Central Heating Guide
C/H Controls Introduction
C/H Thermal Controls
C/H Valve Controls
C/H Function Controls
C/H System Replacement
C/H Controls Installation
Energy efficient home
Central Heating Systems Controls - Efficient settings
The installation of effective central heating controls has a major impact on the energy consumption of heating and
hot water systems. This Guide brings together information on the individual types of controls
that are now available and the most appropriate controls suitable for different heating systems.
It provides information to assist central heating installers and specifiers to make the best choices in
the selection of controls, which will lead to:
improved energy efficiency
reduced running costs
lower carbon dioxide (CO2) emissions.
The Guide covers controls for all domestic central heating systems supplied by mains gas, liquefied
petroleum gas (LPG), oil, electricity and solid fuel.
Effective controls will increase operating efficiency, particularly when replacing or upgrading older c/h systems, but they
also provide the householder with the opportunity to minimise energy consumption by reducing comfort temperatures. Timed heating and hot water
periods can also reduce overheating. Heating fuel is expensive (gas boilers and warm air heaters typically
cost 15-35p/hour when they are operating) and reducing the firing time will make a proportionate
difference to running costs.
The provision of a minimum standard of installed controls is crucial to the achievement of satisfactory in-use
efficiencies for ‘wet’ heating systems (those with a boiler and radiators). Requirements for minimum
boiler efficiency based on SEDBUK – Seasonal Efficiency of Domestic Boilers in the UK – will be introduced in revised Building Regulations
in 2002. The minimum set of efficient controls recommended in this Guide must be installed to achieve SEDBUK efficiency. A number of Government-backed energy
efficiency schemes are being introduced, eg HEES plus (Home Energy Efficiency Scheme) where these
minimum standards of installed controls are specified.
What is a ‘good’ central heating control system? It will ensure that the boiler or heater does not operate unless there is a demand, and it must only provide heat when and
where it is required, so as to achieve the required temperatures. The selection of appropriate controls
plays a key part in the overall running costs of a heating or hot water system.
The cost benefits of controls should not be underestimated. Installing controls on older
heating systems can save up to 17% on energy bills, for example when a full set of controls are
fitted to a system which previously had none.
This is particularly important because over 80% of the energy a householder uses in the home
is for heating and hot water and the use of controls will directly influence this consumption.
WHICH SYSTEMS BENEFIT FROM CENTRAL HEATING CONTROLS?
’Wet’ systems – with radiators, convectors or underfloor heating:
– regular boiler systems – separate hot water tank
– combi boiler systems – instantaneous, or ‘built-in’ tank.
Warm air systems.
Electric storage and panel systems – space and water heating using on-peak and off-peak electricity.
ENERGY SAVINGS FROM GOOD CONTROLS
Heating and hot water accounts for over 80% of the energy consumption in the home.
The installation of a minimum standard of controls in a wet system (which previously had no controls) can reduce fuel consumption and CO2 emissions by 17%.
Controls to reduce higher-than-necessary room temperatures are very beneficial.
Turning down the room thermostat by 1°C will reduce space heating consumption by 6-10%.
Reducing the heating ‘on’ time by two hours a day can reduce consumption by 6%.
Also, over 50% of the household energy costs and
65% of the CO2 emissions come from providing
space and water heating in the home.
This Guide describes installation of the controls for boiler (’wet’) systems,
warm air systems, electric storage heating and hot
water systems. It provides advice on good practice and
considers both new systems and upgrading. More
advanced control functions, such as weather
compensators and optimum start, are also considered.
The Guide provides information on controls for
domestic heating and hot water systems up to a
heat output of 50 kW. For larger systems, it may
be that more sophisticated controls can be justified
– guidance on controls for small commercial
buildings is given in Good Practice Guide (GPG)
132. More general guidance on domestic central
heating and hot water with gas and oil-fired boilers
is given in GPG 284.
This Guide is published as part of the
Government’s Energy Efficiency Best Practice
programme (EEBPp), the building-related aspects
of which are managed by BRECSU.