3
Compatibility
Cosy is a mains powered wireless controlled thermostat that controls the heating and hot water.
This guide refers to the installation of the switch that is used to control the hot water.
Compatibility with hot water systems:
• Cosy only controls hot water on systems with a hot water tank. (i.e. not a combi boiler)
• This version of Cosy can be used with a Y plan hot water system which uses a three-way valve
or an S plan system using individual valves. (see diagrams)
MID-POSITION
VALVE
PUMP
FLOW
Y-PLAN SYSTEM
RETURN
BOILER
ZONE
VALVE
ZONE
VALVE
PUMP
FLOW
S-PLAN SYSTEM
RETURN
BOILER