1980 Minnie Winnie furnace issues

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  #1  
Old 02-27-06, 10:52 AM
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1980 Minnie Winnie furnace issues

Hello. I just picked up a Minni Winnie which I thought was funcitional. Turned out there were lots of hidden issues not mentioned before the sale. One of the major one is the furnace. The LP tank has been tested ok, the stove works fine and the flame is blue. On the furnace, the system comes on and after 30 sec to 2 min, the flames blow out and it has to be turned off. Once turned back on via thermastat, this cycle repeats all over again. I can't seem to keep the flame to stay on. Any help would be appreciated. Does this furnace need replacing? Jasper
 
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  #2  
Old 02-27-06, 01:46 PM
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Are you sure it is not being short cycled by the t-stat? Check and make sure that one of the heat outlets is not blowing right at the t-stat or being deflected right at it. This will cause the t-stat to think the set temp has been reached and shut down the furnace (or a/c by the way, same principal) early, it will then in a couple minutes start up again.
If this is not the case then it is possible that the furnace is not sensing a flame. DSI models will come on, wait about 20 seconds then open the gas valves, and start sparking. The flame might catch then after about 10 seconds it will quit sparking, and close the gas valves. This is something you can hear! the closing of the valves is an audible clunk sound. Its not real loud but it is audible. This is an indication that for one reason or another the furnace is not sensing a flame. If the furnace sparks, lights a fire, then shuts it down right away and lets the blower continue to run for more than a couple minutes, this would lead me to take a look for a reason for a flame sense failure. (for those with newer furnaces, the latest models will shut down the blower after a flame sense failure! saves batteries that way but the unit will still go into lock out and wait for you to do someting about it.)
it is also possible that the exhaust is plugged or partially plugged by something. Mud daubbers love to build nests in areas where propane burning appiances do their business. shut the furnace off and check with a flashlight looking for an obstruction in the combustion exhaust. this is were the furnace blows air outside the unit. This would cause the DSI board to see this as a lack of flame and shut down the fire.
if this is one that you can see the wires going to the electrode check and make sure that they are hooked up and that they fit snug on their terminals. Word of caution make sure that the furnace is off and the t-stat is set to off.. if the unit tries to light at this point it could shock you, also if the board tries to spark with the wire off the electrode or off the terminal on the board it will fry the board! They usually dont survive this. I say wires because some units used to use a seconday wire going to the electrode assebly. now they just use one.
Don't go takin stuff apart willy-nilly if you dont know what you are doing when it comes to your propane system or any of the propane burning appliances.
try simple things first
let me know how it goes.
Eric
 
  #3  
Old 03-01-06, 09:16 AM
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Yes, the furnace will start off blowing, ignite and flame on for 10 sec and the clicking sound will stop, so will the flames with the blower still running. I checked the exhust pipe the best i could and did not find anything. During the 10 sec blast, the exhust seems to be of full volume, which to me seems like a clear pipe. I have also removed the igniter, cleaned it and put it back. LP tank is fine, along with the preasure and regulator. I sent the RV back to the dealer who sold it to me. He thinks is air in the line. . . his mechanic is looking at, along with the fridge. Now that we have determined the problem, what can be done for this issue. Is it a matter of changing the board, or is there something else we can do. The unit it self does not look beat up or heavly used. Its a Colman unit which does not seem to be available anymore. Thanks for the inforation and help.

Jasper
Rookie RVer
Conn, USA
 
  #4  
Old 03-01-06, 02:06 PM
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Join Date: Jul 2005
Location: usa
Posts: 33
Air in the lines will work itself out. If the flame sensing circut is out of the board the dealer should be able to test the board and tell you one way or the other. There is a tester for the boards so that part is easy. It is also possible that the electrode is not set correctly. The spark gap should be about 1/8". too wide or too narrow and the system will not operate correctly.
If the gas pressure has been tested and is ok then those are the next most common causes. The gas pressure must be at 11" of water colum while the furnace is operaing,, but note this, the system should have 11" of water colum with a 50% demand on the system as well. a weak regulator can allow pressure to drop below the minimum and cause the flame to go out or the furnace to shut the flame off. it is also possible that one of the gaskets that seal the combustion chamber is leaking, the combustion air wheel could be loose and not delivering enough air, or the flame sensing wire could be bad.
if the dealer wants you to buy a board ask if it is a OEM replacement. There are companies out there that sell remanufactured boards, and ones that sell ones they make themselves.. some of these are dangerous and could cause improper operation of the furnace. some have caused fires so ask and spend the extra money for the proper item. If you are in doubt call the furnace manufacturer, they can refrence the board and tell you if it is a true OEM board. And if it is the right one for your furnace. They are usually very good about making sure you have the proper board, they have a vested intrest in this matter.. Not so much for the profit of selling a board (most are made by Fenwall) so the board may not even pass through their hands. But for the liability.
Hapdad
 
  #5  
Old 03-02-06, 09:45 AM
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Understood. I was conserned about the same thing. I spoke to the dealer today, and they confirmed its the board. Problem is that Coleman stopped making this furnace years ago, so getting aboard is going to be tricky. I do not exect to pay for this as when i puchased the RV, I was told that all appliances, including the furnace was in working order. Lack of LP in tank prevented us from testing. It has been lest than a week since the purchase. I do understand its new, and had I have known that the furnace was out with this problem (deal knew this) I would have walked away from the deal. So its a matter of responsibility for the deal to fix this. The frig is the same way. I'm not dum, just trusted the dealer and here we are. I guess he did not expect me to start working on her in Feb (winter) and expected for me to wait a couple months to hide these issues. Thanks for the help, as I do appreciate the information.

Jasper
CT USA
 
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