Retrofitting Fan Coils

Fan coil units are the HVAC unit of choice for larger hotels (>300) and where architectural constraints do not allow for air-cooled units. There are many configurations such as pneumatic control, line-voltage control, low-voltage control, or places where there is constant water flow and the thermostat controls the fan to produce heating or cooling (depending on the temperature circulating through the pipes).

Most fan coil retrofit scenarios involve line-voltage controls where the fan coil motor and control elements operate at the same voltage. This means that the water flow control valves, fan speed inputs, and electric heater relays use line voltage (i.e. 208V, 220V, or 277V).

24VAC thermostats are not ideal in this situation since it would force complete replacement of all control elements to work with 24VAC. This type of replacement might render the project unattractive from a cost perspective since additional labor would be needed to replace all these components.

Verdant offers a simple solution to this problem – a voltage adapter. The voltage adapter (FCA-47) can use the existing line voltage feed and produce control outputs at the same voltage that feeds the adapter. With the adapter, all existing components can be reused (valves and relays) and fan speed selection can be maintained. The voltage adapter will provide power to a thermostat or HVAC controller, stepping down the line voltage to 24VAC.

There are some situations where the fan speed controls use line-voltage, but the valves have been modified to use 24VAC. If this is the case, the simplest solution is to install relays to control fan speeds and keep a 24VAC installation.