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[atvalaska]

    been a while since I've had to wire up a boiler system here is a pic of what I want to do ...seems I need a relay to get her done..

[slimjim]

I don't understand what you are looking to do.

[atvalaska]

upper left hand conner ... I need 24 volts to the heat dump z-valve 24/7 ......and I need the 24v Honeywell "damper/air inlet" to  open when the fans come on ...I guess i'm  looking for where to go from the 24VAC  I can wire it to the zone valve ...good...but I need the 24v h-w damper to open when the 120v fire fans kick on ...  how's that ?

[RSI]

I just glanced at this quickly so I hope I read it right.

You have 24v always going to a zone valve keeping it closed. When you lose power or hit high limit it opens?
You want to use the same transformer to power a 24v damper for the draft?

For the 24v damper coming on with the fan, I would just use another transformer and connect it to the same power as the blower and then connect the 24v side directly to the damper.
If you prefer not to do that, it you will need a relay with a 120v coil. Just connect the coil to the same power as the blower and run 24v through the contacts. Or if your aquastat happens to be 2 pole you could run 24v right through that.

[atvalaska]

cool.... z valve says closed ,as long as power is on ...its a safety/heat dump and opens when power is out  ..i figured that  I could power up 1/2 of the transformer and let the "fan" run the other leg ...did not want to buy yet another transformer    what relay and how to wire it ...i'm good a following pics 

[slimjim]

Nice reading RSI, I couldn't understand what he was doing!

[RSI]

No, you can't power the transformer from 2 sources.

A relay probably won't be any cheaper than a transformer and will be more complicated to wire.

If you want to go that way anyway, you would just get a relay with a 120v coil and run the coil wires to the hot and neutral supply going to your fan motor.

Then you would run a wire from the transformer to the common terminal on the relay, run a wire from the normally open contact on the relay to the damper. Then run a wire from the other side of the damper to the other side of the transformer.

[atvalaska]

u rock bud ..I was up there looking at my sit-rep   and u nailed it!   beers to ya!