Question-Can I use my roof mounted a/c in my stationary rv

[brainclutter1]

Hello,
While I'm new to RV.NET, I'm not new to forums in general.
I have a question regarding whether or not,it would be a safety issue to use my rooftop mounted (working) a/c unit to cool my '87 Franklin 35 ft., STATIONARY travel trailer, that has had a wood framed, pitched metal roof added 10 plus years ago.
There is also at the opposite end of the roof, an attic exhaust fan (currently not hooked up to power.).
Can I/should I attempt to use this now enclosed a/c unit, only if I use the exhaust fan at the same time, to avoid overheating..., or should I just scrap the whole idea of using the roof top a/c, altogether..?
I have talked to a licensed electrician, who was not sure if it was legal (in the state of NH) or not, but declined, because he did not want to risk his license.
Any thoughts or advice would be GREATLY appreciated.
Thank you.

[wa8yxm]

The only thing I would be concerned about is this.
THe A/C also removes water from the RV this "Condensate" as it is called drips onto the roof. IF the Roof over the RV has clearance at the sides of the RV so the water can continue to the ground.. Just run the exhaust fan to keep a good supply of fresh air in the "Attic".

If the Attic roof is Sealed to the RV roof. YOu need to provide a way for the water to go to ground.

[brainclutter1]

Thank you John Wayne,
No, not really.
I would have to hire someone to cut a hole into the side of the trailer, then reinforce/frame around the hole to support the weight, then seal it all up to make it all weatherproof.
Besides, I already have the rooftop unit already in place and from the limited tests I have done, it seems to works well...!

[John_Wayne]

Wouldn't it be easier to install a window unit.

[brainclutter1]

Thank you valhalla360,
I have limited access to the fan, so I can not answer as to the amperage, yet.
The trailer has been stationary since 1987 (it still has its 12 volt system for some of the interior lights and the 110/120 volt system is hard wired to a box on a pole out back of the trailer.
I have a small service panel (breakers) in the bedroom.
I do know that fan was never hooked up to any electrical service.
For some reason, the installation process, just stopped and the wiring from the attic fan, was left coiled up, tucked under the back end of my unit.
If I go ahead with this project, I would have a licensed Electrician put an appropriate breaker into my service panel, as well as making sure the a./c has a sufficient breaker as well..!

[valhalla360]

What is your power supply and how big is the ventilation fan?

If it's an older electrical system with a 30amp outlet and it's a big exhaust fan, you might be popping the breaker all the time.

A big fan that will really keep the attic temps down might pull 5-6amps (plus whatever else you have running in the trailer. A smaller fan will pull less but won't keep it as cool. On startup, the air/con will likely be within a few amps of popping the breaker to start with, so it's a question of if you have enough amps to get everything going.

Once going, it will likely work but it's a question of startup loads. This is a common discussion in relation to small generators running air/con but you might run into it.

[brainclutter1]

Thank you,
To everyone who responded.
I very much appreciate you taking the time to answer.
Please, let me offer a few more details to better explain what I'm working with...
My '87 Franklin is 35 ft and sometime in the past 10 years, most of the residents in the park added low pitched roofs to help keep the heavy New England snows from piling up during the off season, when our park is locked up (Sept to May) with no access.
They all are wood framed with corrugated metal roofs.
Some of the units, have attic fans
at one end, behind exhaust louvers, that are either thermostaticly controlled or have just an on/off switch located in the room just below where the fan is.
The opposite end (closest to where the a/c is located.) has no access, yet.
If I go through with my plans, I will have to cut through the perforated vinyl siding, reframe the wood structure at the eave, install intake lovers and try to figure out a system to allow for drainage of the condensation, that I almost failed to consider (Thanks kerrlakeroo & John Wayne..).
Also the center height of the roof is approximately 48 inches, so there isn't much room for maneuvering up there.
I know State Laws vary State to State, but I was wondering if anybody has heard mention that what I want to do violates any type of building codes...?

[John_Wayne]

And don't forget if running the RV unit in the attic you will need some way to drain off the water that the RV A/C will produce.

[valhalla360]

A big ole...depends.

How much space and airflow is there in the attic area?

A ventilation fan would certainly help but again without details of the space hard to say if it will be enough.

If its a small poorly ventilated space, temps could easily push 130F in the attic. On really hot days it can go even higher. The Air/con unit at best will be severely hampered in it's cooling ability in those conditions. Plus it will be pumping more heat into that space. You could easily push it up north of 150F.

Those kinds of temps could be really hard on the air/con unit.

PS: Did an experiment several years back looking at LED traffic signals. We put a temperature probe inside the head in direct sunlight. It got up to 160F and the LED unit generates almost no heat. Black shingles would be far worse than a yellow housing for absorbing heat.

[Farmboy666]

If there is any way for air to circulate from outside it would work, the less air the less efficient it will be. If there is no outside air then I don't know where the exhaust fan will get air from, if there is a grate at the other end I would say your best bet is to hook up the fan for better efficiency. Don't see how it could be against the law but who knows.

[kerrlakeRoo]

A picture of what you are talking about would be a great help.
But, If your AC is inside an enclosure that contains the rest of the trailer, understand that a similar amount of heat will be generated in the roof enclosure as compared to the cool air being placed inside the trailer.
So long as you can give that warmer air a means of escape, with outside ambient air able to replace it you should be fine.

Also understand that the rooftop AC will generate condensate (water) which will drain toward the sides or whatever low point is available, just like you see drain from a window AC. You must give that somewhere to go.

[Chris_Bryant]

Can you actually get to the unit? If the roofover is big enough to get in there, I would try it. If it isn't, I wouldn't trust it.

[TNGW1500SE]

I think I half way understand your question. Your roof A/C is intended to be open to the outside air to remove heat. Running the roof air in an enclosed "attic" will build up heat in the "attic". The heat needs someplace to go. You need to ventilate the "attic".

[DutchmenSport]

I kind of don't understand your situation. An RV air conditioner should work in any type of room or building. The air conditioner has an air intake from inside and then it circulates the air inside the conditioner, passes though the condensing coils, and spits cold air out the other side. I don't see where having any kind of exhaust fan in the building, on the opposite side of the building would make any difference. The air conditioner is designed to run and cool in any enclosed space.

Now, in order to circulate the air in the building (or completely sealed up camper), a circulating fan would help... you know, a simple floor or desk fan to push the air to the other side of the room or down a hall or something. Thus ... some manufacturers use duct work in the roof of RV's for the cold air to make a passage to each end of the camper. But a center blast air conditioner will simply blast the air straight down. You may want a separate fan to circulate the cold air in the room.

But needing an exhaust in the building is not needed at all.

The only thing you'll want to watch for, is to make sure the air conditioner can sit somewhat flat and somewhat level. I've seen RV air conditioners on 5ers where they are located on the roof between the low spot and the high spot on the over hang, at an angle. It looks weird, but I suppose they work OK. Still, if I were doing this, I'd want it as level as possible.

Other than circulation in a room, an RV air conditioner works pretty much like a house window air conditioner. Hot air in, cold air out. Do you need an exhaust to run a window air conditioner?

Edit?
I re-read your post. Are you saying the trailer air conditioner is located between the roof of your trailer and an add-on roof above the trailer? So if running, the air conditioner now way to cool the air conditioner components themselves, thus building up heat and eventually burning something out ... no surround air circulation? If so, then yes, run the exhaust fan. I think I get it.

[Old-Biscuit]

Run the trailer A/C Unit.....if it trips THEN worry about hooking up exhaust fan power and run both