wiring taco 571 to weil mcclain cgi-5 boiler

Old 11-23-12, 07:28 PM
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wiring taco 571 to weil mcclain cgi-5 boiler

I just installed a gas CGI-5 boiler and Aqua Plus 45 water heater. Please assist me in correctly wiring the zone valves.

I have 2 Taco 571 valves. One for the baseboard heat and the 2nd on the loop to the indirect water heater.

I'm trying to wire one of the zone valves for baseboard heat. From the wiring diagram on the Taco box it looks like the 2 black TT wires on boiler go to terminals 2 and 3 on zone valve. Terminal 1 on zone valve goes to one of the leads on thermostat.

Where does the 2nd lead on thermostat go to? I have a black wire coming off the control module of the boiler that is labeled with the letter "C". Is this where I connect the 2nd leg of thermostat?

And do I follow this same procedure for the zone valve I have on the aquastat? Except using the wires labeled DHW instead of the wires labeled as TT?

Also, what is the red wire labeled with the letter "R" for?

Thank You!

Last edited by NJT; 11-24-12 at 07:29 AM.
Old 11-24-12, 07:36 AM
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First off, if you can find the documents you are referring to on-line, please provide links to same so we can refer to them.

You need a source of 24VAC.

The following diagram shows a 'typical' connection for Taco 570 series zone valves.

In some cases the 24VAC source can be taken from the boiler, but in general it is usually best to provide a transformer that supplies this. Reason is that in the event of a problem which might short something out, it is FAR better to have to only replace a $20 transformer than a $200 boiler control. (and way easier too!)

So, save us the time of having to find your manuals and we'll go from there.

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