RV Airflow Systems in a Coleman AC

[WmJSheffler]

Does anyone have experience installing and using this “system” (https://rvairflow.com/) on their Coleman Mach 3 Plus AC units? My objective is to get some performance increase in my Axis coach. My understanding is that the factory installed system is good for at best a 20 degree differential. I am currently getting no more than 15.

[Hugh.vines@att.net]

I put one in my axis 25.2. Cleaned unit carefully and just got back from Alabama trip temperatures were high 80s in day with no shade at all just to test. Very happy. Set temp to 70 and it maintains just like home unit shutting on and off like normal. Cuts noice some but not a lot. Be sure to take your duct covers off and use something to stop airflow from going past your ducts. I used cotton insulation bought on Amazon looks like blue jeans no itch. Increased air flow at ducts like you won’t believe. Best thing I’ve done to RV. Will have no problem taking grands to fla this summer

[Chucke]

Originally Posted by WmJSheffler

Does anyone have experience installing and using this “system” (https://rvairflow.com/) on their Coleman Mach 3 Plus AC units? My objective is to get some performance increase in my Axis coach. My understanding is that the factory installed system is good for at best a 20 degree differential. I am currently getting no more than 15.

Hello WmJSeffler, I did a little research on the rvairflow and talked with the inventer. Super nice guy. I made a few modifications. The space between my roof was thicker by an inch so I added a piece of foam. My oblong holes for the air to flow through were to tall. I narrowed them up using aluminum and pop rivets. I was able to get it all to line up with the airflow device. I pulled the motorhome out a couple days ago in 90+ degree heat and let it sit for an hour or so. Then turned on the AC and let it run for an hour. I went from 93 degrees to 78 by the couch and in the bedroom with the slide out it was 76 degrees. I did not have the blinds pulled. I use a infared thermometer and at the vents it read 41 degrees. We had turned the Television on and noticed we did not have to have it up as loud. The AC was quiter. As Hugh.vines@att.net mentioned, make sure and seal off the ends of your vent passages. I used unfaced fiberglass insulation and sealed it with HVAC tape. I can send pics of all I did to give you a better idea. The inventer is very helpful. We are very happy with the air flow!

[Judge]

So I just installed the RV Airflow in the front A/C of my 2020 Magnitude SV34. My goal was to be able to run the from A/C at night and have more airflow pushed through the ducts in the bedroom so I don't have to run the bedroom A/C at night (unless it is brutal conditions).

I did most of the A/C mods that have been posted on this forum and have been generally happy with the A/C performance since doing so. I thought the RV Airflow might be the final piece of the puzzle.

My first issue is the duct insert are too small for the openings in my A/C unit. Attached are the pictures. The duct inserts pictured in the instructions are black in color and appear to be larger. I'm not sure if they shipped me the wrong inserts or not. I have emailed them the pictures.

As a result of the sloppy fit of the duct inserts the styrofoam piece is also loose fitting. So much so I believe it is probably leaking cold air that is getting sucked back through the evaporator. I used some rubber sealing that I had to try to seal and tighten things up.

I have an e-mail into their suport with the pictuters of the duct and a video showing how loose the styrofoam fits so we will see what they say.

That being said.... from my perspective if you follow all or most of the mods on this forum and make sure the plenum divider is well sealed, I think you can get the same performance gain as the RV Airflow device provides at a fraction of the cost.... and without losing the dump vents should you want to use them.

[Chucke]

Originally Posted by WmJSheffler

Does anyone have experience installing and using this “system” (https://rvairflow.com/) on their Coleman Mach 3 Plus AC units? My objective is to get some performance increase in my Axis coach. My understanding is that the factory installed system is good for at best a 20 degree differential. I am currently getting no more than 15.

Here are 4 atached photos. I am trying to show the sides of the original holes that were 3 inches wide and then filled in with foam board to bring them to 1 and a half inch wide, then trying to show looking at the top that I put a piece of one inch filler foam in for the cold air intake. and covered it with HVAC tape. then there is a pic showing the aluminum pieces I used to finish it off. I did cover all of it in HVAC tape. The hole you have may be to thick for the rvairflow. So i just shored out the hole for a good fit and smooth air flow.

[Chucke]

Originally Posted by WmJSheffler

Does anyone have experience installing and using this “system” (https://rvairflow.com/) on their Coleman Mach 3 Plus AC units? My objective is to get some performance increase in my Axis coach. My understanding is that the factory installed system is good for at best a 20 degree differential. I am currently getting no more than 15.

This is the one inch filler I had to add for the cold air return.

[paulwadley]

Hi Judge

I also emailed the company a few months back to see if they have a kit to fit my Dometic Penguin since it wasn't listed on their website. They finally responded a couple months later telling me they are developing one for that system. I did go through my system and taped up every spot where it appears I am losing cold air. Hopefully that helps this summer when we travel cross country from California to Kentucky. I was thinking of going to a soft start on it also. Looks pretty easy to install.

Paul

[Hugh.vines@att.net]

One of the best thing to do is clean your coils up top. Mine were nasty this year. More than ever before.

[WmJSheffler]

Was this a Coleman Mach 3?

[Scubawise]

Question did this post imply we should check the round ceiling AC vents for leakage? Like remove the vent to see if air is blowing away from the vent?

I will take off the AC COVER and check for leaks does lowes have the foam and hvac tape?

