Installing 24 volt WiFi Thermostat on millivolt stoves

Many stoves use millivolt jacks on their stoves. This poses a problem when you want to use a thermostat that had functions etc...especially things like Wifi.

Basic heat only thermostats, such as mercury filled or the ye old slider style basically just complete a circuit when the temp falls below a specific set point. They don't need to be powered. As soon as you start using thermostats that have digital readouts, have clock, are programmable or connects to WiFi portals, one must power the thermostat. Most thermostats run on 24 volts. Your doorbell on your house may run on 24 volts too. Most central heating equipment will have some kind of transformer that powers the thermostat via the Rh and W wire connections. However,these connections will only power the thermostat when the unit is calling for heat, and that's what the C wire on the thermostat is for...to provide a common neutral wire for when the tstat is NOT calling for heat.

Many pellet and has stoves utilize milli-volt powered tstat jacks. The reasoning is that room heaters such as these should not be used as primary heating systems and as such and controls for them such as tstats should NOT be located too far away from the unit. Milli-volt current will not travel to far away so that is why they are used. What we don't want to happen is to have the stov calling for heat too soon after the unit has gone in to shut down mode. We call it short cycling and it can mess up the logic in the control board of the stove. Not permentaly, but perhaps enough to force the owner to unplug the unit and restart the system.

It the pictures below I have made a powered relay with a 24v transformer to allow a pellet stove with a milli-volt tstat jack to be used with a 24v C wire powered tstat. The one I am using is also WiFi enabled.

I chose the Cheaper one from lowes
Honeywell 7-Day Programmable Thermostat
Item #: 171234 | Model #: RTH6580WF1001

The relay is a RIB UC12 and the transformer I got from Radio Shack.

The wires coming out of the j box to the left are not being used. The orange and the yellow coming out of the bottom go to the stove, the red wire goes to the Rh on the tstat and there is one white wire for the C connection and one for the W connection.

It works like a champ. Here are some benefits...

You can turn the stove on and off from work for your kids, start the stove on the drive home from work and have the house warm when you get home. Monitor the stove in a rental unit or a time share vacation home.

Good stuff!

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Bioburner

Moderator
Aug 4, 2012
7,317
West central Mn
And how many founding Fathers does the system go for?
 

Bioburner

Moderator
Aug 4, 2012
7,317
West central Mn
Not bad at all. Under two Franklins. Medium skill level to accomplish?
 

Don2222

Minister of Fire
Feb 1, 2010
8,629
Salem NH
Good WiFi T-Stat for average guy who has the skill and time to wire up the relay.

What is the Max swing setting? Is there any monthly fee for the Internet use of the WiFi?
Also
Is a box needed to connect up to the internet?
Do you need that red link stuff? It is a little confusing.
http://www.amazon.com/Honeywell-THM6000R1002-Enabled-Internet-Gateway/dp/B006BD1K4A/ref=pd_sim_sbs_indust_2
Also you need a computer to run the setup software. Might be a little PITA.

In my opinion for someone who wants the best like their Harman Stoves and the easiest to use and wire up, the Ecobee EB-Stat-02 is the Top of the Line by far. See pics below.
There is NO monthly fee for WiFi use and the Anto-Short Cycling delay has a max of 20 min for minimum on time. So if your stove takes 15 or 20 mins to shut down, you just set it for 15 or 20 min. Simple

Now here is the good news.
It can be connected to a furnace and powered from the pony relay that puts out 24 vac which drives your Taco zone pumps. ( I installed couple oil boilers in my days. LOL)

For pellet stoves
Just buy the 12 vdc adapter and plug it into the AC outlet. The AC adapter plugs into the Interface Board that you can mount near to the pellet stove.
Then run 2 wires from the pellet stove connection to the R/H and W O/B terminals on the Interface Board.
Run a 4 conductor 18 guage wire from D- , D+ , GND and +12vdc from the Interface board to the same terminals on the T-Stat display and mount the display away from the stove.

The setup wizard will find your WiFi router and connect to it with the built-in wireless card!

Now the real fun begins!
This is the most sophisticated WiFi T-Stat on the market, the reports it can generate are second to none! Even has a 3 year warrenty!
Sure the cost is 3 Bennies but you have the very best!

List of Alerts

Below is a list of alerts. Depending on your configuration, some of these may not apply.
There are also other alerts like low battery and communications alert between the t-stat and interface module plus configurable alerts for Input1 and input2. One of these alerts can be used for a flood sensor which is great if you ever get water in the basement. This feature will pay for the extra cost in the T-Stat alone!

Furnace - Air Furnace Filter - filter needs to be cleaned or changed.
UV Lamp - UV lamp needs to be changed.
Low Temp Alert - Temperature in the home is too low.
High Temp Alert - Temperature in the home is too high.
Heat Not Responding - The system has failed to heat the home.
Cool Not Responding - The system has failed to cool the home.
Maintenance Reminder - HVAC system due for regular maintenance.
Auxiliary Heat Run Time - Auxiliary heat source is running too often.
Auxiliary Outdoor Temperature - Your Smart Si thermostat auxiliary heat has been called to run when the outdoor temperature exceeds the programmed set point.

