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Photos / Re: Upgrading roof air conditioners
« on: September 22, 2026, 05:58:59 pm »
Hi Larry,
First off; I thoroughly enjoyed co-hosting the Solar/LiPo4 battery conversion discussion we presented at last year's Natchez reunion.
Second; Thank you for joining the discussion.
To address the points of your reply.
1. I get it; if it works, don't fix it. A good rule to live by, but, in my case, when the compressor kicking-on (even after adding the SoftStart) keeps you awake, that isn't "working" so I needed to remedy the probem. We had the original (2011 vintage) DuoTherm roof air. I didn't want to wait until it failed during a heatwave-usually, my luck.
2. Yes, having the thermostat/temp sensing unit inside could be improved upon, but that seems to be the state of the art right now, so other options did not seem available.
3. Heat strip: We have never used the heat strip on the Duo Therm. We prefer to use the FAU if we are awake (another noise issue) or a Little Buddy propane unit. We do not camp in very cold conditions, maybe only into the 20s, and we primarily boondock. The L'tl Buddy works very well. the only problem is deciding who will get up in the morning to turn it on:{)
4. I do not remember what the Duo Therm weighed, but I could guess that adding the 12v unit while replacing the DuoTherm, the additional weight was minimal. I had a MaxAir powered fan unit in the sleeping area. The 12VDC A/C unit I installed was 48lbs. I'd bet that there was a 20lb total increase in the weight on the roof. A concern, yes.
5. With the 12VDC unit, I only needed to route the 8ga wire down to the batteries(s). With a split unit, you would need to get the lineset routed between the under-floor unit and the roof unit. I dedided to go the easy way; a self contained roof unit. Also; is there a 12VDC RV split unit on the market?
Reference the 12VDC Install:
I routed the power cable across the roof, encasing it in electrical UV resistant Liquidtite to my refrigerator vent, then down the back of the refer where I installed the circuit breaker, then through the floor and directly down to my battery bus bar which is mounted under the coach close to where the factory battery tray is. . As it turned out, I needed 2 additional feet of cable to reach my busbar. I had some 4 ga lying around so used it for the extension.
The extension of the supplied power cable has stirred up many an internet conversation about how it should be dealt with, usually from owners of long 5th wheels who are installing the AC in a rear bedroom and supplying power from a front-mounted battery bank and the supplied cable would not reach. For us PC owners, that isn't really an issue. I have the 3100 and if I only needed an additional 2' of cable, those with smaller units should be fine. I'm sure, since this cable issue is resistance based, my addition will be fine.
I consider this is a DIY project, but it took me 2 partial days to complete, from the MaxAir removal, roof prep, getting the unit up on the roof, and installing the new AC.
There was another common stumbling block; the supplied bolts caused the interior ceiling unit to project about an inch lower than snuggly fitting up against the ceiling. I just used the supplied bolts and put in some rubber gap trim. It looks/works fine.
EXPERIENCE: Our 2026 road trip involved a drive from SW Utah to Oshkosh, Wi. for the EAA Fly-in, July 20-27. Along the route we used the 12v unit extensively. Most of our camsites were off-grid, as was our campsite at the Fly-In airport, so the 12V unit was our primary cooling. It is super quiet in Sleep Mode and cools the sleeping area well. The unit is so quiet that it really does not block out all of the outside "noise," especially the low altitude military fly-bys as a wake-up call each morrning.
When we did have shore power, we used the new 120VAC unit to cool down the coach, then switched to the 12VDC unit for nightime. The 120VAC unit is also much quieter than the 15 year-old unit replaced, but the fan runs continuously. Reportedly, the current draw is about half that of a non-inverter unit, so when running the AC AND the microwave was an issue, installation of an inverter unit should quell that.
The new units also sport an included interior light, activated by the included remote control, which is very usable:
THE ROOF: The 12VDC unit is considerably lower than the 120VAC unit and the new Inverter 120VAC unit is the same height as the old DuoTherm, so any additional wind resistance isn't an issue.
WITH ALL OF THE ABOVE BEING SAID: We, like Larry have over 800 AH of LiPo4 batteries and 1000 watts of solar on the roof. The solar would charge the batteries fully during the day. After running the 12VDC unit all night, we still had 2/3 -3/4 charge on the battery bank. If anyone else with lesser battery storage is considering such, research using your AH capacity and current draw should be considered.
The inverter options that are available are a step up, if you should find a need to replace your current unit.
https://www.turbro.com/products/greenland-13500-btu-inverter-rv-air-conditioner-with-heat-pump?utm_campaign=GGPSZMZ&utm_source=google&utm_medium=cpc&gad_source=1&gad_campaignid=23984465691&gbraid=0AAAAABX_xBIPDIil-8blZ7sCflBvgKghP&gclid=Cj0KCQjwzsjVBhC3ARIsALnMv4mxeAGcTqBNYLXRXTCKTtX_fb482iCKabgKy_XaKNLGzXiXgms3xF8aAod8EALw_wcB
https://www.turbro.com/products/greenland-12v-dc-inverter-rooftop-rv-air-conditioner
I will post some pictures, as soon as I can locate my SD Card reader/adapter.
