Installing 24 volt WiFi Thermostat on millivolt stoves

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Scott - i have the same wifi t-stat and a millivolt gas fireplace at our cabin. I'd love to set it up so that we can pump up the heat before we head out for the cabin (2 hours) so that it's toasty when we get there.

You call out a RIB UC12 relay and what looks like an Edwards 592 transformer. I'm a little confused as the picture looks like a RIB UC2 relay.

Amazon has the following two items I think would work...

Heath Zenith Door Bell Transformer:
http://www.amazon.com/gp/product/B000BQY88I/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

RIB U1C Relay:
http://www.amazon.com/Functional-De...qid=1387679871&sr=1-1-catcorr&keywords=ribu1c

My questions are:

1. The transformer is 20A @ 24V...the relay is 10A. Is this a problem?
2. The relay only has one coil - the RIB U2C has two. Do I need more than one?

Any help would be great.

Cheers,

Mike


smwilliamson said:
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!

View attachment 112141 View attachment 112140
Click to expand...
 
mdhoward said:
Scott - i have the same wifi t-stat and a millivolt gas fireplace at our cabin. I'd love to set it up so that we can pump up the heat before we head out for the cabin (2 hours) so that it's toasty when we get there.

You call out a RIB UC12 relay and what looks like an Edwards 592 transformer. I'm a little confused as the picture looks like a RIB UC2 relay.

Amazon has the following two items I think would work...

Heath Zenith Door Bell Transformer:
http://www.amazon.com/gp/product/B000BQY88I/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

RIB U1C Relay:
http://www.amazon.com/Functional-De...qid=1387679871&sr=1-1-catcorr&keywords=ribu1c

My questions are:

1. The transformer is 20A @ 24V...the relay is 10A. Is this a problem?
2. The relay only has one coil - the RIB U2C has two. Do I need more than one?

Any help would be great.

Cheers,

Mike
Click to expand...
The transformer is 20 VA That's Volt Amperes, a measure of the maximum power the transformer can deliver to the relay coil. That is more than enough.
The 10 A spec on the relay is the contact rating.
 
mdhoward said:
Scott - i have the same wifi t-stat and a millivolt gas fireplace at our cabin. I'd love to set it up so that we can pump up the heat before we head out for the cabin (2 hours) so that it's toasty when we get there.

You call out a RIB UC12 relay and what looks like an Edwards 592 transformer. I'm a little confused as the picture looks like a RIB UC2 relay.

Amazon has the following two items I think would work...

Heath Zenith Door Bell Transformer:
http://www.amazon.com/gp/product/B000BQY88I/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

RIB U1C Relay:
http://www.amazon.com/Functional-De...qid=1387679871&sr=1-1-catcorr&keywords=ribu1c

My questions are:

1. The transformer is 20A @ 24V...the relay is 10A. Is this a problem?
2. The relay only has one coil - the RIB U2C has two. Do I need more than one?

Any help would be great.

Cheers,

Mike
Click to expand...


The xfmr will be fine with that relay, and no you don't need a UC2
 
Last edited:
Thanks for all of the postings. Using information here and a few other places i installed a wifi tstat for a millivolt gas fireplace insert over the weekend.

tstat: Honeywell RTH8085WF

transformer: http://www.amazon.com/gp/product/B0007N5LJK/ref=oh_details_o05_s00_i00?ie=UTF8&psc=1


No Relay!! Connected the R & W wires from the insert to the Rh and W on the tstat and the transformer wires to Rc and C on the tstat. Everything works as expected and measured output volts at the insert terminals is not changed by the 24V at the Rc and C connectors.

Cons:
- no support for an outside or indoor sensors on the tstat
- the website is very basic, current tstat settings only and email notifications on temperature changes above or below settable thresholds. No temperature history or when the tstat called for heat like the Nest models.
 
bjosephwombat said:
Thanks for all of the postings. Using information here and a few other places i installed a wifi tstat for a millivolt gas fireplace insert over the weekend.

tstat: Honeywell RTH8085WF

transformer: http://www.amazon.com/gp/product/B0007N5LJK/ref=oh_details_o05_s00_i00?ie=UTF8&psc=1


No Relay!! Connected the R & W wires from the insert to the Rh and W on the tstat and the transformer wires to Rc and C on the tstat. Everything works as expected and measured output volts at the insert terminals is not changed by the 24V at the Rc and C connectors.

