Looking for wiring advice for WiFi thermostat(s)

[Athlon]

I'm considering either 3 Nest E's or 3 Ecobee Lite's for my 3 zone system.  I only have 2 wires at each thermostat, so I need to get a C-wire or equivalent to each.

 

Some years ago I replaced the original mercury thermostats with programmable ones. 

 

A picture of the inside of one is here (2 wires with a jumper connecting RH and RC):

 

 

 

At the boiler (oil), I have 3 Honeywell zone valves with thermostat wires connected to the top of them - picture here:

 

 

 

The connections (5) on top of them are labeled: END, SWITCH,  TH/TR, TH and TR - picture here:

 

 

 

The wires all seem to go up to a transformer on the ceiling above the boiler, pictured here:

 

 

 

I need to add a C-wire to my system, and supposedly a FAST-STAT Common Maker will substitute for that.

 

Here's my question - Can I make those WiFi thermostats work with a FAST-STAT Common Maker?  The reason I'm asking is I could not find a wiring diagram with the FAST-STAT Common Maker that looked like my system.

 

Link to FAST-STAT Common Maker: https://www.fast-stat.com/

 

FAST-STAT Common Maker suggested wiring diagrams:

 

https://www.fast-stat.com/wp-content/uploads/2019/11/Instructions-Common-Maker.pdf

 

https://www.fast-stat.com/wp-content/uploads/2018/09/Common-Maker-Additional-Wiring-Diagrams.pdf

 

 

 

 

 

[larryllix]

I doubt the "common maker" will do the job. The units I have seen steal some power from all the wires coming into the stat. This can cause problems for some systems being overly sensitive to the leakage current they "steal". With electromechanical valves that shouldn't be a problem.

If you endure extreme cold weather the battery in the stat may go dead with that technique. It relies on the "stolen" currents to keep the battery charge between closed contact times. If those times are too long the stat can die. A hardware C wire is best.

If you do run a new wire make it a 5 or 6 conductor cable. Tug on the stat end of the cable and have somebody watch the HVAC equipment end to see if the new one could be just pulled through on the old cable. Hopefully you would have easier access to get a new one in.

For HA IMHO, ecobee is the preferred stat over Nest. With all the friction google has created lately I would avoid them and with my son's having three Nest units, most of the cool automatic features get disabled after years of frustration with temperatures not ever satisfactory.

If you are running three solenoids in parallel, you could have a contact overload problem, with any of these newer stats. I would hope there would be some kind of controller box in between, to buffer the heat requests and allow a time delay for the valves to open, before firing up  a heat flame  that cannot be dissipated into the radiators.

Ecobee stats come with a built in common wire "common maker" that can be removed or disabled IIRC.

[paulbates]

I don't think add wire works power C wires. If you can install it cleanly, and from the back, you could get 3 small 24vac transformers and power at the thermostat to not have to pull more wire

Paul

[Athlon]

@larryllix Thanks for the quick reply.  I am leaning toward the Ecobee's based on comments here and in other threads.

I thought I would need 3 of the FAST-STATS.  They seem to work for others who have posted around the 'net. I just don't see how to wire them for my setup.

I thought about pulling new wires as you say. It's quite some distance for two of my thermostats - my guess is they are stapled somewhere. Fishing new wires would be very difficult for at least one of them.

 

[Athlon]

4 minutes ago, paulbates said:

I don't think add wire works power C wires. If you can install it cleanly, and from the back, you could get 3 small 24vac transformers and power at the thermostat to not have to pull more wire

Paul

Although it would take some work to hide each of them, that me be my best option. Thanks for the idea.

[larryllix]

1 minute ago, Athlon said:

Although it would take some work to hide each of them, that me be my best option. Thanks for the idea.

Ecobee stats come with a built in common wire "common maker" that can be removed or disabled IIRC.

[Athlon]

12 minutes ago, larryllix said:

Ecobee stats come with a built in common wire "common maker" that can be removed or disabled IIRC.

It does, but their PEK will not work with a 2 wire system.

[Athlon]

The Ecobee website sent me to the FAST-STAT website, by the way, after I went through their 'will it work for me' tool. That's how I found that device.

[larryllix]

38 minutes ago, Athlon said:

The Ecobee website sent me to the FAST-STAT website, by the way, after I went through their 'will it work for me' tool. That's how I found that device.

I suspect their PEK would work with electromechanical valve loads. However the question still remains whether you have a zone control panel. If you are sure those cables go right to the valves and not an electronic load, the chances are good. The PEK circuit may not try to steal any power from only a two wire connection. Ecobee has no internal battery so I guess I would buy the three and try one, opening the package carefully, if you know what I mean. Rewire the two, if you can and search for another answer for the third.

BTW: I have an ecobee3 and ecobee 4. I wouldn't spend the extra money for ecobee4. I have tried to enable the Alexa features a few times and each time I turn it off again. Very poor sound reception against a wall, doesn't support 5Ghz, won't support many of the newer Alexa features.

