Unbalanced air flow from furnace heating system

[ktderobich]

In my 2019 Cedar Creek Hathaway 34IK I have an issue with insufficient air flow from all the floor vents when running the furnace. The furnace is located under the bathroom and I get a good flow out of the floor registers in the bedroom and bathroom, slight blow at register that is next to island towards the bathroom but none to speak of from the other 2 on the opposite side of island in living area. I covered the registers in bedroom and bathroom and increased the flow from the other 3 significantly. Is there a way to adjust the flow in bedroom and bathroom to force more to the other areas of the coach and not have to just cover them up to force the airflow elsewhere?

[Bama Rambler]

You can buy floor registers with dampers and adjust the flow at each one.

Have you looked in the ducting to see if there's some restriction from kinking or debris? It's pretty common to have both so it may be worth your time to investigate.

[ben31]

Partially covering the registers is the easiest solution. Either that or buying new registers, which allow you to adjust the airflow. The registers closest to the furnace will always get more airflow than the ones farther away. In those cases, partially covering those close ones is the best solution for more even distribution.

In my case, the furnace is directly below the bathroom and bedroom. When the furnace was on, those rooms would be boiling hot and the rest of the RV was cool. We covered about 2/3 of area of those two registers and now the rest of the RV is about the same temperature.

However, like Bama Rambler said, it is worth your time to check the ducting (if you can). I found one of my ducts was flattened a bit. I rounded it out again, and the flow is a little better to that register.

[Cypressloser]

The problem is likely 4' of duct run to the bedroom / bathroom with two registers and 30' of duct through the relatively cold underbelly to the back of the camper. I have taped the underside of our bedroom register shut with duct tape but I wouldn't go any further than this bec. it could cause overheating and possibly start a fire, if there were booster fans that fit inside the duct that would be wonderful. But there is on more question, how isolated or shielded is the thermostat from the warm airflow coming out of the bathroom?

[JohnD10]

My 5'ver was the same way...

Blast of hot air in the bathroom and the bedroom...hardly any in the downstairs kitchen and living room vents.

Turns out that the heating ducts downstairs were full of sawdust and debris from factory.

Even after getting that fixed...still too much air upstairs as the furnace is directly below the bathroom vent.

I bought the plastic louvered vents at Camping World...

DON'T BUY THEM!

They melted within five minutes of turning on the furnace (see photo below).

The toxic smell of melting plastic filled the camper and when I picked them off of the vent they were slimey wet of melted plastic and very soft to the touch.

You can get metal ones that fit at Lowe's, Home Depot and Walmart and they are half the price of the cheapie plastic ones at Camping World.

Funny thing...

I wrote a review with photos of my melted vent covers on Camping World's website, and the company that sells them actually went to Home Depot and bought me two metal ones...sent them to me for free along with a letter telling me that they were seriously going to speak with their engineers and designers about switching to metal ones...

And guess what?

Three and a half years later...Camping World is still selling those same plastic louvered vent covers and no metal option, plus my review with photos was never posted!



Also, I've been told by RV techs that you have to be careful of closing off the two upstairs vents as it can throw the air flow off in the furnace and cause it to overheat or shut off prematurely.

[Flybob]

There could be several issues.


Longer runs have more resistance and hence less flow. Sometimes this can be corrected by partially closing the vents closer to the furnace.


Many times the bedroom vents are run as 2" vs 4". Pop a vent off and look at the diameter of the duct. Not much you can do about this.


Sometimes a vent can be crushed or ripped. Depending where this occurs you may or may not be able to correct it easily. You may be able to check with with an inexpensive remote camera. https://www.amazon.com/Depstech-Endo...wifi+endoscope

[Cypressloser]

Originally Posted by JohnD10

My 5'ver was the same way...

Blast of hot air in the bathroom and the bedroom...hardly any in the downstairs kitchen and living room vents.

