A/C replacement size? 345

[Honkity Hank]

Our 85 345 has the original A/C units which work okay but do not blow the ice cold air we need here in the hot humid south. Thinking of changing out the front unit to a 15,000 btu carrier unit and leaving the rear air in place as is. The thinking here is the larger unit in the front can be used while driving and cool down the front cabin sufficiently (btw we are in the southeast).

Is the 15k overkill? Would we be better off with a 13.5K unit? Or should we change both units to 13,500 btu units?

Also has anyone rewired the main shore power breaker main to a 50 amp main and then re-circuited the front air so it can run simultaneously with the rear air when on shore power?

Thanks for your help

Jeff
Atlanta

[guy99]

I just put in the 15,000 btu unit in my 310. It is not overkill

I have wired a pigtail which plugs into a 50 amp p splits the a and b hot wires into two 30 amp female plus. I then plug the coach in to one of the 30 amps and run a 30 amp extension cord to my read AC (which is plugged into a dedicated receptical in the generator compartment) Works fine.

[swebster]

Jeff,
Welcome to the forums! I'd go 15000 but check on the amps. As you know you can only run one or the other when on shore power. My vote would be for the larger one up front as thats were we spend most of our time during the day or while travelling.

[Nick Danger]

I jjust changed my 13.5s to 15s. Much better cooling. Stephen is right, though. If you only have 30 amp service in your coach, you can only run one unit at a time unless you wire it up like Guy99 did. I'll do that as a winter project.


Guy99......

Can you PM me more details as to how you did yours?

[guy99]

I decided to post the information here in case it is of use to someone else now or in the future.

I didn't install this it was in the coach when I bought it. The coach has a water cooled Honda EV6010 generator. This generator has two output circuits, a 30 amp and a 20 amp. The 30 amp is directly wired through a transfer switch to the coach 'service entrance'. The 20 amp circuit is wired to a female (30 amp RV type) receptacle in the generator compartment. The rear AC is wired through a dedicated circuit breaker to a 30 amp rv type male plug which is plugged into the aforementioned receptacle. So, when the generator is running the rear ac gets power through its edicated circuit. A 50 RV hook up is really a 240 volt circuit with two hot leads an A and a B. The A and B legs cycle out of phase so the the voltage between them is 240 volts. Each leg has a voltage of 120 volts between the leg and the neutral wire.

So, when we are parked and have access to a 50 amp rv plug and I want to run the rear AC I use a special pig-tail which I wired myself. One end is a 4
wire male 50 amp plug, this branches into two 30 amp female plugs. One of the female plugs is wired to the A leg, the neutral, and the ground from the
50 amp plug. The other female plug is wired to the B leg, the neutral, and the ground from the 50 amp plug.

I plug the main coach 30 amp plug to one of the female plugs. I run a 30 amp extension cord from the other female plug to the generator compartment
where I unplug the rear AC from the socket from the generator and plug it into the extension cord. This results in the coach being powered by one leg
of the 50 amp circuit and the rear ac being powered from the other leg. Since each leg of the 50 amp circuit can supply 50 amps before the circuit breaker blows, you must be sure that you 30 amp breaker is working or you could overload the wiring in the 30 amp cords. I also understand that it is possible if the ground (or neutral?) is bad that you can end up with more than 120 volts on the A or B leg. I am not an electrician so please be sure that whatever you do is safe.

Here is a link to a commercial source for the special pigtail:

http://www.rvupgradestore.com/index....ROD&ProdID=142

[GlenCoombe]

Hank, I've just installed a 15K Carrier Air V ducted unit in my 28' and took it to Myrtle Beach this past week. While it's very much still a work in progress the 15K unit cooled the entire coach in spite of only having one duct dumping into the main area of the coach.

For what the difference in cost is the 15K would be my choice. There's more on the forums about this and a good vendor in the Tampa area who passes on great prices.

It's not brain surgury to r & r one into an existing hole.

I'll be posting pictures soon.....

[GlenCoombe]

As an update on the Carrier a/c ducted unit .... I'm finding that the remote control with it's built in auto setting is great. The a/c does not have to run full time and therefore the generator is not put into high gear to keep up with the demand. The unit is very quiet as it's way back in the back of the rig.

Still working with a temorary plenum but know where I'm going... can't wait to run the main branch down the center headliner.

For all those waiting with baited breath I'm going to have the Mrs. bring her super digital camera home this weekend from work. I should have some photos of the work in progress up soon....

