Zone Valve Open, Circulator off

Neil_5

I have gas boiler, with a mono flow convector system. Had a Tekmar 256 installed with the system (new system Sept 04). Stats call for heat, open TACO Zone valve, etc. Since I have a tight curve, my circulator is pretty much on most of the time, however last night I discovered that when the boiler is off (not fired up) the circulator is off. So all along, when I thought the circulator was on, zone valve open, STAT calling for heat etc, the circulator was actually off. Will rewire to have the circulator on when the zone valve turns on.

My questions:

With this set up, circulator off and zone valve open, would I have some flow through the system and would it be sufficient to feed the convectors off the mono flow line? Was I just heating the main pipe (via gravity) all along?

Is is more efficient the old way (circulator off, zone valve opnen) or the new way both zone and circulator on together?

Neil

STEVE N

I think

Your problem may be that your circ it still tied into the aquastat on the boiler. If so.. on reset it kills the burner which kills the circ. If you are using zone valves, you need to install a single zone control with the end switchs from the zone valves connected to the TT on the zone controller. The line side of the controller then goes to the circ. Without seeing it... its hard to tell but this could be your problem.
steve

Joe Mattiello

Taco Zonevalves

Well, it’s great to hear the Taco zonevalve is still operating when the thermostat closes on temperature fall. Not that I’m surprised. However you did pique my interest, who was the manufacturer of the circulator? Anyway, if the circulator is not running, but the valve opened, you will get some flow through thermal siphoning, like the old gravity systems. Unfortunately, it’s difficult to determine the amount of flow if it’s sufficient to satisfy the load. Additionally, as the water cools the flow slows down, so stick with the circulator


Taco, Inc.
Joe Mattiello
Technical Service Technician
joemat@taco-hvac.com
401-942-8000 X 484
www.taco-hvac.com

eleft_4

Neil,

as long as there is a call for heat the circulator is kept running by the aquastat if connected to the circulator terminal at the aquastat. It sounds like it's on the B terminal.

The pump should be connected to the wires coming out of the back of the 256, anyway

al

Neil_5

Problem Solved

256 was set up to turn on/off entire system, independent of the end switch from the taco zone valve. Rewired the pump and all is well.

Thanks,
Neil