How to wire a zone valve on a boiler

Siemens zone valves have a stroke valve design for on/off or basic modulating control to ensure hydronic systems deliver reliable comfort. Metal-to-metal plug and seat eliminates traditional rubber flappers that can harden and chip over time causing leak paths and debris in the system. The valves feature direct-coupled technology for quick ...

Auxiliary limit switches are used in some zone valves to identify whether the valve is entirely open or closed. These switches have signals often used to initiate hot water pumping by activating a pump (circulator) and a boiler. The water then circulates through the circuit, heating the zone until the associated thermostat's temperature is ...Jun 10, 2022 · Summary. In a central heating system, zone valves regulate hot water distribution to the building's different areas (zones). They are often preferred for their extra comfort as well as energy savings. These valves exist in various shapes and sizes, but ball valves with electric actuators are a popular choice for this application. Zone Valve Wiring Manuals Installation Instructions Guide To Heating System Valves Inspection Repair. 2 Thermostat Zone Valve Wiring Heating Help The Wall. Hot Water Boiler Piping Zone Valves Wiring Diagram Quality 1. Combination Boiler With 2 Heating Zones 230v Switching. Domestic Central Heating System Wiring Diagrams C W Y S Plans.sams Member. ive noticed the new ideal logic boilers electrical terminals have now changed there used to be a pump over run terminal in the boiler labeled pump, now the new terminals are just permanent supply and SL1 which shows on the wiring diagram is connected to the port valve orange , this is obvious a switch live to fire the boiler but ...Step 5 - Removing the Zone Valve. The zone valve will be bolted onto the pipe. When it's safe to do so, the zone valve can simply be unbolted and removed from the line of pipe. Be careful when doing this because the valve can stay hot for some time, even when the boiler is shut off. Use the screwdriver to remove the electrical connections from ...Install wiring and electrically ground boiler in accordance with requirements of the authority having jurisdiction, or in absence of such requirements the National Electrical Code, ANSI/NFPA 70, and/or the CSA C22.1 Electric Code.gas valve, igniter and blower. When a room thermostat calls for heat, the IBC starts the system circulator and blower. The IBC runs the blower to purge the boiler flue passages, then turns on the igniter and lets it warm up. After igniter warm-up, the IBC opens the gas valve, turns the igniter off, and checks for flame.

All about 2 Port Valves central heating and Wiring! I'll show you how easy they are to wire on a heating system by ignoring the neutral and earth wires until...The wiring at the thermostat was identical to FIGURE 1, with a spare green wire. The zone valve controlling that zone looks like this (FIGURE 3), after my rewiring, with annotations based on the subsequent diagram (FIGURE 4): FIGURE 3. FIGURE 4. I don't want to brag, but this has been working out perfectly for the past couple of months.In this video I show you how to change the mechanical plumbing part of the valve. In a previous video I showed how to change the motor of a zone valve. The...Apr 8, 2016 · The taco zone valve is explained, taken apart, voltage read, terminal wiring explained and shown in action with water in the top of the pipe falling through ... Thermostat calls. 2. Respective zone valve opens. 3. When zone valve is open, it triggers ENDSWITCH (red wires or endswitch terminals) 4. Endswitch signal to boiler fires boiler and runs circulator attached to aquastat. 5. Boiler heats and pumps hot water.Do you want to learn how to wire your boiler thermostat correctly and safely? Watch this video tutorial from a professional electrician who explains the steps and tips for wiring different types ...1 1. 1. Welcome to Home Improvement. It would be helpful if you were to edit your post to include the model of the boiler and the zone valves. Then, while you're waiting for an answer, take the tour and browse through the help center to learn how to make the most of the site. – FreeMan.

