There are numerous devices used to control the central heating systems in our home as well as the hot water supply. The most basic of these will be a simple timer. You will often see these on low spec boilers as they are cheaper than other controls. The timer is often a simple mechanical device with pins or lugs for each ¼ hour of the day. The pins are moved in or out depending on whether the boiler should come on or go off. As the timer wheel turns round, the position of the pins triggers the boiler to be switched on or off.
A simple room thermostat controls when heating is called for depending upon the temperature in the area where it is located. Choosing the best position for your room thermostat is therefore very important. The device measures the temperature of the air around it so placing it where there are draughts will have an adverse effect. In this situation the cooled air draught might trigger the heating to go on even though the ambient temperature in the room is at the required level. Other areas to avoid are direct sources of heat – radiators nearby or an electrical appliance such as a television. Most often they are fitted in the hallway but may also be in a living room. The important consideration is to decide where in the house you wish to measure the temperature.
Depending on the heating system you have in your home, a room thermostat may trigger the boiler, the pump, or a motorised valve. There are some common errors when setting thermostats. When the house is cold some people think that turning the temperature setting right up will make it heat up more quickly. This is not the case. Likewise, turning the thermostat right down to zero will not cool a room any quicker. It is simply a device which will switch the heating on or off according to temperature at the unit.
Normally the way to get the best from these is to set a moderate temperature of say 18 degrees and allow the room to warm up for a decent length of time. If after a while the room is still too cool, turn it up a degree or two and leave for a while longer. Using this set up method you can establish a setting which provides the most suitable ambient temperature.
Room thermostats can also include a simple timer. This allows you to set temperatures that you require at certain times of day and the timer will take control.
More sophisticated devices are available which control the central heating and the hot water systems. These are called programmers and have varying functionality. Simple programmers allow you to control when the heating comes on and goes off and likewise for the hot water. Most will allow for programming three separate time slots for each. More advanced heating and hot water programmers will allow you to programme different settings for weekdays and weekends, or even each day of the week. The more complex units are necessarily more expensive but give more control. Programmers also tend to have an override or boost option. This means that it is simple to call for hot water and / or heating when the system would normally be off. Boost buttons generally trigger for an hour.
The important thing with programmers is that you can set hot water and heating so that they are only on when they are actually needed thus minimising your fuel bills and reducing energy waste. In the winter for example, you might have the heating coming on half an hour before you get up and going off when you leave for work. Similarly you’d probably set the temperature you want in the evenings and have it come on half an hour before you get in.
A thermostat may be mounted on the outer surface of a hot water cylinder to measure the temperature. Once the set temperature is reached, a signal is sent to the motorised valve which will switch off the hot water circuit.
The external thermostat on some cylinders can sometimes work loose and therefore give a false reading. If you find the water is getting hotter than it used to and you haven’t adjusted the thermostat it may simply be that it has lost contact with the surface of the cylinder. Try re securing it so that there is full contact.