New Heater problem

Refrigerator, stove, furnace, water pump, air conditioner, microwave, water heater, fans, lighting
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kitemanks
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B190 Year: 1994
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New Heater problem

Post by kitemanks »

After noticing some soot on the exit of the furnace and a friend saying it smelled rich, I decided to take the heater apart and fix that annoying screech problem. Well while I had it out I decided to look for wasps nests which I've herd can be a problem.... Sure enough a ton of these babies in the tailpipe. One looked to have been on the burner and I removed them and poked the holes out of the Air supply?? or burner?? section. and then blew it out. Finally got it back in and turned it on.... crossing my fingers it lit with no leaks...... however the burner wont stay lit now I may have touched the thermo couples and probes in there..... anyways anyone know what might cause this??? the probes?? Air leak??? The automatic lighter keeps lighting the fire but its clicking way to much or maybe I couldn't hear this from the screeching before. Any thoughts or help would be great.
Keystone
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Location: Boulder, Colorado

Re: New Heater problem

Post by Keystone »

Hi Kitemanks,
I recently replaced my furnace, and I have a couple of ideas for you based on that experience. I had what sounds like the same problem as you had when I first connected the new furnace to the vent assembly, and the cause was that the exhaust tube was not lined up and overlapping with the vent assembly. Alignment of air intake and combustion product exhaust are both critcal. You've probably already checked that. Also check that the air intake rectangular sleeve fits and overlaps with the furnace air intake. On the new units, there is double sided tape to seal the two parts of the air intake box. Next, it occurs to me that your cleanup has changed the fuel/air mixture. Because it was running OK before your cleanup, with a different mixture that satisfied the logic, you may now have too much or too little air in the mix. As it has been explained to me, the startup sequence is: first the thermostat calls for heat; next the electronic ignition engages and its sensors decide if the fuel air mixture is OK and the exhaust is clear. If all criteria are met, the furnace fires up and keeps running. If not, it shuts down, waits a bit and tries again three times to light. I'm sure this is not a perfect explanation--others with more knowledge please chime in. Here is a link that I found helpful to the furnace parts diagram: http://www.atwoodmobile.com/manuals/fur ... tsList.pdf

Before I figured out the misalignment issue, I called the Atwood/Hydroflame company and they were helpful in making suggestions. One diagnostic they suggested involved holding a hand, wearing an oven mit, about 6 inches in front of the air intake to see if the furnace keeps running a bit longer. If it does work longer with the air supply a bit reduced, I think it indicates that the mix is a little lean. I suspect there is an adjustment on your propane regulator, but I'd leave that to the propane people (who may be helpful in any event as you troubleshoot the problem).

Best of luck, and let us know what you learn. I am not a propane expert, so please know that your safest bet may be to leave it to those who are.

Keystone
Keystone
1994
B190 4x4
kitemanks
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Re: New Heater problem

Post by kitemanks »

Keystone,

This sentence caught my eye. "Also check that the air intake rectangular sleeve fits and overlaps with the furnace air intake. On the new units, there is double sided tape to seal the two parts of the air intake box. Next, it occurs to me that your cleanup has changed the fuel/air mixture." I remember seeing the double sided tape when I had it apart but I didn't pay attention to that during reassembly, I will check that when I take it apart again. I'm not even sure there was a sleeve on this attached to that area. Thanks
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sparky
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Re: New Heater problem

Post by sparky »

Here is a trouble shooting guide that I found several years ago. Found this guide on the internet as I am having problems with my furnace.
http://www.rvforum.net/miscfiles/Furnace_Trouble-2.pdf. It looks pretty good rather simple. There is also a post here about cleaning which I have to do yet. Was out last weekend here in Wisconsin and we had a heavy snowfall. The furnace would not run right.
This is from a post I made in 2009. You mentioned that you had soot at the outlet. The problem that I found with my furnace was what I believe was called the burner. It is a tube with holes in it. The holes were rusted over. I replaced it. Before finding this I would remove the igniter and it was dirty, had soot on the porcelain. I would clean the soot off and the furnace would work for a while then quit. Clean the igniter and it would work again. These components were accesible from the front of the furnace.
kitemanks
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B190 Year: 1994
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Re: New Heater problem

Post by kitemanks »

Thanks for the replies. I have since become a master at taking the furnace out and putting it back in. The exhaust is lined up an in. The intake is aligned with a telescoping section but not taped. The furnace cycles on and off before the correct temperature in the cab is reached. I was thinking this must be a planned cool down to not melt the exhaust pipe or the firing chamber??? does anyone's cycle on and off where you can here the solenoids click and such?? There were a few holes in the tubing near the ends that connect the firing chamber to the fan, but I thought I had shimmied the tubing on where they weren't exposed. I think I will seal the intake with double sided tape, and then loosen the clamps on the tubing and wrap it in that foil furnace tape and see if that helps any.
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sparky
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Re: New Heater problem

Post by sparky »

Yes they do cycle before the thermostat is satisfied and and it shuts off completely. You will notice the air blowing out will cool down. Yes I would guess it is to prevent overheating. Furnace would have a high temp sensor that kicks in.
kitemanks
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Re: New Heater problem

Post by kitemanks »

Just thought I'd update this by saying that buying individual parts could get expensive fast I voted to replace the whole unit with a newer version same brand, and I have had no problems and it works great.
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