Broadly speaking there are two types of hot water systems:

• Combi Boiler - Controls your central heating as required using a timer switch and only heats your hot water when you need it

• System Boiler - Controls your central heating and hot water via a single timer switch

Combi Boiler (Compatible with Cosy - heating only)

Cosy can be used to control your central heating only

System Boiler

Cosy can be used to control your central heating (and hot water depending on your plumbing). It can be difficult to understand how your hot water and heating systems have been plumbed in, if in doubt ask an expert to help.

There will be a separate hot cylinder, next to which will be the pump and one or more motorised valves

S-Plan  Systems (Compatible with Cosy system - Heating and Hot Water)

Below are examples of 2-port motorised valves (typically 2 of these are used in a S-Plan system)


       

Y-Plan  Systems (Compatible with Cosy system - Heating and Hot Water)                                                                      

Below are examples of 3-port motorised valves (typically 1 of these is used in a Y-Plan system)