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Our fifth wheel has Coleman Mach 15K BTU in the living room and kitchen in addition to 13.5K BTU unit in the bedroom area.  The 15K unit isn't cutting the summer heat so I'm investigating any and all options in order to upgrade that unit.  I'd love not having to make the current roof penetration any larger.  Is this another pipe dream of mine?

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How old are your Coleman units and have you had the 15K checked for refrigerant charge? We have two Coleman Mach 15K units on a fifth wheel about the same size as yours (with lots of big glass) and they're doing a great job. Heat index where we are in Maryland was 112 degrees yesterday and we came home from the grandkids' to an RV that was 74 degrees inside - a little below where we had set the thermostats.

Rob

Edit: I see that your fiver is a 2019 so those ACs should be no more than two years old.

Edited by Second Chance

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Something sounds wrong. That is a total of 28.5k ac. That should have no problem cooling your unit. Our prevlious DRV was just shy of 34' and two 15k cooled it good. Can you add freon in a Coleman? 

Edited by GlennWest

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The Coleman's are a sealed unit and don't require a recharge.  I suspect everyone's experience will be different based upon use and heat load, so...

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As far as I know, all of the RV roof air conditioners require the same roof penetration. The problem is that I do not know of any RV roof air conditioner that has a greater output than 15,000 BTU's. You could probably increase things by replacing the one in the bedroom with another 15k unit but like the others here, I am wondering if there is some other problem. If you are in direct sun it may be that the problem is excessive heat gain that no air conditioner is going to overcome. Where are you located for the summer, and has it been sufficient in past years?

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I've been looking for something larger than 15K, but haven't found it.  We're in Texas and this is the first summer where we've camped in "excessive" heat and unfortunately, we were in direct sunlight.  All of those factors, in addition to people and two large dogs make for a pretty hefty heat load.  That's why I'm looking for options that would include auxiliary A/C.

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4 minutes ago, spindrift said:

I've been looking for something larger than 15K, but haven't found it.  We're in Texas and this is the first summer where we've camped in "excessive" heat and unfortunately, we were in direct sunlight.  All of those factors, in addition to people and two large dogs make for a pretty hefty heat load.  That's why I'm looking for options that would include auxiliary A/C.

The past several years we have spent a month at a time at Jojoba Hills SKP Resort in SoCal. It gets very hot there, too. We've seen several folks who have set up external ACs (some refrigerated, some evaporative... which may not work for you depending on which part of Texas you're in). They are ducted into the RV from outside. I've seen this on both towables and coaches. When they leave with their RV, they put the ducting in their storage shed and leave the external AC where it is. Of course, this is a co-op park with permanently assigned sites so they can do that.

Rob

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If I read your signature correctly you have a total of seven people and two large dogs in your trailer. I may be difficult to shed that kind of heat and humidity especially if there are a lot of electronics running (adding heat) or in-and-out the doors. I am not aware of standard RV A/C units any bigger than 15K. 

You could always add a small window unit if you have an appropriate window opening. 

 

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2 minutes ago, mptjelgin said:

If I read your signature correctly you have a total of seven people and two large dogs in your trailer. I may be difficult to shed that kind of heat and humidity especially if there are a lot of electronics running (adding heat) or in-and-out the doors. I am not aware of standard RV A/C units any bigger than 15K. 

You could always add a small window unit if you have an appropriate window opening. 

 

 

LOL... It's not quite than many people all the time, but we have been known to party a bit.  ;)

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Thinking out of the box. I just coated my roof in Henry's Tropic-cool. It is cool to the touch in the direct sun. I literally waked on mine barefooted the other day and sun bearing down. With ducting in roof this has to help. jfyi

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What about adding a portable unit as auxiliary BUT I agree that you should be able to handle that rig with those units, if working properly.

Have you cleaned the fins and the rest of the unit.  While the units are not servicable typically, I have had an AC tech add a fitting to a unit in the past to add refrigerant.  Unit was still working well just not cold enough, so that helped the situation without an expensive replacement.

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Thanks, GW, I'll look into that since I'm not familiar with the product.

RPS...how did your tech determine the unit would benefit from additional refrigerant?

Edited by spindrift

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8 minutes ago, spindrift said:

Thanks, GW, I'll look into that since I'm not familiar with the product.

