Outline Guide to Domestic Heating

Outline Guide to Domestic Heating

If you effectively control your heating you can make real inroads to reducing energy bills.

Modern central heating systems can run very efficiently, providing comfort and hot water for a surprisingly low cost. The overall energy effectiveness of the system depends on firstly the efficiency of the boiler to ensure little potential heat is wasted and second, good controls to ensure the boiler only operates when necessary.

Good control over heating requires four things:

an electronic timer or programmer
a room thermostat
thermostatic radiator valves
cylinder thermostat on hot water tank

If you want to get really sophisticated you can also go for:

"intelligent" heating controls
weather compensation
load compensation controls
full zone control

The Programmer

This is a clock that turns the boiler on and off. I always recommend that you go a controller that gives you lots of on/off periods within any 24 hour period and where possible separate control for each of the 7-days. There are masses of these out there on the market - most of them are very good - email me for some recommendations.

Room Thermostat

If you only have one then it is best located in the communal Living Room. Do not locate it in the hall as it will be affected by the external doors opening. This is a simple device that records the room temperature and inhibits the boiler when a set operating temperature is achieved.

Thermostatic Radiator Valves

TRV's. These switch individual radiators on/off depending on how warm the room that they are serving becomes. They usually have a numbered valve (standardly * - 5 where * is for frost protection).

There is much confusion about what a TRV is for and what it should be set at - lets try and clear this up. For a normal living room a setting of 3 or 4 is usually adequate. For a bedroom a cooler level should suffice (say 2). Turning up the dial on the TRV when the radiator is already ON will not increase the room temperature!!!!! Now pay attention - once you have your TRV's set leave the blummin' things alone - constantly changing them just upsets the balance of your heating system and leads to problems.

TRV's are readily installed by competent DIYer's and cost very little. generally it is recommended to leave one radiator without control - often in the Bathroom or in the room where the Room Thermostat is located. Do not fit a TRV on any radiator in the room where the Room Thermostat is fitted as they will not cooperate - rather they will fight each other and your rooms will not be heated properly. Again there are masses of these out there - email me for some recommendations

Cylinder Stat's

First and foremost it is essential that hot water production and comfort heating are separate functions of the time/programmer. Then fit a cylinder stat to the outside of the hot water storage tank and make sure it is not set above 60^oC.

Make sure that the room thermostat and cylinder stat are linked to the boiler by means of an interlock so that when both house and hot water are up to temperature the boiler will be switched off. If you don't do this the internal thermostat within the boiler heat exchanger will cause the burner to fire up regularly - this is caused "dry cycling" and is a complete waste of energy with the boiler at zero efficiency.

The Advanced Stuff

Intelligent heating controllers are available that combine several of the basic functions and can adapt to changing climate and occupancy patterns. They can also deliver different room temperatures for day and night and learn about the construction of your house and react to its differing patterns of heat loss / gain. All very clever and you should email me for some recommendations

Weather compensation delays or advances the switching of the boiler according to changes in the climate.

Load compensation is the simple measurement of decay (fall) in return flow temperature and the inhibition of the boiler until critical set-backs are achieved. Significant savings are only going to accrue where you are unable to establish an interlock between thermostatic sensors and the boiler but where this is appropriate savings can be 15-20%, equating to the savings achieved by proper thermostatic control. Combi boilers effectively have this technology inbuilt.

Zone Control

Most homes are viewed a single zone with the only controls being TRV's. However, where you can split the heating demands, for example between floors or between Living Rooms and Bedrooms it can provide very substantial savings by simply closing down loops of a heating system and reducing the demand on the central plant.