Confused over AC setup

[Cyberdave]

Found out I have a bad communication cable from the main AC to the stat in the hallway.

During the troubleshooting, the tech needed to call Dometic for some info on the communication setup. The Dometic tech explained that the way the system is setup, there is a communication cable between the two AC units and one to the stat. When we told him that there were two stats his response was why and WTFO??

He explained that the idea of a multi-zone system is to allow you to control both AC units and heat from a single location. By controlling the AC units by zone, you can lower the temp in say, the living area (zone 1) and leave the bedroom (zone 2) at a higher temp or vice, versa. In Auto mode, the stat has control over both AC's and the heater instead of just the main one.

The Dometic tech was unaware that Heartland was installing dual stats as it defeats the purpose of the system and merely makes it a dual AC system that we've had for many years.

Any idea as to why Heartland did it this way?

In the future, I intend to run a cable between the two AC's and do some testing.

 

[danemayer]

Dave,

Why do you think it would be easier to do what you want on a single thermostat that has 2 zones, versus doing the same thing on 2 separate thermostats?

The only difference I can think of is that there would be only one temperature reading instead of two. In our Landmark, the bedroom gets cold much faster than the living room, so I have the bedroom thermostat set at a higher set point to keep the bedroom from becoming a meat locker. I would think if I had one thermostat, the main difference would be I'd pick a different set point for the bedroom zone because the temperature reading would be in the hallway instead of the bedroom. The basic operation would be the same.

Just guessing, but maybe Heartland thinks it might be more difficult for people to learn operation of a 2 zone thermostat.

 

[jimtoo]

Also,, was the bedroom a/c ordered and installed at the factory, or was installation done by dealer?

 

[Cyberdave]

Also,, was the bedroom a/c ordered and installed at the factory, or was installation done by dealer?

Whisper quiet installed by Heartland.

 

[Cyberdave]

Dave,

Why do you think it would be easier to do what you want on a single thermostat that has 2 zones, versus doing the same thing on 2 separate thermostats?

The only difference I can think of is that there would be only one temperature reading instead of two. In our Landmark, the bedroom gets cold much faster than the living room, so I have the bedroom thermostat set at a higher set point to keep the bedroom from becoming a meat locker. I would think if I had one thermostat, the main difference would be I'd pick a different set point for the bedroom zone because the temperature reading would be in the hallway instead of the bedroom. The basic operation would be the same.

Just guessing, but maybe Heartland thinks it might be more difficult for people to learn operation of a 2 zone thermostat.

Agreed, but again that was the Dometic techs point also. Why install their zone system if you're not going to do it correctly? Why not install two simple stats instead?
Personally, i'd rather see a separate temp sensor in the bedroom and a single stat setup as designed

 

[bwc1950]

A properly installed Zone system will have temperature sensors somewhere in the A/C Zone...ie, a sensor in the bedroom and a sensor in the living room allowing you to set different temperatures from one thermostat within the RV and the sensors detect the ambient temp and turn on/off the proper A/C. In the pictures, above the black decal is the bedroom sensor and a zoomed image of the same sensor. And, you do need multiple A/C's, identified by zone on the thermostat. Again, in a properly installed Zone system.

 

[mountainlovers76]

I had dual units installed by Heartland when I ordered my 2014 Key Largo. I never understood why Heartland installed two stats in a zoned capable system either. The second stat should have been a simple temp sensor and the single stat would serve as the second temp sensor and run both units even when set to different temps.

 

[Garypowell]

I am confused too. I thought a zoned system cooled by what an individual zone "wanted/needed". The two above posts are saying one device to turn on the A/C regardless of which temperature sensor calls for cool.

So according to their reasoning if you are cooking in the kitchen and that sensor calls for cooling you will get chilled out in the bedroom too. Not the way I see a zoned system.

I think in the early concept of a zoned system there was one cooling source but dampers controlled the flow of cool air based on a sensor in a given zone.

I think HL's got it right!

 

[Cyberdave]

I am confused too. I thought a zoned system cooled by what an individual zone "wanted/needed". The two above posts are saying one device to turn on the A/C regardless of which temperature sensor calls for cool.

So according to their reasoning if you are cooking in the kitchen and that sensor calls for cooling you will get chilled out in the bedroom too. Not the way I see a zoned system.
I think in the early concept of a zoned system there was one cooling source but dampers controlled the flow of cool air based on a sensor in a given zone.

I think HL's got it right!

What we're saying is that if you have a two zone system, zone one controls one AC and Zone two controls the other AC unit. A temp sensor for each zone would be installed somewhere in the zone being controlled. Zone one would control the main AC by setting it's temperature at a set temp of 70 degrees. Zone two would control the bedroom AC and you could set it at 75 degrees, The zone two ac would only come on when the bedroom temp exceeds your set point of 75 degrees. Otherwise, it operates the same way as it does now.

But, being set up properly, you could use the Automatic function properly and that oops forgot to turn off the front AC and heater is running does not happen.

 

[Cyberdave]

I had dual units installed by Heartland when I ordered my 2014 Key Largo. I never understood why Heartland installed two stats in a zoned capable system either. The second stat should have been a simple temp sensor and the single stat would serve as the second temp sensor and run both units even when set to different temps.

You know, since the cable runs up to bedroom AC, and there is communication cable that is supposed run between the AC units, in theory you could replace the front stat with the sensor and install the comm cable...

 

[danemayer]

I'm not getting it. Maybe someone can explain the advantage of setting up two zones on 1 thermostat versus setting up a single zone on two thermostats. Aren't you doing the same thing except you have to push extra buttons to shift from zone 1 to zone 2?

