Furnace problem continues

[navyAZ1]

Well the new circuit boad worked for a few days but here we are yet again NO HEAT! Today I took a compressor and blew out all the gas lines a lot of an oily substance came out so I thought that might be the problem after this I lit the furnace and it ran well for 2 cycles then on the 3rd cycle the burner would light and then go out after a few minutes and then re-ignite this continued for a long time until I just shut down the furnace. I am at a loss as to what this problem is I have replaced the regulator, the circuit board, had the unit cleaned and igniter readjusted, the sail switch, and limit switch passed testing, and the gas pressure was tested by the RV tech and he said it is fine. I also have replaced the thremostat and still the problem persist. Eventually this lighting and re-lighting goes on for a few cycles then it fails to light completely. The RV tech who has worked on this is at a loss also and says he only knows to replace parts until he finds the fix, WELL PHOOEY, I can do that. I have also been in communication with the head tech at Suburban and he can't diagnose this problem either and really has no ideas as to where to look for the problem. Does anyone out there have an idea that might shed some light on this problem?

 

[cookie]

Well, it sounds like you have pretty much covered everything. Just one silly thought, have you tried a different LP source tank? Might be worth a shot.

Peace
Dave

 

[Paul_in_MN]

I like Cookie's idea of changing LP tanks. It is rare but possible to get LP with water in it. I had such a tank once.

Have you checked the furnace exhaust? Sometimes that is messed up with a wasp nest or a mud dauber wasp nest. If it can't get proper exhaust, it will shut down to keep from overheating the heat exchanger. And maybe the nest is further into the heat exchanger manifold area. You might be able to take a leaf blower to the outside air intake and blow completely through the heat exchanger and out the exhaust side. Do this to see if any wasp stuff comes out, but I think there is a positive vent fan in the exchanger area, so don't blow it very long as you might damage the fan.

Wasp nests are a common problem here in both the furnace and refrig vents.

Paul_in_MN

 

[WSGraffius]

Good reccomendations given above all I can add is most regulators have screen filter in their inlet side and depending how it is mounted and taken apart a floating obstruction could lie in the hose between the regulator and LP source. A short purge of the disassembled line into a clean rag would catch the culprit. One other item I do not see mentioned is the thermocouple, it should sense the heat and once hot signal to keep the gas flowing. If malfunctioning it could shut down the source gas. Also was the "black stuff" found before installing new regulator? If afterwards perhaps it gummed up again.

 

[andy]

check for that oil in the line again an make sure you blow out the jet to you got to get most of that oil ( it more than likely antifreeze ) out of the system

 

[mrcomer]

What about replacing the thermocouple?

 

[jmaguire]

Does the furnace light and burn correctly when it works?
If so, and you are having intermittent shutdowns then you need to check the ground to the unit. If that circuit board is not grounded properly it will cause wierd things to happen. Double check all the wiring to the furnace and make sure all connections are tight.

 

[navyAZ1]

I read in the manual about the "heat sensor" which I assume is like the old thermocoupler on old pilot light units, it did state that this may need to be adjusted to point more into the flame so it senses the heat from the burner. What the furnace is doing is after it lights the first time it burns for quite sometime then it starts this intermitent stuff. When the burner goes out you can hear the burner get louder and then a loud "poof" sound and it cuts off. It then waits a few seconds and re-lights the burner but now the burner only stays lit for 25 to 30 seconds then the loud burn and "poof" again and it repeats the process. I would assume this "heat sensor" is down inside the burn chamber near the igniter. As to changing the gas bottle the furnace has done this on both bottles, but one bottle emptied this weekend so I'm going to take it and have it filled and give it a test.

My greatest frustration is not being able to find an RV tech who seems to understand these furnace problems, everyone I have talked with doesn't seem to know much more than I do. I'm pretty handy but I really don't like working on stuff that I don't fully understand how all the systems are suppose to work. However, if all they are going to do is replace parts until they stumble onto the problem (if ever) well as I said before I can do that.

Today I plan as I said change the gas bottle, change the regulator, purge the lines from the bottles to the regulator, and then remove the furnace once again and go in thru the access panel to the igniter and check out the position of the "heat sensor". I'll let y'all know what happens, thanks for all of your suggestions.

Ron

 

[thomasinnv]

I read in the manual about the "heat sensor" which I assume is like the old thermocoupler on old pilot light units, it did state that this may need to be adjusted to point more into the flame so it senses the heat from the burner. What the furnace is doing is after it lights the first time it burns for quite sometime then it starts this intermitent stuff. When the burner goes out you can hear the burner get louder and then a loud "poof" sound and it cuts off. It then waits a few seconds and re-lights the burner but now the burner only stays lit for 25 to 30 seconds then the loud burn and "poof" again and it repeats the process. I would assume this "heat sensor" is down inside the burn chamber near the igniter. As to changing the gas bottle the furnace has done this on both bottles, but one bottle emptied this weekend so I'm going to take it and have it filled and give it a test.