Zone valve wiring manuals installation & instructions: guide to heatingHoneywell wiring zone valve colours november Honeywell 3 port valve wiring diagramHow do you wire a honeywell zone valve?. Top 7 Wiring Zone Valves Honeywell - Your Home Life. Check Details. Honeywell zone valve wiring colours. Valve zone honeywell valvesHoneywell zone valve ...Taco zone valve 571-2. Screw #1 wire 26 volts connects to a wire where all 4 valve screw #1 are connected. Screw #2 wire is 26 volts and connects all valve screw#2 together and comes from the external transformer. Screw # 3 wire is neutral and connects all valve screw 3 together and comes from the external transformer. That transformer is …How do I choose & install a zone valve, how do I wire up a zone valve, and how do I troubleshoot, repair or replace a zone valve? This article series answers most questions about Heating System Boiler Controls …Zone Valve Wiring Manuals Installation Instructions Guide To Heating System Valves Inspection Repair. 2 Thermostat Zone Valve Wiring Heating Help The Wall. Hot Water Boiler Piping Zone Valves Wiring Diagram Quality 1. Combination Boiler With 2 Heating Zones 230v Switching. Domestic Central Heating System Wiring Diagrams C W Y S Plans.2 posts · Joined 2023. #1 · Jun 21, 2023. Can any body give me a hand, I'm wiring 3 zone valves into a navien ncb-h along with 3 thermostats. I'm planning on wiring directly into the board. I have looked at the manual but only shows 3 connections where as my zone valve has 4 wires coming out of it. Can some one help me figure this out.

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Taco zone valve wiring. My house has 6 zones coming off the boiler . 5 of then are for the heating zones (only use 4, 1 need comes on because it's the second floor, and 1 is for a stand alone heater in the garage that I removed the thermostat) and 1 zone connects to the indirect water heater . The 24 volt power to all these heads is wired on ...The thermostat sends a signal to the zone valve to open or close based on the desired temperature in a particular zone. In a typical 2 wire zone valve wiring diagram, the power wire is usually colored red and the control wire is colored white. However, it is important to consult the manufacturer’s instructions or a professional if the colors ...sams Member. ive noticed the new ideal logic boilers electrical terminals have now changed there used to be a pump over run terminal in the boiler labeled pump, now the new terminals are just permanent supply and SL1 which shows on the wiring diagram is connected to the port valve orange , this is obvious a switch live to fire the boiler but ...Installer Manual - High Efficiency Boilers and Hot Water SystemsThe zone valves should be located on the supply side of the zone circuits to eliminate heat migration into inactive zone circuits. The tee shown below the zone valves is a “bullhead” tee. When both zones are on, return flows slam directly into each other. This creates turbulence and noise. It also wastes circulator head. TACO ZONE CONTROLS WIRING GUIDE Pages Switching Relays – Single Zone Wiring 2– 4 Switching Relays – Oil Boiler Wiring Safety Notice –5 Switching Relays – NONEXP Connected Together with Priority 6– 9 Switching Relays – EXP Connected Together with Priority 10 – 13 Switching Relays – Multiple Indirect Hot Water Heaters 14 – 15

Recently, I had a zone valve go out in my hydronic, boiler based heating system. I had to figure out how the system works so I could get it replaced. I don...The piping layout will be exactly as depicted in Figure 6-6 (single boiler zoned with valves) minus the differential pressure bypass valve. In the instances where I have two zone valves being controlled by one thermostat, I will wire those zone valves to the same zone output on the ZVC. Sorry for the confusion on that. Thanks for the help.-ScottThat is your C connection point. Yes , I have all three #2 terminals on Taco zone valves tied together to one side of the transformer. I connected C -common wire to that wire-nut to C terminal on Nest but it keeps giving me heat delay info message on the display. It recognize new installation with a common wire though.I am installing new zone valves onto this boiler. First I have tben cut and solder the zone valves. Next I need to wire the zone valves. I need a 24 power an...The taco zone valve is explained, taken apart, voltage read, terminal wiring explained and shown in action with water in the top of the pipe falling through ... It's pretty simple actually. When a thermostat calls for heat, the valve for that zone opens, and the boiler is also signaled via the auxiliary switch in the valve. To get a C wire to one or more of the thermostats, you'll simply run a wire from the other side of the transformer on the wall. NOTE: If this diagram is accurate, the white wire to ... These were great systems with the option in a power failure to put the relay switch on manual and open either zone valves on manual or the flow check valve (circulators) and have gravity heat. The generators only job is to operate the gas valve through the safety controls circuit, it does not have sufficient power to operate anything else.Happy Thanksgiving! Upvote. Boilers - Home Heating Steam and Hot Water Systems - Adding Zone Valves to Existing Boiler. - I want to start off by saying I am long time lurker to the DIY forums, but I have definitely come to crossroads that requires me to ask for help. Equipment: Weil-Mclain WTGO-3 boiler controlled by Honeywell Aquastat L8124A.In this video I will show you step by step how to replace Honeywell zone valve motor, power head , and ball valve.https://www.supplyhouse.com/Honeywell-Zone-...Each of the four wires in the diagram represents a unique role in the operation of the heating system. Red is for power, black is for GND (ground), yellow is for the control circuit, and green is for the open/close operation. Knowing how each of these wires plays a part ensures that the wiring and zone valves are properly connected. Honeywell's ...Shows how I remove and install a zone valve motor, but not the pipe/valve portion. I also have a quick overview of my radiant heating system.A 2 zone boiler piping diagram is a graphical representation of the plumbing system for a heating boiler that serves two separate heating zones. It shows the arrangement of the pipes, valves, and pumps that distribute the hot water from the boiler to each zone and back. The diagram typically includes straight lines to represent the pipes and ...

