Quadrafire Castile Insert with Google Nest thermostat

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.

david594

New Member
Nov 28, 2019
1
Cheshire, CT
Hi, I'm a newbie to the Hearth.com forums but I just wanted to be able to share my experiences connecting a Nest theromstat to a Quadrafire pellet stove insert. ( and if you are wondering, i did read the threads from 2wire regarding this topic)

Summer 2018 my wife and I bought a house in a subdivision that didnt have natural gas available. As such we decided to purchase a pellet stove for "supplemental heat" and ended up with a Quadrafire Castile Pellet Stove Insert. Our math indicated for every 5$ we spent in pellet we were replacing ~ $15 in equivalent electric baseboard heat.

The stove is thermostat controlled via a "milivolt" thermostat. And all this means is that off is an open circuit and on is a closed circuit.

For the first year I had my Nest Thermostat(powered via the AC side of the thermostat) controlling a 24vac solid state relay to control H1 of heating via the pellet stove. This was a good option as it could rudentarily turn on and off the pellet stove. The flaw with this was that it was unable to control the output and requiremed me to set the output manually on the stove via the rocker switch. As such the stove being on low at night, would be inadequate to warm the house in the morning in a reasonable amount of time the following morning.

Initial setup:
Initially I built a controller that could interface with the Nest thermost and allwoed it to control stages 1, 2, and 3 (low, med and high) via the thermostat. This worked by all stages flipping a stage 1 relays to connect the thermostat circuit, and stages 2 and 3 triggering relays to change the state of the rocker switch to connect stages mid and high.
The flaw with this was that the Nest thermostat would always going to low first, then after ~30-60 minutes go to medium or hi depending on what it determinted was correct to get up to temp. Unfortunately the thermostats programming of going to first first, then 2nd or 3rd in succession was not idea. The other issue with this was that the thermostats goal was always to get to temp so it could turn off completely. (which is not what you want with a pellet stove).

Final setup.

In the final setup I added a manual switch that would override the thermostat control keeping the pellet stove on set to whatever the manual rocker switch is set to. And I changed the relay wiring such that stage 1 on the Nest thermostat turned on mid for the pellet stove and stage 2 for the thermostat turned on hi for the pellet stove. It no longer requests stage 1 heat, as the stove is normally in this state.

Functionally this lets me use the added rocker switch as an on/off switch for the stove that is independent of temperature. When the thermostat requests stage one heat, it turns the stove to medium, and when the stove requests stage 2 it turns the stove to hi. Functionally this seems to work very well. This lest us just leave the stow manually set on low all of the time, and the thermostat then has the option to override and turn it up to mid or high if it feels the need to increase the temp in the household quickly.

My original setup with the Nest controlling all 3 stages resulted in too many times that the stove was trying to relight.




The end result .

Final setup.
 

Former Farmer

Minister of Fire
Apr 12, 2008
609
NE Wisconsin
Here is what twobraids did :

I took a different approach. Instead of using a Nest thermostat, I use a multistage programmable thermostat. I run the contacts through a PLC and use the PLC to control the heat settings on the Castile insert. It works very well for me and is more flexible than a Nest. I set the thermostat program to start the stove about an hour before we get home so the stove is already starting to "catch up" by the time we get home. I have the differentials set on the programmable thermostat to control which heat setting the stove should be operating at. Low / Medium / or High.

Glad you have your setup working well for you. Happy heating.