Controls and Zones Keep Every Room Comfortable

Absolute controllability is a defining feature of warm water heating systems. Even the most basic systems are fitted with a thermostat and time controller, allowing warmth to be delivered only when it is needed. In addition, individual radiators are fitted with thermostats, allowing precise control over the heating supplied to different parts of the house. The more sophisticated underfloor systems can also be set up and programmed to control the duration and level of heat supplied to individual rooms and zones.

Zoning the Heat: Practical Guidelines for Radiator Systems

Zoning enables heating times and/or temperatures to be set differently in different parts of the house.

For a radiator system, we recommend:

  • In a small- to medium-sized house zoning is not required as the radiators all have individual thermostatic control. They can also be turned off individually.
  • In a large house, set up at least one bedroom and one living zone, as this is practical for most lifestyles. It is also energy efficient.
  • A home office and occasional lounge are also good zoning options.

Radiators: Control Thermostats vs Slave Thermostats

A radiator system has a central programmer to control heating time and temperature. This is typically located in a neutral area such as a hallway, where there are no outside walls and windows to attract solar gains (increase in temperature due to the sun).


Individual radiators have their own thermostatic valve that senses the room temperature. When the room reaches the temperature set on the thermostatic valve, the radiator shuts off. This valve can be turned off altogether in rooms that are not being used. The valve is a slave thermostat, which means it will only regulate heat when the main system controller is on.

It is possible to have two or more radiator zones, with each zone having its own system controller. However, this requires separate piping circuits.


Zoning the Heat: Practical Guidelines for Underfloor Systems

For underfloor systems it is possible to have a thermostat in each room because of the way the manifold is piped, but too many zones defeats the purpose of central heating, and most homeowners find that they do not need very many zones to achieve their desired level of comfort. Additionally, higher control means increased installation cost. In general we recommend:

  • The main living room, kitchen, hall and bathroom all be controlled by one programmer – these are the main living areas of the house.
  • Bedrooms and occasional rooms such as study, second lounge and en suite, be individually controlled with their own thermostat.

Underfloor Controls

An underfloor system has a main programmer like the radiator system. In addition, each underfloor loop can be controlled by a wall-mounted thermostat within each room. These are slave thermostats, so they will only regulate heat when the main programmer is on.

It is possible to incorporate more than one main controller into an underfloor system. The practicality of this depends on the size and layout of the house.

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