NCB-H Combi-Boiler with Multiple System Zone Valves Shown with Manifold Kit Part #30026576B . PDF DWG. NCB-H Combi-Boiler with Multiple Zone Circulators Shown with Manifold Kit Part #30026576B. PDF DWG. NCB-H with Circulator or Zone Valves. NCB-H Combi-Boiler Application - Multiple Zone Circulators Low Temperature Zones Shown.

The Taco Zone Valve Controls should be used in coordination with 2, 3, or 4-wire zone valves. They feature universal thermostat compatibility, and their simple layout eliminates problems caused by incorrect wiring. External indicator lights give instant diagnostic feedback and reduce installation time. Taco 550 Series Heat Motor Zone Valves.If the two red wires power the Zone valve, and the thermostat is used to close a relay to allow currant flow to the zone valve, what is it that triggers the circulation pump? HVAC Technician: Rick , replied 3 years agoPower Open/Power Close Zone Valves Play length: 4:15 minutes. Play video. How the valve is constructed, how to wire to a control, how the valve prevents mechanical hysteresis wear when used as a modulating valve, and how to apply the valve in a heating or chilled water system. Manifolds. ... Boiler Trim Kits Play length: 2:43 minutes.Wiring zone valve heating heat boiler water wire gas hot system schematic valves honeywell controller air forced installation connect guide Need some advice on wiring boiler zone valves — heating help: the wall Wiring plan for fireplace boiler. Zone valve honeywell valves terry sandy plumbingZone 1 and hot water work fine. Zone 2 is stuck in open position (Honeywell 8043f, lever has no resistance). Zone 2 only (and always) provides heat if hot water or zone 1 is requesting heat. However, if Zone 2's thermostat is requesting heat, the circulator and furnace do not come on. This is a one circulator system.When the zone valve fully opens and its end switch makes contact, the red LED will come on, the boiler turns on and a circulator will start if connected to the zone control. For information on Taco’s Zone Valve Controls (ZVC) including catalog sheet, instruction sheets, Visio stencils and our highly praised Zone Controls WiringNot exactly the correct way to wire a zone valve. Those wires go to what is called the 'end switch'. That switch closes when the valve opens, and signals the circulator to run and the boiler to fire. If that switch is not used, and the valve fails in a closed position, your circulator pump will run into a dead head and quickly self-destruct.Here's what you can do to determine if the boiler itself is having a problem: Turn power off to boiler. Disconnect the zone valve endswitch wires from the R and G terminals in the boiler. Place a wire JUMPER between the R and G terminals and turn power to boiler back on. Circ pump should run and boiler should fire.

