The 560 series valves are designed to be installed down-stream of a fan coil unit. Follow these steps to pipe the valve:

1. Connect the discharge of the fan-coil to the unit connection of the valve.
2. Install a tee in the upstream side of the fan-coil supply line.
3. Connect the branch connection of the tee to the bypass connection of the valve.
4. Connect the main side of the valve to the return main of the system.

When the valve is not energized, the system fluid flows through the bypass connection to the return main. When the valve is energized, it flows from the unit connection to the return main. The bypass connection is not a positive shut off when the valve is energized.

Electro-mechanical thermostats have a small variable heater built into them. It tricks the thermostat into thinking that the room temperature is satisfied so the temperature doesn’t overshoot.

The setting of the heat anticipator is based on the current draw of the connected zone valve wiring. A low current drawing valve requires a longer heater wire to create the same amount of heat. A high current draw circuit requires only a short heater wire.

Taco zone valves of the 550, 560, and 570 series draw about 1 amp, so the heat anticipator should be set accordingly. If the thermostat is short cycling, increase the setting to a higher amp setting.

There are a few possible causes:

The 570 series can only hold back 50 feet of head. If a pump upstream of the valve produces more than 50 feet, the valve will be pushed open.

If the manual lever has been pulled down, the valve will be manually opened.

The zone valve is in an environmet which is causing the piston of the operator to stick, preventing the valve from closing.

Taco still offers a thermostat #568-20. It may not look like your original, but it functions the same. Many people mistakenly think the 571 zone valve is a 3-wire zone valve because it has 3 terminals. All the Taco 500 series zone valves are 2-wire, 3-terminal zone valves. The heat anticipator has no bearing on the operation of the zone valve. Its purpose is to trick the thermostat into shutting off ahead of time, allowing the heat left in the piping system to dissipate into the room and not overshoot the temperature setting. The current draw of the circuit had to be matched to the heat anticipator so it would work properly. A lot of the new thermostats do not require a heat anticipator. All of the battery operated thermostats will work with the resistor and the units that require a third wire (C) to get power from the transformer. It is the digital units that either steal power, need the resistor, direct power, or battery. All the other conventional units work, but make sure they handle a current rating of 1 Amp.