Furnace air flow

I just bought a 2019 Elkridge 37BHS. The furnace ducts air via a nice solid duct system and exits via floor vents. My problem is the flow exiting the vents is extremely low. I can put a piece of paper over the vent and it barely lifts it. Dealer says there is not blockages and the furnace itself is pushing air. Their (ridiculous) fix was to put different style vents in so I can close off some. This is clearly not a fix. My bunkhouse room and rear bathroom are super cold. The main living and master barely stay warm. I should note, all vents in system barely blow. Anyone else see this in their units? A buddy next to me in the park has a similar size unit and same style ducting. His furnace and vents blow great!

they are probably correct that there are no "blockages". but its true that the accordion style vent tube has a lot restriction due to the rough walls of it... it creates a strong friction that the air flow must overcome to get to the end of the tube.... the longer the tube, the less efficient it is...

there was a post that went by a couple weeks ago, where the owner dropped the corroplast from under the trailer and straightened out the vent line, and ended up cutting about half of it out because it was so unnecessarily long. and he claimed it increased his airflow out the floor vents many times over....

in addition to it being "high friction", when the vent needs to go thru a tight area, OR, if something shifts in the area that it runs thru, the vent line can collapse a little, which causes a restriction point..

whatever you decide to do, finding out why the furnace that is able to blow plenty of air to get to the end of a properly installed vent line, and yet is ISNT, will be found between the floor and the corroplast...

centerline said:

they are probably correct that there are no "blockages". but its true that the accordion style vent tube has a lot restriction due to the rough walls of it... it creates a strong friction that the air flow must overcome to get to the end of the tube.... the longer the tube, the less efficient it is...

there was a post that went by a couple weeks ago, where the owner dropped the corroplast from under the trailer and straightened out the vent line, and ended up cutting about half of it out because it was so unnecessarily long. and he claimed it increased his airflow out the floor vents many times over....

in addition to it being "high friction", when the vent needs to go thru a tight area, OR, if something shifts in the area that it runs thru, the vent line can collapse a little, which causes a restriction point..

whatever you decide to do, finding out why the furnace that is able to blow plenty of air to get to the end of a properly installed vent line, and yet is ISNT, will be found between the floor and the corroplast...

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I find it hard to believe this is how Heartland allowed this to be designed. Like I stated, It wont even barely lift a sheet of paper when placed over vent. The ducting under the floor looks to be way too wide which Im sure probably hinders performance as well.

centerline said:

there was a post that went by a couple weeks ago, where the owner dropped the corroplast from under the trailer and straightened out the vent line, and ended up cutting about half of it out because it was so unnecessarily long. and he claimed it increased his airflow out the floor vents many times over......

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Not sure if that was me, but I did post something like that a short while ago. I had very low flow form the vent at the far end of the RV. I peeked under the corplast and there was a lot of extra vent pipe in there. I felt it was easier to work from the top so I pulled out the vent box. Then cut off about three feet of extra pipe coiled up under there. It made a significantly noticeable difference in the flow from that vent.

I just went thru this on our 4.5 year old CY as our airflow seemed to have been a bit low since purchase.

To start with, the heater did the common ""blow cold air, then shut down" scenerio. After OKing the propane and 12V systems, the heater was my victim...tracked it down to a groady, pet hair-balled sail-switch..cleaned and heater was happy.

So in the mean time while loosening the heater unit from the flooring, I noticed the furnance box, and seal, was compromised...BIG time. The sheet metal furnace box bottom would not lay flat to the floor and allowed a lot of hot air to blow out between box and floor, rather than directing the hot air into the ductwork to vents.

Tapped the box bottom as flat as possible, made a new high-temp rope gasket that fit around the box-to-duct, and screwed the heater box down for a full seal. Then placed HVAC tape around the entire inside perimeter of box to duct....all air goes directly into the duct. We have another 25-33% airflow "pressure" out all furnace vents now.

Next project is to pull all floor vent covers and HVAC tape all of the ductwork for the "frosting on the cake" furnace heater project finale.

Infinit4r said:

I find it hard to believe this is how Heartland allowed this to be designed.

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it might seem hard to believe, but after you get enough testimonials from people who have had a similar issue, you will realize its true...

I believe Heartland is trying to build a better quality trailer, at around the same price point as their competitors, so in addition to the overall cost, a lot of how its put together depends on the attitude and intelligence of the person laying the system in your trailer the day is was installed....

The furnace ducts air via a nice solid duct system

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It does seem like most of the responses have little or nothing to do with a solid duct system. Given that some people with the same setup have better results, perhaps this is not a "design" problem, but rather either a malfunction of the furnace, or a problem with the installation.

You should make sure the air return inside the coach is not blocked by anything, and check the furnace exterior to make sure the air intake is not blocked by insect nests or leaves. The furnace requires 75% airflow to operate, but you could have a partial blockage that's reducing airflow but still providing the 75% required to operate.

If the furnace is not pushing out sufficient warm/hot air to ANY part of the trailer, the thermostat won't reach its set point, and the furnace will run continuously or almost continuously. If the furnace runs, shuts off, runs, the furnace is probably doing its job.

And on longer trailers, the hot air coming out of the furnace will typically cool quite a bit on the way to the back end of the trailer.

Your Elkridge furnace may only be 35,000 BTU, not the 42,000 found on most Big Country, Bighorn, and Landmarks. In relatively mild cold temps, that's fine. In brutally cold areas, you'll need to supplement a 35,000 BTU furnace that's working perfectly.

If you think the dealer didn't do a thorough checkup, you might ask the service manager to demonstrate airflow on a comparable model on their lot and compare to yours. If there's a big difference, you'll have a convincing case to have the techs dive into the problem further.

Hello,

I had issues with airflow in my Landmark. I sealed up all the the edge of the furnace outlet box, lots of air is lost there. Our bath/ bedroom was fed from a 4 inch duct but the hole that was cut was 2 inches and the 4 inch flange just screwed over, enlarged the hole and flow is considerably better. I also did that others did and cut extra duct off. Sealed up the boots again again in flow. Final was the closest register under the stair I restricted the flow of just this one outlet to help balance the system. Happy now with everything.

CDN said:

Hello,

I sealed up all the the edge of the furnace outlet box, lots of air is lost there.

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That was our largest loss until installing my gasket, attaching box to floor properly, then taping the outlet all the way around....stepped up trailer heating efficiency a bunch.