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Nest Thermostat: https://amzn.to/2sjJvXsFavorite Smart Home Devices: https://www.amazon.com/shop/onehoursmarthomeDoes the Nest Thermostat work with boilers? ...How do you wire a zone valve? What is a zone valve? During this zone valve wiring for beginners video, I simplify the confusing and overwhelming task of wiri...Your original ecobee/zone should have already occupied zone 1 in the ZVC403. This question is a couple months old, so you've probably already figured this out, but to inject that ZVC into your system, all thermostats go into the ZVC, and the ZVC's "isolated end switch" replaces the thermostat wires into your boiler.Sep 11, 2020 ... Honeywell Zone Valve Wiring Get it on amazon Honeywell zone valve https://amzn.to/3mLHGKr www.amazon.com/shop/miheatingguy Milwaukee 2131-20 ...The V8043 Motorized Zone Valve provides two-position (open-close) control of supply water for baseboard radiation, convectors, fan-coil units, etc. It uses a two-wire, 24-volt con­ trol circuit and requires a SPST thermostat. Integral end-switch models permit the sequencing of auxiliary equipment. Quick Fit actuator provides easy snap on and ...A zone valve is a motorized solenoid valve with an end switch. The thermostat for each zone is wired through a 24-V transformer to the zone valve. A mechanical end switch is wired to the thermostat terminals of the boiler operating controls. When choosing a transformer for zone valves, make sure that the VA (volt amps) rating of the transformer ... The C terminal on Relay 2 on the Grundfos box is connected with the red wire to screw #5 on zone 1 valve. The NO terminal on Relay 2 on the Grundfos box is connected with the white wire to screw #4 on zone 1 valve. The NC terminal on the Grundfos box is connected with the green wire to screw #6 on zone 1 valve. Simple. Sequence of operation: Wiring white rodgers zone valves. Hi I have a new weil mclain cga-4 standing pilot boiler and 2 white rodgers 1311-102 zone valves. How do i wire the zone valves to the boiler? The boiler has 2 wires coming from the transformer relay R and G terminals marked 24 v thermostat. Is this where i wire the wires from the zone valves?Boilers - Home Heating Steam and Hot Water Systems - need help wiring taco zone valves - I'm trying to add a 4th zone to my heating system. Currently each zone has its own circulator pump; two of which are wired up each using their own honeywell r845 and the third uses a taco sr501. The zone I'm trying to split isTurn the old powerhead counter-clockwise slightly. Then, pull it out of its mount. Install the new powerhead into the same location and orientation as the old unit. Connect and secure the boiler’s wires to the new powerhead. Turn on the system and check if the zone valve now opens and closes as intended. ….

Thank You Please Like & Subscribe Hope with this video it can help the newbie guys/gals out, and/or the person that is a little confused when it comes to in...Dec 16, 2018 · 16 Dec 2018. #1. I’m hoping someone might be able to help me out with a wiring diagram. The system runs off a combi boiler. There is a main house radiator circuit. There are two additional zones with underfloor heating, each with its own pump and isolator valve. Each of the three zones has its own thermostat. I want a valve to open, the pump ... Then using an approved wire, connect the ground wire to the green ground screw on the pump. Finally, connect the remaining two white wires together and replace the pump cover. Locate junction box on the back of the unit and remove the cover. Connect the running end of the approved wire coming from the pump to the junction.How to wire Honeywell zone valve to a Crown Boiler CWD110ENS - Answered by a verified HVAC Technician. We use cookies to give you the best possible experience on our website. By continuing to use this site you consent to the use of cookies on your device as described in our cookie policy unless you have disabled them.December 2019 in Radiant Heating. I have an old boiler system with two white rodgers 1311 zone vlaves. These connect to mercury thermostats with three wires and work on power open / power close. I am trying to replace the mercury thermostats with wifi thermostats but am encountering problems with this type of series 20 wiring.3 Wire Zone Valve 4 Wire Zone Valve T-stat T T To Boiler N L Line To Transformer Tank • Control Indirect Water Heater Aquastat or Thermostat 24V From Transformer T-stat T-stat NOTES: 1. The switching relay terminals are approved for use with copper wires only. Torque terminal block screws 6 to 7 inch pounds. 2.However, two of the three most common boiler faults can be handled by a competent DIYer and don't always require the attention of a costly heating engineer. 