The delivery of heat from our boilers to the house is often an overlooked area of importance. There are a number of factors that influence choice of radiators:
1. Temperature range being produced by the heating system
2. Design of the radiators
3. Radiator covers
4. Size of the radiators
5. Use of Thermostatic Radiator Valves
6. Location of radiators
7. Insulation of heating system
1. If you have a low temperature system (like Air Source Heat Pump, GSHP etc) then you need to get ‘oversized’ radiators so that it can deliver the lower heat and still reach the internal temperatures desired.
2. The design of the radiator has a large impact on how effective it is in delivering heat. Modern radiators have more ‘fins’ that radiate the heat better. Fancy designs of radiators might have a large effect on their effectiveness.
3. Placing radiator covers over your radiators reduces the amount of heat that each one can give out. They can reduce the airflow around them and this can slow their effectiveness.
4. The size of the radiators has an obvious effect and this could be achieved by having double radiators rather than having a larger spatial area of wall dedicated to the heating system. But the size needs to be calculated against the volume of the room and the type of construction of the building. So poorly performing structures need larger radiators and larger rooms need more heated surface area. Your plumber can calculate this.
5. TRVs are a great way of getting the right temperature in each room. By having controls on each radiator it allows you to set the temperature of each of the rooms. So lower temperatures in bedrooms etc.
6. The location of radiators can also have a large effect. Placing one on an external wall increases the amount of heat lost to the wall, whereas fitting to an internal wall means that the wall acts as a thermal store and will release the heat into the room as well as absorbing it when the heating is on. Many radiators are placed under windows to reduce the incidence of condensation. This can be really advantageous if condensation is likely, but it does reduce the effectiveness of the radiators in delivering heat into the room. Also you may need to locate radiators in certain places due to a number of factors – room layout, furniture, location of secondary heat source (e.g. fireplace). So again ask advice from your plumber as to the best location for each room.
7. You may be in the situation where it is worth insulating the pipework between the radiators, but for most people this is not so important as the heat will be kept in the ‘thermal envelope’ of the house.
Recently we replaced all of our radiators (along with our heating system) and it made a huge difference. This was primarily due to three reasons.
A. Having the correct sized radiators fitted for each room
B. Fitting TRVs on all radiators (this also provides us with an automatic system that removes the need for a central thermostat)
C. Installing modern finned radiators that give off heat much more effectively.
So remember that it is worth having a good plumber and asking to see their workings out (calculations for radiator size etc.).