2 zones 1 thermostat or 2 thermostats?

[kmb1966]

I am considering making some changes to my current a/c setup. I currently have (2) 13.5k Dometic Penguin 2 units ducted system. The front a/c has a thermostat that operates the front unit and the gas furnace. The rear has its own thermostat and operates only that 1 rear unit. I am considering changing to 2 Penguin II 15k btu units each with a heat pump. Newmar support says ideally it should be 1 thermostat with 2 zones, but if that is so, then why did they put 2 thermostats in when it was built? I assume the idea behind 2 zones is so that the 2 units do not battle one another. I have seen some motorhomes with 3 a/c and 3 thermostats. So what is the best way to go with this? 2 thermostats or 1 with 2 zones? How does all this work? :h

[kmb1966]

dougrainer wrote:
IF the CCC wall tstat is NOT in an overhead cabinet the CCC wall tstat is Zone 1 temp sensor. You have all the wiring to do a new change out. I will bet the original replacement, the Penguin was a 10 button control board and will not work with the 5 button and that is why they installed a new tstat in the bedroom. Anybody that did this should NOT be working on RV's. If you buy 2 new Penguins, they will have the onboard control boards already and you just purchase a 10 button wall CCC tstat. ALL the wiring to connect is already there. Doug

great news. Thanks. And you are right, the people that did this install are in fact NO LONGER in the RV business. That's a good thing!

[dougrainer]

IF the CCC wall tstat is NOT in an overhead cabinet the CCC wall tstat is Zone 1 temp sensor. You have all the wiring to do a new change out. I will bet the original replacement, the Penguin was a 10 button control board and will not work with the 5 button and that is why they installed a new tstat in the bedroom. Anybody that did this should NOT be working on RV's. If you buy 2 new Penguins, they will have the onboard control boards already and you just purchase a 10 button wall CCC tstat. ALL the wiring to connect is already there. Doug

[kmb1966]

dougrainer wrote:
Are you the original owner? I ask Because we sold Newmar from 1994 til 2008, and hundreds of DSDP's. NONE--NONE came from the factory with 2 wall tstats. They came with the standard(your year) 5 button Dometic wall CCC Tstat. You then had the rear Zone 2 with the remote bedroom temp Thermister. Now, believe it or not, over those early years I saw a few Newmar's with just 1 Roof AC (DSDP Diesel and Gas model). Usually sold to dealers in the NE and NW. So, is it possible your model came with 1 AC and somebody added an extra and used a wall tstat? OR, there was a problem with the original set up and the Tech that was trying to fix installed that 2nd Bedroom wall tstat? My point being, you should have the communication wiring in place for easy change out to new Penguins and new 10 button CCC wall tstat. I will bet you also have the Bedroom Rear remote Thermister someplace in the Bedroom on the wall. Doug

100% accurate. I am not the original owner, but he is a good friend of mine. YES, it originally had 2 a/c units, but only 1 thermostat. Apparently when the rear a/c had to be replaced, the installer could not figure out how to hook up the system, so they installed a 2nd thermostat for the rear a/c, leaving the front thermostat to operate the furnace and the front a/c.
But I am not having problems with the rear a/c. First it seems to have a cycling problem of some sort. The compressor and fan come on and blow cold air, but before it reaches the set-point, the compressor will cut off and fan will stay on (if in the Fan-ON position). The temps will not be at the set-point, and after 20 minutes or so, the compressor will come back on for approx 10 minutes, then the compressor will cut back off, fan remaining on. This continues to repeat. Sometimes it reaches the set-point (at night I have it set to 70) and sometimes it does not. The rear a/c also has a squeaky blower at times waking everyone up in the middle of the night. uggg. I am trying to solve all this, and will consider replacing both units, but trying to make sure the installer truly knows what he is doing. unfortunately many don't. Yes, also I see a rear bedroom temperature thermistor. I don't know where the others are located. looking for them.
thank you for your help in advance.

[dougrainer]

Are you the original owner? I ask Because we sold Newmar from 1994 til 2008, and hundreds of DSDP's. NONE--NONE came from the factory with 2 wall tstats. They came with the standard(your year) 5 button Dometic wall CCC Tstat. You then had the rear Zone 2 with the remote bedroom temp Thermister. Now, believe it or not, over those early years I saw a few Newmar's with just 1 Roof AC (DSDP Diesel and Gas model). Usually sold to dealers in the NE and NW. So, is it possible your model came with 1 AC and somebody added an extra and used a wall tstat? OR, there was a problem with the original set up and the Tech that was trying to fix installed that 2nd Bedroom wall tstat? My point being, you should have the communication wiring in place for easy change out to new Penguins and new 10 button CCC wall tstat. I will bet you also have the Bedroom Rear remote Thermister someplace in the Bedroom on the wall. Doug

[wa8yxm]

Technically there is no such thing as "one thermostat with two zones" What there is is Two Thermostats in a common housing with a remote thermal sensor and a shared display" So it makes no difference if you use one dual zone or two. Have fun.

[time2roll]

I would take two thermostats any day assuming they have significant separation.

[DutchmenSport]

It will be much simpler to use the existing wiring. If you use 1 thermostat, you'll need to run wires from the second air-conditioner to the only thermostat. That could be a nightmare trying to run wires.

I'd leave it as is and use 2 thermostats as it's designed. FYI, my Montana High Country has a heat-pump/Air conditioner up front that shares a thermostat for both AND the furnace. The back one is the same type of thermostat, capable of all 3, but only 1 wired air conditioner, no heat pump or furnace.

I don't see any advantage to what you are thinking, except a project to utilize your time.

[ependydad]

On my current rig, I have 3 air conditioners and 2 thermostats. Only 2 are ducted (both on the shared thermostat).

On my last rig, I had 2 air conditioners and 2 thermostats. Both were ducted.

Basically, it doesn't matter.