1. Boiler losing pressure. If your boiler loses pressure it could be one of a few things. Most commonly, it will either be a leak, you've recently bled your radiators and the system has ...The old owner have installed 4 Honeywell V8043E1012 zone valves to a Hydro therm HC 165 gas boiler. For some unknown reason he had all 4 zone valves connected to only one thermostat controlling the whole house. I want to wire them properly having a separate thermostat for each zone. The wiring the previous owner did is a nightmare.Zone valve wiring boiler water valves hot diagram piping honeywell diagrams 1080 conclusion use highperformancehvac. Need help with wiring diagram for a 2 thermostat, 2 zone valve, withThermostat wiring zone wire three valve taco heating rodgers schematic hot water diagram connection doityourself Thermostat honeywell thermostats heater ... How to wire a zone valve on a boiler, An automobile tune-up consists of a check of a vehicle’s fuel filter, air filter, spark plugs, spark plug wires and battery. The PCV valve, belts, lights and tires are also checked..., Taco Comfort Solutions engineers and manufactures high efficiency indoor heating, cooling, and air quality comfort systems. Purchase Taco products at Supplie..., Fluid Temperature Range: 50 F to 200 F. Electrical Connections: 18" leads. Power Consumption: 7.7 VA. Nominal Timing: 15 sec. Valve Action: Spring return to close. Dimensions: 4" high x 3-1/2" wide x 2-3/8" deep. Auxiliary End Switch: SPST. End Switch Rating: 50 VA pilot duty @ 24 V. Static Pressure (psi): 125 psi. , Jan 24, 2016 · Learn how to fix your hydronic heating by changing the zone valve motor with this easy tutorial. Watch the video and save money on repairs. , The wiring at the thermostat was identical to FIGURE 1, with a spare green wire. The zone valve controlling that zone looks like this (FIGURE 3), after my rewiring, with annotations based on the subsequent diagram (FIGURE 4): FIGURE 3. FIGURE 4. I don't want to brag, but this has been working out perfectly for the past couple of months., Delta T = The water temperature drop desired. Typically between 20 and 30 F. for an outdoor furnace. 500 = This is a constant number for water. if you are using a glycol mixture use 470 for a 50/50 mix. Be sure to properly size the piping and pumps to deliver the required minimum flow for the furnace., If the boiler kicks on, the end switch in the motor is bad or improperly wired. If not, the there's a problem with the panel or the wiring between it and the zone valve. 4. If you follow the wiring from the zone valve end switch to the panel and jump it there, if the boiler kicks on, the wiring is the culprit., How do I choose & install a zone valve, how do I wire up a zone valve, and how do I troubleshoot, repair or replace a zone valve? This article series answers most questions about Heating System Boiler Controls on central heating systems to aid in troubleshooting, inspection, diagnosis, and repairs. , Weil McLain and zone valves. kevsul1 Member Posts: 28. November 2021. I have a Weil McLain cga-5-pidn that I’m switching the three zone valves to taco 3 wire. The boiler has 2 wires labeled “stat” and 2 wires labeled “R” & “C”coming off the controller inside can tge “stat” wires be used as my TT wires for the zone valve end ..., Tried that and page cant be found. the zone valve box has a diagram for wiring zones but im not familar with this, thats why im looking for help to wire this in. boiler manufacturer states for mutiple zones to use another transformer to power zone valves. What Im looking for is a walk thru this wiring installation., The VN Series Zone Valves and Actuators are space saving compact 2 or 3-way ball valves, factory assembled and tested with electronic rotary fail-in-place or electronic-fail-safe actuators. Actuators provide 2-position or modulating control (with position feedback) of hot or chilled water with up to 50% glycol in residential and commercial HVAC ..., Turn power off to boiler. Disconnect the zone valve endswitch wires from the R and G terminals in the boiler. Place a wire JUMPER between the R and G terminals and turn power to boiler back on. Circ pump should run and boiler should fire. If not, then something going on with boiler., See full list on inspectapedia.com , 29 Sep 2012. #1. i have just installed a vaillant ecotec plus 637 and a megaflo unvented indirect cylinder, model 250i. the system has 2 heating zone valves for up stairs and down stairs and a dhw zone valve. i also have 2 room stat a wired honeywell t6360 for up stairs and a wireless honeywell hc60ng for down stairs. the boiler has it's own ..., 5). Attach a “spare” wire to the C terminal – such as the Black wire for C or Common. 6). Attach the Light Blue wire to the X/Aux terminal for Auxiliary heat. 7). Attach the Dark Blue wire to the B terminal for Reversing Valve for Heating. 