Recovery Options
Recovery options allow the Smart Thermostat to learn
how your heating and cooling system works, taking into
account infrastructure, weather and historical operating
performance so that your home is a comfortable
temperature as soon as you walk in the door.

Smart Recovery Heat
The thermostat will start recovery at the optimum time to
ensure the set point is reached at the programmed time.

Smart Recovery Cool
The thermostat will start recovery at the optimum time to
ensure the set point is reached at the programmed time.

Random Start Heat
Programming a time in this section will produce a random
delay when there is call for heat. In applications with
multiple heating systems, this prevents all systems from
activating at the same time, creating a peak power demand.

Random Start Cool
Programming a time in this section will produce a random
delay when there is call for cooling. In applications with
multiple cooling systems, this prevents all systems from
activating at the same time, creating a peak power demand.

Thermostat Name
You can customize the name of your thermostat to suit
your needs (i.e. Main Floor). This is useful if you have
multiple systems or zones. You can view and edit your
thermostat name in the About menu on your thermostat
and also in your online Web Portal.

Utility CPP Setting

This section is only applicable if your utility company is
running a Critical Peak Pricing program that you have
agreed to be a part of. Contact your local electrical utility
company for information about programs in your area.

CPP Response
Your utility may send voluntary events to your thermostat.
You can choose to always accept these events. In which
case, you would just be notified that an event is in
progress. Or if you choose Ask Me, when the Utility issues
an event, you will be asked if you want to participate.
If you do not acknowledge the event prior to the start, the
system will default to yes.

During a Critical Peak Pricing event the Utility may select
an energy saving strategy, or allow you to use your
preferred strategy. Select from one of the options as
your preferred energy saving strategy to be used during
Critical Peal Pricing events.

Absolute Temperature
Set a specific heat and cool set point to be used when
an event is initiated by the Utility company. If the set
point at the time of the event is more favorable (lower
in heat mode or higher is cool mode) than what you
have programmed, the thermostat will use the more
favorable set point for the duration of the event.

Relative Temperature
Program a temperature set back (heat) or set forward
(cool) from your existing set point. For example, if you
program a 4oF set forward, and your current cool set
point is 76oF, During an event your thermostat set point
will change to 80oF until the event has expired.

System Off
If this option is selected, the thermostat will turn off for
the duration of this event.

Duty Cycle
This option allows you to program the maximum amount
of time the system will run during a 1 hour period. For
example if you select 30%, the air conditioner will run for
a maximum of 18 (0.3 x 60) minutes regardless of whether
the set point has been met. 0% essentially turns the
system off, whereas 100% runs the system at full capacity

Click pics to enlarge:
 

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The Honeywell Tstat is pretty simple and best of all, cheap for wifi. No monthly fee to access wifi other than your ISP...which you will need access to with any wifi thermostat. It has lots of features. I haven't got in to them all bt since the tstat is going to be mounts in the same room as the stove...short cycling is not an issue.

The skill level for this is pretty easy. Perhaps harder to network it than build the box and wire it.

The post isn't so much a discussion of what wifi tstat is best but rather some info on how to adapt a millivolt controlled system to a 24v powered system.
 

Don2222

Minister of Fire
Feb 1, 2010
8,629
Salem NH
The Honeywell Tstat is pretty simple and best of all, cheap for wifi. No monthly fee to access wifi other than your ISP...which you will need access to with any wifi thermostat. It has lots of features. I haven't got in to them all bt since the tstat is going to be mounts in the same room as the stove...short cycling is not an issue.

The skill level for this is pretty easy. Perhaps harder to network it than build the box and wire it.

The post isn't so much a discussion of what wifi tstat is best but rather some info on how to adapt a millivolt controlled system to a 24v powered system.
Sounds good and the price is great!
 

WoodPorn

Minister of Fire
Aug 24, 2009
1,503
South of the beloved Patriots
Scott, This sounds like a great option. Me thinks you maybe should have entered into the engineering arena.

Don, we need to put a character counter on your acct and set a maximum of like 100.
 
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part numbers of said components?
basic electrical J Box - $5.97
Electrical cord with plug - $3.99
RIB Relay #RIBU2C - $21.97
Radio Shack 12v-25.2v Transformer #03A12 - $7.99
Honeywell Model #: RTH6580WF1001 TSTAT - $109.00
some wire and nuts - $5.00 or so

$153.92 + tax

Takes about 30 minutes to wire it up, see my diagram attachment on OP

image.jpg
 
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Don2222

Minister of Fire
Feb 1, 2010
8,629
Salem NH
Hello

I do like the 24 volt relay with the Honeywell T-Tstat, it may be good for the one room shed. However, who is going to fix it or warranty it when it breaks?

