Community Forums

Vanwill · 08-10-2015, 06:44 PM

Quote:

Originally Posted by BFlinn181

Seems to me Dometic was being perfectly honest and not trying to misinform you. How would the manufacturer of A/C units know if your RV has wiring to support what you asked? If, as you think, the rear A/C is controlled by the rear thermostat, and the same for the front A/C and thermostat, then you probably don't have the wiring in place to operate both units from one thermostat location, they are independent of one another. A multiple strand cable would have to be strung to connect the two A/C to one thermostat.

Why, Bob, did I think the manufacturer should be able to answer a simple question? Because I gave them the model numbers and serial numbers of EACH of the two roof units and EACH of the two thermostats I had and told them I had a SINGLE telephone-type cable going to each thermostat. I told them I had no interest in having a single thermostat control both units, that two separate thermostats, just as I have now, would be just fine with me, and I would purchase whatever updated thermostat they suggested. I only wanted to know if my present thermostat wiring would work. Do you think YOU could answer that question given all that information? Did you actually READ my post?

Vanwill · 08-10-2015, 06:59 PM

Quote:

Originally Posted by slowmachine

My Endeavor was originally equipped with two Duo-Therm13.5k heat pumps and a single four-button thermostat. In this system, there is one "phone" cable that runs from the thermostat to the Zone 1 roof unit, usually in the front of the RV, and another "phone" cable that runs from the Zone 1 unit to the Zone 2 unit (and so on, if there are more than two). The furnace can also be connected to the same thermostat, but doesn't have to be.

The new 15k Penguin 2 heat pumps and single 12-button CCC2 thermostat use the same wiring. My AC runs through ceiling ducts that connect in the middle of the coach. On the passenger side, I can extend a tape measure through the duct from the farthest forward ceiling register to the farthest aft. It is one uninterrupted duct. On the driver's side, the duct is interrupted by the shower skylight. If your coach now has two thermostats and you want to run the whole system from a single thermostat, and you have a duct system like mine you can easily snake a "phone" cable through the ductwork to connect the two roof units. The actual temperature sensor is in the roof units, not in the thermostat, so it really doesn't matter where the thermostat is located. When configured like this, the control board on the Zone 1 unit staggers the fan and compressor startups for the two zones, so you shouldn't have to worry about the large startup power draw. To me, this seems much better than two independent zones with no power management.

Mike
2000 Holiday Rambler Endeavor 40PBD
Freghtliner XC, CAT 3126B

Thanks, Mike. That clearly answers my question. You are probably right about the advantages of the single thermostat system. I had not thought about staggering how the two units might start. I may look into that in the future. For now, I'll just stick with two T-stats. And yes, my ductwork runs all the way from front to rear without interruption. I've already found it partially collapsed in an inaccessible place, and had to make some T-shaped "props" I could shove into the duct with a flexible rod. That made a huge difference in airflow, but the units are both 15 years old and showing it.

I wanted to ask Dometic whether there would be any differences in the way the inlet/outlet had to be run (similar to the Newmar problems)--whether I might have to do any re-routing of the ductwork in the area of the rooftop unit. But after the BS and non-answers I got from them, I decided to turn to this forum for someone who had actually made the switch. All I have to do now is compare the baseplates of the old Penguin and the new Brisk Air II to make sure that any re-routing is not really difficult. If there is a significant problem, I'll just order the Penguin.

Thanks again for your help!

head gamez · 08-18-2015, 08:11 PM

Our rear AC went out this past weekend while at the beach, so I am in the same boat you are. My plan is the replace it with a heat pump unit, and eventually replace the front with the same.

Having said that, I still have allot of research to do to determine if I can do that and what is needed.

Our system (2002 Fleetwood Expedition) sounds different than what has been discussed here. Both of our units are controlled on one panel with separate sliding temperature adjustments. They each also have sliding setting selectors to toggle between heat, fan, on, and auto. When in the heat position, the temperature slider controls the furnace. Obviously when in the ac mode each slider controls one ac. Unfortunately I don't remember the brand of the units or the controller, so will have to look into that tomorrow. However, given the small amount of info provided so far, can anyone provide any input on if and how I can do the change?

Thanks, and more info to come.

70gsconvt · 08-19-2015, 04:37 AM

I have one electronic thermostat that switches between front a/c, rear a/c, and furnace. Then the fan switch is lo/med/hi/auto. Easiest thing is to see what brand is on the roof and give the manufacturer a call and see what their tech guys recommend for an easy install. Good luck.

I may be waiting until spring now to do mine. No sense dropping $1400 only to have it sit in a garage for the winter.

TQ60 · 08-19-2015, 07:44 AM

The control system for heat pump also controls furnace as heat pump works down to ce% tian point then furnace is used.

Work with the manufacturer of the ac units to determine which replacements are compatible with your existing controls or if controls need to be upgraded then which control will be compatible with old unit left in service.

Or upgrade all and sell old working stuff.