8). Attach the Orange wire to the O terminal for Reversing Valve for Cooling. Thermostat Wiring ..., Step 5 - Removing the Zone Valve. The zone valve will be bolted onto the pipe. When it's safe to do so, the zone valve can simply be unbolted and removed from the line of pipe. Be careful when doing this because the valve can stay hot for some time, even when the boiler is shut off. Use the screwdriver to remove the electrical connections from ..., Web wiring a boiler and zone valves 33018 views 32 replies 18 participants last post by tdb , oct 23, 2008 c captkirk discussion starter · sep 28, 2008 i have. Web How To Wire A Boiler Zone Valve Step 1. Turn the boiler power supply off at the main electrical panel. Web the boiler's r and w ports should be connected to the zone valve's red ..., Boilers - Home Heating Steam and Hot Water Systems - C-Wire for Nest Thermostat with WeilMclain Ultra 155 Boiler/13 ZoneValve - Hi, WeilMclain Ultra 155 Boiler and 13 Honeywell Zone valve installed in my house. I have most of the nest thermostat (Learning and Nest E) and all of them are working fine without having, All of the other wiring is identical to the 230V switching version described previously. Heating active. When heat is required (zone 1 in this diagram), the thermostat contact closes, which connects 230V to the output terminal 3. This is connected in the wiring centre terminal 7 to the zone valve, so the valve motor opens. (Highlighted in red)., The system has a one zone Taco switching relay and five Taco zone valves. BTW, the thing works great. So on a call for heat I would assume that the zone valve opens and the secondary circulator starts up directly. But this doesn't seem to be the case. The valve opens but the secondary circulator doesn't come on., The wiring diagram for a 3 zone heating system outlines the connections between the thermostat, zone valves, and the boiler or furnace. Each zone of the system has its own thermostat, which communicates with the zone valve to control the flow of heated water or steam to that area. The diagram shows how these components are connected and how ..., Our boiler now has 120-V primary power going through a switch to a transformer supplying 24-V secondary power to the gas valve. All boilers and hot air furnaces that are vented through chimneys will have a spill switch, rollout switch, and flue damper. The flue damper motor is wired separately at terminals 1 and 4., I have been given the task of wiring a hot water boiler with 5 zone valves. the boiler has a low voltage wire comming out of the side of it. The electrician has already wired the 120v but I think he still needs to include the low water cut off after the service switch on the side of the unit., Installer Manual - High Efficiency Boilers and Hot Water Systems, Learn how to fix your hydronic heating by changing the zone valve motor with this easy tutorial. Watch the video and save money on repairs., Options. If that's a spring return (or wax) normally closed valve, the power has to stay on as long as it is to be kept open. If it's a power open, power close valve, then a simple thermostat simply won't work. You will have to have a relay to operate the valve. Relay is operated from the thermostat., LWCI Wiring Centre Hub" Boiler • 230V a.c. Cyl. Thermostat C 12 HTS3 Motorised Valve Pump g 10 M Mains Input Mains Function Leads VALVE CH VALVE live the d is used is to terminal sale Model WT724R, WV724R C y.. Thermostat IS 12 g 11 Pump 12 13 15 16 Links made by Mains Input Mains Boiler Motorised ZA6 CH ZONE 2 5 N E 6 is Hw CIRCUIT VALVE CH ZONE, The Hive (N) & (L) should be connected to the N and L 'load' terminals of the same 3A fused spur as the boiler. Hive Terminal (3) 'heating on' is the live supply that goes to the underfloor heating motorised valve's live wire. The motorised valve will also need a neutral, again from the same supply as the boiler., Troubleshooting and fixing my Honeywell Zone Valve. When zone valves fail they can leave you without heat, usually at the worst time. Take the time and learn..., The zone valves. This is how I wired the power connector to the zone valve (honeywell V8043F1036). Share Sort by: Best. Open comment sort options. Best. Top. New ... I've got a similar set up, except, when an HVAC guy did various upgrades to the electric boiler, they manually set all the Honeywell valves open, and connected the thermostat to ..., Operation/External Diagnostics: When any thermostat calls for heat, the appropriate zone valve is energized and the yellow light goes on. When the zone valve is fully open, the red light goes on and energizes the end switch relay. The green light should always be on, indicating that power is connected., 3. Be sure that any excess solder, flux, or other foreign matter is thoroughly removed from the valve bore. 4. With valve body mounted in the line, remove the head assembly from the carton, and carefully wipe stem with a soft cloth to remove any dust or grit. 5. The valve head may now be assembled to the valve body., The C terminal on Relay 2 on the Grundfos box is connected with the red wire to screw #5 on zone 1 valve. The NO terminal on Relay 2 on the Grundfos box is connected with the white wire to screw #4 on zone 1 valve. The NC terminal on the Grundfos box is connected with the green wire to screw #6 on zone 1 valve. Simple. Sequence of operation: