For as long as we have had central heating we have had heating controls. These used to be fairly crude as they dealt with the temperature of the whole house from a single thermostat.
The last few years have seen a rapid development in control technology,
For as long as we have had central heating we have had heating controls. These used to be fairly crude as they dealt with the temperature of the whole house from a single thermostat.
The last few years have seen a rapid development in control technology, which can make a significant difference to accuracy, efficiency and heating bills. As is often the case, there is now a plethora of choice and it is difficult to know what is best.
What is Wrong with our Existing Heating Systems?
A combi boiler will use just a single timer or programmer, as water is heated as required. There are serious question marks over whether this is a good idea for the homeowner as it offers the bare minimum level of control.
Similarly, a simple indirect hot water cylinder will have a thermostat fixed to the cylinder to measure the temperature of the water in it. The implication of this is that all the water in the cylinder will be at the same temperature and the boiler will run to heat it until the desired temperature is reached.
A thermal store offers far more control as it will store water at a range of temperatures. If we have underfloor heating we want water at around 40°C but we also want domestic hot water at 64°C to kill legionella bacteria. The controls inherent in a thermal store allow us to do that without wasting energy.
Should I Still Use TRVs?
The old-style analogue room thermostat is still being installed, usually one to each floor. At best, these are accurate to +/-2°C — poorer quality ones can double that inaccuracy. A programmer allows the heating to be switched on and off multiple times each day, and to deal with hot water separately. This is a better option than a combi boiler, but by not much.
More common now are thermostatic radiator valves (TRVs). These are fitted to the radiator, with graduation typically from one to six. They give no indication of the actual temperature in the room, beyond comfortable or uncomfortable. These were popular for a few years but have, thankfully, fallen out of favour.
The big change in the past few years has been the realisation that different rooms need different temperatures at different times, often referred to as zone control.
What is Zone Control Heating?
Zone control actually means controlling the heating in each room, and it can be done in one of two ways: centrally or individually.
- Centrally: An underfloor heating system will be controlled centrally. A thermostat in each room reports back to the central programmer where the homeowner sets the time and temperature for each room.
- Individually: For radiator systems a similar level of control comes via programmable radiator thermostats. These are battery powered and allow for precise control of the time and temperature in each room. They are fitted like TRVs and some simply replace the body of a pre-existing TRV so that the heating system does not have to be drained down.
There are also wireless options that can be programmed from a central point, otherwise each thermostat has to be programmed individually.
How do Remote Heating Controls Work?
A phone app allows the user to change the temperature or timing of the heating and/or hot water system from wherever they happen to be.
Some, like the Nest and Tado, are said to be intelligent in that they learn the user’s habits and automatically change their settings to meet prevailing conditions. They can apparently detect that the homeowner is not in the house and will delay switching the heating on, or turn it off.
These systems have a device in the house that connects to the existing control system, which is accessed via a phone app. The thinking is that if the user has a ‘busy’ lifestyle (eg going out after work) the app will allow them to adjust the heating accordingly.
There are significant cl