Pilot Light

[Silver Threads]

Was wondering if anyone else has had the problem of keeping there heater pilot light lit? We can light the furnace and it will heat up the trailer, then when it kicks off, the pilot light goes off to. My husband blew out the lines but it didnt help. It helped all the other appliances, but not the heater. Any ideas?
Thank you!

[Lumatic]

First I am no expert in this area and others out there undoubtably know more than me.

It could be multiple causes. A bad regulator on the tanks. dirty pilot orifice or bad thermocuple is what I would shoot for first. The water column pressure on the regulator should be about 11 inches or the pilot flame can float off. Try cleaning the pilot orifice with brake cleaner but don't poke anything into it.

If you have an NT22 furnace, as I have in my Tradewind, there is an old recall because the crossover tube between the blower and combustion chamber falls apart and you can be pumping carbon monoxide into the trailer.

My experience in finding someone to service a furnace of this vintage is no one will touch it because of liability. Sorry, I'm in the same boat.

[Silver Threads]

Thanks, I will tell him to try it, it sure cant hurt. We bought the propane/ co2 detector, it hasnt went off yet, so i guess that is a good sign.

[TomW]

Tammy,

I had the exact issue you describe. The problem ended up being a partially clogged pilot light jet. The jet is located at the end of the gas line near the pilot light itself. In my case, the furnace had to be removed to gain access to it.

As I recall, the jet had two small orifi instead of one big one. Soaking in solvent before blowing the jet out with shop air was all it took to fix the problem.

Tom

[lewster]

Originally Posted by Marshall

First I am no expert in this area and others out there undoubtably know more than me.

It could be multiple causes. A bad regulator on the tanks. dirty pilot orifice or bad thermocuple is what I would shoot for first. The water column pressure on the regulator should be about 11 inches or the pilot flame can float off. Try cleaning the pilot orifice with brake cleaner but don't poke anything into it.

If you have an NT22 furnace, as I have in my Tradewind, there is an old recall because the crossover tube between the blower and combustion chamber falls apart and you can be pumping carbon monoxide into the trailer.

My experience in finding someone to service a furnace of this vintage is no one will touch it because of liability. Sorry, I'm in the same boat.

It's like you took the words right out of my mouth. Just remember that you should never put anything thru any gas orifice opening other than solvent, compressed air and maybe some dental floss! Anything else will distort the precision-drilled opening and cause problems witthh the flame shape.

[Silver Threads]

So, will I need to take the furnace out? It looks as though I can get the front cover off without taking it out. Will taking the cover off be sufficient for what I need to do?

Thanks,
John

[rickandsandi]

Originally Posted by Silver Threads

So, will I need to take the furnace out? It looks as though I can get the front cover off without taking it out. Will taking the cover off be sufficient for what I need to do?

Thanks,
John

Possibly John, which furnace do yo have?

[Action]

It depends on furnace location and type.

>>>>>>>>>>>>>>>>>>Action

[Silver Threads]

Well, it is a Suburban furnace, cannot get to where I can see a model number on it. It is located right underneath the stove top at the end of the counter. I can lift what seems to be a front cover off of it, but I have to remove a sliding panel from in front of it first. Gotta get ready for church now though, so that will have to come tom.

Thanks,
John

[Inland RV Center, In]

Originally Posted by Silver Threads

Was wondering if anyone else has had the problem of keeping there heater pilot light lit? We can light the furnace and it will heat up the trailer, then when it kicks off, the pilot light goes off to. My husband blew out the lines but it didnt help. It helped all the other appliances, but not the heater. Any ideas?
Thank you!

You have two problems.

1. More than likely, the LPG pressure has dropped, It should be between 11 and 13 inches of water column pressure, preferably 12.5 inches.

2. Periodically, the furnace must be remove and taken apart, to clean out the dirt and sand that it has sucked into the combustion chamber. The combustion chamber is very small. When you reduce it's volume, however slight, then the furnace will light and run just fine. BUT when the furnace shuts down, it will "suck" the pilot light out. That is exactly how you have described the operation.

There is no short cut to correct the problem.

You cannot blow out the dirt with air.

The proper fix is;

1. Remove the furnace.
2. Remove the burner log from the combustion chamber. You will usually find it partially clogged up as well. You can clean the slots with a hack saw blade.
3. Tap the combustion chamber with a hammer. That will loosen other dirt and rust.
4. Since the combustion chamber is like a sideways "S" you must tilt the combustion chamber side to side, which allows the dirt and rust to move from one chamber to the next, and finally out through the hole where the burner log was located.
5. Dump the dirt out on some paper.
6. Have someone stand by you, to give you "smelling salts" when you faint when you see how much foreign material will fall out.
7. Check the gasket on the blower assembly as well as the gasket between the burner log and combustion chamber. If more than 10 years old or so, they will need replacement.
8. RV Furnaces should be removed and cleaned every 4 to 7 years, maximum, depending on the frequency of use and the area that it was used in.
9. You can almost bet your last dime, that if your furnace has been used and not taken apart and cleaned within the above time frame, that you will dump out at least one or two "cupfuls" of foreign material.
10. That reduces the cubic volume of the combustion chamber enough, so that the pilot light will be sucked out, everytime the furnace shuts down.

