Furnace problems

[kaz1]

Just returned from a 13-day trip with our model 2607 and the TT performed for the most part just great, but one problem we ran into was a loud, train-like whistle sound that would intermittently come from the furnace. It happened about 3-4 times per night, but the furnace would otherwise work fine. Now that we are home we have tried to recreate this sound so that the dealer can hear it but, of course, it now remains silent. Has anyone had a similar experience. Thanks.

[camprat]

Not sure of what to tell you. I would pull your front grill & check and see if anything maybe lose by the blower & go outside by the fresh are intake & vent make sure both are clear. I had the make up air fan (inducer fan) act up & had to pull the furnace back about 1/4" they had jammed the fan at little.

[The_Stuff]

could be from just extended use overnight?

[herk7769]

No age of the unit posted, I wonder if its a bearing.

[rockwood06]

Some times wind can cause this, while the unit is operating and pulling in air if it is windy and the wind is blowing hitting directly on the same side of the camper where the intake is you can get this sound. The induction fan has a certain cfm that is needed to operate, by forcing additional air like wind to the operating fan you can get this sound.

[herk7769]

That makes sense. The combustion air squirrel cage blower is on a common motor shaft with the output air squirrel cage blower.

If it was very windy the air pushing into the combustion air exhaust port could cause back pressure which could cause binding resulting in variations in motor speed. A worn or damaged bearing might "sing" under those conditions.

Could that be what you were hearing?

[rockwood06]

If this the cause of the sound you are hearing there is one way to stop it, on homes with 90+ gas fired furnaces both intake and exhaust pipe are ran out side of the homes foundation, on the intake pipe there is a 90 degree elbow attached to the end of the pipe on the out side wall and it is turned down and on the exhaust or discharge pipe it is turned up. This is one reason why it is done on homes to keep air from being forced in. Now this is not done on campers and it is really not needed because it doesn't happen that often and it wouldn't look good, so if you attached a 90 degree elbow in the downward position on the intake ONLY then this would stop that train sound on windy days, but I would leave it as it is.

[kaz1]

Thanks for your replies. The TT is a 2010 model and we had used the furnace a few times in the spring without any problem. There was really not much wind at all on this trip though we did (unfortunately) hit the cold front that hit the southeast the first week of November. I did realize that the noise seemed worse when the temps outside hit the 40s/50s so I had actually thought that maybe this had something to do with it. The temps are supposed to drop this week at night so we are going to try to run it again, and will also at that time check out some of your suggestions. Thanks!

[giebeje1]

I have a 2010 2901ss and have the same train whistle sound a couple of times a night recently...can't really relate to anything (didn't have wind at all on one night it happened)...let me know what you find out.

[jimh]

i had a home unit that would squeel every so often that turned out to be a loose squirel cage. the set screws were tight and that part didn't move. u could hold the shaft and turn the cage. i've only seen one do that. it's something else to throw out there.