Turns out that the heating ducts downstairs were full of sawdust and debris from factory.

Even after getting that fixed...still too much air upstairs as the furnace is directly below the bathroom vent.

I bought the plastic louvered vents at Camping World...

DON'T BUY THEM!

They melted within five minutes of turning on the furnace (see photo below).

The toxic smell of melting plastic filled the camper and when I picked them off of the vent they were slimey wet of melted plastic and very soft to the touch.

You can get metal ones that fit at Lowe's, Home Depot and Walmart and they are half the price of the cheapie plastic ones at Camping World.

Funny thing...

I wrote a review with photos of my melted vent covers on Camping World's website, and the company that sells them actually went to Home Depot and bought me two metal ones...sent them to me for free along with a letter telling me that they were seriously going to speak with their engineers and designers about switching to metal ones...

And guess what?

Three and a half years later...Camping World is still selling those same plastic louvered vent covers and no metal option, plus my review with photos was never posted!



Also, I've been told by RV techs that you have to be careful of closing off the two upstairs vents as it can throw the air flow off in the furnace and cause it to overheat or shut off prematurely.

Funny, I too bought plastic registers but they were sliders and they also melted. The heat coming out of the bathroom register is a mind blowing 160 deg. F.

[TGR]

My 5th wheel arrived with a similar situation where the bathroom and bedroom had very high airflow from the furnace but the living room and kitchen had almost no air flow. The dealer fixed the problem for me. They installed a baffle in the ducts with the high airflow, which increased the airflow to the other vents. Home heating systems have adjustable volume controls that allows you to balance the heating system airflow. I suspect my dealer put in some type of partial obstruction to tune the airflow.

My only concern is that one or more heat lines is crushed or disconnected and not allowing proper airflow. My furnace has a manifold with several outlets that go to different locations. I recommend you check out the integrity of the ducts before trying to control the volume of air to the bathroom and bedroom with a partial obstruction in the duct or with and adjustable vent. Also, as you balance your heating system, you might also want to check your basement heat duct to be sure you aren’t sending too much air into your basement.

[SailorSam20500]

Last spring on a a trip down to Florida, the front section of my trailers underbelly tore free of it's fasteners. We pulled into a campground to find the underbelly, heat ducts, and wiring drooping or dragging back to the axles. I spent an hour pulling the underbelly completely off and securing the ducting and wires.

After I got home, I took a long look at the ducting because I was experiencing low airflow in two of my registers (front of trailer for me, furnace is at the back).

Turns out, the flimsy mylar ducts were way too long. The runs to the front of the trailer were poorly laid out - one was at least 40 feet long - on a 26 foot trailer! To get max airflow in flex ducts, they are supposed to be as taught as possible. To improve my air flow, I replaced most of the ducting with rigid aluminum. I used one section of heavy flex aluminum on a short run. I aluminum taped all joints. There was one 3 foot section that runs between a grey tank and the frame where I was forced to use the mylar ducting, I couldn't get anything else into the space. However, that section is now stretched taught and was covered with cut rigid ducting to keep critters from chewing on it.

After the changes, airflow to the front of my trailer improved significantly.
I posted pictures of the work on another thread.

[Villagerjjm]

You can pay to have someone check the ductwork for kinks or obstructions, or do it yourself. You can buy scope kits at Harbor Freight that will get into those tight places and you can see the progress on your cell phone. If you have a shop vac, get some flexible tubing and clean out the ducts. Mine are on the floor, so they get quite a bit of dirt and debris in them. I went to Lowe's and bought metal vents that can be closed up. I have there installed in place of the cheap plastic ones that came factory installed with no way to control the air flow out of them. Easy fix and now the whole trailer is a lot more comfortable.

[ktderobich]

Thanks, I plan to check those items out. I have been intending to buy a borescope camera so that I can inspect the duct work.

[ktderobich]

Thanks for the ideas.