[Athlon]

4 minutes ago, larryllix said:

I suspect their PEK would work with electromechanical valve loads. However the question still remains whether you have a zone control panel. If you are sure those cables go right to the valves and not an electronic load, the chances are good. The PEK circuit may not try to steal any power from only a two wire connection. Ecobee has no internal battery so I guess I would buy the three and try one, opening the package carefully, if you know what I mean. Rewire the two, if you can and search for another answer for the third.

BTW: I have an ecobee3 and ecobee 4. I wouldn't spend the extra money for ecobee4. I have tried to enable the Alexa features a few times and each time I turn it off again. Very poor sound reception against a wall, doesn't support 5Ghz, won't support many of the newer Alexa features.

I'm not clear on what you mean by that (highlighted your post). I have no idea which wires (connections) to use if I try the FAST-STAT. I'm clear on the thermostat end of the device, but not so much at the boiler end for me.

And, yes, the wires from the thermostats go to the zone valves I pictured above.

I can get the Ecobee Lite's for $70 each between now and the end of the year from my power company. It's a great deal for sure. I'm allowed no more than 3 for the deal, and I'm sure I can purchase them one at a time if I want to experiment. But I don't want to even do that if I have no idea where to start with the boiler end of the FAST-STAT.

[larryllix]

5 minutes ago, Athlon said:

I'm not clear on what you mean by that (highlighted your post). I have no idea which wires (connections) to use if I try the FAST-STAT. I'm clear on the thermostat end of the device, but not so much at the boiler end for me.

And, yes, the wires from the thermostats go to the zone valves I pictured above.

I can get the Ecobee Lite's for $70 each between now and the end of the year from my power company. It's a great deal for sure. I'm allowed no more than 3 for the deal, and I'm sure I can purchase them one at a time if I want to experiment. But I don't want to even do that if I have no idea where to start with the boiler end of the FAST-STAT.

You had posted you thought you could rewire two of the three stats. I would do that and figure out a way to handle the third ecobee. Their PEK (supplied) may not do the trick but if their advice is suggesting another route then upgrade your installation thinking to that. $70 is very cheap but I am "used to" Canadian prices.

Make sure you are not guaranteeing any utility you will always allow them to mess with your temperatures. The Nest agreements could be manually overrode when my sons got their deals.

I just realised something. You have three hot water zones and are using three stats, one for each zone?

[Athlon]

6 minutes ago, larryllix said:

You had posted you thought you could rewire two of the three stats. I would do that and figure out a way to handle the third ecobee. Their PEK (supplied) may not do the trick but if their advice is suggesting another route then upgrade your installation thinking to that. $70 is very cheap but I am "used to" Canadian prices.

Make sure you are not guaranteeing any utility you will always allow them to mess with your temperatures. The Nest agreements could be manually overrode when my sons got their deals.

I just realised something. You have three hot water zones and are using three stats, one for each zone?

Sorry for any confusion. Yes - I have a 3 zone system. Heat only. Hot water system with oil fired boiler.

Two of my thermostats are far from the boiler - my guess is those wires cannot be pulled - they are very likely stapled somewhere. For me to even test that, I think I would have to get above the firewall above the 24v transformer pictured in my first post. The third stat is not as far, but is on the other side of a load bearing wall (family room room over garage).

 

[larryllix]

Just now, Athlon said:

Sorry for any confusion. Yes - I have a 3 zone system. Heat only. Hot water system with oil fired boiler.

Two of my thermostats are far from the boiler - my guess is those wires cannot be pulled - they are very likely stapled somewhere. For me to even test that, I think I would have to get above the firewall above the 24v transformer pictured in my first post. The third stat is not as far, but is on the other side of a load bearing wall (family room room over garage).

 

ewwww. Usually running a new cable up to the attic, across and then down the stat wall is best, or the same method via basement. It can get complicated though.

For basement, I was taught to drill up through the bottom plate with a large bit ~3/4 - 7/8" and then drop a string with a nut on the end down from the stat hole. Keep bouncing and pendulumming the nut, until it drops through the hole. I did this once through two floors. You just keep bouncing until you feel the string go tight again.

[smacbride]

I had a similar system in my mountain house and I went with the battery powered GoControl Z-Wave thermostats.  I setup heating programs with an ISY box and used MobiLinc to turn them up from home before I went up to the mountains.  

Like you I was not able to pull new wires as they were stapled, and I didn't want to have an external power wart wire running down the wall. One of the thermostats didn't have a wall outlet below it either.

Something to think about.

[Athlon]

4 minutes ago, larryllix said:

ewwww. Usually running a new cable up to the attic, across and then down the stat wall is best, or the same method via basement. It can get complicated though.

