AC Upgrade Help!

[Perry42985]

I recently purchased a 37' 5th wheel with 4 slide outs. It currently has 1 AC but is pre-wired for a second. I want to replace the existing and add a second unit. I live in Texas and need all the cooling I can manage. I have heard great things about the Coleman Mach 15's, what are your thoughts?

Please help with the following:

What size units?
Make and model suggestions?
Heat pump, heat strip or neither?
Should I try to stay under 30amps total?


Thank you in advance!

[dcg9381]

Not a lot of difference in 13.5k and 15k honestly. Are you adding a non-ducted AC with controls on the unit? Or a ducted unit? Or a unit that is controlled by the central thermostat?

If you're using the thermostat, that may focus what units are compatible.

Be aware that you need to order ducted/non-ducted and the right control setup.

[Dayle1]

Perry42985 wrote:
The FW is wired for 50A. The existing unit is old and on its last leg so I and to replace it as well. Would the additional unit typically run into the ducting system?

If you remove the interior frame for the bedroom vent, you will probably see the end of the duct for the second A/C, there should also be 120V ac wire and small gauge wire to connect to the thermostat. At least that was how mine was. But I also discovered that rather than ducting out both sides, there was only one. And since there were only 5 vents total, I was concerned that two units would just have too much air flow for limited ducting and vents. So, while I could have installed a ducted 2nd A/C, I instead opted for a non-ducted unit that is still controlled by the multi-zone thermostat. So, you might do a little more investigating before actually purchasing any specific unit.

Generally, the best prices are on 13.5k btu units and while a 9k unit may be sufficient for the bedroom, the 9k may actually cost more, have a worse SEER number and therefore use the same amount of power. Also, you might consider height of the 2nd A/C and it's impact on max trailer height. Anyway, I went with a low profile 13.5k unit that only added 3 inches in trailer height compared to the top of the bathroom skylight.

[Tiger8r]

Been two or three years ago but was told by Rv technician Coleman Ac were better and were cheaper to work on because of the way they were laid out. If you put new Acs in your trailer put two 15000. Camping anywhere along the coast will take both.

[BarneyS]

We just replaced our 9 year old Dometic 15,000btu air conditioner with one from Atwood which they claim puts out the equivalent of 18,000btu. It is a ducted unit with remote control thermostat and included heat pump. It is quieter than our previous unit and seems to put out a lot more air. We are very pleased with the choice. I like the fact that it has two fan motors instead of one doing double duty.
Camping World has it on sale here.
Barney

[pianotuna]

Yes the 2nd unit should go into the duct work system.

[wildtoad]

In my old hurricane the bedroom vent that was pre-wired also was setup to feed the existing ductwork.

[Perry42985]

The FW is wired for 50A. The existing unit is old and on its last leg so I and to replace it as well. Would the additional unit typically run into the ducting system?

[Greentow]

If your current one is working well, AND a 15K, leave it and add a 13.5 in the bedroom. We have a 39ft rig, the A/C's are ducted and do very well. We were in Kerville last June and the did very well. Both are Dometic.

[wildtoad]

Maybe an obvious question is: is your FW wired at 50 or 30 amp? If 30, then you may be limited to running one at a time, unless you run a separate power source to the second unit. Just before I sold my 2000 Hurricane I had to replace the roof AC and the new unit was a Coleman 13500 which did a good job. I think Coleman (or whoever really makes them) are a good unit.

My new 2016 Bay Star Sport had a Dometic 15k heat pump and we chose to use the heat side the other week on our maiden voyage. It dipped into the high 30's one night and it worked just fine. I'm not sure how efficient a roof mounted heat pump is considering in our case the return ducts are right next to the output vents.

Obviously we have not had it long enough or under really hot conditions to test the cooling in summer conditions.

[donn0128]

Is your current AC 15K? If so, leave it alone and install a duplicate brand 13.5K unit in the bedroom. That should be sufficient.

[eHoefler]

We have Dometics, 15,000 and 13,500. Heat pumps won't work under 40*-45*, won't even come on. I have a heat strip in the 15,000 main one ducted throughout the coach. When running space heaters, we use the heat strips to help circulate the heat without it blowing cool air. heat strips will work regardless the outside temp. Heat strips will not heat your coach when the outside temps dip below 45*-50*. they make it nice to circulate the air without blowing cold air.