Furnace won't run on 12v

Discussion in 'Heating / Cooling Systems' started by mflanagan, Mar 31, 2007.

  1. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    If I am hooked up to shore power my furnace runs fine. I turn the thermostat on, the fan kicks in, 10 seconds later the igniter clicks and Whoosh! Furnace ON!

    If I unplug the Shore power, I turn on the thermostat, the fan kicks in....and just run and runs. The igniter never clicks and it never lights.

    I know the Propane is turned on because the furnace works when I'm on shore power and the stove lights. I know the battery works because I can turn on the lights and the pump in the PUP when disconnected from shore power. I am fully charged because I have the charger on it and it says it is charged. BTW I am using 2 6v Golf cart batteries (shouldn't make a difference).

    What else can I check?

    Thanks all!

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     
  2. tnchuck100

    tnchuck100 New Member

    Messages:
    573
    Likes Received:
    8
    Joined:
    Feb 8, 2007
    Does the fan appear to run slower on the battery than when on shore power? If so, there is a thing called a sail switch. This senses the movement of air through the furnace. If does not sense air movement it will not start gas flow or the igniter. This switch may be binding and the shore power provides just enough additional push to operate this switch.

    This is only one possibility.

    <b>Chuck & Mary - Sparta, Tennessee
    '00 Dodge Dakota <img src=../Images/icons/icon_smile_suv.gif border=0 align=middle> '05 Palomino Pony <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle>
    '03 Harley Davidson Ultra Classic <img src=../Images/icons/icon_smile_bike.gif border=0 align=middle> '04 Timeout <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle></b>

    Edited by - tnchuck100 on March 31 2007 18:52:27
     
  3. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    Yes! I noticed that it does run slower on battery. Where do I need to check this switch?

    Thanks!

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     
  4. tnchuck100

    tnchuck100 New Member

    Messages:
    573
    Likes Received:
    8
    Joined:
    Feb 8, 2007
    I have never had one apart so I don't know where it is located. I know about this switch because I studied the manual that came with mine. It was shown in the schematic diagram but not where it was physically located. Open 'er up and look. Logic tells me it must be like a piece of light sheet metal that can move when air passes by it.

    <b>Chuck & Mary - Sparta, Tennessee
    '00 Dodge Dakota <img src=../Images/icons/icon_smile_suv.gif border=0 align=middle> '05 Palomino Pony <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle>
    '03 Harley Davidson Ultra Classic <img src=../Images/icons/icon_smile_bike.gif border=0 align=middle> '04 Timeout <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle></b>
     
  5. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    Will do! Meantime hopefully somebody will chime in here. Like you say, it must be a flap that is triggered when a certain amount of wind hits it. Then it, in turn triggers a switch.

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     
  6. tnchuck100

    tnchuck100 New Member

    Messages:
    573
    Likes Received:
    8
    Joined:
    Feb 8, 2007
    One thing you might try to help confirm this. Start the furnace on shore power. While it is running remove shore power and let the battery run it. Does it stay lit or shut down?

    <b>Chuck & Mary - Sparta, Tennessee
    '00 Dodge Dakota <img src=../Images/icons/icon_smile_suv.gif border=0 align=middle> '05 Palomino Pony <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle>
    '03 Harley Davidson Ultra Classic <img src=../Images/icons/icon_smile_bike.gif border=0 align=middle> '04 Timeout <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle></b>
     
  7. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    OK....I Turned on the furnace (12v only) and the fan came on. I went out and plugged in the shore power and the fan went a lot faster and the igniter went and it lit. I waited a little while and made sure heat was coming out and then I unplugged the power. The fan went down significantly and the heat decreased so it must have shut off.

    So it seems that 12v doesnt work at all with the furnace. Also the wind coming out of the furnace on 12v is so pitiful that a mouse couldnt get warm standing next to it. You can berely feel it blow at all. Is there a setting to turn up the fan on 12v?

    Looks like I have an ATWOOD Everest Star 7900/8000 Hydroflame Furnace.



    Thanks again.

    1997 Dutchmen 1204
    1997 Isuzu Trooper

    Edited by - mflanagan on April 01 2007 12:48:41
     
  8. tnchuck100

    tnchuck100 New Member

    Messages:
    573
    Likes Received:
    8
    Joined:
    Feb 8, 2007
    What is the battery voltage with the furnace fan running?

    <b>Chuck & Mary - Sparta, Tennessee
    '00 Dodge Dakota <img src=../Images/icons/icon_smile_suv.gif border=0 align=middle> '05 Palomino Pony <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle>
    '03 Harley Davidson Ultra Classic <img src=../Images/icons/icon_smile_bike.gif border=0 align=middle> '04 Timeout <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle></b>
     
  9. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    Hmmmmm. I'm beginning to suspect my batteries per this thread HERE

    My 3 stage charger says it's charged though. It's raining right now so it'll be a bit before I can put the voltmeter on it.

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     
  10. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    OK. I just checked this morning and together both 6v batteries read 12.84. Does that seem a little high? I tested a couple different times and thats what it came to.

