Can I add a zone valve?

A zone valve is no problem. Sweat it in, attach to thermostat, make sure both have proper power (usually 24vAC).

Just make sure there is power nearby for a wall-wort (adapter, like for laptops and such).

Alternatively, you can run wires down to get power from the boiler, but for this temporary upgrade, I'd just buy a power supply and the thermostat ONLY connects to the zone valve.

Downside: It is possible the zone valve and tstat want heat, but the other (existing thermostat) zone is not calling for heat.

If you think that is going to be a likely or common occurrence, you will want to connect the new tstat back to the boiler as well as the zone controller. It all depends on what you have and want to do.

Do you have pics of your boiler and controls? If we can see the controls/model and your boiler setup, it's likely someone can direct you how best/easiest to connect it all

CoalisCoolxWarm wrote: ↑

Wed. Jan. 19, 2022 8:01 pm

A zone valve is no problem. Sweat it in, attach to thermostat, make sure both have proper power (usually 24vAC).

Just make sure there is power nearby for a wall-wort (adapter, like for laptops and such).

Alternatively, you can run wires down to get power from the boiler, but for this temporary upgrade, I'd just buy a power supply and the thermostat ONLY connects to the zone valve.

Downside: It is possible the zone valve and tstat want heat, but the other (existing thermostat) zone is not calling for heat.

If you think that is going to be a likely or common occurrence, you will want to connect the new tstat back to the boiler as well as the zone controller. It all depends on what you have and want to do.

Do you have pics of your boiler and controls? If we can see the controls/model and your boiler setup, it's likely someone can direct you how best/easiest to connect it all

I'm not worried about the zone valve being open and waiting for heat from the zone hooked up to the circulator. If it's a little cold upstairs it's not a problem, the downstairs calls often enough! I do have a Taco single zone switching relay (sr501-4) that I was thinking I could pirate the 24v from since it is hooked up and currently inactive...although that might be just stupid talk


(the plumber initially had both my oil and coal hooked up to this incase I decided to do a switchover to oil during the summer, but the circulator ran constantly if the t-stat called and my boiler could never get up to temp so I changed the wiring so EVERYTHING runs through the triple aquastat). As shown:
I'm a little confused about the wiring, I understand when the t-stat connected to the zone valve closes it completes a 24v circuit to power the valve to open. Advise me here, in my understanding the T T terminals on my triple simply close the switch (relay,right?) to run 120v through the circ terminals, (provided the boiler temp is at least at the low +/- diff) correct me on this please. So unless I have a zone valve on EACH zone I shouldn't tie this into the T T terminals or I'll just be circulating water everywhere all over again...since I would pretty much be:

Zone 1 call = Circ run, zone valve could be open or closed
Zone 2 call = Circ only runs if zone 1 is calling zone valve will be open

taco's website wiring

I have attached the wiring manual for the SR501-4. You want the typical wiring diagram.

A few answers:

1. TT is a direct short from thermostat when calling for heat. You can test this by simply using a small piece of wire and touching both terminals.

2. The 24vac terminals PROVIDE 24vac to power thermostats that require it. Either battery powered or 24vac powered thermostats will work.

3. Power for the zone valve is at the bottom, "Circulator" and provides 120vac.

I cannot tell which model your zone valve is from the pic?

In a typical configuration, you would add a Tstat to the TT on SR501-4, run 120vac to N&H on SR501-4, Run 120vac from N(white) and either 4 (NO or NC depending on your usage). Usually NO, then tstat triggers running pump), and run wire from 6(NO) and 5(NC) to ADD to the TT terminals on the triple aquastat, so the boiler knows it is getting a call for heat and should be running.

With your configuration it will be a bit different, but if you can provide the zone valve model, we can figure that out, too

Make sense?

Mine is a 572-2, can't find the table I found before explaining the -2 different, dunno if that's just a model revision or something I should be worried about.

CoalisCoolxWarm wrote: ↑

Sat. Jan. 22, 2022 1:22 pm

3. Power for the zone valve is at the bottom, "Circulator" and provides 120vac.

But it says I need 24v ...not 120? What am I missing? I was planning that this whole thing will be isolated from the rest of the system...the SR501-4 is not currently in use.

I've attached the installation instructions for the Taco 572-2 zone valve.

Let me think on the 24VAC and inverting the thermostat. A Schmitt would work, but may be a different way based upon the wiring you have....

Okay, for the group to review....

1. Skip the zone controller. It doesn't invert and it switches 120vac AND is powered by the same 120vac input.

2. Connect upstairs Tstat to a 24VAC relay, using NC (example link below). It should be a 24vac powered Tstat powered by the boiler. 24vac from boiler to one terminal of NC on relay. Other NC terminal on relay to zone valve terminal #1

3. Put zone valve into the upstairs line after the split between upstairs and downstairs zones

4. 24vac power from boiler to the zone valve terminal #2

5. Install new Tstat downstairs and run to TT on boiler

Intended function:

When upstairs tstat is not satisfied, its 24vac energizes relay, which OPENS the zone valve to allow water to flow into upstairs zone.

When upstairs tstat is satisfied, the relay is de-energized, which CLOSES the zone valve to only allow water to flow into downstairs zone.

New downstairs Tstat and/or upstairs Tstat can trigger or turn off boiler using TT terminals at boiler.

https://www.amazon.com/Power-Relay-Module-Control ... B089Q7MXTR

Retro_Origin wrote: ↑

Sat. Jan. 22, 2022 1:01 pm

I do have a Taco single zone switching relay (sr501-4) that I was thinking I could pirate the 24v from since it is hooked up and currently inactive...although that might be just stupid talk

If the SR501 has a 24 volt AC output, run it to the zone valve but run one leg of the 24v through the thermostat as a switch.

You could get fancy if your zone valve has an End Switch. If it does you could run thermostat wire from the End Switch down to the "T T" terminals on the triple aquastat. This would trigger a heat call when the zone valve opens, activating the pump.

-Don

Thanks guys! As far as the hydronic side, since I have to partially drain the system to sweat in the zone valve, am I ok to let the boiler on and just turn off the shutoff valves pre-circulator and post flow valve (and of course, disconnect the circulator so it doesnt try to run)? This would mean when it's time to fill my autofill valve is going to dump cold tap water right into the boiler but I don't see a way of getting around that unless I either let the whole boiler chill down or just let it fill real slow... either way it seems less than optimum. Letting the boiler cool all the way down isn't so nice for the winter either.