For anyone living in theirs always check for rebates as often some may exist for energy savings and maybe can apply...

bamaboy473 · 08-19-2015, 06:21 PM

For those of us that live where A/C is a must, and heat is seldom, could I install a third A/C unit into the hole where a fantastic fan currently fits?

Wiring is there, hole is there, and we don't cook anything that would require an exhaust fan.

Comments pro or con?

BFlinn181 · 08-19-2015, 08:27 PM

Quote:

Originally Posted by bamaboy473

For those of us that live where A/C is a must, and heat is seldom, could I install a third A/C unit into the hole where a fantastic fan currently fits?

Wiring is there, hole is there, and we don't cook anything that would require an exhaust fan.

Comments pro or con?

I'd hope you have a 50 amp RV to handle the load. You'll have to wire it for the 120 v and the wires to a thermostat, but there are many 3 unit rigs out there.

harleyjt · 08-19-2015, 08:35 PM

Quote:

Originally Posted by bamaboy473

For those of us that live where A/C is a must, and heat is seldom, could I install a third A/C unit into the hole where a fantastic fan currently fits?

Wiring is there, hole is there, and we don't cook anything that would require an exhaust fan.

Comments pro or con?

The wiring that is there is only 12v. You would need to run some 110v up on a separate circuit.
jt

70gsconvt · 08-20-2015, 05:06 AM

Sounds like you would need to run a standard romex #12 wire up there from the breaker panel. Then you could just get a manual unit with the controls right there rather than running another wire back to a thermostat. But most of these units draw around 12 amps or more, so you would need to be connected to a 50 amp power source for all of them to work at the same time plus all the other electronics in the coach.

ga traveler · 08-20-2015, 05:27 AM

Quote:

Originally Posted by bamaboy473

For those of us that live where A/C is a must, and heat is seldom, could I install a third A/C unit into the hole where a fantastic fan currently fits?

Wiring is there, hole is there, and we don't cook anything that would require an exhaust fan.

Comments pro or con?

Even if you have a 50 amp cord, while running three air cond. , you will not have much amps left over. If I were going this way, I would run a cord straight to the AC. Most campground outlets have 30 and 20 amp outlets.

bamaboy473 · 08-20-2015, 05:47 AM

hmmm, small glitch in the plan with that 120V wiring. How does one run a piece of Romex up to the roof? Do snakes work, or is it about removing panels?

Old Scout · 08-20-2015, 06:03 AM

Sorry--I havent read all 67 posts here but there are a few things that you have to solve for when replacing or adding new A/Cs. First--a simple A/C unit is cheaper than a heat pump but the advantages for being able to use CG electricity for heating [above 35 degrees] is significant over the longer term. Second--many, if not most, older units are nolonger compatible with new units so motherboards and cables/t-stats have to be changed; as a minimum, dip switches have to be set/matched between shared units. Third--two or more units will need a 50 amp [vs 30 amp] wiring to work--a 50 amp plug is actually 50 amps on two legs so actually 100 amps of power. You might use an existing "hole" in the roof to add another unit but wiring a 120v circuit once the roof is sealed, is a major issue, unless you dont care so much about how it might look.....good luck

BFlinn181 · 08-20-2015, 08:28 AM

Quote:

Originally Posted by ga traveler

Even if you have a 50 amp cord, while running three air cond. , you will not have much amps left over. If I were going this way, I would run a cord straight to the AC. Most campground outlets have 30 and 20 amp outlets.

50 amp RV service actually yields 100 amps. Even at a generous 20 amps per A/C, that leaves 40 amps available. I know 20 amps exceeds what a A/C draws, but allowing for start up amps, it still leaves plenty. The only caveat is to be sure to distribute the loads evenly on both legs of the 50 amp service.

wa8yxm · 08-20-2015, 02:59 PM

There are two (point one) different procedures for replacing ROOF AIR Costs vary depending on which method is used.

When my Carrier Air V (no longer made) failed I replaced the UPPER UNIT only with a compatible unit (ADVENT AIR, I do not recommend this brand, I think Coleman also makes a compatible unit)

Basic Replacement of upper unit.

Remove filters and inner (Ceiling) grill work.

Remove 4 bolts

Unplug cable(s) from control box

Up on the roof

Lift new unit to roof (This is the reason I paid to have the job done)

Lift old unit off ceiling (lower) unit and set aside,
Set new unit on and position (NOTE you may have to replace the gasket, IN fact I suggest it,, Procedure is lift off and lay new one down)

Line up the bolt holes and install 4 bolts, plug in cable repalce lower cover test.

Procedure in my case same as above save remove one (Compressor I suspect) jack from Control box and replace with the one in the Adapt-a-kit, Plug in adapter cable.. (This is part of the unplug/plug back in)

Costly method Different non-compatible upper unit.

Remove Upper unit as above, Remove lower unit, Replace both.

Depending on Thermostat and wires in RV replace those as well (Very costly if you need to re-wire)