Again, trying to blow out the dirt with air will "NOT" correct the problem. That could also cause some damage to the combustion chamber.

Many repairs can and do have short cuts.

This repair does not have a short cut.

Remember, no short cuts when dealing with an explosive material, such as LPG.

If you don't feel qualified to do the repair, take the trailer or furnace to a shop that you can trust. The qualifying test for that shop is have them tell you the proper way to clean a RV furnace. If they tell you anything other than the above, move on to another dealer.

Please post the results you find when you disassemble your furnace.

Others I am sure would like to also know what you found.

Andy

[Lumatic]

So orifii is to orifice as hippopotami is to to hippopotomus? Or did you just make that up Tom?

Hey Andy,
If you got your internet eyes on. As far as I know parts for those old Suburbans are no longer officially available. Where can I get the gasket material you were talking about?

On my 71 Suburban NT22 you don't have to pull the furnace cabinet. Take off the front cover (you may have to cut an access hole in the shelf above to get at the clip. Then remove one screw holding the furnace proper to the
metal cabinet and voila the whole guts slides out on a track. Of course you have not forgotten to disconnect the gas line and the screws on the inlet/outlet vent on the outside of the trailer, right?

[Silver Threads]

Thanks Andy, I will let you know how it goes. Sounds like a lot of work ahead of me!!

[Inland RV Center, In]

Originally Posted by Silver Threads

Thanks Andy, I will let you know how it goes. Sounds like a lot of work ahead of me!!

Anything worth doing, should be done the correct way, at least to most owners.

That is especially true when dealing with a possible life threatening device such as a furnace.

Taking short cuts, rarely pays dividends, especially with an Airstream.

Andy

[Inland RV Center, In]

Originally Posted by Marshall

So orifii is to orifice as hippopotami is to to hippopotomus? Or did you just make that up Tom?

Hey Andy,
If you got your internet eyes on. As far as I know parts for those old Suburbans are no longer officially available. Where can I get the gasket material you were talking about?

On my 71 Suburban NT22 you don't have to pull the furnace cabinet. Take off the front cover (you may have to cut an access hole in the shelf above to get at the clip. Then remove one screw holding the furnace proper to the
metal cabinet and voila the whole guts slides out on a track. Of course you have not forgotten to disconnect the gas line and the screws on the inlet/outlet vent on the outside of the trailer, right?

We have what is still available, which is two of the three that you will need.

The third one is for the blower assembly. You can make that gasket yourself using gasket material found at most any auto parts store.

However, do not use that gasket for the burner log or electrode, as the heat will ruin it in short order.

Andy

[Mikell]

I'm in for the same. I had trouble getting mine working, and thought maybe I should just replace the whole furnace with a newer unit. I'll pull the existing unit out and inspect it, then make a determination. It can't be too complicated, but the risk to safety is high if things aren't done right in this area. I was reading on catalytic heaters. No thanks, I prefer to wake up not dead.

[Silver Threads]

I have another question, how do you get it out, and what is a sail switch and where might it be located? My husband worked for a coule of hours trying to get the furnace apart but to no avail. We really dont want to have to take the entire cabinet apart if we dont have to. Is there a trick to it?

[lewster]

........is also called an 'air prover switch' and will be located somewhere on the blower housing. It is a momentary contact switch that is normally open, and has a long piece of lightweight metal attached to it. When the blower powers up, the air in the chamber pushes on the metal 'sail' and closes the switch, telling the furnace that there is sufficient air flowing thru it to allow the gas valve to open and continue with the ignition process.

You can test this switch for continuity with an ohm meter...zero reading when open and a definite reading when you close the sail with your finger (FAN OFF!!!). You can also trace the electrical path to be sure that the thermostat and ECO (high limit switch) also have continuity.

As far as removal, I've never had to take out a unit that old, but generally, you remove that front of the cabinet and look for hold-down screws at the floor level. Disconnect the LP and electrical and out it should come.

I'm sure some of the restoration experts here will know the exact procedure.
Have fun and be careful!!!! If you can't figure something out, have a QUALIFIED professional look at it, as with all LP appliances, they CAN kill you if improperly serviced. BE SAFE!!!

[Silver Threads]

Hello,
I have just about decided not to clean the furnace myself, but rather find somebody that is qualified. In the begining the pilot would light and stay lit most of the time, the heat worked good. Every once in a while when the furnace would kick back on it would blow out the pilot. Well, I blew out the gas lines with air, the stove, oven, and fridge all worked better after this. However the pilot will not light at all now, seems that the air made it much worse.

John

[sfixx]

Originally Posted by Silver Threads

...... Every once in a while when the furnace would kick back on it would blow out the pilot......

That's a little different variation on your initial description and reminds me now of my furnace problem. I described it in the thread "furnace goes whoosh". I was able to get a stable pilot that survived lighting by cleaning the gas valve. The valve was a little gummed up which allowed a small amount of gas to leak by causing a small explosion upon lighting. That's what blew out the pilot. With the pilot access cap off the flames even shot out of the hole!

Good luck,

Steve

[Action]

Originally Posted by Silver Threads

Hello,
.Well, I blew out the gas lines with air, the stove, oven, and fridge all worked better after this. However the pilot will not light at all now, seems that the air made it much worse.

John

Sounds like you blew debris into the pilot light mechanism.

>>>>>>>>>Action