Basically a clean roof, no caulk, and roll it on. They also sell it in a thick paste. Put on with putty knife. Use it first around things, tight areas, and any ethernabond tape. State issuses if use other on eternabond. But the "repair and seal" on first and works fine. Used presure washer. Some don't like the ides of silicon on the roof. But they have caulking tubes also so I see no problem. Just forget Dicor

Edited by GlennWest

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Anyone can add a fitting that knows how to sorder. You would also have to pull a vaccum and charge it up.If in yur shoes I would do this. Something has to be wrong. The Tropic-cool is still a nice upgrade. Pretty shinny roof also. But 3 campers left this park we in and went ot a covered rv park down the road for same reason. But they were 30 amp units with 1 ac. We in Port Arthur Texas

Edited by GlennWest

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What's wrong is too many people opening the door too many times!  Want a couple of big dogs?  Let me warn you, the Newfie leaves a trail of saliva that would make The Blob jealous.  :)

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Oh my. That exsplains a lot. I cn be outside in this heat and leave storage door open and DW will holler. It makes a difference.

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1 hour ago, spindrift said:

Thanks, GW, I'll look into that since I'm not familiar with the product.

RPS...how did your tech determine the unit would benefit from additional refrigerant?

It wasnt cooling to specs.

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5 hours ago, spindrift said:

RPS...how did your tech determine the unit would benefit from additional refrigerant?

The proper way to determine if your present air conditioner is working properly is to measure the temperature of the air as it enters the unit and also measure it as the air exits the unit. A properly working unit should cool the air passing through it somewhere between 18° to 24°. If the change is greater than about 26° it will probably freeze up if there is any humidity and that is usually caused by too little airflow through the coil, which could be something as simple as a dirty inlet air filter, or it could also be partially plugged cooling coils that need to be cleaned. Too little cooling and it could be that the cooling coils are dirty, the coils outside that disburse the heat removed are dirty, partially plugged, or the vanes on the coil need to be straightened with a air conditioner coil comb to straighten them. This is often the result of hail. 

      shopping?q=tbn:ANd9GcRd_T6n9KRtygGpci5C3    air conditioner coil comb

If your air conditioner is cooling the air passing through it by at least 20° it is probably doing the very best that it can and you need to find a way to decrease the heat gain of the RV or add another air conditioner. 

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As Kirk said.  If air inside coach is 90 F then discharge should be around 70 f. Of course as temps fall in coach, temp out of unit will drop also. So 80 F in coach will be 60 f out of vents. Outside ambient temps play a small factor, but if condenser is clean and straight cooling fins, and blower is blowing correctly, you should have the 20 degree drop inside. Most RV's have a lot of windows and poor insulation, and some are even painted dark colors which will absorb heat. Once it gets in the mid 90's here in South Texas, I am happy if my two 15000 btu roof units maintain 78 F.

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The first step is make sure it is working as it is meant to work.

Remove the inside cover and make sure the divider is in place and sealed.  You don't want any possibility of the input and output mixing inside the unit.  Use foil duct tape, not the cheap stuff.

While inside the unit insure the duct work is sealed to the plenum and not blowing cold air into the ceiling.  Use the foil tape as needed.

Next remove each ceiling vent and use the same foil duct tape to insure all the cold air comes out the opening and not into the ceiling.

Any luck?

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After spending August in Las Vegas, I learned a hard lesson. Never open doors and windows during hot weather, but rather keep the air conditioning running 24/7. When doors and windows are opened, everything soft absorbs humidity and heat. This can triple the load on the air conditioning system, ie:overwhelm it to where it cannot cool adequately.

Air conditioning only works well when it dehumidifies the air too. Air conditioning/chilled air was a byproduct of inventing a dehumidifier. Mr. Carrier perfected the first practical air conditioner/chilled air.

Building on what Customer1 said; use an inspection mirror to look into the ceiling duct ends. I read one man's experience where the ends of the foam ducts were open on the ends, which allowed chilled air to just blow into the end caps. I  think he temporarily stuffed old towels into the ducts beyond the furthermost registers.

Edited by Ray,IN

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21 hours ago, Customer1 said:

The first step is make sure it is working as it is meant to work.

Remove the inside cover and make sure the divider is in place and sealed.  You don't want any possibility of the input and output mixing inside the unit.  Use foil duct tape, not the cheap stuff.

While inside the unit insure the duct work is sealed to the plenum and not blowing cold air into the ceiling.  Use the foil tape as needed.

Next remove each ceiling vent and use the same foil duct tape to insure all the cold air comes out the opening and not into the ceiling.

Any luck?

Do this first. I've read many posts on the internet of AC units not cooling properly

and many times it was this divider board that separates the intake air from the

discharge air. The factory doesn't install it properly and it becomes dislodged.

My main AC is ducted but I open the vents on the ceiling cover to let more air

directly in the living room. 

I'm in Sun City, AZ where temps have been in the triple digits. It takes both

the main and bedroom AC but can easily maintain 78-80 degs.

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