Weil McLain and zone valves

kevsul1

I have a Weil McLain cga-5-pidn that I’m switching the three zone valves to taco 3 wire. The boiler has 2 wires labeled “stat” and 2 wires labeled “R” & “C”coming off the controller inside can tge “stat” wires be used as my TT wires for the zone valve end switch? I’m thinking I can’t…. I have 24v on one of the stat wires and when I wire it straight to the thermostat in the space the boiler fires up which is great but I need to incorporate the zone valves. Any help advice or suggestions would be helpful thank you.

Ironman

Here’s the diagram:

unclejohn

You should use a isolation relay to separate the thermostat and zone valves from the boiler controls.  The zone valve energizes the relay and wire the open relay contacts to your boil tt. 

Ross_7

Here's a diagram. Courtesy of Raypak. Please look on page 22.

EBEBRATT-Ed

I have wired the Taco valves bot ways with and without an isolation relay. I prefer using rib relays because the indicator light tells me when the valve is open and the end switch has closed and I don't like intermingling transformer wiring which gets confusing.

I don't really like the idea of wiring them without an isolation relay but it does work and as Taco explains in there instructions the two transformers are only connected in one location so it's not an issue.

I like the Taco valves as they have a higher Cv than other valves of the same pipe size but I would prefer them even more if they were 4 wire.

Seems to me Taco could easily make a 4 wire actuator for the existing valves. In fact they could bring the 4th wire out and have 4 terminals and you would just install a jumper to use it as a 3 wire for existing installations

kevsul1

kevsul1

This is how I wired the boiler first and it smoked my transformer. I believe because I have 24v on one of my “tstat” wire what this diagram is calling TT wires so when my end switch made it shorted out. I was going to wire it like this when I go back to see if this works. 

kevsul1

Ironman

Look at my diagram again. 2&3 go to “TT”, not 1&3.

Use “C” to feed the thermostats.

EBEBRATT-Ed

@kevsul1

What @ironman said + you can't power 3 zone valves off TT on the boiler, the transformer is not large enough and will smoke. You need at least a 40 va transformer for 3 zone valves. 50 va is better

Ironman

EBEBRATT-Ed said:

@kevsul1 What @ironman said + you can't power 3 zone valves off TT on the boiler, the transformer is not large enough and will smoke. You need at least a 40 va transformer for 3 zone valves. 50 va is better

Also: make sure that both transformers have their hot and neutral connected at the same points so they don’t buck each other.

STEVEusaPA

I think I would just get a Taco zone valve control and make it simple.