[dtrussell]

Originally Posted by ktderobich

In my 2019 Cedar Creek Hathaway 34IK I have an issue with insufficient air flow from all the floor vents when running the furnace. The furnace is located under the bathroom and I get a good flow out of the floor registers in the bedroom and bathroom, slight blow at register that is next to island towards the bathroom but none to speak of from the other 2 on the opposite side of island in living area. I covered the registers in bedroom and bathroom and increased the flow from the other 3 significantly. Is there a way to adjust the flow in bedroom and bathroom to force more to the other areas of the coach and not have to just cover them up to force the airflow elsewhere?

We also had the same problem in our Cardinal. After poking around I did find that the vent pipe going to the vent under the stairs leading to the bedroom was almost cut in half by two electrical cables going through it. I rerouted the wires and replaced the vent piping with a hever flexible dryer vent. In addition I did cover 3/4 of the bedroom vent as well as 1/3 the bathroom. Still was not happy with the results so I added a register mounted fan from Amazon to the last register at the end of the kitchen island.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I did have to rework the vent to get the fan to fit but it was worth it.

[saus]

Also, I've been told by RV techs that you have to be careful of closing off the two upstairs vents as it can throw the air flow off in the furnace and cause it to overheat or shut off prematurely.[/QUOTE]


Has anyone else heard of this? I have the same problem and I was thinking about covering mine as well.

[Villagerjjm]

In response to the member who noticed the extra lengths of duct in the under carriage of his trailer: Did you ever think that that length was needed to distribute more heat to keep the under carriage warm during freezing temperatures? I have a few sections that do indeed wind around components that would need some heat during a freeze. I can adjust the air flow to accommodate the needs as they arise with the vents that I bought.
With todays technology, you can rig temperature sensors that will transmit over a private network so that you can "see" everything that is occurring in your rig. You can also rig up cameras that will detect rattlesnakes, skunks, rodents under your rig and will sound automatic alarms if they spot a bear in your vicinity. You can set incandescent lamps to activate on an "as needed" basis to provide heat or light. You can buy a dehumidifier that will activate when the humidity reaches a pre selected level and / or buy a vent that will turn on when pre set conditions are met.

It all depends on how much money you want to spend.

[jricherson]

I just bought my toy hauler and thought the storage area was extra warm when I was running my furnace. I removed the panel to the area where the furnace is located and noticed the cheap duct foil tape was not even connected to some parts of the furnace box and tons of air was escaping. I also noticed the round blank discs where you can attach more outlets were leaking and one was half off. I sealed all of them with 3M 3340 foil duct tape. Now I get ample air (not as much as I think it should) and furnace will not run as long. I wonder what the duct sealing looks like in the belly but am happy now.

[ktderobich]

A lot of good ideas and things I can look at. I did go to Lowe’s and buy the adjustable vents and replaced the 2 in the bedroom and bathroom. I didn’t cut them completely off but quite a bit and that made a big difference. It forced more air to the other 3 vents and better balanced the heat in the coach.
Thanks for all of the feedback.

[whj77372]

Glad for this topic. Does anyone know how the thermostats control the heat? 2018 Cardinal 3825: three thermostats, three ACs, one furnace. Which thermostat controls the heat? There must be one that controls the furnace?

[steven skare]

I had some heating issues with my 2001 Bounder 36 FT Motor Home. The duct work going under the Shower and sink was disconnected at the bedroom . I also had the same issue with one of the ducts under the couch. I went and bought some elbows and some extra aluminum ducting. Now it is working great.

[Bama Rambler]

Originally Posted by whj77372

Glad for this topic. Does anyone know how the thermostats control the heat? 2018 Cardinal 3825: three thermostats, three ACs, one furnace. Which thermostat controls the heat? There must be one that controls the furnace?

Usually the thermostat in the main living area is the one that controls the furnace.

One way to tell is to turn them all off and then turn them to heat one at a time and see which one turns the furnace on.