Heating Help

New Thermostat 3 Wire Hot Water Boiler System

I have a 3 stage hot water boiler system with three different thermostats in my house. I went to change out the first thermostat downstairs with a new digital that said it was compatible with a hot water system. The only thing is the wiring diagrams are different, the three wires I have on my old edwards engineering thermostat are W6 , R5 , and 4B .. Could anyone shed some light on which socket these wires go in on a new digital, or if this will even work at all. I really need to change it out because its hard to set accurately because the old lens is faded pretty bad.

Thank you for your time,

The other end?

Where do the wires go on the other end? It sounds like you have a 2 stage t-stat but it could be something else.

What type zone valves do you have?

Are they White-Rogers 1311 style perhaps? If so, 4 is power open, 6 is power closed, and 5 is common. But not all digital stats will work with these. You can call the tech support number on the literature and find out. Some stats will work after changing one of the settings in the setup program. White-Rogers has a digital that is compatible.

thanks

Thanks for the help. The wires are not colored and I are all grey.. I have included a picture if that helps..

Looks like three-wire snap contact type thermostat

but down by the boiler there should be Zone Valves (look like grey boxes with wires going to them).