Cons:
- no support for an outside or indoor sensors on the tstat
- the website is very basic, current tstat settings only and email notifications on temperature changes above or below settable thresholds. No temperature history or when the tstat called for heat like the Nest models.
Click to expand...

Glad you got it to work!

Not sure which Honeywell stat that is. I have never seen that model number. I assume its one of their "wifi" models.

For Honeywell stats to be able to utilize indoor and outdoor sensors you need to go with their "redlink" versions and accessories. They connect to the internet via a redlink gateway which costs about $100. I use that system in my house where I run 4 separate zones (basement, 1st floor, second floor, and pellet stove). It is a little pricey up front but IMO worth it hands down in the long run.

The decent redlink millivolt honeywell stat costs about $100-120, internet gateway about $100, outdoor sensor about $50. So all in around $250. In addition you can had multiple "averaging" wireless indoor sensors and handheld remote. Not sure what the wifi version of the Honeywell stat costs, but I am going to bet around $200-300, so its pretty much a wash.

Ryan
 
Last edited:
bjosephwombat said:
Thanks for all of the postings. Using information here and a few other places i installed a wifi tstat for a millivolt gas fireplace insert over the weekend.

tstat: Honeywell RTH8085WF

transformer: http://www.amazon.com/gp/product/B0007N5LJK/ref=oh_details_o05_s00_i00?ie=UTF8&psc=1


No Relay!! Connected the R & W wires from the insert to the Rh and W on the tstat and the transformer wires to Rc and C on the tstat. Everything works as expected and measured output volts at the insert terminals is not changed by the 24V at the Rc and C connectors.

Cons:
- no support for an outside or indoor sensors on the tstat
- the website is very basic, current tstat settings only and email notifications on temperature changes above or below settable thresholds. No temperature history or when the tstat called for heat like the Nest models.
Click to expand...

First time poster so be kind...=). I'm so trying to follow your lead, but have hit a roadblock. I have a gas insert fireplace by Kingston (ZDV4236) that I want control wirelessly via the Honeywell. I picked up the RTH6580 tstat (same as yours but with hard buttons/not touchscreen-enabled) and the same transformer. I did NOT pick up the relay identified in the original post. I am currently using a Skytech 5301P to regulate temp without issue, save for the no WiFi of course...=). I had an electrician friend stop by and run power from the 24V transformer to where the Skytech is/Honeywell will be. There was a red and black wire that ran from the millivolt valve terminal block to the Skytech. We plugged the 24V power and the red and black wire into the thermostat. Thermostat powered up, I registered it on Honeywell's site, and controlled it from my notebook. All good on that side but unfortunately the most important part isn't working: I can't get the fireplace to kick on. I set it to HEAT, cranked the temp to 90, and let it sit. Nothing. Fireplace would not kick on. I'm thinking we didn't have the red and/or black wires from the millivolt terminal block plugged into the right spot on the thermostat, but maybe it's something else. Any thoughts/guidance would be appreciated.
 
This is a guess.....
Is the fireplace looking for a 24v signal, and the t-stat is merely dry contacts?
 
WoodPorn said:
This is a guess.....
Is the fireplace looking for a 24v signal, and the t-stat is merely dry contacts?
Click to expand...
That's exactly what my electrician was thinking, given that the Skytech has 4 AA batteries in its "On/Off/Remote" transceiver box...the box that the red and black wires from the millivolt terminal block ran into. If that's the case, and given the available 3 connectors on the millivolt terminal block (marked TH TP, TP, and TH respectively), any thoughts on where to run 24V power back to it? The red and black wires currently are connected using the TP TH and TH connectors on the terminal block.
 
I believe this is where the cube relay comes into play. If you look back at P1, SMWilliamson's schematic shows the tstat powering the coil on a cube relay and closing the contacts on the stove, kinda backwards of my previous post but the same principal. Look into the stove owners manual and see what it is that the stove is looking for (signal)
 
The relay contacts simply provides a contact closure for the millivolt circuit. The power for this circuit comes from a thermopile in the fireplace that is heated by the pilot light.
The 24 Volt circuit involves the thermostat, transformer and relay coil, all in series.
When the thermostat closes it's "contacts" it activates the relay.

