13500 BTU vs. 15000 BTU

[Eddie25]

I've got a 2012 Eddie Bauer 25' that came with the 13500 BTU A/C. We had several times this summer where the A/C just couldn't keep up. I'm adding the rear and side awnings to help with some of the solar pass through issues but I've also got pricing on upgrading to a 15000 BTU Dometic. I just don't know enough about A/C to know if that will make a significant difference and I can't find any articles to help. Anybody know A/C well enough to offer counsel?

Thanks,

Josh

[Ridgerunner3]

I upgraded from a 2002 11,000 btu AC to a new 15,000 btu Dometic heat pump in 2012. My rig is an 2002 Safari 25. Good upgrade for my case. I don't know if it would be worth the money in your case. I think the awning idea is good. I had my heat pump installed at Jackson Center and cost over $2k.

[polarlyse]

I'm not an AC tech so this is worth exactly what it cost. It is my understanding that AC systems work best and most efficiently when under a load. In other words, oversizing the AC with the thinking that it will be more productive may not be true. Before deciding you might check around and get some good advice. We too have been in some very warm areas and our 13.5 k unit worked marginally. So I understand your inquiry. It was an older trailer with an older AC unit then we now have. We have not yet been in any extreme heat to see how this newer rig compares. Time will tell

[Aviator]

WE have friends we camp with regularly here in the Georgia sun, and they installed a 15K unit on their 25' and it works great. I installed a Penguin II with heat pump on our 34' and it works, OK, but I regret spending the extra $ on the heat pump. It runs louder, and cools less than the A/C only unit.

[thomp]

When I bought my 23 foot I had Bates upgrade the A/C to 15K and have been glad I spent the extra money on it. I need every bit of the extra cool it puts out in the July and August in North Carolina, etc....

[Captain Hank]

Before you upgrade make sure your unit is operating correctly. It should have a minimum of 14-22F drop in temp from return to discharge. Before doing the temp test make sure it has been operating for a while to stabilize. If it does not have the correct differential it could be low in refrigerant, coil could be dirty or obstructed, filter could need cleaning.

[lewster]

Originally Posted by Captain Hank

Before you upgrade make sure your unit is operating correctly. It should have a minimum of 14-22F drop in temp from return to discharge. Before doing the temp test make sure it has been operating for a while to stabilize. If it does not have the correct differential it could be low in refrigerant, coil could be dirty or obstructed, filter could need cleaning.

In A/C lingo, that is called the DELTA 'T' and it should be 18ºF - 22ºF temperature differential between the cold air coming out of vents of the unit (discharge) and the air being sucked back in to the unit at the filter plate (return air).

I also find it hard to believe that a heat pump has less cooling capacity than an A/C only unit of the same BTU rating. They both have the exact same internal components (blower motor, compressor, evaporator and condenser coils) with the only difference being a reversing valve that changes the directional flow of the refrigerant that allows the coils to switch their functions.

Newer units are also using a different refrigerant (R-410A) than the older R-22 units and have different compressors. This change, done several years ago, might be the cause of any increase in noise level and possible lower cooling capacity of the newer units when compared to the R-22 units.

[Morgan guy]

I have a 27' FB Classic and changed out the 13.5K unit for a 15K model (heat pump) because it was not cooling sufficiently. When the technician checked it, he said the motor was dragging some and not operating up to specs. In conjunction with the change, we also made some insulated covers for the skylights and vent fans. All of the above changes helped to keep the AS cooler and comfortable. You will never have a frigid trailer on a really hot day but you can certainly make it more comfortable.

[Aage]

Seeing as how you have a 2012 trailer, I would expect that the white thermal paint was applied at the factory.

But if it wasn't, it could make a 10 to 20-degree improvement, according to what other Airforums members have seen.

[Jackcat2]

We got a roll of 2' wide aluminum like insulation from Home Depot and made panels for the skylights, fantastic fans, and all of the windows. We cut to fit between the glass and screens on the windows. Really helped a lot, were in AZ at 110 degrees in sunlight for 3 weeks. Very easy and quick to put in and take out when conditions allow.

[Aviator]

Thanks, Lew. I appreciate the information on hp vs non-hp.

[mtbguy]

Originally Posted by Jackcat2

We got a roll of 2' wide aluminum like insulation from Home Depot and made panels for the skylights, fantastic fans, and all of the windows. We cut to fit between the glass and screens on the windows. Really helped a lot, were in AZ at 110 degrees in sunlight for 3 weeks. Very easy and quick to put in and take out when conditions allow.

I used the same reflectix Home Depot insulation and it works great in Georgia heat. It makes a noticeable difference in how heat soaked the inside gets before you turn the A/C on.

[carl2591]

a big thanks to the US EPA.. fell for the BS about R-22 and now you have to buy expensive r-22 or upgrade to a new r-410a unit which as noted by lew is noisier and less powerful. The pressures needed are very high compaired to R-22.. Same thing happened with r-12 to r-134a change over with the lack of performance but not quite so bad.

I have not worked on roof top units recently.. last one was r-12 and they would freeze you out at half the size..

Originally Posted by lewster

Newer units are also using a different refrigerant (R-410A) than the older R-22 units and have different compressors. This change, done several years ago, might be the cause of any increase in noise level and possible lower cooling capacity of the newer units when compared to the R-22 units.

[Silver Goose]

As for noise on mine, curiosity kicked in and I removed the shroud and plastic housing that covers the squirrel cage blower. I discovered a bit of end play on the motor shaft that was allowing the blower to lightly touch the housing. After loosening the set screws and repositioning the blower and verifying nothing touched on either end accounting for the end play, I tightened the set screws and buttoned everything up and found the A/C to be noticeably quieter, relatively speaking. I believe a bit of end play is normal on these motors.

[Silverflames]

I also had dirt dobbers build a nest on my dometic fan, right next to the coil. Rattled like crazy until I got it off.

If the compressor and fan are running full time, and the AS is still to hot, it's time for a bigger unit. If the compressor kicking on and off, you might not be getting enough power to keep it running. Do you have a volt meter in your AS?