Boiler + Wifi Thermostat + C-Line Adapter Question

CIPHERSTONE

My search fu isn't great here. Situation:

Boiler :
Peerless Boiler MI
https://www.peerlessboilers.com/wp-content/uploads/2016/08/MIMIH_II_IOM_web0419.pdf

Current thermostat:
Ancient Honeywell

Current Wiring (from boiler):
Red wire, white wire

New Thermostat:
YoLink Thermostat
https://support.yosmart.com/hc/en-001/articles/17921808844697-YS4003-YoLink-Thermostat-User-Manual

24V Plug in Transformer
Plug 1: 24v
Plug 2: 0v
https://www.amazon.com/Thermostat-Transformer-Compatible-Honeywell-Doorbells/dp/B08ZN4D751

Testing the thermostat at home, if I wire the 24v terminal on the adapter to the "C" connector on the thermostat, and the 0v connector on the adapter to the "R" connector for the thermostat the thermostat powers on. Attempts to wire the 0v wire to something else besides "R" on the termostat

The thermostat only has one "R" connector, which it lists as:

C C or COM 24VAC COMMON TYPICALLY CYAN, SEE NOTE #1
R R, RC, RH 24VAC POWER TYPICALLY RED

I would like suggestions on how to hook this up at the house. My goal is to avoid damaging the boiler.

Would I for example:

Option A:
Adapter 24V Wire to YoLink "C"
Adapter 0V Wire to YoLink "R"
Boiler "R" wire to YoLink "R"
Boiler "W" wire to YoLink "W"

Option B:
Adapter 24V Wire to YoLink "C"
Adapter 0V Wire - leave unused - Tested leaving 0V wire disconnected at home with just the 24V wire to YoLink "C" and thermostat would not power on.
Boiler "R" wire to YoLink "R"
Boiler "W" wire to YoLink "W"

Option C:
Return YoLink for a thermostat that has a dedicated/seperate "R" and "RC" inputs.

Option D:
Some other config

Option E:
Break down and call boiler tech, pay a ton of money

Honestly, any reply here I will appreciate more than you can imagine. Thanks in advance.

CIPHERSTONE

Advice given to me on another source:

Your problem is that you need another wire for C wire. So you have one for R, one for W and one for C. Think of it as a circuit. Power goes from the boiler transformer and into the thermostat from R and leaves the thermostat and back to the transformer on C. The W wire is another path, but that triggers the boiler to run. So you are short a wire.

This would seem to suggest my only real course of action is:

Thanks pandaman that is helpful. Seems like the options I have are:

A) buy a different thermostat that has a dedicated C and RC separate from R and W. Use the adapter I have on C and RC and keep boiler R and W isolated to R and W.

B) contact my boiler hvac and see if they can add a C line to the boiler itself so that R, W and C would all be supplied by the boiler to use the current thermostat which I have an interest in to use in conjunction with other home automation devices. (Return the 24v adapter I bought)

Jamie Hall

24 volt from adapter to R

0 volt from adapter to C

red from boiler to R

white from boiler to W

HVACNUT

Its only a 2 conductor thermostat wire? You're sure there's not a third wire that's wrapped around the bottom or was cut off?

Whether you have the Beckett or Hydrostat, both have 30 va transformers and are capable of handling the load of one 24 volt powered thermostat if there is a third wire.

I've never heard of YoLink, but it reminds me of The Mod Squad.

CIPHERSTONE

https://forum.heatinghelp.com/discussion/comment/1848000#Comment_1848000

I didn’t see another wire but I’ll admit that I need to take a second look to see if one was cut off in the casing.

Yolink makes a ton of different smart sensors you can use in home automation. I have one of their external theme sensors in my outdoor well pump room.

For example you could place water sensors inside under different thing and have a plumber install a water shutoff device on your main and if a water sensor detected water the water main device could auto shut off water inside the house etc.

This is for a remote house 1.5 hours away so being able to remotely check on things is helpful especially lately with the arctic weather.

CIPHERSTONE

Having two 24v sources running into R won’t be a potential issue?

Derheatmeister

IMO….Add a Stat/Fast-Stat "Common maker"… Or a 2 wire Tekmar 564.

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1848011#Comment_1848011

Not a problem.

On using "smart home" devices. Remember two things. First, reset the user name and password on every single one. It doesn't have a user name and password? Don't connect it to your home network, unless you want the whole world on that network.

Second, remote sensing is wonderful — but remember that if the power fails (say in a storm), so will all your remote sensing stuff, unless you have an automatic changeover generator…

Derheatmeister

https://forum.heatinghelp.com/discussion/comment/1848017#Comment_1848017

One would still have access to the Thermostat if a UPS is installed to power the Router and the thermostat. 😉. Edit: Our newest router from Comcast even has a backup battery and a Cell number.