Renfrewshire Council

Gas heating systems

Modern gas central heating systems are safe, controllable and efficient to run but have a number of controls that may not be fully understood.

Using heating controls properly can:

  • improve the comfort of your home
  • reduce the energy used and therefore cut fuel bills
  • provide adequate room temperatures for the elderly and infants
  • avoid the risk of condensation dampness

Why have controls on a gas central heating system?

For a gas central heating and hot water system to operate efficiently it must be controlled so that heat and hot water is provided at a suitable temperature, when and where required.

Most systems include a:

  • boiler (which can be a condensing, condensing combi, conventional or conventional combi model)
  • hot water tank
  • room thermostat
  • radiators
  • thermostatic radiator controls
  • programmer

The boiler
A boiler heats up the water which is circulated through radiators. It also heats a coil in the hot water tank and this heats the water stored inside for household use.

If your boiler is a 'combi' (combination) boiler then the water is heated instantly when the hot water taps are switched on. The thermostat on the boiler controls the temperature of the water circulating around the system. Please refer to the manufacturer's instructions for the optimum setting of the thermostat.

Hot water tank
Most hot water cylinders have a thermostat; this is recommended to be set at 60°C. It is useful to cover hot water cylinders with a minimum of 8cm of insulation to retain heat.

Radiators are used in gas central heating systems. The water is heated by the boiler and travels through the radiators, giving out heat.

Thermostatic radiator valves (TRVs)
TRVs are found on radiators in rooms other than where the room thermostat is placed. The TRV senses the air temperature in the room and can be set higher in the rooms you use most and lower in rooms used least such as bedrooms. They can also be used to turn an individual radiator on or off.

Room thermostat
This is usually found in the living room or hallway and is recommended to be set at 21°C and 18°C for each room respectively.

The room thermostat will respond to the temperature in the room where it is situated. When the room is warm enough it sends a signal to the central heating pump to stop heating the radiators until the temperature drops below the set level. At this point they will come on again.


The programmer is usually situated in the kitchen and can be set to control the times when the central heating and hot water are switched on and off.

The average heating period is about 8 hours each day. But this depends on your own personal circumstances. The majority of time clocks allow you to set two 'on' and 'off' periods during the day i.e. 8.00am - 10.00am and 4.00pm - 10.00pm.

In order to wake up to a warm house set the heating to come on approximately 30 minutes before you get up and then in the evening set the heating to turn off about 1 hour before you go to bed. This will account for the time it takes for the house to warm up and cool down.

There are a variety of programmers for operating central heating (CH) and hot water (HW). The majority have the following controls.

  • On/Constant -HW/CH is on 24 hours each day.
  • Off - the HW/CH is completely off.
  • Once - the HW/CH comes on at the first "ON" time selected and turns off at the second "OFF" time selected.
  • Twice/Auto - the HW/CH comes on for the 2 selected time periods.
  • Hot water only - the heating system will not operate.
  • If you have mislaid your instructions on how to operate your programmer you can request a copy from the manufacturer. 
  • If you are a Council tenant and require further information please contact the energy management unit on 0141 618 6198.

Gas safety

Natural gas is a very safe fuel to use in your home. But it's vital that you know what procedures to follow if you smell gas:

  • Turn the gas off at the meter (usually located in a meter box outside your home).
  • Make sure all appliances are turned off.
  • Open a window to let the fresh air in and gas out.
  • Do not smoke or light any matches or naked flames.
  • Do not switch lights or electrical goods on or off.
  • Phone the Transco Emergency telephone number on 0800 111 999.