Taco ZVC403 not turning on boiler pump on one zone

williamrbecker

Hi, any help would be great...this system worked well for me the last 10 years but Zone 1 is now not working. Zone 1 has both a timer and a sensor to turn on the pump. Last year it became intermittent, this year inoperative for both the timer and sensor. Zone 2 and 3 are on timers and both work fine. The Taco green light is on, and the zone 1 red light and yellow light are illuminated but pump is not on. I do notice in this case that the red light is somewhat fainter and flickers a bit. Could that mean the zone 1 valve could be stuck midway and there is not enough flow to trigger the boiler pump?When I turn on zone 2 or 3 fluid is passed through zone 1 as well and the zone 1 red light lights up bright, so the zone 1 valve I believe is open. Any ideas?

STEVEusaPA

What kind of 'timer' and 'sensor' are you talking about? And how do they fit (wiring/operation) into the picture.
Do you have any pictures?

williamrbecker

Thanks! The timer is an Intermatic spring wound interval timer (you twist it to turn it on for the number of hours you want). The sensor is a Tekmar Ice Sensor 090 that is part of an automatic snow melt system, Tekmar Show Detector and Melting Control 665. Both the timer and the snowmelt system charge or cross two wires to activate the boiler and pump. These two wires meet at the same point at the Taco ZVC403 zone 1 connector.

GW

Try disconnecting the the zone valve wires And thermostat wires for that particular zone. then jump your r w. Does the light now look normal?

Solid_Fuel_Man

Is there an end switch on this, or are #3 and #4 jumped?