I just got the remote sensor module for the Ecobee. Their call in tech suppoort is one of the best!
http://www.hvacpw.com/Ecobee-RSM-01-Remote-Sensor-Module-p/eco-rsm-01.htm

With this module, I can not only check the outdoor temperature and the humidity in the same room as the pellet stove with the smartphone, but also the temperature in the other rooms so I can boost up the stove temp to make the whole house more comfy!
If there is any water in the basement, I can get a nice alert when working!

Features
Control Sensors
With the help of the ecobee Remote Senosr Module you can take control of your comfort with the ability to:


    • Use a sensor to control your comfort instead of the thermostat.
    • Average temperature and humidty sensors in your home to get optimal comfort throughout your home.
    • Use your already programmed high and low temperature alerts with a control sensor to let you know if there are problems with your system.
Monitoring
Monitor temperatures and humidity of various locations with the ecobee RSM. Set thresholds to alert you if something isn’t right.

Outdoor Sensor
Get accurate weather data for your home with an outdoor sensor. The information gathered will be used to configure HVAC algorithms to help your system maintain the most comfortable conditions for the most amount of savings.

Sensor compatability
HoneywellC7189U indoor sensor
C7089U outdoor sensor
TekmarD076 indoor sensor
D079 slab sensor
D084 flush mount sensor
Johnson Controls
HT-6703 humidity sensor
CD-W00 CO2 sensor
Other temperature sensors can be supported by just entering the B value or the resistance
reported by the sensor at 70°F (21°C) during the configuration process.


 

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I'm sure that ecobee has you all smitten but from what I can tell you haven't wired it up yet. I wish you would stop hacking up my posts to push your own agenda. We get it. I say this you say that....I made mine and it works. If I put this system together for someone I suppose they could just call me if it isn't working.
 

Don2222

Minister of Fire
Feb 1, 2010
8,629
Salem NH
I'm sure that ecobee has you all smitten but from what I can tell you haven't wired it up yet. I wish you would stop hacking up my posts to push your own agenda. We get it. I say this you say that....I made mine and it works. If I put this system together for someone I suppose they could just call me if it isn't working.
That is a good job wiring up that T-Stat, may I remind you that the title of this post is:
"Installing 24 volt WiFi Thermostat on millivolt stoves"

Therefore my input is exactly inline with this topic! ! ! I am also showing how to wire up a 24 volt WiFi T-Stat. In this case it is much easier with the Ecobee because all you have to do is get the optional AC adapter and plug it in, instead of spending alot of time at Radio Shack.
 
To what benefit it is going to be to know what temp the other rooms are or even the outside temp if the stove can only react to conditions in the room it's installed in? You may be smart and all but more isnt always better.

Damn it, I just made something kinda cool for the people...I shared it with ya all. Blue print, part numbers and everything...I even ran it for close to week before I posted. Go head there master...show me what you got. Wire it up buddy. Report back to us.
 
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That is a good job wiring up that T-Stat, may I remind you that the title of this post is:
"Installing 24 volt WiFi Thermostat on millivolt stoves"

Therefore my input is exactly inline with this topic! ! ! I am also showing how to wire up a 24 volt WiFi T-Stat. In this case it is much easier with the Ecobee because all you have to do is get the optional AC adapter and plug it in, instead of spending alot of time at Radio Shack. Then the 24 volt AC connection is not used!
Your costs $300 and has an ugly cord running up the wall from an outlet.
 

Don2222

Minister of Fire
Feb 1, 2010
8,629
Salem NH
Your costs $300 and has an ugly cord running up the wall from an outlet.
You can mount it down near the outlet or lay it on the floor. Yes, it is more money but you get many more features and a 3 year warranty.
Some people will like yours and others will like this, just nice to have a choice.
 
Your pushing a tstat.... I'm showing people a way to power the tstat using millivolt output jacks. You jump in and hijack my posts I do t really care what tstat people use, but if it needs 24v to power it, here is a solution. Thanks for being objective and generally excited towards my ideas. Secretly we all know you want to be me...wait till you see the next skunkworks project. Gonna be hard for you to contain yourself, just sayin.
 
You can mount it down near the outlet or lay it on the floor. Yes, it is more money but you get many more features and a 3 year warranty.
Some people will like yours and others will like this, just nice to have a choice.
So your gonna monitor the cold air in at the floor with yer tstat? Let me know how that works.
 

Don2222

Minister of Fire
Feb 1, 2010
8,629
Salem NH
To what benefit it is going to be to know what temp the other rooms are or even the outside temp if the stove can only react to conditions in the room it's installed in? You may be smart and all but more isnt always better.

Damn it, I just made something kinda cool for the people...I shared it with ya all. Blue print, part numbers and everything...I even ran it for close to week before I posted. Go head there master...show me what you got. Wire it up buddy. Report back to us.
If the pipes are freezing in the other room, it might be nice to know! Some people have large homes and may really want to know that so they can remotely fire up a second stove.
I do intend to connect it in, it has been so very busy! I am surprised you had time for all that?
 

BrotherBart

Modestorator
Staff member
Get a room. ;lol
 
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