2 zones, 2 pumps, 2 stats

Its complex. The XX terminals went to the TT terminals on the burner/boiler controller. With the ZR501, depending on how it is wired, whatever you use as the dry contacts with no power on them, that will automatically switch closed when the thermostat calls, needs to have two low voltage wires to the same TT terminals on the boiler/burner. If you have oil and a tankless coil, they both need to be wired through something with ZC/ZR terminals to power the circulators.

Your question is a complex electrical control problem to those that don't understand boiler control wiring.

OK, I see what was done. At some point, someone used the 2nd floor stat to control the HW pump relay, which energized the taco pump for the first floor. Why, I don't know. Provided both pumps work and are hooked up to run their respective zones for 1st and 2nd floor zones, The first floor t-stat which controls the taco pump relay will energize the first floor pump, and the 2nd floor t-stat goes to the HW pump relay T-T terminals. T-stat connections are to the T-T terminals. X-X off the HW relay will go to the boiler, and N/O-Com on the taco will also go to the boiler.


Mike T.

You don't understand what was TRIED to be done, but wasn't.

Take the R832.

The two thermostat wires (low voltage) connect to the TT terminals. Were not dealing with the XX terminals yet. The line voltage goes to #1 and #2. That powers the control and low voltage control that operates the relay. Wires #3 and #4 go to power the circulator. When the thermostat closes and makes a call, the relay closes and energizes #3 and #4, starting the circulator pump. When the thermostat calls, the pump starts. You want the burner to start. That also closes dry contacts on the control that energize X-X which will be connected to TT on the boiler control that starts the burner. Only the thermostat and pump that are connected to the 832 will run. Trust me. That was the original zone.

They added a zone.

The Taco ZR501 is a replacement relay that will replace ANY heating relay like it. It will replace any Honeywell or white rogers relay that is made to do heating switching relays. You just have to connect the proper wires to the proper terminals. It wires up just like a 832. Once you figure out how the control wires up like a 832, it operates just like the old one. Its that they BOTH must start the burner, but NOT each others respective circulators. Each relay when jumped will start the burner AND the circulator that the relay controls, but NOT the other relay.

Sparky Wannabe didn't understand how the SR501 works. The first time I saw a Taco 501 was the last time I bought and installed a 845 relay. The 501 is just too handy and easy.

I think that the 501 was wired wrong.

Here's the SR501 wiring diagram.

http://www.torrco.com/DOCUMENTS/102-169.pdf

SWEI said:

And the Caleffi ZSR-101, a direct competitor.

That may be. I only had access to the Taco ones.

Taco and Caleffi were once engaged. The engagement was broken off. I've often wondered who benefited the most. I remember the Eat & Meet I went to where they showed us the Taco SR501 and how it would replace any switching relay made, a direct replacement for all.

For me? No more Honeywell 800 Series relays.

Way back to before then.

Taco had junk for a decent float vent. No better than a Amtrol 700. Then, back last century, they came out with the Taco 400. Cast brass with a top that came off and you could repair it if you felt like it. It had "Made In Italy" right on the side of the castings. Things changed during the last century.

Far better that the Norca sweat gate valves of the 1970's. Every discount wholesaler sent them with every job. They were of such quality, that the quality guys took the nice painted ZMAC handles off and put the valves in the scrap barrel. It cost more to remove the handle than it did to take out a bad one and replace it with a Wolverine Brass one.

Empire said:

Icesalor, was what I said incorrect? Not sure if you were referring to me.?

Nothing you or I say is incorrect. I was expressing my opinion or an experience of mine. I was trying to explain how I understood them to be wired and how they were supposed to work. My experience was with a lot that were mis-wired and how I had to come to understand so I could fix them.

Unless you understand, it is as hard to wire an R832 to a R845 as it is to wire a SR501 Taco relay to either of the others until you understand how they work and what they will do.