Is it cheaper to use a window unit other 2 rooftops ?

I would always choose to use the rooftop AC as in our coach it is vented so the cold air is sent to all areas of the coach. With a window unit you will be getting a huge blast of cold air right at it's location and hardly anything off in another room. We have found that ours cools really well and we actually seldom need the thermostat set any lower than 80 and we have never used both units at the same time. We however have never stayed in an extreme heat area in the summer (like the southern states)so we might use both if we stayed south.

I think Cousin Eddie would use a window unit but not this Eddie.

craig7h wrote:
Your unit as you stated already has two units installed. So it would be cheeper to use them instead of buying a window AC.

X2!

Even if the operation of the window unit were cheaper, factoring in the cost of the unit, you would never realize a pay back.

Also, the wall construction of your trailer is not designed for the weight of a window unit. Let alone bouncing it down the road.

Good question.
Firstly, if you have two 15,000btu units that is the equivalent to a 2.5 ton window unit. A 2.5 ton window unit will be a 220V model. Do you have 220V available? I believe a 15,000btu is the largest available window unit powered on 110V.

Putting that aside, a new, efficient 15,000 btu, 110V window unit (example) draws 12A. I believe that is the rating for an equivalent 15,000btu rooftop unit but couldn't find that reference.

Can anyone here come back with actual measured rooftop current measurements?

I'm going to say no, a window unit would not be a big enough electric bill savings to make it worth your effort.

The only way I see a window unit saving you on the EBill is installing a 12,000btu in the living room and turning off the bedroom ac (assuming floorplan). You may even consider sleeping in the living room with just the 12K running. There are small window units for ~$200 so it may take a year to recover this.

Your unit as you stated already has two units installed. So it would be cheeper to use them instead of buying a window AC.

Some of the smaller low end trailers use window type units for their AC. If you think that it is practical and you can properly install it without leaking, then go for it.

fordsooperdooty wrote:
The usual 13,500 BTU or 15,000 BTU units are built and engineered for RV use. Bumpy roads, vibrations, voltage variences, exposed to weather, etc.

A window unit is supposed to sit semi-permanently mounted firmly to an window sill that DOESN'T jiggle, bounce, go 60 mph down a road and rattle it's teeth.

Which is going to last longer?

X2...Even with the unit sitting for extended periods it will still sustain damage from transport. Also think about the thermodynamics of a window unit which is designed to deliver a direct blast of air into a room vs a rooftop unit that is designed just for your rv and is already setup for maximum efficency.

the unit will be stationary several months at a time. Hence the question.

The usual 13,500 BTU or 15,000 BTU units are built and engineered for RV use. Bumpy roads, vibrations, voltage variences, exposed to weather, etc.

A window unit is supposed to sit semi-permanently mounted firmly to an window sill that DOESN'T jiggle, bounce, go 60 mph down a road and rattle it's teeth.

Which is going to last longer?