy to spot that might be worth 2 amps? Single DC light on in a compartment you seldom open?
  • Edd505's avatar
    Edd505
    Explorer
    Oct 18, 2020
    GO to iRV2 and message old biscuit, he's an expert in RV electric.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Oct 19, 2020
    DC is always AT the furnace
    Comes from the FUSED Source (DC Dist Panel) to the furnace controls
    Furnace controls would be either a 'Timed Delay Relay' OR 'PWR' circuit on the circuit board (model/vintage dependent)
    DC also goes to the Thermostat

    2A Draw is high when not running

    Find/ID the Source Fuse and see IF it is being used for something else then just furnace

    Furnace motor can draw 8 - 11.5 Amps (Model dependent)
    But only when running

    See Pgs 34 - 36 for wiring diagrams

    Suburban RV Furnaces
  • Fisherman's avatar
    Fisherman
    Explorer
    Oct 19, 2020
    Lwiddis wrote:
    “My generator is not working so I was dry camping.”

    Generators are not considered a “hookup.” Consider solar.


    And what does your solar have to do with his furnace situation, absolutely nothing.

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