The joys of buying used. The uncertanty of buying at a auction. Did'nt hear it run, but looked good, had a low bid and won it. Had to wait a few days to pick it up due to the weather.
Checked the fluids , belts, Pumped the gas 3 times and it started and purred. Drove great.
All the appliances were changed. Now for why to do things right TFT.
The furnace a Atwood 8531 IV , @ 30000 btu, was installed upside down. Startup issues included a loud shotgun blast with fire out of the vent. Oh dear!! Took the furnace out and to a local RV shop, $330 later a new gas valve. Reinstalled it upside down to the same issues.Took it out again and Installed it right side up but had to move the vent about 6". Had to extend the gas line also but it works like a dream now. At 30000 btu beats the 16000 it came with and i have 3 ducted outlets.
Problem was a sticking sail switch because of it being upside down .

1975 19" c class

Ahh the joys of Rving.

Worse news: Check the specs for total discharge duct area - my bet is that the ductwork for the 16K BTU furnace is nowhere near enough for the 30K BTU.

Less than minimum is a serious hazard...

quote:

Originally posted by Rusty:
Worse news: Check the specs for total discharge duct area - my bet is that the ductwork for the 16K BTU furnace is nowhere near enough for the 30K BTU.

Less than minimum is a serious hazard...

What?
I do have the Specs which has no mention of a duct discharge requirement. But I did increase the ducting from 2 to 3. Also the 85001V series design allows for space utilization. Also allows for bottom discharge.
It is a powerfull furnace and i get good heat to the back bathroom. Also being larger I was told the furnace will cycle less, heat quicker.
Anyway thanks for the input Rusty, if you have more info on that let me know!

The only spec I could find (except for a troubleshooting comment that "duct area is insufficent") was about back pressure.

Anyway, if it were I, I'd call and ask; possibly with your extra duct, the installation meets the minimum. Nevertheless, IMHO, it's not something to trifle with. Tomorrow I'll check on the specs on my furnace (36K BTU) and let you know - I think mine's an Atwood, also.

I took the furnace in to a Rv dealership for the repair. I did get a chance to talk to the tech about the size issue and he said it was fine, also I talked to 2 different Atwood Tech's about the furnace troubles i was having, but did'nt ask about this subject.
But your right Rusty, " better to be safe than sorry" Let me know what your research come up with.

Dale

My 36K BTU furnace kept my coach toasty at my sister's last December in -5°F weather (with 25 K winds), so unless you seek out Yellowknife in January, you'll be WARM! I'll let you know what I find out.

My furnace is the Hydro-Flame (Acquired by Atwood in 1993) 8531-II; handbook specs 36 sq. in. (1-4" duct is 12 sq. in.). The 8521 and 8501 (in the book) call for 24 sq. in.

Static water test is preferred (there's a test fitting), and the book calls for 0.30" water.

Rusty
Sounds like you have the earlier model for my 8531 IV , is yours not 30K btu?
Anyhow not to get into a p- war, I know i have a toasty unit. Remember im from Calgary Canada and it was -8 here in March/ May. Had my issues with dewinterizing it and having that spring freeze. That story is in a different thread.

Dale

The spec sheet (without identifying the model) says 36K BTU; it's hand-written on the erection diagram - I think it should be 30K (hard to tell if it's a "6" or "0"), as the book rates the model at 31K BTU.

Anyway, we have the same basic model. That oughta' keep you warm!

Just a update, with the modification to turn it right side up, meaning it was not installed correctly the first time (was bought this way) this furnace works great. Being on a thermostat, I have no overheating of the MH, it is warm and I like warm if not toasty, I spent a few nights in it to test it out and I was comfortable enough to well.. Sans the comforter. On the plus side, uses small amount of propane for the heat output. Now I say "let the summer begin"

Rather than start a new thread, I thought I'd continue this old one since we have Dalton's old Class C now. The furnace does put out alot of heat quickly, I think maybe it is too large for the unit and might cycle on/off alot. But that is not today's problem.
The furnace only runs for about 30 seconds then trips off. The culprit is a switch near (not on) the furnace marked "off/reset" which an internet search leads me to believe is a hi temp safety. The exterior metal box of the furnace gets too hot to touch - is that normal?
Ideas? Other than take it in to a dealer.

If the overtemp is kicking out there could be inadequate air flow in the plenum around the firebox. Check to be sure that the blower fan is moving enough air. The fan may be loose on the motor shaft, the fan may be blocked on the intake side or the output heat ducts may be blocked. Without air flow to draw heat away from the firebox it will heat up quickly.

Good luck!

Figured it was either restricted ducts or inadequate intake.
I tried taking the duct grilles off to reduce friction, did a quick check for obvious kinks or blocks, even tried running it with the plenum lid off. Same result. Lots of hot air coming out, but the switch resets.
As for the fan... hard to get at stuff. Do I have to remove the entire furnace box to access the blower?
I would have thought that this furnace needed outside combustion air, but all I see is a vent and a big hole in the side of the furnace box but no connection to the outside, other than the exhaust port. Normal?

Both Suburban and Dometic furnaces use out side combustion air. On the coach exterior where the furnace sits should be a vent, this vent takes in combustion air and exhausts it. When the furnace is running you will feel the heat if it is working right.

Yes, you need to remove the whole furnace insides. The exhaust vent has a long screw that you need to remove also. The furnace painted housing can stay in place after the front is removed and insides pulled out.

I failed to say that you need to disconnect the propane, thermostat and electrical connection. Shut off the propane at the tank. Remember propane is heavier than air and will accumulate in low closed off areas,