Controlling Zone Circulator on Radiant Loops that also have zone valves?

rick in Alaska

When either radiant thermostat calls for heat, the zvc box will enable the boiler and the system pump, and power open the zone valve. When the zone vale opens up, it will send 24 volts to the RiB and turn it on, which will close the relay and turn on the radiant pump.
As it is wired, pin 1 of the zvc output is the hot wire for the relay, and as the zone opens up, it allows the common wire to carry through and make the circuit for the RIB. It really doesn't matter where you make the connection for the 24 volt hot, but since pin 1 of the output is hot on all outputs, it is just an easy place to catch it.
Hope this makes sense and I didn't forget anything, or cross something.
Rick
Sorry didn't realize it was upside down, and don't know how to fix it.

HomerJSmith

Kudos, rick, I think you got it. One can use a SPDT pilot relay. A lot simpler. One could mount the relay on a knockout on the bottom of the 406-4 and make all the wiring connections in the 406-4.

https://www.supplyhouse.com/Rheem-RIBU1C-Enclosed-SPDT-Relay

rick in Alaska

That's the one I am talking about.The RIB, which is short for relay in a box. Those relays are really nice, compact, relatively cheap, and quiet. And I really like the led indicator so you know it is on.
Rick

HomerJSmith

Wait a minute, I think I see a flaw in this diagram, rick. What do you think?

With this setup thermostat 1 would need to close for the zone valve 1 to open as is shown and then turn on the radiant pump and if ZV1 is operating ZV2 can operate, too. However, if only ZV2 is operating and ZV1 is off, then how does the radiant pump turn on? I think you would need 2 RBI relays, one for each zone valve.

rick in Alaska

I will have to open up a zvc to check. I was thinking that pin one on the zvc was hot all the time, but it could be the switched leg. The for sure way would be to just run the power to the rib directly from the transformer. I was just using the pin 1 because it was easy to get to.
Rick

HomerJSmith

I think this is how it is wired up, internally. Pin 1 is switched by the thermostat.

You wire the RBI relay coil to the transformer as you said. How would you wire directly to the transformer? This is how it might be done as I think your diagram is sound. Yes, take the power from the "R" wire on the "B" transformer after the fuse, going to the coil of the RBI relay instead of pin 1 going to the coil of the RBI relay and keep your drawing the same. I believe that would work. Then you would only need one RBI relay.

The ZVC 406 has a board relay somewhere between the thermo "R" & "W" connections, but that shouldn't make a difference in connecting the RBI relay coil to the transformer. It is just not diagrammed in my drawing.

rick in Alaska

Pretty much just cut in to the transformer wire and splice a line to the RIB.
Rick

HomerJSmith

Case Closed! This has been exhausting.

ColdTurkey

Sorry for the delay, I've been traveling and simply haven't gotten to this. Plus this winter has been warm here so far for the most part we've been opening the zones manually and starting the circulators by on-off switch.

I want to thank HomerJSmith specifically for the help. And the others. Because this is just a temp fix, I'm ordering the fanbox today and doing as per his schematic, if it uses a bit more electricity than optimal, that's okay. I will update how it goes.

In the late summer/early fall I will see to the upgrades. I do have a question, are the flow rate limiters necessary on a loop with a variable pump or can the variable pump basically do this job on it's own? I know the pump pushing water on two zones/loops, but the zones/loops are pretty much open at different times of day - the bathroom is set to warm up in early morning and then cool down, and the kitchen is midday to late evening, it has a ton of heat capacity thanks to the thick concrete slab it's was set in. Also, where on the system would I put the hose valve for flushing? Right before the pump I guess?

HomerJSmith

Yes, variable pumps need circuit balancing valves to correct for uneven circuit lengths. An ECM pump is nice and I would replace an existing pump with and ECM pump if the original pump failed. It would take some time to save in electrical costs to cover the cost difference which would be about $100 +. Beside you already have a functioning pump, and it doesn't run all the time.

Rick's suggestion will work too and be a little cheaper than my suggestion. We got that ironed out.

ColdTurkey

I used Rick in Alaska's idea and used a RIBU1C. Works like a charm, thank you all for the help. It took me a while to figure out the exact wiring but it was as y'all said.

From the possible configurations:

https://www.functionaldevices.com/support/faq/#q1

Yellow is Comm, Orange is N/O. Blue N/C wire is not used.
White/Blue is 10-30 VAC/DC, White/Yellow is Comm. White/Black 120 Vac not used.



ZVs are Taco 570 gold series, connected to zones 4 and 5 here.

Make sure zone valves are on same transformer (1-3 or 4-6). Splice into correct transformer. Jumper 3&4 connections together on each Zone Valve since the daisychained wire from the bottom screw of the Taco 3 screw valve goes to RIBU1C instead of Zone Control.



The box will always light up Zone valve open when thermostat calls but the RIB LED indicator light replaces that.

Easier than I thought.

HomerJSmith

Good Job!

clammy

I didn’t read through all the posts but when faced w a heating system hi temp using zone valves and the boiler pump mounted on return of boiler and a additional pump and mixing valve is added for radiant . It seems that when ever your radiant calls your main pump would run even through there zone valves are closed aside from adding a seperate tee on the supply and a seperate tee on the return after the system pump is one way or this . Which is add another zone valve piped between your supply and return and in between add two tees your mixing valve and pump . This way when a call for radiant it’s zone valve open boiler pump operates and then your radiant pump goes on . I use this when I have multi zone valves and a boiler pump mounted on return . If you just put a tee on the supply and return of your boiler and then pipe the mixing valve and pump you will usually have ghost flow and issues due to pumps and zone valves and mixering valves ,you will end up w gravity flow in some cases . I ve found that if you can’t repipe the boiler then this method works fine . The reason being if you just added two tees to what’s there w no zone valve you will get constant flow through the valve due to the boilers pump operations on any call for heat . Basically you add another zone valve pipe it from supply to return ,have a straight piece of pipe put 2 tees close together w a good length of straight pipe before and after ,off of the two tees pipe your mixing valve and pump . It works like a charm . Don’t know where I can up w it definently stole it but I have used it many times it can also be used a a remote shuttle run hi temp run out to a mixing station remotely installed , it has its application but it does work .it really sounds like you need to repipe the boiler w a additional pump for the radiant aside from the zone valve pump . I used this when others refused to repipe the pumps on the boiler and wanted to add a pump for radiant . Sorry if the wording stinks but use your imagination and think like water lol peace and good luck clammy