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Old 07-05-2015, 06:10 PM   #1
Artemus Gordon
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Third Air Unit on 3750!

This weekend in Red Bluff we had 117 during the day and low was 89. We have two 15k air units that work great for the 3750's bedroom and kitchen. The living room has always been a problem when heat reaches 113-117 which we get in Redding through July and August. With our Bernese Mt Dog's heavy coat we need more cooling. I want to place a 13 k unit, in the location of the LR fantastic fan. Need thoughts about this project from my friends. I know I don't want it attached to central air vents, I want it dedicated to front LR. Please give me thoughts about brands, power issues I might face, pitfalls etc. Thank you all in advance! This does live us with three fantastic fans still in place. I kind of hate losing the forth one in LR, but I don't want a new hole in the roof!
 
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Old 07-06-2015, 02:14 AM   #2
Glenn the fifth
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Hello Artemus. I just installed the Coleman Mach 8 low profile (8 1/2 inches) on the front of ours. It really cools well and seems to be built well. I bought the 15K unit, but there is also a 13.5K unit (can be found for somewhere around $750.00) and it is non ducted. It weighs about 85 pounds and was pretty easy to get up on the roof. We have had some 106 degree days here in Winthrop, WA during the start of our vacation and I think I could still hang meat up here in the bedroom. Good luck! Glenn
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Old 07-06-2015, 02:42 AM   #3
bncinwv
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Fantastic fan is DC power which will not help in terms of supplying electric. May have to check if AC power is prewired and is available there first. Sandi Faircloth and David Hubbard had this exact thing done to their 3750FL (sfaircloth). If they do not chime in, a PM may get you some additional information. I second the idea that you will most likely want a low profile model, rig height measurements may be in order.
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Old 07-06-2015, 03:15 AM   #4
DQDick
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Proper running of the 110 will be your issue (not just getting the power there, but load balancing etc.). A number of the larger class A's are coming with three AC's now.
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Old 07-06-2015, 03:26 AM   #5
richfaa
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It would not be cost effective for us as we are not in that kind of temps but we had thought of it as the two A/C's we had on the 06 3400 and now this 13 3402 Big Sky struggle to keep us cool when we do see those very high temps .These A/C units draw anywhere from 10 to 12 amps and IMO the biggest issue would be where to wire it in. It would not be a good idea to have two A/C's on the same leg. It would take some serious power distribution however if I were in your area of the country I believe we would be doing it.
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Old 07-06-2015, 04:38 AM   #6
BB_TX
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With only two hot legs you will have to have two ACs on one of the legs. But with 50 amps available on each leg it should not be a problem. However, I would try to determine which leg had the fewest high amp devices already wired to it such as microwave, water heater, clothes dryer, etc.

The main problem will probably be getting a new wire from the distribution box to the ceiling. And you would need to wire it from a new dedicated 20 amp breaker, not try to share another existing breaker.

Also ask what is the quietest AC available. The 13.5k we added to our bedroom is LOUD. I know they advertise very quiet ones now.
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Old 07-06-2015, 05:09 AM   #7
bncinwv
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I have always wondered if there would be any merit to using a portable floor standing air conditioner on an as-needed basis. Could be stored when not needed and should be relatively simple to fabricate a window vent to allow the exhaust hose to be used when needed. Just a thought, but would be a heck of a lot cheaper than a roof mounted unit. For instance, just for fun, check this out (less than 10 amps draw):

Portable Air Conditioner

There are many other options available.

Bingo
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Old 07-06-2015, 05:31 AM   #8
johnregrus
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Just last week I saw a Montana with third air conditioner installed at my dealer RV Traders in Mesa Az.
The service manager told me Keystone had advised him it could not be done because of the power requirement.

He took the power from the pre-wire for the washer and dryer as the 5th wheel he was working on did not have a washer/dryer installed.

All three air conditioning unit run without a problem and the outside temperature was 114F.

The service manager is Neldon call him for advice. He is a great guy who will take the time to explain how he did the install.
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Old 07-06-2015, 10:03 AM   #9
BB_TX
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For the wiring you might consider using surface mount wiring channel. Depending on how far the run it may not be too intrusive.
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Old 07-06-2015, 02:02 PM   #10
WaltBennett
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Quote:
quote:Originally posted by bncinwv

I have always wondered if there would be any merit to using a portable floor standing air conditioner on an as-needed basis. Could be stored when not needed and should be relatively simple to fabricate a window vent to allow the exhaust hose to be used when needed. Just a thought, but would be a heck of a lot cheaper than a roof mounted unit. For instance, just for fun, check this out (less than 10 amps draw):

Portable Air Conditioner

There are many other options available.

Bingo
This isn't a bad idea, but it does have to have a vent. Wonder if one could hook it to a washer/dryer vent?
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Old 07-06-2015, 02:18 PM   #11
bncinwv
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Quote:
quote:Originally posted by WaltBennett

Quote:
quote:Originally posted by bncinwv

I have always wondered if there would be any merit to using a portable floor standing air conditioner on an as-needed basis. Could be stored when not needed and should be relatively simple to fabricate a window vent to allow the exhaust hose to be used when needed. Just a thought, but would be a heck of a lot cheaper than a roof mounted unit. For instance, just for fun, check this out (less than 10 amps draw):

Portable Air Conditioner

There are many other options available.

Bingo
This isn't a bad idea, but it does have to have a vent. Wonder if one could hook it to a washer/dryer vent?
Possibly, but it would not help on a 3750FL, unless you wanted additional air conditioning in the bathroom where the washer/dryer closet is located. If used in the living room, I would think a simple fabricated wooden or plastic insert for the slideout side windows would be a relatively easy job. Could even use the front facing windows to keep the heat away from the awning area or on the off side as well. The one I looked at only weighs around 50 pounds so it could easily be used in the living room area and only lose a little over a square foot of floor area.

Bingo
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Old 07-06-2015, 08:05 PM   #12
Artemus Gordon
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Bingo, you got me thinking and your suggestion is excellent. I think, I could put a nice vent arrangement next to the heater vent, going into basement. It's a inexpensive way to cool that area. I can isolate one 110 outlet and get vent installed professionally. Store unit in winder and keep fantastic fan. I would simply keep basement door cracked when operating unit. Bingo, thanks for the idea!!!
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Old 07-07-2015, 01:31 AM   #13
TLightning
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Most of the larger motor homes have three ACs. However, I don't know how they are wired...other than they are the normal 50 amps.
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Old 07-07-2015, 03:16 AM   #14
bncinwv
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Quote:
quote:Originally posted by Artemus Gordon

Bingo, you got me thinking and your suggestion is excellent. I think, I could put a nice vent arrangement next to the heater vent, going into basement. It's a inexpensive way to cool that area. I can isolate one 110 outlet and get vent installed professionally. Store unit in winder and keep fantastic fan. I would simply keep basement door cracked when operating unit. Bingo, thanks for the idea!!!
It may be even simpler than that, if I remember on our 3750 the hose that leads to the living room heater register is exposed in the basement?? You may be able to use the heater vent itself and use some kind of manifold in the basement that can switch between heat flow and air conditioner exhaust?? That way you would not affect the integrity of the rig for future trade purposes since the manifold could easily be removed. Just a thought and of course if you go this route, I am sure all of us forum-ites would be very interested in details and photos of your installation!!
Bingo
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Old 07-07-2015, 04:05 PM   #15
Artemus Gordon
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Thank you again. That's the direction I am going!
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