Modern central heating systems can run efficiently providing warm and comfortable homes at a surprisingly low cost. The overall effectiveness of a heating system depends on two things: a high-efficiency boiler, which ensures little potential heat is wasted, and good controls, designed to ensure that the boiler is only working when heat is needed in the home.
Good heating controls require a minimum of four things:
• an electronic timer or programmer
• a room thermostat
• thermostatic radiator control valves (TRVs), and
• separate thermostatic control on the hot water system
Hot water cylinder thermostat - This section does not apply to combination (Combi) boilers, but only to systems with a separate hot water tank. Firstly, it is most important that the hot water can be controlled by the programmer separately from the central heating.
Some older systems only allow the heating to run when the hot water is on; this can be quite wasteful of fuel. Secondly, there should be a thermostat on the hot water tank - this is usually strapped to the outside fairly near the bottom. This controls the water temperature - it should not normally need to be set higher than 60°.
Basic Room Thermostat - This is best located in a living room, rather than the hallway, as is commonly done, as the hall temperature can be affected by the front door being used. The thermostat records the home's temperature and if it is at or above the set level (and 20°C/68°F is usually adequate) stops the boiler from operating the central heating. This is a minimum requirement under current regulations.
Intelligent Room Thermostat - Intelligent heating controllers learn how long it takes for a house to heat up in different weather conditions. These also often allow for different temperatures to be set between day and night and give a much better control over central heating, although they cost somewhat more than normal controls.
Programmable Room Thermostat - Incorporate built in thermostats and temperature sensors. These need to be sited in a living room rather than by the boiler, but can often represent a good investment.
The room thermostat and the hot water thermostat should be wired up to the boiler in what is known as an "interlock". This means that if both the house and hot water are at temperature, the boiler will be switched off. If this does not happen, when the water temperature inside the boiler itself falls, an internal thermostat will cause the boiler to heat up this water - a process known as "dry cycling". All the energy used in this cycle is wasted as it is not used for any useful purpose.
The timer or programmer - The electronic timer or programmer decides when the boiler is able to run. It is not true that boilers work best when they are running continuously or that energy is saved by leaving the heating on all day, even if the home is unoccupied.
Whenever the boiler is firing it is using energy, and whenever the home is being heated to a temperature above that outside, it will be losing heat to the outside world. In spring and autumn there is no need to keep the heating on all day; a reasonably well insulated home can be left to cool down slowly with the heating timed to come on perhaps an hour or so before people return home from work.
A seven day timer is also strongly recommended, so that it is possible to set a different heating pattern for weekdays and weekends. Some timers allow different patterns for each day of the week; this can be useful for those working part-time or on shifts that vary from the conventional Monday-Friday work pattern.
Thermostatic Radiator Valve (TRV’s) - These switch individual radiators on or off, depending on how warm the room that they are located in is. They usually have a fat valve at one end, marked with a * and numbers from 1 to 5. The * setting is to protect against frost; it will typically leave the radiator switched off unless the temperature falls below about 6°C. For a normal living room, the setting of 3 or 4 is likely to be about right; for a bedroom a cooler temperature will normally suffice.
Zone Valves - Most homes have a single heating zone - the only controls in the rooms are by TRVs. However the need for heating in the main living rooms can be quite different from that in bedrooms, with the latter requiring lower temperatures for longer hours. When a new central heating system is installed, it is possible to fit a full zone control that has different pipe loops and separate thermostats for two (or more) areas. This can save significant amounts of fuel in larger houses.
Blue Flame Heating Solutions are Energy Efficiency certified and will advise you of the best options available for your individual requirements using a combination of the controls listed above contact us 01382 84 83 84
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