Navien NCB-240

Bill Julian

Wiring issue.
I have 2 zone valves and 1 system circ. Zone valves are 3-wire got them connected to the Navien in the proper place. My question is the Taco 571 ZV which wires do I connect to the ZV. In other words terminal 1, 2 and 3 on the ZV?

Ironman

T1 is power from the thermostat.
T2 is common from the transformer.
T3 is the end switch which connects to T2 when the valve opens.

Bill Julian

Thanks for that but that is not what I am looking for. I have a Navien board in the NCB-240 in there I have a place to connect a 3 wire 571 Taco Zone valve which I have done. Now to connect to the actual zone valve is my question. Which of each of the 3 wires from the navien go to the zone valve. I have 1,2 and 3 on the ZV and I have 3 connections on the navien.

You just can't connect any of the 3 wires from the Navien to any spot on the ZV. I need to know which wires go to each (1,2,3) on the ZV.

Bill Julian

GOing from Navien directly to ZV. no transformers or t stats.

Ironman

Do you have the Navien manual with a wiring diagram?

109A_5

Hello @Bill Julian,
You must have a special version of the Navien NCB-240, since I don't see any place to connect a 3 wire Zone Valve to it (other than the way @Ironman illustrated). In the situation illustrated below (from the manual) the Zone Controller is a separate unit. Screw terminal 3 (End Switch) on the 571 Taco Zone valve is not used, not needed, just the Heat Motor is connected.

Additionally, the NCB-240 does not have enough extra 24 VAC capacity to power the Zone Valve Heat Motor.



https://www.navieninc.com/downloads/ncb-installation-operation-manual-en

Bill Julian

Navien NCB 240 110 3 wire ZV connection right side bottom green panel bottom. Called Navien an that is where I am to wire the 3 wires going to the zone valve. Again my question is which wires do I connect to the ZV? Looks like I may have to call Navien again. Thanks

Bill Julian

No separate TACO ZV controller necessary.

Bill Julian

This is from Heating help itself.

Bill Julian

Zoom in to panel <img src="https://us.v-cdn.net/5021738/uploads/editor/vs/bo8kfzt6tcf2.jpg" alt="

Bill Julian

Zone valves wiring without separate TACO board

109A_5

Hello @Bill Julian,

Bill Julian said:

Zone valves wiring without separate TACO board

I don't think this is true. Look at the current rating of the output, it is only 0.75 Amps a TACO 571 draws 0.9 Amps. It may work, but may be a warranty violation if something fails early. And their (Navien) Zone Valve control logic seems incompatible.

Maybe this is just bad English " NO (Normal Open): Power is supplied when the zone valve is operating, and power turns off when the zone valve stops.". Wouldn't this just close the valve before the call is complete ?

You would have to measure it to see if their Zone Valve power logic is appropriate for your Zone Valve.

So far, to me, these Zone Valve outputs were designed to only support a specific (secret) Zone Valve, not the typical Taco or Honeywell which require power to open them and power to keep them open for the whole call. And the NCB-H manual shows a diagram how to use Zone Valve control from other manufactures. I understand what you want BUT that boiler apparently does NOT directly support the use of a TACO 571 Zone Valve IMO.

dko

First clarify exactly which Navien you have. Everyone tends to say NCB-240 but they have had 2 iterations since then.

NCB-240
NCB-240E
NCB-240/110H
NCB-240/130H

edit: Saw photo, it's the H

Recommend using separate zone valve controller if you are going to use 571s.
I know of a few 570 series in operation with the NCB-H models but not long enough to say they'll work fine without busting the contacts long term. As it does exceed the amp rating. You just have to remember not to wire the end switch, just terminals 1 and 2 to NO and COM respectively. Do not plug anything into NC on the Navien or Terminal 3 on the 570s.

Or just switch to honeywell/taco sentry zone valves.. for peace of mind.
Don't forget to wire your external taco pump to Z3 and change the setting in the controls to zone valve system.

Bill Julian

The Navien repr near me says opposite. Wire NC and COM to the Navien from the ZV, don't use terminal 3 on ZV only need 2 wires on the ZV and Navien. Confusing here.

dko

When there is a call for heat, you will see 24V between COM/NO. When there is no call for heat you will see 24V between COM/NC.

Navien rep is wrong and something you can easily test yourself. just wire a thermostat into the navien and turn it up (or simply jumper). measure the voltages yourself.

Bill Julian

Thanks for that/ What about the Taco 571? Where does NO and COM go regarding screw 1 and screw 2 on the taco?

Bill Julian

Update I got no voltage wiring it to the NC connection. Got 25V on the NO connection. Zone valves however seem on and off. Its like they do not open all the time. Not sure why

dko

#1 to NO. #2 to COM.

570 series can take up to a minute to fully open. quiet operation

These valves normally cut power to its heater wires and back on again repeatedly throughout the call for heat as described in the picture below. These are power hungry valves and this way they don't draw full power for the entire duration. If the end switches were used, it would remain closed and you would not see any indication of it cutting power. You are not using the end switches in this case.

Bill934

Thanks for that Ya it is frustrating the 571 does not energize and then does. Wonder if taco zone controller would do a better job? Previous application was using separate transformer?/. Costly though

Bill Julian

Incidentally why can't I use the end switch so the ZV will stay open and only close up T Stat open?

Bill Julian

Frustrated going with Pumps removing the ZVs. They are on and off not heating the house properly.

Bill Julian

Also Navien manual shows Taco 571 Screw 1 (Top screw) connecting to Navien COM, and 571 Screw 2 middle screw connecting to NO on the navien.
I have screw 1 on 571connecting to the Navien at NO, and screw 2 connecting at the navien at COM.
What gives?

Bill Julian

dko

Where did you connect the 007 pump on the navien precisely? and have you changed the setting to zone valve system in the programming? Outdoor reset installed and/or using the navien on ODR curve?

Any error codes?

What exactly goes on when the zone valves are going on and off? Is the boiler still firing? Or does the boiler go on and off as well?

Take photos up close of the wiring on both zone valve and PCB (of both pump and ZVs).

Bill Julian

System pump on Zone 3 (per Navien, Navien tech said don't use zone 1 only zone 2 and 3.) System pump on zone 3. Settings set to Zone Valves. No outdoor reset, no error codes, boiler firing ok they get heat ok but not enough zone valve shuts what seems to be prematurely. Called Navien 4 times everything correct, but the wiring as you see in the photo screw 1 and 2 I have opposite as per Navien tech support but not the Navien manual.

dko

~nm

Bill Julian

Nm?  I’m changing to circs