For basement, I was taught to drill up through the bottom plate with a large bit ~3/4 - 7/8" and then drop a string with a nut on the end down from the stat hole. Keep bouncing and pendulumming the nut, until it drops through the hole. I did this once through two floors. You just keep bouncing until you feel the string go tight again.

I could try that - if I can get that done, I could power the stats from the basement with a dedicated power supply.

[Athlon]

6 minutes ago, smacbride said:

I had a similar system in my mountain house and I went with the battery powered GoControl Z-Wave thermostats.  I setup heating programs with an ISY box and used MobiLinc to turn them up from home before I went up to the mountains.  

Like you I was not able to pull new wires as they were stapled, and I didn't want to have an external power wart wire running down the wall. One of the thermostats didn't have a wall outlet below it either.

Something to think about.

This one? GC-TBZ48  https://www.gocontrol.com/detail.php?productId=3

How long do the batteries last? I'm assuming you do not have a C-wire attached.

[smacbride]

1 minute ago, Athlon said:

This one? GC-TBZ48  https://www.gocontrol.com/detail.php?productId=3

How long do the batteries last? I'm assuming you do not have a C-wire attached.

Yep, that's the one.  The batteries last about a year or so.  My system was only two wires, had the old mercury thermostats on the walls.

[Athlon]

1 minute ago, smacbride said:

Yep, that's the one.  The batteries last about a year or so.  My system was only two wires, had the old mercury thermostats on the walls.

Certainly an option - thanks. I have Alexa as well.

[Athlon]

I ordered one Ecobee Lite (decided on those) along with one of these:  https://smile.amazon.com/gp/product/B07HRK7CWX/

I'm thinking I can easily drop the cord down inside the wall and run it under the baseboard to the nearest outlet. Luckily, the outlet I'll use at each stat is hidden.

Funny thing is, about 5 minutes after I ordered them, Ecobee support got back to me - I emailed them last week with the same question I posted here.  They told me if I can find the Common connection on my boiler's control board I should be able to user the FAST-STAT device even though I have only 2 wires at each stat.

I think I'll be more comfortable with the device I ordered from Amazon at each stat.  I'll post back here when I have it working.

EDIT: I'll purchase the other two if I have success with this first one.

[paulbates]

I don't have an eco be but 300ma should be enough for each unit. However, I'd double check the eco power requirements. There's one comment for the transfomer about buzzing (its the one that's a 3 rating). You don't want to start off close or over the requirements

Paul

[Athlon]

5 minutes ago, paulbates said:

I don't have an eco be but 300ma should be enough for each unit. However, I'd double check the eco power requirements. There's one comment for the transfomer about buzzing (its the one that's a 3 rating). You don't want to start off close or over the requirements

Paul

Excellent point - did not think about that.  From the Ecobee website: 

Power Consumption: less than 3.5 VA

I'll have a separate one at each stat.

 

[paulbates]

If VA = V * A,  so, A = VA/V

If voltage is 24v and 3.5 is VA

A = 3.5 / 24

A = 0.145 = 145ma = I think you're good

@larryllix - does that look right? Larry knows his electrics

 

[larryllix]

18 minutes ago, paulbates said:

If VA = V * A,  so, A = VA/V

If voltage is 24v and 3.5 is VA

A = 3.5 / 24

A = 0.145 = 145ma = I think you're good

@larryllix - does that look right? Larry knows his electrics

 

Perfect. assuming the wall wart companies rate their outputs and not their consumption. I believe they do.
Their are class2 plug in wall warts with 24vac outputs but I think they are magnetic core transformers, create heat, and are inefficient.
Actually on second thought, with an AC output none of them are going to be switching powers supplies.

[paulbates]

11 minutes ago, larryllix said:

Perfect. assuming the wall wart companies rate their outputs and not their consumption. I believe they do.
Their are class2 plug in wall warts with 24vac outputs but I think they are magnetic core transformers, create heat, and are inefficient.
Actually on second thought, with an AC output none of them are going to be switching powers supplies.

In summary, @Athlon should be ok with a 300ma transformer per thermostat that is rated for less than 1/2 that

Paul

[larryllix]

3 minutes ago, paulbates said:

In summary, @Athlon should be ok with a 300ma transformer per thermostat that is rated for less than 1/2 that

Paul

YES. IMHO!

The strange electrical thing is, he will have to tie his live wires together at the stat. Two wires in a stat means live (R) and switched call for HVAC wire (W). To provide a common the stat he will have to feed the stat R and C with the transformer. The transformer will not provide any power to the HVAC system, only the stat.

If this is the route chosen and an inside wall, I would drill small hole above the baseboard, under the stat and use a curved coathanger wire to poke up through, to the thermostat hole. Fish your wallwart cable down and out the hole at the bottom, then run it along the top of the baseboard or in a grove of the baseboard, depending on style, to the receptacle. At least the wire running up the wall will be concealed. If there is already an existing cable down through the basement ceiling, you would know where the joist pocket is and could use the method I posted earlier.