351M Island heat vent

[Rocketsled]

Our 351M's island heat vent doesn't push out a lot of heat. Most of the heat comes out in the bedroom, and the temperature sensor is way back next to the Garage Door.

Our warranty folks are suggesting a $500 helper fan that isn't covered. I've seen other threads where people have corrected the factory installation and it's improved things, but this duct goes from the furnace, through all the wiring and plumbing in the middle of the trailer, then dives under the floor to come up in the island...I don't wanna drop the floor under the trailer or otherwise tear apart the island, or run the risk of damaging something while messing about around the rats nest.

I'm pretty handy and am wondering about cutting in a new vent under the cabinets, next to the fusebox. If you've seen the area behind the pass-through, it would be a very short straight shot to the furnace.

Has anybody done this? Does anyone have a similar problem?

[Jkwilson]

Just pull one side of the coroplast loose. Not nearly as complex as you might think.

[TucsonJim]

If it were mine, there's a couple of things I'd do.

1. If you or anyone you know has a snake camera (endoscope), I'd run it through the duct to see if there are any pinch points, holes, or places where it's come loose. If so, you should be able to pinpoint where to take action.
2. Replace the vent in the bedroom with one you can shut close or restrict the airflow. This will divert more warm air to the island. This has been a pretty successful modification on other units.

Jim

[Country Campers]

I removed the vents on our island and found that the duct needed some taping work. I also found when I dropped the underbelly that one of those ducts was pinched between the floor and the top of the grey tank, both ducts going to the island was way too long.

Brian

[Rocketsled]

If it were mine, there's a couple of things I'd do.

1. If you or anyone you know has a snake camera (endoscope), I'd run it through the duct to see if there are any pinch points, holes, or places where it's come loose. If so, you should be able to pinpoint where to take action.
2. Replace the vent in the bedroom with one you can shut close or restrict the airflow. This will divert more warm air to the island. This has been a pretty successful modification on other units.

Jim

You know, I have a Harbor Freight Endoscope and never seem to find a reason to use it.

If the duct is restricted, I think I'd rather make a new outlet for it (under the cabinets) than drop the bottom and re-run, seems like a less intrusive repair.

I also saw in another thread that someone T-d off the duct to the beroom and routed the other side of the T to a spot in the wall near the stairs. That seems like an easy thing to do as well. I'll mangle the design as necessary when I get the trailer back and get eyes on the problem.

[ncitro]

Our bunkroom had poor airflow, I had to drop the coroplast and pull it out and rerun it. The duct was about twice as long as it needed to be with the excess wadded up under there. Well worth opening it up to see whats going on in my opinion.

[Country Campers]

Also worth noting to be careful when adding a new vent "under the cabinets". Most times in the "hutch" area , or area near the pass thru storage and the furnace, there is a return air located at the bottom. This is used by the furnace to pull air out of the coach and heat it before returning via the duct work. If you install a new vent close to that area you may be providing too much hot air back to the furnace.

Brian

[OffToHavasu]

If it were mine, there's a couple of things I'd do.

1. If you or anyone you know has a snake camera (endoscope), I'd run it through the duct to see if there are any pinch points, holes, or places where it's come loose. If so, you should be able to pinpoint where to take action.

Jim

You had to go and say endoscope. My doctor just told me at my annual physical, "You know, 45 is the new 50." Thanks Jim!

To solve the bedroom heat being too much on our 351M, I picked up some 4" duct dampers. I took the main connector off the furnace, added a little extension to the adapter and installed the duct damper and have it closed all the way. To note, even with a damper closed all the way, it still lets air by. For now, I think this has solved the "too much hot air" in the bedroom. This process also added more flow to the garage for the heater, which was also lacking.

We haven't been out much during the winter, but when I let it run over night in front of our house, everything seemed more balanced.

[Rocketsled]

You had to go and say endoscope. My doctor just told me at my annual physical, "You know, 45 is the new 50." Thanks Jim!

To solve the bedroom heat being too much on our 351M, I picked up some 4" duct dampers. I took the main connector off the furnace, added a little extension to the adapter and installed the duct damper and have it closed all the way. To note, even with a damper closed all the way, it still lets air by. For now, I think this has solved the "too much hot air" in the bedroom. This process also added more flow to the garage for the heater, which was also lacking.

We haven't been out much during the winter, but when I let it run over night in front of our house, everything seemed more balanced.

I know it's not the same thing, but when the guy came to fix our home furnace, he found most of the house vents closed...we'd close them when things got too hot and close them when things got too cold and just never opened them back up again...There's something like 4 main vents (garage, living, bath, bedroom) and if the island isn't blowing well, and we block off the bedroom, I'm wondering if that's going to mean there's not enough total flow?

[howson]

I know it's not the same thing, but when the guy came to fix our home furnace, he found most of the house vents closed...we'd close them when things got too hot and close them when things got too cold and just never opened them back up again...There's something like 4 main vents (garage, living, bath, bedroom) and if the island isn't blowing well, and we block off the bedroom, I'm wondering if that's going to mean there's not enough total flow?

There's definitely a minimum flow requirement. You'll find it in the furnace's installation manual.

Unfortunately an owner may find out they blocked off too much airflow when the furnace overheats and shuts down to protect itself. (I'm sure Curtis, OffToHavasu hasn't reached or even come close to this much blockage.)

If the flow discrepancy is bad enough checking the duct runs is a prudent step. I admit that I haven't done this yet, as we rarely use our furnace and it will be quite a bit of work.

Howard

[OffToHavasu]

There's definitely a minimum flow requirement. You'll find it in the furnace's installation manual.

Unfortunately an owner may find out they blocked off too much airflow when the furnace overheats and shuts down to protect itself. (I'm sure Curtis, OffToHavasu hasn't reached or even come close to this much blockage.)

If the flow discrepancy is bad enough checking the duct runs is a prudent step. I admit that I haven't done this yet, as we rarely use our furnace and it will be quite a bit of work.

Howard

I think since it was the one vent, I shouldn't have an issue. If it does become an issue, I'll move the damper and add a dump line and have it return somewhere else.