Central Heating Controls Design

By tradition central heating and hot water control systems are installed by plumbers as part of the heating installation. Because plumbers have no proper training in electrical systems they use standard wiring plans prepared by the controls manufacturers, these plans are simplistic to suit the standard of competance of those installing such systems; these wiring plans should really be called Janet and John sheets which is a more realistic name than wiring plans.

A brief consideration of a heating and hot water system will demonstrate that the traditional method of control is inefficient and therefore running the heating system is more costly than necessary. The hot water system now has to be controlled by programmer and thermostat; at best the heating system may be controlled by zoned systems and thermostatic radiator valves, this can leave the boiler and pump running to supply heating to rooms where the thermostatic radiator valves are closed. A better system is to have motorised valves controlling the heating in each room with those valves each having a switch that closes when the valve opens which then starts the boiler and pump; the switch opens when the valve closes to switch off the pump and boiler. The motorised valves are controlled by individual programmable thermostats located in each room of the dwelling, the setting of each programmable thermostat should reflect the rooms useage and temperature requirements, the initial cost of such a system is higher however the heating costs will be lower. The wiring for this type of system is obviously more complex than the standard Janet and John systems which is why they should be installed by an electrician. It will no doubt be the electrician that carries out the earthing and bonding of the system, also since the heating and hot water control system forms part of the fixed wiring installation it will need to be tested in accordance with the IET Wiring Regulations not a task for a plumber.

Just a small point the normal domestic motorised valve uses a motor to open the valve, once the valve reaches the end of it's travel the motor stops however the power supply is still connected to the motor thus whenever the valve is open approximately 6W of electrical energy is used to keep the valve open, not a lot but since we are all pressed by the political masterclass to turn our televisions off at the mains as leaving them on standby consumes 0.3W of electrical energy why have they not encouraged the replacement of those valves; that is a clear demonstration of what a bunch of incompetants politicians are, they really don't have a clue about the real world. The valves suggested above only use power during the opening and closing cycle, each of which is approximately 30 seconds at 7W, thus saving far more electrical energy, than turning of a television, as well as giving better heating control which saves money on the heating fuel.