No heat from floor registers

[jasin1]

I looked up a suburban furnace 35000 model and it was interesting to see they have the static pressure rated at .2” wc instead of under .80 for residential systems..55 cfm per 4 “ pipe vs 35…although they rate it at 375 cfm total and require only 4 -4” supply’s
They do not include any open ducts that blow into the basement in the duct calculation so I guess that’s where the extra cfms end up

I wonder how often some debris or insulation gets caught on the return opening on the sides of the furnaces? I’d imagine anything bouncing around loose would get sucked up to the furnace reducing airflow.

They also said adding too many ducts can cause the sail switch to malfunction

[slow]

You just reminded me of a mod I did to increase the air flow on our current FW.

Our bathroom vanity is near the furnace. I noticed that the vanity door would get sucked closed when the furnace was operating. So I added an additional return air register and air flow improved to the hot air registers.

[jasin1]

Originally Posted by slow

You just reminded me of a mod I did to increase the air flow on our current FW.

Our bathroom vanity is near the furnace. I noticed that the vanity door would get sucked closed when the furnace was operating. So I added an additional return air register and air flow improved to the hot air registers.

That’s good. Yeah you can almost never have too much return air.

[Bruce406]

I had this problem in my Cougar 22RBSWE. A squirrel had found a way into the floor and after chewing through a flex duct packed the system with pine cones. The only way in was to cut through the bottom. Good luck.

[WDPatterson]

Originally Posted by PeteK

Recently used the furnace for the first time. It worked like a champ except I was getting no heat from the floor registers. The volume of air from vents mounted in the cabinets was great, no issues at all. I took the grill off under the fridge and did verify that all ductwork was connected to the furnace. I couldn't see anything wrong visually.

Can you get to floor ducts via the belly without taking the coroplast down? It's a rear kitchen so I'd have to get all they way to the rear. I am still under warranty, but really hesitant to take it tot he dealer as I want to use it this year.

May try to get a camera I can snake in there... Any other ideas?

Thanks

2021 29RKS

Do you have a multiples speed heater fan??... If so, what speed are you running it at??

[rlh1957]

Turn furnace on, go outside with camper door closed. Open underneath bay and check for airglow and heat in the bay. Many rigs have bay heating to keep pipes/plumbing from freezing.
The furnace plenum isn’t designed or installed by HVAC engineers.
If it was you wouldn't feel hurricane at one end snd nothing st the far end.
An air plenum had to be designed for the length and number of turns to have equal pressure at all registers.

[PeteK]

Originally Posted by WDPatterson

Do you have a multiples speed heater fan??... If so, what speed are you running it at??

Just one speed fan.