Dometic A/C and Thermostats

[Parcany]

Just got a answer back from Jayco about the thermostat and a/c on our 27RL. Was told that the thermostat could be off by 20 degrees and as far as Dometic is concerned it is ok. I told them that they should go back to whats has worked before[Colman] and that 20 degrees is way to far apart..Was not happy and am sure other people that have bought Rv's are not also.

[JimD]

Are you referring to a mechanical thermostat? I think those things may work with a bi-metallic spring which controls a mercury style relay/switch. I use to calibrate an old home unit by rotating it on the wall. Those are sensitive to being level. A little off-level and the temp would be way off.

One of my first changes in my 2017 Greyhawk was to dump the mechanical thermostats in favor of Coleman digital. Worth every penny!

[Parcany]

Nope a digital thermostat.

[2edgesword]

The one in our trailer is accurate within a couple of degrees.

[JimD]

My Coleman digital thermostat appears to be very accurate. What I set it for is what I get as measured on its display plus another thermometer I have in the area.

Digital control should be very accurate otherwise why bother. I simply don't believe a thermostat can be 20 degrees off.

Are they referring to a wall mount control or a built-in one? If built in, I can see it being off more than a wall thermostat.

[Parcany]

This is a new 2018 Jayco travel trailer with a Dometic a/c and a wall mounted Thermostat. from what I have read is that there is no replacement part like on the Coleman side. I only told you what was sent me from Jayco. I hope that nobodys is off by 20 degrees. When we had the Coleman we were within 1 degree and that was nice

[pconroy]

Are you sure you heard that correctly? The only time I've heard "20 degrees" tossed out in the context of Air Conditioning is:

"Your AC is operating normally if the conditioned air is 20 degrees less than the outside, ambient air temp."

I'm having a hard time accepting a 20* delta on a thermostat.

[Parcany]

Originally Posted by pconroy

Are you sure you heard that correctly? The only time I've heard "20 degrees" tossed out in the context of Air Conditioning is:

"Your AC is operating normally if the conditioned air is 20 degrees less than the outside, ambient air temp."

I'm having a hard time accepting a 20* delta on a thermostat.

Like I said I got a e-mail stating that.

[poohbear]

Originally Posted by pconroy

Are you sure you heard that correctly? The only time I've heard "20 degrees" tossed out in the context of Air Conditioning is:

"Your AC is operating normally if the conditioned air is 20 degrees less than the outside, ambient air temp."

I'm having a hard time accepting a 20* delta on a thermostat.

Mechanical stats should be within 3 degrees accuracy & digital less than 1 degree. Those Dometic stats are 3 wire " communicating " & only a Dometic will work without spending a lot of money.
I had a call once on a hvac system & it was not shutting off getting the house cold. I checked so many things on that tstat finally after an hour scratching my head put up a new one. Waited around to see if I had actually solved the problem , but no, kept running. I'm standing in that hallway thinking I'm kinda warm here & the light bulb over my head lit up. The lady had dozens of photos of her family up & down the hall and had just had about a dozen track lights installed to shine on the photos which also shined on the tstat. She learned to set her tstat a little warmer or turn off the lights but a 89 year old lady isn't turning off the lights on her Grandchildren.