[Honkity Hank]

Okay, I was going to buy the new A/C unit yesterday but then decided I should inquire as to which mfr to buy. Carrier, Duotherm, or Coleman. Any opinions out there and why? (15,000 btu) will replace the front unit, non ducted. Is heat in the ceiling unit useful?

Thanks again.

Jeff
1985 345

[Chaplain Kent]

I can give no advice on the AC since we rarely use ours. Maybe when we get to Georgia this April it will be warm enough. However, on the subject of the heat strip forget it. What you are going to get is a single strand of toaster wire which only gets warm and smelly and gives off no heat. A good electric heater will be a much better investment and do a much better job for you. Last December my son and I were in Canton, OH, temperature in the low teens with just an electric heater during the day. I never use my heat strip.

[guy99]

Jeff,
One of the considerations in what brand you purchase is the question of the 'pan' that is found under the original units. The function of the pan is to collect condensate so that it can be directd down the drain tubes which are already in place. It's a little complicted and there is much written here on the subject.

As I recall you can get new pans for the Duotherm, I don't know if the Coleman will fit your existing pan, and the Carrier can be modified to not use a pan.

Changing the pan can be a pain since it is attached to the top of the unit with vulcum.

Guy

[thenewkid64]

If the units are OEM, they are likely Coleman units. The pan is not going to come off in one piece so it will have to be replaced.

there is a pan available for the Duotherm "Penguin" model, not the brisk air. The penguin is a very good unit, but it is also not cheap. The carrier units are a lower cost alternative, seem to work well and are quiet. There is no additional pan to buy, but you will need to do some mods to attach the drain lines.

[Silvertwinkie]

I have a 15k unit on our 25' Safari and it was the best thing I could have done. It's like the story of the 3 bears. The 11k unit is too hot, the 13.5k unit, too cold( not really), the 15k unit is just right for 25' or larger!

If you can swing the electrical and any logistical issues, it's the unit to have. Period.

[lewster]

Ken,

From what I've seen and worked on in the AC units, I will make the following observations.

Dometic Penguin: nice units, very expensive, ultra low profile. Dometic is a difficult company to work with on my end.

Coleman: The Mach unit uses good but older, basic technology. It will cool your coach but there are better units for the price (or close to the price).

Carrier: Since they entered the RV market, they have added innovative design and engineering to their units and just came out with a low profile unit, They are very well made, use very high quality components and route the evaporator drains over the condenser to cool it and minimize run-off. A great way to get rid of the excess water that these units produce, IMHO.

I have replaced a number of Dometic units recently, some as young as 1 year old due to compressor failure, along with several Machs. I have yet to replace of service any Carriers.

[Honkity Hank]

If I go with a Carrier unit will I need to modify the pan that is attached to the coach roof? I don't mind having to reroute drain lines etc but I would like to keep the exisitng pan in place.

Thanks,

Jeff
85 345

[Honkity Hank]

I ordered the carrier 15k unit, all reports are very positive on this unit, it sprays the condensate water onto the coils to increase efficiency and to reduce run off and apparently can be fitted to the existing pan.

I used PPL motor out of texas, they have a warehouse here in Atlanta so we saved shipping costs. Will let you know how the install goes.

Jeff

[guy99]

Jeff,
I think you don't use a pan with the carriers. I think they have a built in pan which you need to modify to connect to the drain lines.
This thread has some discussion:

http://www.airforums.com/forum...hlight=carrier

Also there are some pictures here:
http://www.airforums.com/photo...id=4716&page=2

There maybe better sources, maybe someone else will chime in.

[Honkity Hank]

Update on my ac replacement progress. We removed the existing unit and since the pan was no longer needed I removed the existing pan. It was stuck down with copious amounts of vulkem so removal was somewhat of an effort. I then removed the vulkem and wire brushed the area where the new seal fits. This created and good surface for the new seal.

(In hindsight I think I could of just trimmed up the existing pan to be slightly larger than the Carrier gasket rather than removing it.)

Some effort then spent to straighten the roof panel where it was bent or warped. The roof has a curve to it and the gasket of the Carrier Unit is flat so I used a belt sander to give the front and rear gaskets a slight bow and then placed the unit in the hole. I used vulkem under the gasket to give me more piece of mind for leaks, I will run a bead around the outside later.

The interior shroud also needs to be trimmed up to fit the curved roof as it is flat and the ceiling is curved, another couple of hours should finish this project up.