Furnace trouble

[CBari]

This weekend my furnace in my horse trailer acted up. I need a little help. It is a suburban nt-16se. It lights and functions correctly but the heat put out very low. The flame is all blue as it is susposed to be. The out put air is luke warm at best mostly cold. The exhaust is clean and hot as normal. What am I missing.



I haven't torn into it yet as I am at a loss of where to start looking.



Is there some ducting that could have come loose. Mine is just set up to blow out right at the unit. I don't have the accessory ducting that some have.



thanks

 

[HBarlow]

Pull it out and inspect it on a bench. If it hasn't been used all summer you could have a dead critter or a nest blocking airflow. They're easy to remove from the trailer.

 

[mrtrombley]

Just take the inside louver off and try looking inside at the furnace before pulling the furnace out. You might be able to see from there. I have taken my furnace out a couple times, and although it wasn't that bad, it still was quite a bit involved (especially when it quit in 15-20 degree weather). Everything is tucked in there pretty tight. Make sure you mark the wires before disconnecting them, and you have to shut off then disconnect the propane tube. The propane feed can be difficult to get out of the way, because it doesn't bend or move easily.

I assume the blower motor is working from what you said but make sure the cage is spinning, that's what blows the heat into your trailer. Also check the fuse for it.

 

[CBari]

I pulled the front cover and the cabinet opening off so I could get at it. The blower is blowing good, it is just not getting hot. I can touch the burner chamber after it has been running 10-15 and it is warm but not to hot to leave my hand on. Flame looks good and blue no yellow anywhere. The only think that I see that the burner looks like it only burns for about 2 inches but the chamber it is in is a lot longer than that.

 

[B.G. Smith]

Sounds like the orifice is partially obstructed or pressure too low. . If you can access it, try running a wire into it to remove obstruction. The pressure should be 11 inches of water column. bg

 

[Bill Stockard]

I pulled the front cover and the cabinet opening off so I could get at it. The blower is blowing good, it is just not getting hot. I can touch the burner chamber after it has been running 10-15 and it is warm but not to hot to leave my hand on. Flame looks good and blue no yellow anywhere. The only think that I see that the burner looks like it only burns for about 2 inches but the chamber it is in is a lot longer than that.

I'll bet there is a mud dauber or wasp nest on the underside of the burner causing only part of it to work. Years ago I had a similar problem with an Atwood heater. After I fixed it, I installed a mud dauber screen, sold at RV supply stores, over the heater intake/exhaust and have never had a problem like that again.



Bill

 

[CBari]

I will try cleaning the burner and the orface tonight but if the screens work I shouldn't have a dirt dauber nest as I have had the screens on for the last 3 years.



As for low pressure the hot water heater and the fridge seem to work fine.



I bet there has to be some obstruction with the burner.

 

[JMetzger]

Spiders can cause a problem around the burner also & they can get in from inside the rig.

 

[AClayton]

I am going to go out on a limb here because I have seen it before..... although somewhat rare. I am going to suggest that maybe the return air is restricted and preventing full airflow out the supply air ducts or/ front of the furnace in your particular case. If the furnace is installed in a base cabinet, the return air has to be sucked in through the sides or back of the unit. If camping supplies or cargo is packed too close to the furnace or the return air vent is blocked or partially blocked, it will restrict your supply airflow. Don't think it is gas pressure related because you posted a pretty blue flame and no yellow... ..... which indicates good combustion. Spiders will cause erratic operation yes, but generally it won't fire and if it does - it is a very inefficient flame.



Check your return airflow and get back to us!!





Alan

 

[RVTRKN]

If return air is blocked, it will have warmer than normal air. Check the inside of the heat exchanger as Bill has mentioned, and you still might want to check the pressure. There is an adjustment for it but have the proper gage to check this first. BTU of the flame can be an issue, if your able to touch the heat exchanger surface without getting burned.

 

[jeepit]

Is it possible your ductwork has come apart under a floor and all the hot air is being lost?

 

[CBari]

Well the burner tube holes except for the first 2 inches worth were rust completly closed. I am still cleaning the combustion chamber want to make sure that it isn't rusted out anywhere. I did find a dirt dauber nest on the intake side. Which makes me wonder what good the screens really ar