My greatest frustration is not being able to find an RV tech who seems to understand these furnace problems, everyone I have talked with doesn't seem to know much more than I do. I'm pretty handy but I really don't like working on stuff that I don't fully understand how all the systems are suppose to work. However, if all they are going to do is replace parts until they stumble onto the problem (if ever) well as I said before I can do that.

Today I plan as I said change the gas bottle, change the regulator, purge the lines from the bottles to the regulator, and then remove the furnace once again and go in thru the access panel to the igniter and check out the position of the "heat sensor". I'll let y'all know what happens, thanks for all of your suggestions.

Ron

what you have described in this last post is a fuel problem, not an electronic problem, not a thermocouple problem, not a sail switch problem etc. the flame "getting louder" happens when the fuel delivery changes, usually increases to the point that the flame is "pushed" away from the burner tube. Most likely the regulator in the furnace is the culprit. when mine started acting that way a few years ago nothing that was done would fix it, the regulator assembly at the furnace had to be replaced. you can put a water column indicator on the propane system and watch what happens when the flame "gets louder". if there is no change in the water column then the main regulator is fine. If the water column shoots up then the main regulator needs to be replaced. the easiest place to tap in for the water column indicator is usually behind the fridge. you can easily make one at home if you can't find one.

 

[navyAZ1]

I believe you're correct Derrick that it is fuel, but maybe not the regulator at the furnace? I say this since I went and had my empty tank filled today and switched to it after checking and finding that there is not a "heat sensor" in the burn chamber the only electronic item in there is the igniter. So, I put everything back together and as I said switched to the newly filled gas bottle and so far the furnace has worked fine for 3 cycles so only time will tell.

I think I will drain the other gas bottle and have it refilled again and see if this takes care of the problem. If not than I'll need to go to your idea and check the regulator at the furnace. I'm really getting quite good at handling the R&R on this furnace thanks for the help.

Ron

 

[SmokeyBare]

NavyAZ1,

You do realize now... you have become Heartland owners Resident Expert on Furnace problems... Folks will soon flood your Private Message box with questions... asking for your Expert Opinion about their Heating issues...

We're Proud to have you on board... >> GRIN <<

Sure hope the fuel change will give you relief !!

Marv

 

[sunflower]

You didn't get into butane somewhere did you?

 

[navyAZ1]

Well the fuel source change didn't help, the furnace ran for one cycle last night and then it failed to light again and would just shut down. The only thing I know to do now would be to run the pressure test like Derrick suggested and possibly change the valve at the furnace. If this doesn't fix it my wife has suggested we trade this BH in for a 2010 model 3055RL that way we will get a "new" furnace. This valve at the furnace is about the only thing I haven't replaced.

 

[navyAZ1]

You didn't get into butane somewhere did you?

Nope, don't think so I don't even know of any place that sells butane anymore?

 

[JohnDar]

Your rig is a 2008 and the Suburban furnace warranty is two years (3 on the heat exchanger). Might be time to invoke it, if it hasn't run out.

 

[navyAZ1]

Your rig is a 2008 and the Suburban furnace warranty is two years (3 on the heat exchanger). Might be time to invoke it, if it hasn't run out.

Suburban and the RV repair guy have both told me the warranty has run out.

 

[JohnDar]

Suburban and the RV repair guy have both told me the warranty has run out.

I was afraid that was the case. No extended warranty on your rig either, I suppose.

 

[navyAZ1]

Well we finally have an answer as to what was wrong with the furnace. I gave up on all the local RV techs who just wanted to replace parts until they figured out what it was. I stumbled onto a web site called "JustAsk.com" it cost $15 for me to communicate with a tech and so he and I sent messages back and forth until we found it. After I had told him all that had been replaced and or tested he told me to go thru a series of test step by step until we determined that the problem is the gas valve on the furnace. It was pretty simple to find with the tech telling me just what to check and what I should find if it is bad or okay. That is a great web site if any of you really get stumped give it a try, they have techs for RV's, cars, and trucks. This fellow was associated with R&K RV in Paducah, KY and was quite knowledgeable as to what to work on. So, now we have heat and none to soon as the really cold temps are headed our way down here in SW Georgia.

 

[JohnDar]

Cool! Or should I say "WARM?"

 

[boatto5er]

Glad you got it resolved Ron!