3 wire steam zone valves

TonyS

Restarting a steam system that has been shut down for 5 years. Zone valves are Honeywell 3 wire R W B connected to Honeywell 3 wire t 87 fs. What do I need to do to convert these zone valves to 2 wire stats?

Dave in QCA

You Can't

On this type of setup, one wire is common, one wire opens the valve, the other wire closes the valve.  It simply requires 3 wires.

Why to you wan't a 2 wire thermostat?

Unknown

TonyS

It depends on the type of valve you have,, as far as I can see Honeywell only has 1 spring return actuator.

http://customer.honeywell.com/TechLit/pdf/63-0000s/63-1257.pdf

TonyS

I was looking for a way to use

an off the shelf Tstat. I suppose I could incorporate a double pole relay to energize the off cycle. Thanks

TonyS

I will have to get

the model numbers Dave. They look pretty old. They are not spring return and they use a cam to close an isolated end switch that in turn completes the circuit on this millivolt steam boiler. 

nicholas bonham-carter

valve changeout

http://www.valvestore.com/



these people have all sorts of valves-can you change the ones you have now for new ones?--nbc

Dave in QCA

you could keep the t87f

You could save money on the job and keep the T87F thermostats.  They are about as reliable as they come.

If you are looking for something that is programmable, there are plenty of those available that are 3-wire.  Should'nt be that hard to find them, there are plenty of those good old 3 wire zone valves around.  They don't stick open or closed, they just keep working. That's probably why Honeywell doesnt make them anymore, too reliable!

Dave in QCA

Here's a 3-wire programmable heat only T'stat

http://www.amazon.com/White-Rodgers-1F80-0471-Programmable-Non-Programmable/dp/B0035UGKJM