Systems and components©

Boiler is the source of heat for the heating system

The Sundial C Plan is designed to provide independent temperature control of both heating and hot water circuits in existing pumped heating, gravity domestic hot water heating installations. Time control must be provided by programmer.

The control performance satisfies the minimum standard for Building Regulations Part L1, although the gravity hot water system may require upgrading to fully pumped. New systems must be fully pumped, controlled by S, S Plus or Y Plans.©

According to experts at the Energy Saving Trust, as well as British Gas, the idea that it's cheaper to leave the heating on low all day is a myth. ... (Using a timer's best, because your thermostat is designed to turn your heating on and off to keep your home at the temperature you set it.)

Shown here there are some images of common controls, there are more and they are used to monitor temperature, set the time when the heating comes on and conserve energy.©

The reason this system is called a ‘S’ plan heating system is because of the shape of the system when drawn schematically. Heated water from the boiler is diverted to the hot water coil or the radiators depending on which service the programmer is asking for and which thermostat is calling for heat. The 2 port valves serve one service each. For example there is only one 2 port valve for the hot water cylinder and a separate one for the heating system. Therefore you need a certain sequence of switches to work in order for the system to operate ©

The reason this system is called a ‘Y’ plan is because of the shape of the 3 port valve. There are many 3 port producers including Honeywell, Horstmann and Danfoss to name but a few.

Heated water from the boiler is diverted to the hot water coil or the radiators depending on which service the programmer is asking for and which thermostat is calling for heat. The 3 port valve also acts as a switch to turn on heating system components©

Gravity fed hot water is exactly that, when the programmer is in an 'ON' period for Domestic Hot Water (DHW); the boiler lights and a large volume of water is heated up. Because the cold water is more dense than the newly heated water, the cold water falls back down to the boiler, displacing the less dense hot water which is consequently moved up to the cylinder.

Should the room thermostat call for heat (during a hot water period), it simply switches the pump on, circulating heated water through the radiators. As such it is not possible to have heating without hot water©

Circulating pump is used to push the water around the system from the heating system©

Radiators are heat emitters that convect the heat out into the room from the boiler©

Two pipe pumped heating and gravity hot water©