TACO SR501

Darren_14

you can do it. I've attached a drawing that should work, like others said it kind of depends on the rest of your controls and how fast the valve opens.

chuck172

TACO SR501

Can the TacoSR501 relay, controlled by a thermostat, be wired to operate both a circulator and a 24 volt zone valve simultaneously?

JohnNY

Yes.

I would think N and 4(N.O.) to the pump.

R (assuming that's the hot terminal, otherwise use W here) to 6(N.O.).

5 and 24(C) to the zone valve motor wires.


If I'm wrong, someone please correct me.

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Joe Mattiello

SR501 can power a zonevalve

Yes, you can power the zonevalve and the thermostat using the SR501 single zone relay. Keep in mind you have less then 15VA to work with, because we do need to pull in the relay also. Bring the thermostat into the R, and W terminals, and use the W and com terminals to power the valve. FYI, the W, and com, terminals can be used as a 24 vac signal, or output. Please advise, if you have any questions or concerns.

JohnNY

Joe,

Won't wiring the valve to W and com just supply constant power to the valve? Won't wiring to the switched terminals open the valve on a call for heat, which is probably the intended application here?

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The Wire Nut

Switchero

If they are using the standard wiring conventions then John is correct. R and Common (C) should be 24 VAC constant supply. The W would be the switched 24 vac (eg switched "C") from the T-Stat.

So the zone valve would go between W and Com. But as Joe mentioned there is limited current available, and also, you will be switching the zone valve through the t-stat and all its wiring. That might be too much of a drop and cause issues.

Perhaps it would be better to put in a 24vac transformer with its primary (120 volt side) connected in parallel with the pump (eg terms. N and 4(n/o) and the 24 volt secondary to the valve.

Also, is the wiring to the boiler's TT on the Data Sheet wrong? Looks to me that you'll never have a closed contact to the boiler. I think they have either the terminals mislabeled or the diagram backwards. It would seem to me that the boiler TT should be on what they call 5 (n/c) and 5 (n/o)....

Alex (The WireNut)

chuck172

Taco's response

Here is the response I got from Taco:

From: Mario Silva
Message: Chuck, you will need to power the t-stat and valve separately and use the isolated end switch of the valve to signal the SR relay panel to turn the pump on. If you need any further assistance please feel free to contact us anytime.

What do you guys think?

The Wire Nut

It makes sense, especially if you are using a thermal zone valve. A motorized valve opens fairly quickly and I don't think that the pump will be dead-headed for any appreciable period. However, a thermal valve takes a long time to open and the pump will not tolerate pumping into a closed line for long.

It also is a bit of a fail-safe in that if the valve fails to open the pump won't get stuck dead-heading.

If the pump has a by-pass of some sort, depending on your configuration, then I don't think it matters which of the 2 ways it's wired.

All that being said, it doesn't take any more parts to have the end-switch trigger the Taco, just a bit more wiring. So why not?

Alex (The WireNut)

The Wire Nut

Ooops

Darren,

Check your drawing, the way you have the pump wired won't work. You need to take the bottom leg of the pump and put it on N!

I see you also corrected the drawing of the contacts on the 24 volt side of the relay...

Alex (the WireNut)

Darren_14

Sorry

Alex,
You are correct, I was in a hurry! This should be better.

Josh M.

Perhaps a modification is in order

Joe,

You know, I have done this about 10 times with an SR501. And it is a good application.

What would it take to have a couple of contact lugs there for a zone valve? It would work with any TACO zone valve....

chuck172

thanks

Thanks to everyone who replied. This is a great forum!