 

[bwc1950]

Actually, I wish that I had Zone control in my house….right now, in my house, I have one A/C and one thermostat located in the hallway. Say I set the temp on the thermostat to 78 and my livingroom is on the sunny side of the house. It may be 85 in the livingroom BEFORE the hallway (thermostat locale) gets above 78 and turns on the A/C…when the hallway gets back to 78, the A/C kicks off, livingroom still in the 80’s….
RV zone system…. 2 A/C’s, 2 temp sensors, one controller with multiple zone selection. One A/C in the RV livingroom and one sensor in the livingroom. 2[SUP]nd[/SUP] A/C in the bedroom and a 2[SUP]nd[/SUP] sensor in the bedroom. At the controller (in the hallway of the RV), I set the livingroom A/C Zone to 78. Since I’m not sleeping, I turn the bedroom A/C zone to 82. When the livingroom sensor hits 78, a signal is sent to the Zone Controller Thermostat and the controller tells the livingroom A/C to turn on and the bedroom A/C stays off. If and when the bedroom sensor senses a temp reaching 82, the bedroom sensor sends a signal to the Zone Controller Thermostat and the controller tells the bedroom A/C to turn on. Vice/versa to turn them off.
A Zone controller that controls multiple A/C’s from one location or two thermostats, one for each A/C does the same thing except that the original thermostat is probably located in the hallway of your RV and not in the livingroom and the 2[SUP]nd[/SUP] thermostat is probably located somewhere in the bedroom……
In my motorhome, I had 3 A/C’s. In the photo, the Zone 2 sensor is to the left of the Thermostat. Just so happened that the thermostat was installed in Zone 2, hence the nearby sensor. But, one controller, 3 Zones all automatic and all controlled by one thermostat.
Lengthy, but I hope that helps explain it a little better. Took me a few try’s, but after I got it, I liked it much better than the thought of multiple thermostats.

 

[Cyberdave]

Hi Dan,
For me;
1. Enable control of both AC's via one stat instead of running two.
2. Enable you to set the auto mode so it will work as designed

If you think about it, with a temp sensor in place of the stat in the bedroom, doesn't change how the bedroom AC works. You control the temp just as always but from one stat.

 

[RVNEWBIE]

Mine is set up the same way with two thermostats, but no sensor in the bedroom. I have the stat with zones showing, but cannot set any but zone one and apparently the only thing the bedroom stat does is turn the front ac on and off. we have not been in ours on a trip that requires heavy ac yet, and I will be looking at just how this all works. Many of the ones we looked at in Atlanta a couple months ago only had one stat and the sales people showed us the sensor in the bedroom. I do not remember what brands those were as we looked at so many. But I do know that our Key Largo has no such sensor in the bedroom. Our only trip out having to run AC only required the rear.

Joe

 

[Cyberdave]

Mine is set up the same way with two thermostats, but no sensor in the bedroom. I have the stat with zones showing, but cannot set any but zone one and apparently the only thing the bedroom stat does is turn the front ac on and off. we have not been in ours on a trip that requires heavy ac yet, and I will be looking at just how this all works. Many of the ones we looked at in Atlanta a couple months ago only had one stat and the sales people showed us the sensor in the bedroom. I do not remember what brands those were as we looked at so many. But I do know that our Key Largo has no such sensor in the bedroom. Our only trip out having to run AC only required the rear.

Joe

Essentially, you have the same setup as a standard rig. Control the front ac with one stat and the main AC and heater via the stat in the hallway. There should have been a sensor where the stat is and wired into hallway stat. There should also be a comm cable between the front and rear AC units

 

[danemayer]

Mine is set up the same way with two thermostats, but no sensor in the bedroom.

I think all thermostats have a temperature sensor built in. You pick a "set point", say 72 degrees, and when the thermostat senses 72 degrees, it turns the air conditioner off. There's usually a one or two degree gap before it turns back on (to keep it from continuously cycling on and off), so it will probably come back on when it senses the temp has risen to 74.

This is usually pretty easy to demonstrate on the front bedroom A/C unit because the room is so small relative to the size of the A/C unit that it cools down rapidly.

Our owner-written Heating and Cooling Guide provides some advice on how to effective use the two thermostats.

 

[2psnapod2]

to be zoned, there needs to be another phone type line run from on T-stat to the other. Money won so no wire.

 

[Cyberdave]

to be zoned, there needs to be another phone type line run from on T-stat to the other. Money won so no wire.

But the funny thing is, it would cheaper to unroll x feet telephone cable and spend very little money installing it and a temp probe and still be ahead over the cost of another stat.

It makes no sense to install a zone control system then not actually create the zones.

Dan, yes staggering the temps is essentially the same either way. But, when setup properly, you control everything with one stat. You can set zone one (main AC) for 72 and zone two (bedroom) for 76 and the bedroom AC will only come on at the set point of 76.

The advantage is the ability to control all HVAC from one stat and to me that is a distinct advantage of zone systems.

 

[2psnapod2]

True. But it doesn't always work the way we think it should!

Sent from my DROID BIONIC using Tapatalk

 

[riverrat]

I also have the Whisper quiet installed by Heartland, I agree that it should be set up with one muti zone stat as per the stat used, they have it set up where you can run the a/c and the heater at the same time in the bedroom. On the other hand having a stat in the bed room if you need to change the temp in the middle of the night I can reach it from the bed. I'm installing aux heat in the livingroom a/c and going to single stage stat to support it. I have already installed a programble stat to run the furnace and fantastic fan. No more getting up in the morning to kick up the heat and jump back in bed till the chill is gone. I will install a single zone in the bedroom because if you hit the wrong button in the middle of the night you may be in a diff zone, now you have to try and get it back to zone one what a pain in the middle of the night with a flashlight hoping not to wake up the misses.