10 CPM Thermostat Inconsistent

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Atomicskr

Member
Nov 20, 2018
33
Annapolis, MD
I installed the Honeywell thermostat from ESW last winter and now I'm having an issue with it. The thermostat for the stove (Honeywell) is installed about 2 feet from the thermostat that control the AC and Heat Pump (EcoBee) and both are about 20' from the stove. My issue is that the Honeywell thermostat will not keep a consistent temperature in the room. For example, if I set the Honeywell to 76 the EcoBee will read 79 when the Honeywell stops calling for heat. If I set the Honeywell to 75 the EcoBee will read 71 when the Honeywell stops calling for heat. Has anyone else had a similar issue? Or can you recommend a better thermostat to use?
 

zrock

Minister of Fire
Dec 2, 2017
1,118
bc
See if you can find a schematic for one or the other thermostats. Sometimes they have a adjustable pot inside for the temp so you can fine tune it if its out... Or just off set your temp settings on both thermostats so they play nice together their only 4 deg dif so i would just fine tune them to play nice... Different manufacturers are going to be different as well.
 

Atomicskr

Member
Nov 20, 2018
33
Annapolis, MD
The issue isn't that thermostats match. The issue is that the difference between 75 degrees on the thermostat and 74 degrees is about 7 degrees in actual temperature. If the thermostat is set at 74 it's 71 degrees actual temp in the room. If I set the thermostat to 75 degrees it's 78 actual degrees in the room.
 

zrock

Minister of Fire
Dec 2, 2017
1,118
bc
im not sure where you are getting 7 from but your are comparing 2 different thermostat values all thermostats are going to read slightly different especially 2 different brands.. Have you taken my suggestion above and seen if their is a adjustable pot for the display temps so you can fine tune it closer? They may have glue over the top so the end user cannot play with them. I have had to adjust a few
 

Atomicskr

Member
Nov 20, 2018
33
Annapolis, MD
I verified with a third thermometer. Setting the honeywell at 74 yields a room temp of 71 degrees. Setting the honeywell at 75 yields a room temp of 78. So changing the honeywell setting by 1 degree (74-75) yields a difference in room temp of 7 degrees (71-78).
 

zrock

Minister of Fire
Dec 2, 2017
1,118
bc
Ahhh i got ya now i was reading the first set of numbers backwards..LOL Now the question becomes is it the stove creating the issue or is it the thermostat. Your first post your comparing 2 different thermostat's and i know in my house i have 3 things that read temp and im out about 4 deg between the 3. Have you tried swaping the ecobee over to the pellet stove and see what happens? Maby even buy another cheep thermostat and see what happens as you can always return it. Have you pulled the cover off the thermostat? i had issues with mine and it was actually dust had built up on the sensor
 

johneh

Minister of Fire
Dec 19, 2009
3,631
Eastern Ontario
I have 2 new Honeywell stats side by side
1 for the new propane furnace 66
1 for the new wood furnace 67
They both read different only buy 1 deg.
now witch one is right
check kitchen temp reads 65
check office temp also reads 65
So which 0ne is right
don't care wood set at 70 propane set at 71
house is comfortable
Life is good
 
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Atomicskr

Member
Nov 20, 2018
33
Annapolis, MD
I've checked out the honeywell thermostat and it looks clean.... I've been thinking about just buying another thermostat, will any thermostat work or does it need to be the specific model I bought from ESW?
 

ericofmaine

Burning Hunk
Feb 8, 2012
196
Southern Maine
Any millivolt thermostat will work.

Eric
 

Atomicskr

Member
Nov 20, 2018
33
Annapolis, MD
Finally got around to replacing the thermostat and problem is solved. The two stats still don't agree on the temp, but the room temp stays completely consistent, so I'm calling it fixed. Thanks for the advice all!
 

zrock

Minister of Fire
Dec 2, 2017
1,118
bc
good to hear... now that you have one as a spare tear it apart and see if you can find a pot that adjusts the room/display temp. I know early digital thermostats had a pot in them that you could adjust. Have not had to do this in years last time was between a gas fireplace and furnace... Got em tuned to match and then realized how much the gas fire place was costing to operate and ripped it out