line voltage control to 2nd zone pump


Old 10-15-10, 12:02 AM
milmut_doinit's Avatar
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line voltage control to 2nd zone pump

hi I'm trying to add a second zone to an older weil mcclain furnace (boiler). I have hydronic heat, so the second zone will have a circulator pump. how do I get power to that second pump and control that second pump (the 2nd zone) with a separate thermostat? it seems that I need another relay switch installed, do I or is there a way to rig the line voltage to come on separately for each circulating pump based off of the current "fan center" relay mounted on the junction box within the furnace housing?

p.s. the relay says
the contacts are labeled 1-6, but 2 and 5 seem like there is no metal contact (which I would think that's where the other controlled pump would be connected to if there were contacts)
thanks for the help
Old 10-15-10, 06:56 AM
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I moved you over to the boiler section, since I have not been around boilers much. someone here should be able to help out.
Old 10-15-10, 10:55 AM
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You sed "a second zone", so I believe that means that you currently have one pump that is wired to the control center on the boiler, and your thermostat is also wired directly to this control center...

There are two ways to set up zones:

1. Using ONE pump, feeding a 'manifold' on which are mounted electric 'zone valves' which would open and close depending on which thermostat was calling for heat.

2. Using individual circulators for each zone. In this case there are controls that would fire the boiler if EITHER thermostat called for heat, but only the pump for that zone would run.

You of course are talking about the second option.

In this case, there are a few things you will need to do.

You will need to isolate the first pump from the boiler control so that it may be switched independently of the other pump.

You also need to remove the thermostat wiring to the boiler.

You will need TWO relays... one for each pump. Each thermostat would wire to each relay. The relay would then do two things, fire up the boiler, and run it's associated pump.

OR a single panel such as a TACO SR-503 type. (Google it...) These panels have multiple 'channels' and all the wiring is self contained. There are terminal strips to wire the thermostats and the circs to, and for AC input to the panel. Another terminal strip is for the wires that go to fire the boiler. Probably about the same money as two separate relays, but less wiring.

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