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     
  11. denverd0n

    denverd0n New Member

    Messages:
    77
    Likes Received:
    0
    Joined:
    Mar 17, 2006
    How did you test the voltage? When you are plugged into shore power it should be charging the battery. If you unplug it and immediately check the battery voltage then you will get a high reading. You should unplug the PUP from shore power and let it sit for at least a half an hour. Two or three hours would be better, and overnight would be perfect. Then check the battery voltage and see what you're getting. If it is above 12.7 volts then the problem is not your batteries.

    If the batteries themselves are good the next thing I would do is check the wiring to the furnace. Maybe you have a bad ground, or a wiring problem that is causing a a serious voltage drop to the furnace.

    Finally, on my furnace, I took the front grille (inside the PUP) off to allow better airflow across the sail switch, and this fixed the problems I was having with the furnace not lighting.

    Good luck!
     
  12. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    I tested with shore power disconnected. However I did have it charging overnight thus the slightly high reading. I may have to retrace my wiring to see if there is a problem. Does everything go thru the inverter?

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     
  13. tnchuck100

    tnchuck100 New Member

    Messages:
    573
    Likes Received:
    8
    Joined:
    Feb 8, 2007
    Was that 12.84 v with the furnace fan running? As denverdOn said, let the batteries set an hour or so before doing this load test.

    <b>Chuck & Mary - Sparta, Tennessee
    '00 Dodge Dakota <img src=../Images/icons/icon_smile_suv.gif border=0 align=middle> '05 Palomino Pony <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle>
    '03 Harley Davidson Ultra Classic <img src=../Images/icons/icon_smile_bike.gif border=0 align=middle> '04 Timeout <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle></b>
     
  14. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    No, that was 12.84 with no load. I will let the batts settle a while and re-test. Then turn on the fan and test under the fan load and get back to ya'll

    Thx for all the help guys!

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     
  15. Duff

    Duff New Member

    Messages:
    41
    Likes Received:
    1
    Joined:
    Nov 20, 2006
    Location:
    Loveland, CO
    My guess is the batteries are shot. Probably a shorted cell, which will look voltage wise OK but try to put a load on it and the voltage will drop a lot. It also could be a high resistance junction in your wiring but my bet is the batteries.

    If you don't have a battery load tester, save yourself a lot of grief and take the batteries to your local auto parts store and ask them to check them under load. Most will happily do this for free, and it will once and for all tell you whether your batteries are good.

    Let us know how the batteries test, and then we can help diagnose from there.

    Duff W0XYZ
    Loveland CO
    '06 Fleetwood Graphite
    '97 Toyota 4Runner
    '06 Nights in a PopUp-2
    '06 Nights in a Cabin-13
    '07 Nights in a PopUp-0
     
  16. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    Well, that is a possibility but I just bought them both as a matched pair at Sams Club (2 6v Energizer Golf Cart Batteries) The sticker says 11/06 on them. I guess I could take them to get them tested though to be sure.

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     
  17. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    Well that was it. It was the batteries! I didn't even fool around, I just exchanged them at Sams with no hassle and stuck them back in and instantly heard a weird noise inside the PUP I had not heard before. I have one of those 'Fan-tastic' vent fans with the motorized hatch door that was popping up. I just thought the motor to lift the vent door was shot so I paid it no mind, but it just didn't have enough 12v juice to run it.

    Furnace fan was as strong as on shore power and ignited no problem!<img src=../Images/icons/icon_smile_happycamper.gif border=0 align=middle>

    Thanks so much for all your diagnostic skills. I was so sure it wasn't the batteries because they were new, held a charge, and ran other stuff in the PUP no problem. Still very weird but I've already moved on!

    Thanks all!
    Flan

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     
  18. Lost in Space

    Lost in Space Member

    Messages:
    521
    Likes Received:
    3
    Joined:
    Mar 18, 2007
    Sorry to change the subject but why did you choose two 6 volt golf cart batteries rather than one 12 volt deep cycle? (I know you have it wired for 12 volts, I just don't understand the reasoning behind doing it. Enlighten me!

    --------------------
    Dana & Claudia
    The Happy Campers
    '05 Jeep Wrangler Rubicon
    '04 Palomino Pony 280
     
  19. tnchuck100

    tnchuck100 New Member

    Messages:
    573
    Likes Received:
    8
    Joined:
    Feb 8, 2007
    You're welcome. Glad you have it fixed.

    Lost In Space: 2 - 6 volt golf cart batteries? That arrangement gives you MUCH greater capacity.

    <b>Chuck & Mary - Sparta, Tennessee
    '00 Dodge Dakota <img src=../Images/icons/icon_smile_suv.gif border=0 align=middle> '05 Palomino Pony <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle>
    '03 Harley Davidson Ultra Classic <img src=../Images/icons/icon_smile_bike.gif border=0 align=middle> '04 Timeout <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle></b>

    Edited by - tnchuck100 on April 03 2007 17:45:24

    Edited by - tnchuck100 on April 03 2007 17:46:43
     
  20. mflanagan

    mflanagan New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Jan 20, 2007
    A regular Group 27 Battery will give you around 100 Amp hours per charge (give or take)

    2 6v Golf cart batteries will give you about 220 Amp hours. Also Golf cart batteries can discharge about 70% without adversely affecting the health of the battery. And it can do it over and over again like a true Deep cycle.

    Somebody correct me if I'm wrong on these numbers.

    Flan

    1997 Dutchmen 1204
    1997 Isuzu Trooper
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.