Chilling discovery on a SF42 Furnace

[BlueLine]

My first need for heat, resulted in no heat at all in our 1999 Winnebago 34V with a SF42 Furnace. The RV is used so I expect problems, and I've dealt with them. The heater a SF42 would go thru the cycles when I selected heat, but would not ignite.I attempted to purge the chamber three times as outlined in the manual, but still no ignition. I wasn't enamored with the idea of electric space heaters, so I went on an inspection probe into the bowels of this relatively simple device. I've read on previous posts that critters and insects can infest the unit. What I found is deplicted in the photo attachment: http://www.irv2.com/attachments/phot...auber_SF42.jpg
All is well again after several hours of removal, inspection, cleaning, reassembly and soap testing. I'm going to install a fine metal mesh inside of the intake and exhaust cover, unless someone has some adverse feelings on this, hopefully it may negate the need for going thru this exercise again.

[RV Wizard]

I would recommend using the already manufactured, external, stainless steel covers but only in times of the year the unit is not in operation. You would (or maybe not) be surprised how easily the combustion air/fuel mixture can be disturbed and the unit not perform properly and consistently.

[Monacoach]

When you say purge is that lighting your stove? If not then definitely light your stove first to purge air out of the lines then shut stove off and try furnace.

[BlueLine]

Thanx for the response Mike. Since I've got it operable again I sure don't want to upset any ratios. I put the screens in this afternoon, but they'll be out in the morning. I'll look for the solid covers when we get near a Camping World.

[BlueLine]

Thanks for the reply Monacoach. The stove was already working and I had loosened the connection at the furnace to confirm gas flow. The problem was that it would not ignite so I followed the proceedure layed out in the Winnebago Operations manual, which is normally my last resort when I can't get something working, you know it's a guy thing, but it still would not ignite. The reason for the failure to ignite was the attachment photo. The mud daubers didn't just set up residence,... they built a whole condominium and invited friends and relatives. After the cleanout all is well and "we have ignition". I'm going to take RV Wizard's suggestion for a seasonal blank cover.

[AFChap]

I have used the stainless mesh "bubble look" covers over the intake & exhaust of my two furnaces for 7 years now, and a similar large square type of the water heater vent. I have NEVER removed them for any purpose, and have never had a problem with the furnaces. I know Suburban and others do not recommend leaving them place while operating the appliance, but I have experienced no problems... I did have a spider web in the water heater burner tube once. There are other ways for them to get in, but a mud dauber likely would not.

[Poptop]

I too have used the screen covers year round on the furnace inlet/outlet for probably 20 years to prevent instusions. I've not had a problem but now I'm not so sure I want to continue it though.

[TXiceman]

The furnace manufacturers advise to not use any screened cover over the vents. we have had the covers on ours for years and no problems. It is most likely lawyer and a cover your tush statement.

Ken

[RVhauler]

Same here. Have had the covers over furnaces and water heater for about ten years. never remove them and haven't had any problems to date

[Monacoach]

Was at Lazy days last week and attended a few of their seminars. It was mentioned at one of them not to use mesh as it restricts air flow and could cause problems. Another interesting point was that we should never close any vents in the attempt to increase heat to another room. Apparently when you close the vents, the air pressure decreases instead of increasing also a problem.