Old Furnace

[indianhillsted]

I own a 1983 Shasta. I bought it used several years ago, but am just starting to use it.

On a weekend trip, the furnace worked fine one night. But the next night would not stay lit.

This is probably a silly question...

Is the thermostat on the furnace mechanical or does it require the battery to be charged? This is a very old camper. The AC electrics do not work, but that battery does. However, the only interior light is broken so (I thought) I had no need to keep the battery charged.

Could this be my problem (dead battery)? I tried adjusting the pilot screw as well to no avail.

Thanks in advance,
Ted

[TheViking]

I own a 1983 Shasta. I bought it used several years ago, but am just starting to use it.

On a weekend trip, the furnace worked fine one night. But the next night would not stay lit.

This is probably a silly question...

Is the thermostat on the furnace mechanical or does it require the battery to be charged? This is a very old camper. The AC electrics do not work, but that battery does. However, the only interior light is broken so (I thought) I had no need to keep the battery charged.

Could this be my problem (dead battery)? I tried adjusting the pilot screw as well to no avail.

Thanks in advance,
Ted

Ted,  It could be that with your dead battery it is just the fan for your heater that is not working.  It needs electric to push the heat.

[indianhillsted]

Gosh...now I really feel stupid. I didn't know there should be a fan. Do all furnaces have fans? Keep in mind, this thing is over 20 years old.

That still does not explain why one night it worked just fine and the next night it did not. I never heard a fan the first night, but we were plenty warm so I have to assume it was working.

Let me give more details...

The night it did not work. I could get the pilot lit but when I went to start the burner, it would only burn for a few seconds (perhaps 10-15 secs), then there would be an audible click and the whole thing would shut off. I adjusted the thermo control to both extremes with no change.

I suppose to test it out I could just go charge my battery, but if for some reason it works and I find out the thermo has nothing to do with the battery then that will not be the reason it is working and I may be stuck again with cold kids.

Thanks

[mike4947]

Sounds like an old style furnace they called a gravity heater. Worked like the old octupus furnaces in houses with just convection moving the heat. Most didn't have any electrical connections and were basically a space heater mounted so they'd have exhaust venting.
It's been too long since I had one, but a can give you a little advice. They still have parts and instuctions for them. See if you can find the data plate on the furnace and contact the maker for any info.
Second word of advise would be to clean out the burner and tubing. Spiders for some reason love propane and it's very possible a piece of web got stuck somewhere.

[deniski]

We too have an old popup with an old furnace.  You must have the battery working in ours for the fan and thermostat to work. Without those two items, the furnace will not work at all.  We actually took the popup to a local furnace etc repair shop and had it fixed once for more money than I am willing to admit was spent.  

When it's time to light the furnace in our popup, it's also a good time for me to take a little walk  :Z    My poor husband (6'2") has to lay on the floor, look through a teeny tiny little hole while trying mucho many times to get the little pilot to light, and then pray that the fan doesn't blow it out first thing.....   Generally he repeats this process about five times and then the dumb thing stays lit and heats up the space.  And that's AFTER we had it FIXED.    :yikes:

Good luck!!

[Steve-o-bud]

If you have a forced air unit, you will have some sort of air exhaust/intake port on the outside. If this is the case, if your battery is dead, the unit will not operate. On our Bayside, which has an electronic pilot-less ignition, the sequence is that the fan comes on, then the burner ignites. I've run out of propane and the fan still runs, it just blows cold air.
 
Also, if it were some sort of forced air unit, you would defintely hear the fan comming on.
 
If this is some sort of radiant heater, I think it will still need some power to operate the control circuit to turn the burner off and on.
 
However, my thinking is that you may have a problem with the thermocouple. This is the brass looking device, which is placed so that its tip is in contact with the pilot flame. This produces a small voltage when heated, which is used by the furnace to detect whether the pilot is lit, and if it is not, then it shuts off the gas, to prevent you from blowing up your trailer. This is why when you light the pilot, you must hold the red button down, this holds the valve open while the thermocouple is heating up.
 
I think the click that you are hearing is the valve closeing. Are you giving the thermocouple enough time to heat up? (may take a couple of minutes of holding the button down).

[hoppy]

Some real early Hydra-Flame units used no electricity at all.

 My 1978 Palomino had one of these. No fan, (convection heat as noted by mike4947) and only a tube that served as a thermostat. A numbered dial on the gas regulator at the base of the heater box (a big coffee can) served as the heater setting.

  It sounds that since you are able to light the pilot and it stays lit, there is no problem with the gas supply. The problem seems to appear once you take the gas control from PILOT to the ON position that the burner ring lights momentarly, and then there is the click sound of the burner shutting off. Once this happens, is the pilot still lit?

  If so, I suspect the thermocouple directly above the pilot light has become faulty.

  Another possibility (although tougher to repair) is that a critter has set up housekeeping in the main venturi tube leading to the burner ring. This is what happened to mine, and I needed to take the furnace out of my PU to take it apart.  In my case, the burner would stay lit, but burned with a very yellow, sooty flame. Mine happened to be a muddabber nest in the main tube. In your case, this tube maybe blocked to the point that the burner can't stay lit.

  Hope this helps.

 PS: Do all the other propane appliances work OK?

 Make sure there is no problem with the other "stuff" before tackling a furnace problem.