wiring a Taco SR-506 with heat exchanger

[Deleted User]

You can't do this with a single SR, but you can definitely do it with two.

You'd connect the two pumps on the far side of the heat exchanger to the second SR. Wire the XX terminals on the second SR to a zone's TT pair on the existing SR, and run the HX pump through that zone's circulator contacts. Leave the rest of the zones and their pumps wired into the existing SR.

When either of the zones behind the heat exchanger call, the second SR will turn on the correct pump and close its XX contacts. The existing SR will see that as a call from the HX, and turn on the HX pump. It'll close its own XX contacts as well, so the boiler's aquastat will also see the call.

Mark

aktom

wiring Taco SR-506 with heat exchanger

system is P/S with 3 loops using secondary(including heat exchanger) and 3 pump loops that use the heat exchanger. Currently the the heat exchanger pump is wired in to the boiler primary loop pump so both pumps come on when boiler tt is activated. Is there a way to wire this controller so the heat exchanger pump comes on only when a zone using the exchanger calls for heat?

carol_3

Are you using zone valves, and if so do they have end switches. If so, it seems you could use the end switch to bring on the appropriate heat exchanger pump.

aktom

No zone valves just pumps, grundfos 15-42. enclosed is a drawing of the system. What I want to do is when a thermostat calls for heat in a zone served by heat exchanger the pump for the zone comes on, the boiler comes on with TT connection and the heat exchanger pump comes on. Currently the heat exchanger pump comes on any time any zone calls for heat. Thanks and Have a very Pleasant Thanksgiving.

[Deleted User]

Need another SR

You can't do this with a single SR, but you can definitely do it with two.

You'd connect the two pumps on the far side of the heat exchanger to the second SR. Wire the XX terminals on the second SR to a zone's TT pair on the existing SR, and run the HX pump through that zone's circulator contacts. Leave the rest of the zones and their pumps wired into the existing SR.

When either of the zones behind the heat exchanger call, the second SR will turn on the correct pump and close its XX contacts. The existing SR will see that as a call from the HX, and turn on the HX pump. It'll close its own XX contacts as well, so the boiler's aquastat will also see the call.

Mark

[Deleted User]

Need another SR

You can't do this with a single SR, but you can definitely do it with two.

You'd connect the two pumps on the far side of the heat exchanger to the second SR. Wire the XX terminals on the second SR to a zone's TT pair on the existing SR, and run the HX pump through that zone's circulator contacts. Leave the rest of the zones and their pumps wired into the existing SR.

When either of the zones behind the heat exchanger call, the second SR will turn on the correct pump and close its XX contacts. The existing SR will see that as a call from the HX, and turn on the HX pump. It'll close its own XX contacts as well, so the boiler's aquastat will also see the call.

Mark