How to Hook Up a Zone Valve on a Hot Water Baseboard Heater

Hot water baseboard heaters used in rooms and other areas of a home may be individually controlled by zone valves and thermostats. Zone valves are electrically activated devices that control the flow of hot water to the heater. Each valve in the system operates with an assigned thermostat. You can hook up your baseboard heater thermostat to a zone valve using the proper materials, tools and basic do-it-yourself skills.

Flat-head screwdriver
Thermostat wire, 18-gauge
Razor knife
Wire strippers
Wire cutters

Instructions

- 1
  Turn off the electrical power to the boiler and zone valves at the main panel.
- 2
  Locate the 24-volt zone valve transformer. The transformer is usually in close proximity to the hot water boiler and is connected to the boiler control box.
- 3
  Separate 2 inches of the bonded 18-gauge thermostat wires, using a razor knife. One wire is typically white and the other is white with a red stripe.
- 4
  Strip 1/2 inch of insulation from the ends of each of the two wires, using wire strippers.
- 5
  Connect the two wires in any order to the two 24-volt output terminals on the transformer. Tighten the terminal screws clockwise, using a flat-head screwdriver.
- 6
  Run the wire from the transformer to the zone valve terminals assigned to the baseboard heater. The zone valve terminals are visible on the backside of the valve.
- 7
  Cut the wires at the zone valve, leaving several inches of slack.
- 8
  Separate and strip the wires as you did in Steps 3 and 4.
- 9
  Connect the white wire to the terminal marked “TR”. Tighten the terminal screw using the screwdriver.
- 10
  Connect the striped wire to the terminal marked “TH/TR”. Do not tighten this terminal yet.
- 11
  Separate and strip another pair of 18-gauge wires as in Steps 3 and 4.
- 12
  Connect the white wire to the “TR” terminal on the zone valve. Tighten the terminal screw clockwise using the screwdriver.
- 13
  Connect the striped wire to the “TH/TR” terminal with the striped wire from the transformer. Tighten the terminal screw.
- 14
  Run the two wires to the thermostat. Cut the wire length as needed at the thermostat.
- 15
  Separate and strip the wires as indicated in Steps 3 and 4.
- 16
  Connect the striped wire to the thermostat terminal marked “R”. Tighten the terminal clockwise using the screwdriver.
- 17
  Connect the white wire to the terminal marked “W”. Tighten the terminal screw.
- 18
  Restore power and set the thermostat to the desired temperature to check the zone valve operation.

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