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Old 12-07-2011, 02:02 PM   #1
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1994 25' Excella
Los Angeles , California
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My furnace blows... out its own flame

Hi guys,

Here's another fall furnace fiasco.

I've got a '94 Excella with the self-igniting furnace. The furnace fan had been making a noise (like the blades are dragging against something) so I hadn't been using it. I had not turned it off, just pushed the thermostat switch down.

Then on a super cold night earlier this week, I'm trying to stay warm with a little electrical space heater (which is not really doing the job) when all of a sudden the furnace comes a-blasting and beautiful heat come out of every vent. Within minutes I'm toasty and marveling at the self-repairing furnace, which is not making such a big noise anymore.

Then last night, I'm looking forward to some more toastiness, so I set the thermostat at 65 degrees and head to bed. The thing came on a couple of times, but by morning the trailer was absolutely freezing and there was just cold air coming out of the vents. Stove works fine, so there's still plenty of gas. I turned the furnace off and back on a couple of times per the instructions, but always the same result. The fan begins to spin, but the self-igniter no longer works. And now there's the smell of unburnt gas.

Then I noticed that the exhaust pipe (the one that expels burnt gas to the outside from the furnace) is blowing a lot of cold air now when the fan is on. As if the blower fan has ground a hole in the inner heating chamber over time and is blowing cold air through it, instantly snuffing out the flame. Is this a possible scenario?

This being my first furnace problem, I don't know how it's really supposed to work. But if you do, please help me eliminate some of the guesswork.

Cheers!
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Old 12-07-2011, 02:10 PM   #2
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Hmm, that's an odd one. Is it a Suburban and orginal?
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Old 12-07-2011, 02:16 PM   #3
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It's a Hydro Flame unit, Model 8531-11



Dunno if that's standard issue for these.
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Old 12-07-2011, 02:34 PM   #4
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I don't have a clue; I've had my problems with Suburban, but never one like that. Sorry. Have you the manual and/or is the company still in business?
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Old 12-07-2011, 05:07 PM   #5
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Although it is not a Suburban, which is all I have experience with, I am sure the Hydro Flame has two blower wheels, like the Suburban, one for moving air over the combustion chamber, the other to supply air for the flame. So, with no flame, cold air coming out the exhaust vent is completely normal.

Just what the problem is you are having is hard to tell. Could be low battery voltage, slow blower motor due to dry bearings, bad sail switch which needs enough air passing by to allow the gas valve to open, bad high limit switch (common on Suburbans, may be a problem on Hydro Flames, and on and on.

But cold air from the exhaust is normal with a forced combustion system as most all RV furnaces have.
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Old 12-07-2011, 05:33 PM   #6
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Agree with all the above, the fact the furnace came on rules out the thermostat, the board could be at fault, as our Suburbans are wont to. Generally, if you don't hear the "clunk", it's not firing. Bad electrode, limit switch, ect. I would research the furnace and find someone with experience to go through it completely. It could be something so simple as bees getting in the exterior vents and plugging the flow,which would cause the furnace to shut-down. The furnace is a '94, after all.
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Old 12-07-2011, 05:52 PM   #7
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I don't know about your furnace, but the high limit switch can be replaced without removing the furnace on our's.
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Old 12-07-2011, 06:04 PM   #8
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Quote:
Originally Posted by idroba View Post
Although it is not a Suburban, which is all I have experience with, I am sure the Hydro Flame has two blower wheels, like the Suburban, one for moving air over the combustion chamber, the other to supply air for the flame. So, with no flame, cold air coming out the exhaust vent is completely normal.

Just what the problem is you are having is hard to tell. Could be low battery voltage, slow blower motor due to dry bearings, bad sail switch which needs enough air passing by to allow the gas valve to open, bad high limit switch (common on Suburbans, may be a problem on Hydro Flames, and on and on.

But cold air from the exhaust is normal with a forced combustion system as most all RV furnaces have.
Aha... two fans... oxygen to the flame... I see it now. But there's enough valves, wires and switches here that I've never heard of before. I have very little time to experiment and futz around anymore (which is quite sad) so I think this is one I'll be referring to the local traveling RV repair service. Do you have recommendations for a good one in the L.A. area?

Thanks for all your help, guys!
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Old 12-08-2011, 09:42 PM   #9
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1994 25' Excella
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Now it totally blows... awesomely!

Guys,

Pardon me as I wipe some of that egg offa my face. This proves my total newbiousness. Here's what ACTUALLY happened:

Today I come back to my lair and I have a couple of hours to futz around with the furnace. So with a flashlight and a screwdriver I went looking around in there.

Soon I found the reason for the grinding noise: It came from the back of the smaller fan that drives fresh air to the burner. The main motor sits in a collar that is adjusted by one screw. I loosened the screw and shoved the motor/fan assembly to my right. Tightened it back *just so*. Noise gone.

