Thor Forums

[gmtech16450yz]

Originally Posted by Long & Winding road

GM Tech - I did your Vent mod today! WOW - the two front and two rear vents really blow the air now. I hate to be over optimistic but I would guess 40% more (like to put 50% more but im trying to be conservative). I used some frost king to block the air flow as each end of duct work.

Nice! Yeah I think there's a ton of room for improvement in the way Thor did those ducts. I ran my finished AC tonight for awhile and I'm VERY happy with the improvements.

Airflow into and out of the unit is drastically increased, tested and verified by watching amperage and by putting an airflow meter across the inlet and outlet. I did add the second vent to the ceiling panel, differently than you'd expect though. I modified the ceiling panel duct routing so that the outlet air comes out of the two added vents and the inlet air not only comes in the stock locations, but also comes in from the front opening. It made a huge difference in how much air is going in and out of the unit. I even moved the control box to the side of the evaporator core area so it's out of the airflow.

I monitored my inlet and outlet temps while turning my added electric fans on and off. Outlet temps dropped 3-4 degrees almost immediately when the electric fans are turned on. Outlet temps went back up after turning fans off. They work, same as they did 25 years ago on that old Coleman roof air. Everything I did was incremental, meaning there wasn't one mod that made it completely different, just a bunch of little optimizations that combine to make the entire unit work better.

I need another hot weekend to compare before and after temps, hopefully this next weekend we'll take the boat out again. I did get some temp numbers for you guys already though, 72 degree inlet air and 38 degree outlet air with WAY more airflow (which normally raises the outlet temps)! I have no idea how it will do in super hot conditions, but I'll take that 34 degree split for now. It absolutely will work better in super hot conditions. How much? We'll see.

I did order a 13.5k Mach 8 Plus -heat pump and condensate pump version for the back vent location. I'm going to duct it into the stock ducts, when the front 15k or the back 13.5k are on by themselves, they'll be able to feed the entire duct system from either end. When they're both on at the same time, it's gonna be a cr@pload of really cold airflow coming out of all the duct vents, the extra vents I added on the front 15k and the extra vents I'll put on the rear 13.5k too! I can't wait to get in another 100+ degree situation and let the inside temps get to 99 degrees like they were. My guess is I'll be able to have the inside coach temps down into the '70's in probably an hour or so after starting at 99 degrees inside. We ran that 15k for 10 hours straight after it was 99 degrees inside the coach and the best it did was 80-82 degrees. F that.

The other thing that will be nice is I can run the rear Mach 8 in heat pump mode and have that warm air come out all of the coach vents. That will be a nice addition to the gas furnace when it's cold out. When on hookups, I'll be able to run the heat pump on the quiet low fan speed and leave it on all night instead of having to use the propane furnace. It won't put out the amount of heat the furnace will, but it will distribute it through the coach a little better.