AC Duo-Therm upgrade 13.5k to 15k (DIY)

[cb1000rider]

We're considering replacing our 13 year old 13.5K Duo-Therm AC units on our 1999 Holiday Rambler, mainly for increased performance while driving when it's *really* hot (say, like over 100 degrees). I'm going to do them one at a time, starting with the front unit and using it to see if it's worth upgrading the rear.

Apparently Duo-Therm makes a 15k Penguin low-profile unit for ducted systems.

Although not listed here apparently there is a 15k low profile unit with Analog relays (part number 620426).

We have the existing, I think it's 4 button, thermostat which I'm sure is analog. For now, I'd like to retain it.

Questions:
1) How much trouble am I looking at replacing a 13.5k unit to a 15k low-profile unit. Again, we're ducted, and I want to retain the usage of my existing thermostat and rear 13.5k existing AC. I'm planning on doing this myself and can get the new unit on the roof...


Anything else I should know? Troubles I might run into? Things to watch out for?

[nightriderrv]

Just make sure you get the ducted ceiling package for the new A/C they don't come with it, might not hurt to have foil tape to tape up the duct after the A/C is replaced. Just get the units straight and don't tighten the mount bolts too much

[TAZ]

I just added a second rear AC unit. The hardest part will be getting it on the roof. I cheated and used my trackhoe. If you have some help getting liftedmp the install should be real easy. I was surprised how easy it was.

[cb1000rider]

So the 13.5 unit and 15k units simply interchange? IE - no changes in mounting bolt pattern or roof hole in terms of mounting? This is the main thing that I'm worried about...

Thanks for the heads up on the vented vs non-vented versions. I'll make sure I order the right one.

We have a 13.5k unit in back also...

[mgscott4]

I read somewhere that you can get an A/C on the RV roof by leaning 2 planks from the bed of a pickup up to the roof and pull the A/C up the planks with a rope. I think you leave it in the box and unpack it on the roof.

Sounds like it will work.

[TAZ]

Originally Posted by cb1000rider

So the 13.5 unit and 15k units simply interchange? IE - no changes in mounting bolt pattern or roof hole in terms of mounting? This is the main thing that I'm worried about...

Thanks for the heads up on the vented vs non-vented versions. I'll make sure I order the right one.

We have a 13.5k unit in back also...

AC units all use a standard 14inch cutout. Bolts all connected witching the standard 14 inch cutout. As long as you buy a ducted ceiling unit you will be fine. You will need to connect the electric and thermostat but if you are a DYI you will have no problem.

On my unit I planed to spend a day installing it but I was done by my second cup of coffee in the morning. I was lucky I had a way to get it on the roof. Using 2x4rampsmin a pickup may be a good idea. Get a friend to help hoist it up the day before and you can do the rest on your own.

[cb1000rider]

Thanks.. Looking at the manuals of the Dometic (Duo-Therm) units, I found that they all required the same mounting hole size.

So we're trying to determine two things now:
1) Which model (Both are 15k BTU.)
a) Go with the Penguin II (low profile) - About $770
b) Go with the Brisk Air unit - About $530
2) Confirm that the model we choose can work with our 5-button thermostat, which I'm sure is analog and controls our 2-AC RV...

[TQ60]

What is the model of the existing ones?

Dometic support can advise what you need for swap.

They will tell you which unit as well as thermostat or adaptor to allow existing cables to be usef

We may be interested in your old one (s).

One of ours died, 23 years old with digital control that is not compatable with current models, may be able to use an older one

[cb1000rider]

I'm not sure the models of the existing ones - I just know they are duo-therm (dometic) 13.5K BTU models.

I have original docs on the coach, but does anyone know where the model number would be listed on the unit(S)?

[Midniteoyl]

Remove the inside grill and look..

Isnt the penquin a heat pump? http://www.dometic.com/enus/Americas...ctdataid=99493


edit: One is, one isnt..