Wriggled wires. Blew out dust. Which means I blew the dust out of the compartment back into my face. Hacked and wheezed a bit. Found a jammed wire with a slightly frayed coating... one of two yellow wires leading to the ignite/gas valve assembly. Re-fired it a couple of times without success. Then I noticed there's no gas smell anymore.

So I go into the trailer and check the burner on the stove. Dead. Apparently it was not enough pressure for the furnace, but enough pressure for the stove to fool me that there was enough gas two days ago.

So the lesson here for all to see is: If the furnace doesn't ignite anymore, it *might* be because your gas tank's getting low.

The bonus lesson: If the fan makes a big grinding noise, check that screw to adjust the center collar of the motor/fan assembly. Made a world of difference for me.

Now on Propane Tank #2, Starship Excella has gone through 3 furnace heating cycles beautifully. It sounds and works $1500 better after 45 minutes of poking around! The water heater is back on... Jack FM... and so is the disco ball.

And that's that on that one.

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Old 12-08-2011, 09:47 PM   #10
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Congratulations godaddy! It takes a really big man to admit to a dumb mistake like that. Of course, -I- have never done anything as silly as That! :koff:

Only kiddin' ya there, pardner
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Old 12-08-2011, 10:45 PM   #11
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Quote:
Originally Posted by godaddy64 View Post
Guys,

Pardon me as I wipe some of that egg offa my face. This proves my total newbiousness. Here's what ACTUALLY happened:

(snip)
Now on Propane Tank #2, Starship Excella has gone through 3 furnace heating cycles beautifully. It sounds and works $1500 better after 45 minutes of poking around! The water heater is back on... Jack FM... and so is the disco ball.

Why not leave both tanks on and let the automatic regulator change from the empty one to the full one by itself?

(yes, I know, then you will have two really empty tanks, cause you didn't look to see the red flag up... but I always look)
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Old 12-09-2011, 10:16 AM   #12
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1994 25' Excella
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Quote:
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Why not leave both tanks on and let the automatic regulator change from the empty one to the full one by itself?

(yes, I know, then you will have two really empty tanks, cause you didn't look to see the red flag up... but I always look)
er... red flag? There's a red flag? Where?

My trailer has a y-valve with a toggle lever out by the propane tanks. I just kinda figured it was a real simple "use one tank while you get the other one filled up" scenario. So I turned off one tank, toggled the lever to the other tank, and turned it on. What do most people do?

Aage this might be a dumb mistake, but it's nothing compared to some of the other blunders I've pulled off. So I guess over the years it's built my real big manliness to the point where I can laugh at stuff like this. If you're not learning, you're not living I say.

And I know one thing for sure: I had a big smile on my face this morning as I woke up after a comfortable night's sleep. No noise. Just a steady, gentle fluffing of 70 degree warm clouds...

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Old 12-09-2011, 11:14 AM   #13
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Furnaces Suck - LOTS of Propane

Get the other tank filled or you're gonna be chilly tonight. I have a spare 20lb tank - plus the 2 30lb ones on my trailer tongue. In winter I do leave both tanks open, and when it goes dead cold (always at 3:00 AM it seems) I'll put the spare on and refill both of the bigger ones first thing in the morning.

On my regulator there is a glass cap between the tanks that sticks up. It probably has a rubber cover on top that doesn't go down all the way. There is a green band around the base of this cap when there is plenty of Propane feeding through the regulator. In cold weather it's a good idea to check it OFTEN. The green turns to red when the tank is getting ready to stop flowing due to low pressure. Before you do anything else to diagnose any propane appliance problem, you'll want to check this.

Red cap - if you're using ONE tank, you turn the valves to open the other one, and take the first to be filled. both tanks open, pull both and put on the spare. No spare? T.S. Even Walmart won't sell an exchange bottle after 9:00 PM - you'll be very lucky to find an all night gas station that will.

Glad you got it fixed and saved a bundle. Paula Ford
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Old 12-09-2011, 11:25 AM   #14
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I've said this before and been jumped all over but will say it again. I would never run the system with an open line regardless of the switch position on the regulator.
If that regulator switch fails or the pressure drops in the tank you are running on and it tries to auto switch over to the other line you will be venting raw propane into the atmosphere. I full timed in my trailer for 7 yrs and it gets very cold here. I invested in two extra tanks, that way I could have two full spares on hand.
In cold climates it is advisable to run with both tanks open. When the ambient temperature is low and you are using the system the pressure in the operating tank will drop down to a point where it may not be high enough to supply the furnace properly. At that point the regulator will switch over to the reserve tank and your furnace will continue to operate properly.The regulator will continue to switch back and forth between tanks until both are completely empty. That way when you go to refill you are filling empty tanks. They charge a flat rate to fill and this way you get your money's worth.
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