Central Heating & Hot Water Controls

Warm air boilers and heating systems were trendy in the large housing estates in the 1970’s and 1980’s. These have now been superceded by water-filled radiator systems which can be found in all new developments.

There are still a surprising number of warm air systems around with many owners quite happy with them as they’re quiet, efficient and take up less space in the home. On the other hand, there are some who dislike the systems and report problems with draughts, dust being wafted around the home and problems with temperature control.

Draughts are usually a result of incorrect system design or incorrectly set outlet grills. Some gas engineers will be quick to condemn these systems which often leave the homeowner out of pocket when it comes to replacing them with conventional radiators. In the majority of cases there is nothing wrong with the systems which only require maintenance and cleaning, work we are more than happy to carry out.

Hot water with warm air heating is not the same as with a water-filled central heating boiler. Either a hot water cylinder with electric immersion heater or an ‘ascot’ style gas-fired instantaneous water heater can be used. The best option is the ‘Janus’ water heater accessory which fits inside the warm air heater casing. This is a miniature gas boiler designed to heat just a hot water cylinder, and this works very well.

An ordinary modern domestic heating system has the following major components. (The first five have controls that the user can set or adjust):

1) Boiler 2) Programmer 3) Room thermostat 4) Hot water cylinder thermostat
5) Radiators 6) Hot water cylinder 7) Diverter valve 8) Pump

And here's how they work together as a whole system...

1) The boiler has two separate functions. To heat your hot water tank and to heat your house.

3) Your programmer contains a clock and two time switches (channels) which turn the hot water and central heating services on and off at pre-selected times of day (or night).

4) Once the system is turned 'on' by the programmer, the boiler will be turned on and off by either the "room thermostat" and the "hot water cylinder thermostat". Each thermostat will turn the boiler on when heat is needed, then turn it off again when it isn't.

5) The "diverter valve" is an electrically operated valve which switches the hot water flowing from the boiler to the radiators or hot water cylinder depending on which thermostat is calling for heat. If both are calling for heat at the same time the valve will assume a 'mid-position', sharing the flow between cylinder and radiators. The diverter valve is sometimes called a 'mid-position valve' for this reason.