Suburban Model SF-30FQ

RobK · 09-24-2022, 07:44 AM

Hi all, I'm looking for some guidance on my Suburban Model SF-30FQ.

The furnace starts as it should and heats up.

It seems that the only outbound air movement may be from the fan intake as the output is minimal.

Also, if I chance my thermostat from auto to manual and select high or low there is no discernable difference.

Not sure if the fan is working aside from the furnace.

Any thoughts???

**chuckster57** · 09-24-2022, 07:51 AM

Furnace fan is one speed only, the auto/high/low function is for the AC fan.

"It seems that the only outbound air movement may be from the fan intake as the output is minimal."

what fan intake?

RobK · 09-24-2022, 07:59 AM

Quote:

Originally Posted by chuckster57

Furnace fan is one speed only, the auto/high/low function is for the AC fan.

"It seems that the only outbound air movement may be from the fan intake as the output is minimal."

what fan intake?

I'm not extremely knowledgeable about furnaces but I'm guessing that it has to have a means to pull the air in to be heated and passed back out? Thanks for the explanation on the fan speed. That was driving me crazy. So any thoughts what may be reducing the heat output? I took off the front panel and can feel the hot air coming out somewhat but doesn't seem to be adequately heating the camper and minimal output flow at the vents.

**chuckster57** · 09-24-2022, 08:05 AM

The furnace has a fan that pushes air across the plenum and out of the "box" its housed in. there may be round ducts attached to the box or there may be a rectangular slot in the bottom that the air goes into. If either of those are not tight and proper the air will not distribute properly. You shouldnt "feel" any hot air blowing at the intake screen, if you do then you have an issue like I described.

RobK · 09-24-2022, 08:57 AM

Quote:

Originally Posted by chuckster57

The furnace has a fan that pushes air across the plenum and out of the "box" its housed in. there may be round ducts attached to the box or there may be a rectangular slot in the bottom that the air goes into. If either of those are not tight and proper the air will not distribute properly. You shouldnt "feel" any hot air blowing at the intake screen, if you do then you have an issue like I described.

So yes mine has the bottom vent that feeds into the floor vents. The only reason I'm feeling heat out the front is because I took the front panel off to check inside to make sure there isn't any obstructions. With the front panel in place it runs but just doesn't seem to provide good airflow to the floor vents. There are 5 vents - 2 in the living room, 1in the kitchen, 1 in the bathroom and 1 in the bedroom. I have a 38' park model. I'm thinking I may need to replace the floor vent covers so when we need heat in the bedroom at the far end of the camper I can close some of the others and redirect the airflow to the other end. Granted it was cold last night getting down to about 42 degrees. I know that makes the furnace work harder. I appreciate your help!!! I am thinking about replacing my thermostat with a digital version like was mentioned in another post you helped out with. Not sure if you have any info or thoughts on that??? Also noted you are a fellow retired LEO. I've been the same since 2001 from a local agency here in RI.

**chuckster57** · 09-24-2022, 09:57 AM

Congrats on the retirement from LE. if your furnace blows down like mine, then you might want to take the front cover off the furnace and tape the joint where the furnace blows into the ducting. There was probably a fiber gasket there at one time but they seem to get torn or out of shape allowing alot of air to escape into the underbelly.

rhagfo · 09-24-2022, 12:12 PM

Also check the duct for blockage.

**JRTJH** · 09-25-2022, 02:20 PM

And check all those "dryer duct hoses" connected to the plenum. If one of them is loose and leaking air, that "escaping air" won't be pushed through the other vents and into the cabin. With the "miserably low air volume produced by a 12 volt RV furnace" any air leak will noticeably affect air flow into the cabin.

Also keep in mind that an RV heating system will NOT produce the volume of air movement that you have in a S&B home. Honestly, if you can lay a kleenex on the register and the furnace will move it, that's typically the "it passes the air test" at most dealerships.

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