using diodes in ac circuit ....please help!!!

[hvacr9]

I have a hot water heat project that has 6 zones.6 seperate pumps are powered by six seperate spst 24v coil relays.I now have added another circuit that I want powered whenever any ONE relay is energized.

Can I just use six diodes one off of each hot leg of coils down to the added circuit relay.

Is there another way or am i way off track?

Im trying to avoid having to buy 6 dpdt or dpst relays since I already have panel wired and just currently want to add circuit.

Any help or suggestions on how to achieve this would be greatly appreciated !!!!

 

[Willbe]

Can I just use six diodes one off of each hot leg of coils down to the added circuit relay.

Sounds like no, but post a schematic.

 

[hvacr9]

basically the common leg on all relays are daisy chained together.Each thermostat will close when ther is a call for heat and 24 vac goes to other leg of coil.I want to power one more relay with 24vac off each thermostat relays without the current backfeeding to unenergized coils.Im not an electronics person whatsoever,just good with relay logic and am trying to keep from changing all the relays to accomplish this task

 

[KMoffett]

If your new (AC?) relay will work with half-wave rectified 24VAC, then diode OR'ing it to the other relays should work. I would try it with one diode and the relay, to see if it pulls in and drops out appropriately, first. The other possibility is use a 24VDC relay and filter capacitor...with the diode OR circuit.

Added: I just tried running a 6VAC relay (didn't have a 24VAC) with just a diode from a 6VAC transformer. It pulled in, but buzzed loudly. Added a 500µF/16V capacitor across the relay coil, and it worked perfectly. I think your idea will work.

Ken

 

[Willbe]

If your new (AC?) relay will work with half-wave rectified 24VAC, then diode OR'ing it to the other relays should work. I would try it with one diode and the relay, to see if it pulls in and drops out appropriately, first. The other possibility is use a 24VDC relay and filter capacitor...with the diode OR circuit.

Added: I just tried running a 6VAC relay (didn't have a 24VAC) with just a diode from a 6VAC transformer. It pulled in, but buzzed loudly. Added a 500µF/16V capacitor across the relay coil, and it worked perfectly. I think your idea will work.

Ken

If there's no downside, that's a pretty good trick!