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groundhogy's avatar
groundhogy
Explorer
Nov 25, 2015

furnace flare ups..

I have a suburban brand furnace.
It worked fine all last winter but in the spring
I had to replace the control board.

Now it fires up fine, but sometimes I get this
loud PUFF. and it blows out the flame and the furnace
has to restart.

Then sometimes it flares up into like a kaos confused
flame. There is a little window where you can look in.
With the normal flame, you see like 5-6 rows of nice
little blue dots of flame at the burner. In kaos mode
you don't see that but see blue all over the place.

thanks,
groundhog

8 Replies

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  • ken56's avatar
    ken56
    Explorer
    Nov 26, 2015
    My experience with residential furnaces tells me there is a crack or a hole in the heat exchanger. DO NOT SLEEP IN THE UNIT UNTIL YOU KNOW FOR SURE WHAT THE PROBLEM IS. Carbon Monoxide will enter the living area, a DEADLY SITUATION. Like the above post said, a 25 yr. old furnace is not worth repairing. Be safe and replace it if you intend to keep using that trailer.
  • dougrainer's avatar
    dougrainer
    Nomad
    Nov 26, 2015
    groundhogy wrote:
    Doug, How does one get inside the firebox?
    I have the NT-30SP


    You remove the furnace, take the side plenum fan blade covers off. You then remove the glass access plate and THAT will allow the burner to pull out. You then turn the furnace casing over and over while blowing compressed air thru either the burner access or exhaust to remove all the rust and sediment build up. You also remove the steel gas inlet with the orifice from the rear. That opens up all the holes in the casing to blow things out. Inspect the casing. If you find rust thru or corrosion thru, throw away the furnace and buy a new one. Not worth repairing a 25 year old furnace. Doug
  • groundhogy's avatar
    groundhogy
    Explorer
    Nov 25, 2015
    Well, I do remember as I turned it various ways when servicing,
    that I could hear rust shaking around all in the fire box.

    But then, from what Golden said, when I went to replace the unit, there
    was some lateral static force on the 3 pipes (connected to firebox) that
    exit the RV. So I am now scared that it could have cracked upon reinstallation
    in the RV. The firebox is old, but it was still working very well last winter.
  • Chris_Bryant's avatar
    Chris_Bryant
    Explorer II
    Nov 25, 2015
    What Doug said- even if it's the newer stainless burner, it sounds like it is at least partially clogged.
    Regardless, the whole unit really should be pulled, cleaned and inspected for cracks/rust holes.
  • dougrainer's avatar
    dougrainer
    Nomad
    Nov 25, 2015
    If you have the Suburban NT series with the round access glass hole for the burner, odds are the cast iron burner is DIRTY and clogged. You probably need the burner pulled and cleaned. I use a standard Hack Saw blade to clean the slits in the burner and then blow it out. Doug
  • Golden_HVAC's avatar
    Golden_HVAC
    Explorer
    Nov 25, 2015
    SOunds like a cracked heat exchanger. You probably need to take it to a pro, at the very least it might need to be taken apart and cleaned very well inside the firebox area, or if cracked it would need replacement.

    What year is the RV?

    Fred.

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