First time using Atwood propane heater

[folivier]

On my new to me 2006 Monarch SE 30' I have 1 Atwood propane heater B531-IV DCLP 24,000 BTU with ducts under the kitchen sink, behind passenger seat, down hall, in bedroom, and in the bathroom. It finally got cold enough here (40's) to try it out. Heater fired up, I'm at 9400'. But I was only getting heat blowing out of the duct under the kitchen sink. Nothing blowing out of the other floor ducts. I pulled the intake grate under the fridge off. Then pulled the duct shroud off. There is a plastic duct going to the duct under kitchen sink and the duct shroud directs heat into the floor ducts for the others. But all of the heated air was going into the plastic duct. So I used aluminum duct tape to close off most of the plastic duct so that more heated air enters the floor ducts. It works better but not as well as I'd like. The heated air is more evenly distributed now. I guess that's all I can expect at altitude with that size heater.

[Martinvz]

Is your furnace under the fridge, possibly? That is where ours is and it works fine. I will not be able to get a photo to you today of how it is installed. Possibly tomorrow. 
You could see if there is an obstruction in the duct leading to the floor ductwork. 

[96 EVO]

Something else going on there!

Shouldn't need to partially block one duct.

[cbr046]

If you can get your hands on an infrared camera it will show you if there's any leaks, including hotspots on the floor. 

Same for an inspection camera.  You can fish it down the duct from either end looking for obstructions (rodent nest?) or breaks in the duct.  Those pesky rodents love to steal your heat.

- bob

[Tom Cherry]

13 hours ago, cbr046 said:

If you can get your hands on an infrared camera it will show you if there's any leaks, including hotspots on the floor. 

Same for an inspection camera.  You can fish it down the duct from either end looking for obstructions (rodent nest?) or breaks in the duct.  Those pesky rodents love to steal your heat.

- bob

A Laser Thermometer....always handy for checking tires and such....will also work.  YES....an infrared will show the "HOT and COLD Spots", but if you are methodical....you will see where they start to change and transition...

[jacwjames]

I have a suburban furnace, it has more ducts and seems to distribute heat better then what you describe.

But at one point I was working on something in the basement where the heat ducts are run and noticed that mice got to one of the ducts.  Had to patch it.  Just something else to look for. 

[Bill R]

My rear heater duct network because of design does not distribute air flow to the bedroom very well.  So I purchased vent grilles with dampers and replaced all of the exiting grilles with these.  I adjust the dampers depending on where I want more heat. 

https://www.homedepot.com/p/Venti-Air-10-in-W-x-4-in-H-Steel-Floor-Register-Steel-Brown-for-Duct-Opening-of-10-in-W-x-4-in-H-HFB1004/307703908

[folivier]

My ductwork appears to be a shallow rectangular channel that runs under the floor front to back. The shroud at the heater ducts air into this channel. Except for the plastic duct that directs air to a register under the kitchen sink, that's the one that I modified.

Without tearing up the floor to expose that rectangular duct I can't tell if it is damaged or leaking anywhere. I'm bringing it to storage this week so may not be able to continue this until the spring. Thanks for the tips, I may be able to borrow a thermal imager later to look for air leaks.

[Martinvz]

You may want to invest in a borescope so that you can see the inside of that duct. These are not that expensive and do a good  job in showing you the insides of the duct (in this case). Hopefully you can find the cause without exploratory surgery.