Kirk
First off; I thoroughly enjoyed co-hosting the Solar/LiPo4 battery conversion discussion we presented at last year's Natchez reunion.
Second; Thank you for joining the discussion.
To address the points of your reply.
1. I get it; if it works, don't fix it. A good rule to live by, but, in my case, when the compressor kicking-on (even after adding the SoftStart) keeps you awake, that isn't "working" so I needed to remedy the probem. We had the original (2011 vintage) DuoTherm roof air. I didn't want to wait until it failed during a heatwave-usually, my luck.
2. Yes, having the thermostat/temp sensing unit inside could be improved upon, but that seems to be the state of the art right now, so other options did not seem available.
3. Heat strip: We have never used the heat strip on the Duo Therm. We prefer to use the FAU if we are awake (another noise issue) or a Little Buddy propane unit. We do not camp in very cold conditions, maybe only into the 20s, and we primarily boondock. The L'tl Buddy works very well. the only problem is deciding who will get up in the morning to turn it on:{)
4. I do not remember what the Duo Therm weighed, but I could guess that adding the 12v unit while replacing the DuoTherm, the additional weight was minimal. I had a MaxAir powered fan unit in the sleeping area. The 12VDC A/C unit I installed was 48lbs. I'd bet that there was a 20lb total increase in the weight on the roof. A concern, yes.
5. With the 12VDC unit, I only needed to route the 8ga wire down to the batteries(s). With a split unit, you would need to get the lineset routed between the under-floor unit and the roof unit. I dedided to go the easy way; a self contained roof unit. Also; is there a 12VDC RV split unit on the market?
Reference the 12VDC Install:
I routed the power cable across the roof, encasing it in electrical UV resistant Liquidtite to my refrigerator vent, then down the back of the refer where I installed the circuit breaker, then through the floor and directly down to my battery bus bar which is mounted under the coach close to where the factory battery tray is. . As it turned out, I needed 2 additional feet of cable to reach my busbar. I had some 4 ga lying around so used it for the extension.
The extension of the supplied power cable has stirred up many an internet conversation about how it should be dealt with, usually from owners of long 5th wheels who are installing the AC in a rear bedroom and supplying power from a front-mounted battery bank and the supplied cable would not reach. For us PC owners, that isn't really an issue. I have the 3100 and if I only needed an additional 2' of cable, those with smaller units should be fine. I'm sure, since this cable issue is resistance based, my addition will be fine.
I consider this is a DIY project, but it took me 2 partial days to complete, from the MaxAir removal, roof prep, getting the unit up on the roof, and installing the new AC.
There was another common stumbling block; the supplied bolts caused the interior ceiling unit to project about an inch lower than snuggly fitting up against the ceiling. I just used the supplied bolts and put in some rubber gap trim. It looks/works fine.
EXPERIENCE: Our 2026 road trip involved a drive from SW Utah to Oshkosh, Wi. for the EAA Fly-in, July 20-27. Along the route we used the 12v unit extensively. Most of our camsites were off-grid, as was our campsite at the Fly-In airport, so the 12V unit was our primary cooling. It is super quiet in Sleep Mode and cools the sleeping area well. The unit is so quiet that it really does not block out all of the outside "noise," especially the low altitude military fly-bys as a wake-up call each morrning.
When we did have shore power, we used the new 120VAC unit to cool down the coach, then switched to the 12VDC unit for nightime. The 120VAC unit is also much quieter than the 15 year-old unit replaced, but the fan runs continuously. Reportedly, the current draw is about half that of a non-inverter unit, so when running the AC AND the microwave was an issue, installation of an inverter unit should quell that.
The new units also sport an included interior light, activated by the included remote control, which is very usable:
THE ROOF: The 12VDC unit is considerably lower than the 120VAC unit and the new Inverter 120VAC unit is the same height as the old DuoTherm, so any additional wind resistance isn't an issue.
WITH ALL OF THE ABOVE BEING SAID: We, like Larry have over 800 AH of LiPo4 batteries and 1000 watts of solar on the roof. The solar would charge the batteries fully during the day. After running the 12VDC unit all night, we still had 2/3 -3/4 charge on the battery bank. If anyone else with lesser battery storage is considering such, research using your AH capacity and current draw should be considered.
The inverter options that are available are a step up, if you should find a need to replace your current unit.
https://www.turbro.com/products/greenland-13500-btu-inverter-rv-air-conditioner-with-heat-pump?utm_campaign=GGPSZMZ&utm_source=google&utm_medium=cpc&gad_source=1&gad_campaignid=23984465691&gbraid=0AAAAABX_xBIPDIil-8blZ7sCflBvgKghP&gclid=Cj0KCQjwzsjVBhC3ARIsALnMv4mxeAGcTqBNYLXRXTCKTtX_fb482iCKabgKy_XaKNLGzXiXgms3xF8aAod8EALw_wcB
https://www.turbro.com/products/greenland-12v-dc-inverter-rooftop-rv-air-conditioner
I will post some pictures, as soon as I can locate my SD Card reader/adapter.
Kirk