Furnace blower question

Grounded · 10-05-2010, 08:11 PM

Just fired up the Surbuban furnace on the 2004 Sandpiper and have a question about the blower on this unit. It's ducted with four floor outlets. The furnace is located in the middle of the trailer. The duct in the rear of the trailer has good airflow, the next duct in line has so so flow and the one in the bathroom is has very light flow so does the one in the bedroom. Does this sound normal or does it sound like I might have a leak somewhere?
Thanks.

camprat · 10-05-2010, 08:27 PM

I had coachman years back that had the same problem, I had to make a little airfoil for my first grill inside the duct about 3/4-1" to get the air out. my cat is some what that way. But I like sleeping cold anyway.

You may try covering the end duct just a little & see what kind of air flow you get out of the middle. They have the duct run straight shot to each end.

LadyWindrider · 10-05-2010, 09:26 PM

It may also be time to trace the ducts, (find them physically), and make sure they haven't blown a connection apart, or crimped a hose.

cmcct · 10-05-2010, 11:11 PM

Another thing to check is how much "extra" duct is left in the runs when they were installed. I know on my trailer, I pulled out 5 feet of extra duct that was installed in a rather snake like fashion with a couple of spots routed behind water lines that just about choked off the airflow all together. Spend a little time, remove the extra (because every bend and kink will reduce the airflow at the outlet) and run it as straight as possible. Another thing to try is take your longest run of duct and connect it to the outlet on the furnace that is closest to the blower.

**Herk7769** · 10-06-2010, 07:20 AM

Be careful what you remove in "extra duct" because that duct is a part of your "underfloor heat" system to keep your pipes and tanks from freezing during winter camping.

I agree you would get better efficiency and air flow if you straightened it some, but routing around your plumbing serves a purpose.

The tank heaters (if equipped) only heat the tanks themselves (and the exposed portion of the galley tank dump pipe if equipped with a galley tank).

SaskCampers · 10-06-2010, 07:25 AM

One thing you could do if you can't find a cause is add a duct booster fan. The are just a section of heater duct with a small axial fan to boost air flow. The only issue is the fans are usually 115v but I am sure you could fix it up somehow.

jimh · 10-06-2010, 04:11 PM

i believe i'd just see how well it heats the way it is. it may be something as simple as the air trying to move in a streight line and the one in the back being in that direction. if that is the case, u will have to restrict the ones in the rear to force air up the ones in between.
before u do anything, see how evenly it heats the way it is. it may be ok.

hummmm...i believe i just repeated one of the above answers....

Grounded · 10-07-2010, 09:47 AM

We're off next week for two weeks in the NC mountains. I'm sure we'll see how well it works! Thanks for the info.

rockwood06 · 10-07-2010, 11:22 AM

Some manufactures use what is called a distribution box, this is a box where all of the duct work comes off of , then is routed to the floor defusers. There is a few reasons why this is used but the biggest reason is so that this box will collect and discharged air under pressure, this know as static pressure or resistance which then forces the discharge air to move down into the duct work and then out of the defuser. The only way to contol the amount of air to each defuser is to install dampers in each take off, this is used to balance the system so that the air flow is the same out of each defuser.

Now Rockwood does not use this type of system, the duct work is connected right to the furance. If you have 4 floor defusers then there is 4 runs of duct work off of the furnace with no box. There are a few thing that could be wrong if you have a defuser that is not operating correctly, 1. the duct work may be pinched or 2. it could be what is hit or miss, with the way the duct work is connected to the furnace air flow may discharge more into the other three and starve the last one and that could be anyone of them, 3. the duct work may have come apart either at the furnace and or the floor defuser and maybe a hole somewhere in the duct line between the two.

As far as having extra duct work, chances are the manufacrure will not waste material, they will use what is needed, but if they left extra it will effect the air flow.

I as well have a lack of air flow in the bedroom, but all of the rest is fine, and from what I understand this is commond.

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