[Chucke]

Originally Posted by Scubawise

Question did this post imply we should check the round ceiling AC vents for leakage? Like remove the vent to see if air is blowing away from the vent?

I will take off the AC COVER and check for leaks does lowes have the foam and hvac tape?

Hello Scubawise, Our celling duct work has voids that dont do anything exccept allow cold air to stay in the celling. I have taken off the vent covers furthest forward and the two furthest towrd the rear. There is space that runs past the last vent in the run. I filled all four cavities with insulation and then used HVAC tape to seal them up. This forces the air to come directly into the motorhome. I bought the tape and insulation at lowes home improvement.

[gnach]

Originally Posted by Chucke

Hello Scubawise,... There is space that runs past the last vent in the run. I filled all four cavities with insulation and then used HVAC tape to seal them up. This forces the air to come directly into the motorhome.

In my Axis the "duct" voids run from the front cap to the back cap. Blocking that void after the final vent louver forces the air out those louvers instead of building up back pressure. While you're in there look for construction debris, I found chunks of ceiling foam.

[Judge]

The best things to do to maximize performance with your A/C units are:

- Remove each vent cover, clear out loose construction debris, trim the styrofoam to maximize airflow and then use insulation or spray foam on the end of the last ducts front and back to keep air pushing into dead spaces.

- Remove the inside cover and make sure the plenum divider is centered properly and then use duct tape or aluminum tape to seal around the edges.

- Make sure the all debris has been cleared from the entrance to the ducts.

- Make sure the freeze sensor is installed into the coils of the evaporator and not dangling free.

- Remove the top cover on the roof and wrap the airbox with adhesive style insulation.

- Add a piece of pipe insulation to the low pressure pipe gong from the compressor to the evaporator.


If you do all of these things and make sure the outside condensor coils are clean each season, then you A/C should perform at its best and I think the RV Airflow kit is not going to be necessary.

[Scubawise]

01) where is this ocated? - Make sure the freeze sensor is installed into the coils of the evaporator and not dangling free.
02) which is easier to work with - insulation or spray foam
03) will lowes have this ..is there a brand or pics video of what to wrap - Remove the top cover on the roof and wrap the airbox with adhesive style insulation
04) can i use the same hvac tape? - pipe insulation

[WmJSheffler]

A 2018 thread titled "Try this first before you buy 2nd AC unit or bring your unit in for AC service" recommends allowing the temperature probe to hang loose in the return air area.

[Judge]

Originally Posted by WmJSheffler

A 2018 thread titled "Try this first before you buy 2nd AC unit or bring your unit in for AC service" recommends allowing the temperature probe to hang loose in the return air area.

There is a lot of misinformation about that sensor. Some might think what I am about to say is incorrect but based on my research it isn't.

The purpose of the freeze sensor is to detect whether the evaporator coils start to freeze over. If the sensor detects this occuring, it cycles the compressor off so the ice melts and flow can resume through the coils. If ice builds up on the evaporator coils, it will restrict the airflow.

If the sensor is just dangling, then it does not do its job and detect ice build up. As a result the compressor keeps running and the problem gets worse.

If you look up the part number and description, is it actually "Freeze Switch / Sensor" and not "Temperature Sensor."

[Judge]

Originally Posted by Scubawise

01) where is this ocated? - Make sure the freeze sensor is installed into the coils of the evaporator and not dangling free.
02) which is easier to work with - insulation or spray foam
03) will lowes have this ..is there a brand or pics video of what to wrap - Remove the top cover on the roof and wrap the airbox with adhesive style insulation
04) can i use the same hvac tape? - pipe insulation

1) The Freeze Sensor is located inside the unit. You need to remove the inside cover to see it. It has a white wire and it runs up to the evalporator (air intake side).

2) Self-adhesive insulation is easiest to use the outside of the airbox on the roof.

3) Frost-King Duct Insulation works well.... https://www.lowes.com/pd/Frost-King-...lation/1081449

4) I used rubber pipe insulation on the short pipe coming out of the compressor. I used metal duct tape to seal up the divider.

[WmJSheffler]

Thanks for the clarification of this part’s function (and its name). The debate on its optimum placement continues, nevertheless.

[Scubawise]

01) where is this located? - Make sure the freeze sensor is installed into the coils of the evaporator and not dangling free.
02) which is easier to work with - insulation or spray foam
03) will lowes have this ..is there a brand or pics video of what to wrap - Remove the top cover on the roof and wrap the airbox with adhesive style insulation
04) can i use the same hvac tape? - pipe insulation
---End Quote---

1) The Freeze Sensor is located inside the unit. You need to remove the inside cover to see it. It has a white wire and it runs up to the evalporator (air intake side).
*** Thanks this is clear

2) Self-adhesive insulation is easiest to use the outside of the airbox on the roof.
*** i an reviewing exactly what will help once outside cover is removed. I am watching this video there is a pic below. Do you insulate these coils ? with duct table or some rubber around them?

https://www.youtube.com/watch?v=fv5KBhdEvNg

3) Frost-King Duct Insulation works well.... https://www.lowes.com/pd/Frost-King-...lation/1081449
*** need to use this on the airbox? i need to find exactly what an airbox it?
will get from lowes

4) I used rubber pipe insulation on the short pipe coming out of the compressor. I used metal duct tape to seal up the divider.
*** will measure and get pipe insulation from lowes and metal duct tape same as HVAC tape?

[Scubawise]

i see this is the compressor and we can place rubber pipe insulation on all these little pipes and help?