[clyon51]

In one post you said you had a 4 button CCC and in another you said 5 button. Whatever the case, the control boards on BOTH AC units must be the same and compatable with whatever CCC you are using.

So if you kept the rear AC and put in a new one in the front, it would need the same control board as the rear. Or, you may need a new CCC and upgrade the rear board.

I have not worked with the new Dometics or the new CCC2 theromstats. Just be aware of all this before you make any purchases.

[cb1000rider]

4 button.. And as indicated above, the Penguin II comes in heat pump and non-heat pump flavors.

So I dug out the documentation:
The AC units are Model number 57915.622 (Brisk Air Series, 13.5K)
The Comfort Control Center (CCC) is part number 3106463.007, 4-button.
The coach has a furnace, which we need to control also.

I think I understand. My options are:
1) Keep my existing 4-button CCC. When swap AC units, I need to retain my existing control board. I assume the control boards swap in easily? However, I wonder if newer control boards do a better job.

2) Upgrade my front AC, but a new AC will require a CCC2 (5-button) if I'm not swapping boards. As the new CCC2 will not work with the rear AC, I'll need to purchase a control board for that unit. This option seems to add $250 to the cost of not upgrading the rear AC.... Note that replacing the rear AC is about $530, so this seems like a bad choice.. unless the control boards are much better? I can sell the old 4-button for around $80.

So I think I'm clearly leaning toward keeping my existing control boards, unless that's a bad idea or the new control boards improve performance.

I'm also assuming if I upgrade to the CCC2, it will control the furnace and there are enough existing wires for full functionality.. IE, I'm not going to have to gut this thing and install a few extra pair of control wires.

[clyon51]

Originally Posted by cb1000rider

4 button.. And as indicated above, the Penguin II comes in heat pump and non-heat pump flavors.

So I dug out the documentation:
The AC units are Model number 57915.622 (Brisk Air Series, 13.5K)
The Comfort Control Center (CCC) is part number 3106463.007, 4-button.
The coach has a furnace, which we need to control also.

Let me clarify here a bit. The 4 button CCC is outdated and I understand some parts are no longer available. My '99 came with a 4 button and I converted to 5 button. That took buying the 5 button thermostat and a new control board for each AC. Dometic has now came out with a CCC2, you can see it here:

Dometic 3312024.000 Duo Therm Comfort Control Center 2

So right off the bat I would recommend a 5 Button CCC. Or you could look into the new CCC2 to see if it will be compatable with the ACs you intend to purchase.

Looking at this document you provided, 57915.622 (Brisk Air Series, 13.5K) it appears this unit is designed for an analog thermostat, which would not work with any CCC, at least as documented. That's not to say it cannot be converted.

Here is how I would proceed.
1. Upgrade to at least a 5 button CCC.
2. Talk to the Dometic dealer (or tech support) to find out what models are going to be compatible with the CCC you choose.
3. If you have a specific model you want, find out if it can be converted.
4. If you decided to retain the present rear AC, you will need to replace the control board to be compatible with the 5 button CCC.

No worries about the furnace, the existing data cable from the furnace will simply be plugged into the Zone 1 control board. The new control board's DIP switches will need to be set for Zone 1 as well as for the furnace to be controlled by Zone 1. The new Zone 2 (rear) control board's DIP switches will of course have to be set for Zone 2.

[cb1000rider]

Thanks.. This has gone from update the single front AC unit to 15k to upgrade the thermostat and both AC units.... I guess that's just the nature of the beast.

I did get another piece of information in regard to retaining the rear AC with a new control board:

Also the CCC2 control board will not fit into the roof unit electrical box without some modification as the side mounted connectors are too close to the sheet metal. If your control boards are in 6x6 metal boxes in the ceiling then there is no problem as long as you order the same style as a replacement.

Can anyone confirm that existing thermostat wiring is sufficient to handle the CCC2 and new AC units?

I think I'm going to proceed with the full upgrade. I'm going to look to sell the existing 13.5K units first, which may be easier if I can demo them fully functional like they are right now.