Replace Thermostat

270S · 05-03-2018, 06:33 PM

I want to replace the FR supplied POS Thermostat. Off by 4 degrees, unable to calibrate, .... Strictly elec ac & elec heat control. Any suggestions & why. Must have calibration capability. Current thermostat is Dometic.

Casey r · 05-03-2018, 06:56 PM

* Select models.System InitializationA system initialization will need to be performed by the installer afterthe system is installed.• Make sure the Single Zone LCD thermostat is in the Off condi-tion. See page 4, "Quick Reference To Control Buttons".• Press the "+" button and, while holding it, also press and holdthe On/Off Mode button for three seconds. LCD will show― ― . Press the On/Off Mode button again to turn system off.This completes the initialization.The furnace On/Off temperature differential should be set at this time.See "Mode Description - Furnace" on page 9 for further informationon furnace mode differential setting.

Have you tried this.
I've owned my 5th wheel a little over a year and have had to perform the intialization a couple time. When ever it starts acting stupid.

cjd10 · 05-04-2018, 04:25 AM

When you say electric heat are you referring to the heat strips? That looks like the thermostat I just installed and mine will control the heat strips and the propane heat.

Martsing · 05-04-2018, 06:16 AM

I swapped ours out last year and never looked back. https://smile.amazon.com/Coleman-833...=thermostat+rv

Marty

Casey r · 05-04-2018, 08:52 AM

If your Dometic thermostat is the one in your picture. It is like mine. The thermostat has 3 wires. According to Dometic it is more of a remote control than it is a thermostat. I would check into it a little more and try the initialization procedure before I tried replacing the thermostat. I think your going to find out what I did and that it’s going to require a different control module and 2-3 more wires run between the thermostat and the controller.

5picker · 05-04-2018, 09:06 AM

Quote:

Originally Posted by Casey r

If your Dometic thermostat is the one in your picture. It is like mine. The thermostat has 3 wires. According to Dometic it is more of a remote control than it is a thermostat. I would check into it a little more and try the initialization procedure before I tried replacing the thermostat. I think your going to find out what I did and that it’s going to require a different control module and 2-3 more wires run between the thermostat and the controller.

This is spot on.

Dometic seems to be migrating to a 'network' type control system (to accommodate R/Vs with two or three A/C units) and replacing what is basically now a 'sensor' is more difficult as the controls are all up in the A/C unit.

Casey r · 05-04-2018, 09:24 AM

Quote:

Originally Posted by 5picker

This is spot on.

Dometic seems to be migrating to a 'network' type control system (to accommodate R/Vs with two or three A/C units) and replacing what is basically now a 'sensor' is more difficult as the controls are all up in the A/C unit.

Spent many hours and many phone calls with prime time and Dometic trying to fix a thermostat issue in where it would pick a random temperature to set to after the unit had been running for 1 - 3 days Finally fixed it .

rockfordroo · 05-04-2018, 09:40 AM

Quote:

Originally Posted by Martsing

I swapped ours out last year and never looked back. https://smile.amazon.com/Coleman-833...=thermostat+rv

Marty

Can't use a Coleman-Mach in place of a Dometic. Dometics use ground switching while Coleman uses positive switching.

270S · 05-04-2018, 10:13 AM

Summary Reply to all the great posts.

MY system "works", but the display is consistently 4 degrees off - too high - that is when 90 is set, it thinks it is 86. When 74 is set it thinks it is 70. I want an accurate temp sensor that is capable of being calibrated to the correct temperature - at least within 1 degree. 4 is unprofessional.

The Coleman 83303862 Digital Thermostat is NO More, although there were some on Ebay, ..., but as rockfordroo says, can't use it anyay.

Does the initialization affect or resolve the temp sensor being off??

***** UPDATE ****
Jut found correct manual and it does not show any initialization or anything else available.

Casey r · 05-04-2018, 10:16 AM

I would try it. It’s my understanding it’s a hand shake between all components to make the are all accounted for and speaking the same language. Only take a few seconds and costs nothing. Bonus

270S · 05-04-2018, 10:36 AM

Quote:

Originally Posted by Casey r

I would try it. It’s my understanding it’s a hand shake between all components to make the are all accounted for and speaking the same language. Only take a few seconds and costs nothing. Bonus

We crossed time wise on posts - see previous.
The manual is only 1 page and no init available
Is there a 9 page manual I am missing?

