Another Furnace Question

[Canonman]

We had the occasion to do a little cold weather camping this past week. We've camped before with temps in the 20's. This time, thanks to a Canadian cold front, we found ourselves dry camping in the single digits for several nights.:eek:
So here's the question: We've never really had good air flow to the heat vents in the bathroom and the bedroom (upstairs). Also didn't care a whole lot since we like it a little cooler for sleeping. But, when it got really cold we thought it might be nice to have a little more warm air flowing to the front of the Cougar. Has anyone experienced this same problem and were you able to find a solution??
So far, I've installed "closable" registers in the kitchen and living room in an attempt to force more air forward. Not much help. The ducting to the upstairs registers is visible from the cargo area and looks to be intact with no damage or restrictions. I'm thinking about tearing into it further but thought there might be some tribal knowledge here I could take advantage of. Some of you more experienced pros might know of a test I could do to make sure the furnace is actually putting out the proper CFM to the registers.
Appreciate the help!

[busterbrown]

I don't think "proper CFM" and RV's should be used in the same paragraph. There are ways to properly seal up the duct-work in the underbelly to help with air flow to the front of your coach. Accessing it through the coroplast will be your biggest hurdle.

I'm not aware you can do anything to help with airflow at the blower. Maybe the moderators, John or Chuck, can offer some insight.

[chuckster57]

Depending on how the furnace is ducted, you may be losing airflow at the “box”. Often times there are circles cut into the box and the ducting has a flange with a tab. Line up the fitting and it twists into place. I’ve seen them off completely and other times not fully engaged

Some furnaces sit on the floor and blow down into ductwork. There is a fiber gasket between the box and the ducting, I’ve seen that gasket not placed right or broken/missing. Find the return to your furnace and remove that grill. Then have a look, turn on the furnace and feel for air flow loss. There are flow tests but we don’t have the expensive equipment to perform it.

[hankpage]

Starting under the steps, I replaced all the flex vent "Slinky" stuff with aluminum 4" vent pipe and it greatly improved the flow to the bedroom vents. It made the pass through a little neater too. Removing the step was not as hard as I thought it would be, only a few screws hidden in the carpet.

http://www.keystoneforums.com/forums/picture.php?albumid=267&pictureid=6633

[Canonman]

Depending on how the furnace is ducted, you may be losing airflow at the “box”. Often times there are circles cut into the box and the ducting has a flange with a tab. Line up the fitting and it twists into place. I’ve seen them off completely and other times not fully engaged

Some furnaces sit on the floor and blow down into ductwork. There is a fiber gasket between the box and the ducting, I’ve seen that gasket not placed right or broken/missing. Find the return to your furnace and remove that grill. Then have a look, turn on the furnace and feel for air flow loss. There are flow tests but we don’t have the expensive equipment to perform it.

Furnace is installed in the horizontal position and is downdraft into the ductwork going to the living area. I'll check the seal around the downdraft connection for any leaks. I've got some regular duct seal aluminum tape that i'll likely put on as long as I have the access open. Next step will be to empty the basement and access the connections where the two flex ducts connect to the living area ductwork to see if there is any loss there. Depending on what I find and the degree of difficulty, I may take Hank's suggestion and replace the flex pipe with 4" ducting.
Thanks guys for the help!

[JRTJH]

One of Keystone's "inherent design features" (yeah, right) is to install "belly heat ducting" that meanders through the underbelly. It's not insulated, 4" aluminized flex duct that comes in 12' lengths. Typically, Keystone installs the entire 12' section, even if the "to and from" connections are only 2 feet apart. They (Keystone) claims that the other 10' "meandering around the holding tanks" will supplement basement heat (2" hot air duct) and is a "design feature" of the Polar Package" or "Arctic Protection Package" ...

I found two "meandering ducts" in my underbelly, one ran from the forward part of the main cabin floor system, around the black tank and forward gray tank, then up into the pass-through (behind the water heater) and then coiled once before it was connected to that "passthrough overhead duct" that connects to the bathroom and bedroom heat registers. I straightened up part of the "belly flex duct" and removed the coiled duct behind the water heater. It improved the bedroom hot air flow, but the main area floor and the passthrough are now noticeably colder without that heat loss and air flow loss from the "too long flex duct meandering through the belly"....

It's sort of a "give and take" situation. Give the heat to the tanks/belly and take it from the front two registers (bedroom and bathroom) or take the heat from the tank/belly and they'll be colder.

It's been said many times, that you can only provide a specific BTU output from an RV furnace. Where you "share those BTU's" makes a significant difference in comfort vs system protection. Not everyone needs system protection at the expense of main cabin comfort, some other members need system protection to keep their RV "livable" in sub-arctic conditions"... Keystone tries to "split the difference" or maintain a "happy median" but both main cabin comfort (bedroom airflow) and underbelly protection tend to be compromised to obtain that "happy median"....

Do what you can to improve on the airflow losses, but realize that if you put those BTU's in the main cabin, they won't be heating the belly and your overall protection MIGHT be reduced in extremely cold conditions.

[Roscommon48]

this is why we don't camp in the cold...trailers suck at heating.


when cold we just turn on on electric heater...it is quieter anyway.


good luck