ZVC 404 zone panel

Joeyo

I have 2 zone valves that are heating 2 baseboard loops with one circulator. Added a radiant zone with its own circulator and zone valve. Tried wiring off the dry contacts with end switch, with priority off. No luck...

I want them to run independently. Is it even possible with this board?

HVACNUT

Did you use Zone 4? Top for the thermostat, bottom for the zone valve, the radiant circulator to Neutral and Hot to N.O. on the Zone 4 Priority relay. T

EdTheHeaterMan

See EDIT below

Here is an easy way to use that ZVC 404 relay. do not use Priority , because you want all zones to be able to operate all the time. Priority will disable zones 1, 2, and 3.

Use one of the regular zones (not on priority) to operate a RIB 2401B relay, Connect blue/white to #1 on that zone. Connect yellow/white to #2 on the zone. Jumper 3 & 4 on the zone. this will operate the 24 VAC realy and send a signal to operate the boiler when there is a call for heat from the zone thermostat.

Connect 120 VAC hot to Orange wire on RIB. Connect Yellow to Hot of circulator motor. Connect Common on circulator to 120 VAC Common.

If I have your piping figured out correctly, The zone valve for the low temp zone is not needed. I learned this by accident, becaust i did the same thing as you did. Several years after the install (in my own home) I had a zone valve actuator go bad. To get heat to the failed zone I swapped the low temp zone valve head with the defective zone valve head. I locked the low temp valve in the open position. I placed a jumper between 3 & 4 so on a call for heat the burner would heat the low temperature. (I thought the low temperature zone would just overheat with the valve locked open). After several days I realized the low temp zone was not over heating with the valve stuck open because the circular would not operate if there was no call for heat and the stuck and without the circulator for the low temp zone operating there was too much resistance in the low temp zone to allow any heat from the boiler to enter the zone… the pump must be on. That is when I realized that I did not need a second 120v pump relay to operate the low temp zone. Just add a RIB to that zone to bring on the pump.

There is one problem with your piping arrangement here. If only the radiant zone is calling the system pump will be operating against 2 closed valves. In order to solve this problem I would repipe the low temperature feet on the discharge side of the pump. this way the pump can operate and some high temperature water will be moving to the low temperature zone to keep the pump from dead heading against the 2 closed valves.

EDIT:

If you are not using a Condensing boiler, then the return water to the boiler may cause condensation of flue gasses with your current piping situation, now that you added the low temperature zone. Check with the manufacturer's instructions for imstalling a bypass to keep the return water to the boiler above 135°F. If you have a condensing boiler, then there is no problem with low temp return water. It actually an advantage ans will operate at a higher efficiency.

Joeyo

Yes zone I used zone 4 and wired radiant circulator and secondary circulator for baseboard zones with priority off but it still was shutting down BB circulator when radiant zone was calling

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1809728#Comment_1809728

Read my post carefully. You must use the selected zone as a 24 volt zone. that is where the RIB relay comes into play. The end switch and extra end switch and the NC/Com/NO contacts are for DHW priority feature. Since you are not using the DHW feature of this ZVC control, those relays and terminals do not do what you need them to do. Purchase a RIB 2401B from Supplyhouse.com or Amazon.com or your local hardware store or plumbing or electrical supply house.

https://www.functionaldevices.com/product/RIB2401B

HomerJSmith

I don't see why you are using a Taco Sentry ZV. What purpose does it perform? The Grundfos pump should have a check valve in the volute.

I assume that you have a thermostat for the radiant zone. I would wire it as follows: @HVACNUT is right. The thermostat wires to Zone 4 TT. Priority switch in the off position. The wires from the ZV motor goes to the Zone Valves connection at the 1 & 2 terminals of Zone 4. Jump terminals 3 & 4. I cant see where you are bringing 120V ac in to the panel. Connect the 120V black to the Common and the pump black wire to the NO terminal of the dry Zone 4 relay contacts of the COM & NO. The other wire (white?) from the pump connects to the 120V ac power coming into the panel's white wire. The green wire from the pump connects to the 120V ac power ground coming into the panel.

You will have a lag time for the capacitor in the ZV to charge up. Up to 90 sec.

EdTheHeaterMan

@HomerJSmith

I believe that wiring the low temperature zone (zone 4 in this case) circulator pump connected the way you describe will operate in a call from zone #1, #2, & #3 with the priority switch off. That might over heat the low temperature zone.

Agree that @Joeyo does not need a low temperature zone valve. That should be put on the shelf for future repair parts as needed.

Not sure what the NC/C/NO relay does when Priority Is switched off.

However I have used the RIB idea successfully on more that one occasion. I came up with it because i believe I tried your idea and had the overheating problem. So long ago I cant remember. (now I know why folks said "He forgot more about control wiring than you will ever know" when I was younger)

EdTheHeaterMan

Easy Peazy

Dont forget about that system pump deadheading when 1, 2, or 3 are closed and 4 is operating

Joeyo

The boiler is a cast iron 80% mid efficient peerless boiler, about 12 years old. So there is no way for me to be able to control fintube circulator to only come on when one of the zones is calling? Thanks for the info

EdTheHeaterMan

Yes there is. but you can't do it with a ZVC control only.

You will need a separate control for the low temperature zone to operate only that circulator.

The circulator for the hi temperature zones must be connected to the ZVC control and the circulator for the low temperature zone connected to the SR control. If either control is calling for heat the end switch or 5 & 6 will operate the burner thru the boiler control. the boiler control will not operate any circulator.

You should consider repiping the near boiler piping to eliminate the possibility of flue gas condensation.

Joeyo

So if I go with rib relay, remove zone valve for low temp and install a tee just after other circulator so it doesn't dead head I should be good??

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1809751#Comment_1809751

That is one way to do it. Please read the edited post above with the SR 501 diagram added. Both wiring designs will work. One will not need to have the piping changed.

hot_rod

Another uopgrade option is to use ECM circulators in Delta P mode. Then the dead head is a non issues, flows balance and you use 50% or less electrical energy to spin the pumps.

Joeyo

Lowes had the SR 501, it was 6$ cheaper than supply house 🤔. Removed zone valve as well. Everything works great! Thanks for your help, I appreciate it