Iwannacamp · 05-04-2018, 10:39 AM

https://cdn.ltvdns.com/leisurevans.c...Thermostat.pdf

STILL LOOKING

270S · 05-04-2018, 10:44 AM

Quote:

Originally Posted by Iwannacamp

https://cdn.ltvdns.com/leisurevans.c...Thermostat.pdf

STILL LOOKING

I have the 3313192 manual, but mine is 3316250.012
Attached is the 3313192 manual

Iwannacamp · 05-04-2018, 10:57 AM

http://manuals.dometic.com/download.php?file=2220

ANOTHER

Iwannacamp · 05-04-2018, 11:22 AM

Just a thought... where does the stat get the temp reading for the control/display? If the sensor is in the stat? Maybe it's touching something? Maybe the stat is picking up a reading from the wall...insulate hole. Maybe it has a sensor in the wall that's getting false reading or out of calibration. I dunno.

270S · 05-04-2018, 03:33 PM

Quote:

Originally Posted by Iwannacamp

Just a thought... where does the stat get the temp reading for the control/display? If the sensor is in the stat? Maybe it's touching something? Maybe the stat is picking up a reading from the wall...insulate hole. Maybe it has a sensor in the wall that's getting false reading or out of calibration. I dunno.

It is internal to thermostat that is mounted on an internal wall so OAT is not a factor. It is a constant 4 degrees off due to a bad manufacturing calibration.

rockfordroo · 05-04-2018, 03:45 PM

Quote:

Originally Posted by Iwannacamp

Just a thought... where does the stat get the temp reading for the control/display? If the sensor is in the stat? Maybe it's touching something? Maybe the stat is picking up a reading from the wall...insulate hole. Maybe it has a sensor in the wall that's getting false reading or out of calibration. I dunno.

Quote:

Originally Posted by 270S

It is internal to thermostat that is mounted on an internal wall so OAT is not a factor. It is a constant 4 degrees off due to a bad manufacturing calibration.

Looking at a similar unit here:

https://www.campersinn.com/product/n...-270s-583448-9

It appears that your Tstat is mounted on the bathroom wall on the opposite side of the bathroom sink. It appears that your water heater is located under the kitchen sink, which is also very close to the T-stat. If you Tstat is off in the high direction (thinks it's warmer than it really is), it could be seeing warm air from the water heater in the wall behind the T-stat.

Others have reported problems like this; they've removed the Tstat from the wall and stuffed some insulation into the wall void to solve the problem.

I've never heard of being able to calibrate a digital Tstat, but .....

Iwannacamp · 05-04-2018, 04:09 PM

As a note.. I have a Honeywell stat you can make display whatever temp you want... you can set at minimum/maximum set temp. Some stats have an electronic sensor under the cover that it uses to decide what to do(I guess they all do) and i assumed...

Could be a crappy stat...

270S · 05-04-2018, 04:37 PM

I've never saw such crap until 2 years ago when I got involved with the RV Industry. One does not normally have to calibrate much of anything any more because they are made correctly by the manufacturer in the first place - not in this industry.

Again, don't confuse the subject matter. It is the thermostat, not installation, location, whether I took a shower, or used the kitchen, ... Nothing is on just the AC for dehumidify! If you want to confuse the subject, the rear AC went on when it was 35 degrees outside a few months back and it was set to 86!

Point is, these thermostats are crap! From original first post, I was looking for a good replacement "I want to replace the FR supplied POS Thermostat.", not how to jury-0rig or fix crap.

rockfordroo · 05-04-2018, 05:49 PM

Quote:

Originally Posted by 270S

I've never saw such crap until 2 years ago when I got involved with the RV Industry. One does not normally have to calibrate much of anything any more because they are made correctly by the manufacturer in the first place - not in this industry.

Again, don't confuse the subject matter. It is the thermostat, not installation, location, whether I took a shower, or used the kitchen, ... Nothing is on just the AC for dehumidify! If you want to confuse the subject, the rear AC went on when it was 35 degrees outside a few months back and it was set to 86!

Point is, these thermostats are crap! From original first post, I was looking for a good replacement "I want to replace the FR supplied POS Thermostat.", not how to jury-0rig or fix crap.

Well, excuuuuse me for trying to help you!

I had already told you that you need a Dometic because they switch the ground; most other Tstat's switch the positive. So google Dometic Tstats and buy whichever one you think is better than the one you have.

Don't try anything else anyone has suggested; it's not what you asked for!

Good luck.

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