Taco Zone valve voltage readings

Paul Fredricks_5

1 & 2 should have 24v going to them when the t'stat is calling. 2 & 3 is the end switch.

George_15

Taco zone valve voltage readings

Last week I had a problem with my Taco zone valves not opening. It turned out to be a loose wire and all 6 zone valves are working fine now. What I did notice, is that I still don't measure 24v AC at the zone valve terminals 1, 2 or 3 even when all is working fine now. Of course I do get 24 V at the output of the 2 transformers. Is there a reason for this?

I think that's what threw me off when I was trying to troubleshoot it last week and I wasn't getting 24v at the zone valves when all 6 were connected. Thanks!

jp_2

what were

you getting? 22V, 18V 12V ????

George_15

Actually I am not getting any voltage... just reading several mV. The zone valves are working though.

Should I be able to read a constant 24v at any of the terminals, whether open or closed?

Joe Mattiello

Taco 570 series zonevalve operation

The motor of the 571 is a heat motor. We energize an electric heater that is wrapped around a wax filled chamber. When the thermostat calls for heat, 24 volts is applied to the 22 ohm heater. when the valve has opened .125 to .150 " the heater is turned off. When the piston starts to retract, a leaf switch closes again, energizes the heater again until the piston has moved out to it's position, and then the heater is turned off. The heater is on for 10 seconds and off for 20 seconds. This cyclical process continues as long as there is a demand, and the end-switch terminals 2, and 3 stay closed. Attached is a old document that gives a good explanation of the zonevalve operation. Hopefully this helps you.