If a thermostat can be set up for "dry contacts" you can connect it directly to the fireplace. Dry contacts means that it doesn't provide any Voltage to the load. This is usually set up by removing a jumper on the thermostat terminal board. You will have to read the manual for your thermostat to see if it is able to operate in that mode.
 
Hi guys, thanks so much for posting this info. Can you help me with the wiring for the relay.
I check out the website and don't understand the schematics. I posted the URL below. Basically 24volts on one side and Millivolt on the other but I can't tell how to connect it.


(broken link removed to http://www.functionaldevices.com/pdf/datasheets/RIBU2C.pdf)


smwilliamson said:
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!

View attachment 112141 View attachment 112140
Click to expand...
 
What kind of stove do you have, Dditillo? Most don't need all this fancy wiring. smwilliamson is really talking about very sophisticated thermostats. The normal kind you see that are programmable, have digital clocks and readouts like you see on most of those in HD and Lowes just have a couple of AA batteries in them and simply complete the circuit from two terminals on most stoves except some Harmans. You want to do some research however and find ones that have 'swing' adjustments on them. Most of the Honeywells I've studied do NOT. The Lux and mine do have the swing, which allows you to adjust the time between each startup by widening the on and off temperature set points. You can read the manuals for them on the HD site.
 
Now my curiosity has been peaked. I originally had a Nest installed for my oil furnace (prior to the pellet stove) and I loved it. Once I got the pellet stove, I sold off the Nest to recoup some cost since the oil furnace was rendered (mostly) irrelevant. I do have the common wire available to power the Nest and that worked. I'm wondering if I could wire a relay in line and have the P43 as the primary and the oil as the secondary...
 
Sorry for being dark for a while as I hadn't been back to my place since March. Good news: Putting in the relay as indicated in smwilliamson's first post on this thread got everything to work! The Honeywell 8580 is now firing the Kingsman Marquis millivolt fireplace and I can control the tstat via the Internet remotely! All good, but just one remaining question. Instead of an RIB relay, my electrician had an IDEC relay and when it powers on due to the temperature falling below the tstat heat setting, the fireplace turns on but there's an audible buzzing sound coming from the millivolt connectors/unit on the fireplace. Is this being caused by the IDEC plug in he's using, or the IDEC in general? Should I switch to the RIB U1C?
 
spaceboyusa said:
Sorry for being dark for a while as I hadn't been back to my place since March. Good news: Putting in the relay as indicated in smwilliamson's first post on this thread got everything to work! The Honeywell 8580 is now firing the Kingsman Marquis millivolt fireplace and I can control the tstat via the Internet remotely! All good, but just one remaining question. Instead of an RIB relay, my electrician had an IDEC relay and when it powers on due to the temperature falling below the tstat heat setting, the fireplace turns on but there's an audible buzzing sound coming from the millivolt connectors/unit on the fireplace. Is this being caused by the IDEC plug in he's using, or the IDEC in general? Should I switch to the RIB U1C?
Click to expand...
Something's getting too much juice
 
This is a great post, now if I can ask you professionals a question. I would like to hook a wireless tstat to my quadrafire mt. vernon and have the tstat located where my ac/furnace tstat and my whole house swamp cooler tstat are located. The reason for wireless is the design of my attic and location of the stove will make it tough to run tstat wire. Do I have any options for a wireless tstat?
 
Hi all, have a current 2 wire millivolt Napoleon gas fireplace for summer home, heat only no AC. I am interested in installing the Honeywell wifi thermostat RTH9580WF sold at HomeDepot and have also heard that this stat may be able turn on my millivolt system without using a Relay. Similar to bjosephwombat. I plan to add 24volt plugable tranformer. I know Honeyewell mentions in the user manual this termostat do not work with millivolt system. Though I wonder if that is just because it requires a 24volt transformer, not able to get straight answer out of them as to why it would not. A couple of questions.

I plan to connect like this:
Transformer wire: White (24v) transformer wire to C and black (0v) transformer wire to RC of thermostat
Heat system wire: White wire to W and red wire to R on thermostat

Question:
1. Do I really need to remove Jumper from RC+R? I do not have any other elements such as AC, just heat only system.
2. When the heat turns on from tstat what voltage should I expect to see coming from W and R on thermostat to the fireplace gas valve?
3. Do these 24 volt thermostats actually send voltage to the millivolt valves or just close circuit to start heat system?
 
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