Heating Controls

There are three categories of Heating Controls that can be entered for the assessment on an existing dwelling. These are:

• Standard Controls
• Time & Temperature Zone Controls
• Compensators

For a central heating system powered by a boiler, standard controls include:

• Thermostat
• Programmer
• Thermostatic Radiator Valves (TRVs)

Ideally you want to have all three of these registered on your EPC assessment as being present in your property. If any are missing, or what you have in the property doesn't qualify, consider changing the controls so that you can legitimately register all of these as being present.

A thermostat and a programmer can often be designed together within a single device, so if the device that you set the target temperature with and also set the on/off times for your boiler are the same device then that is providing both functions.

For TRVs to be registered as being present, they need to be fitted on at least 50% of your radiators. Often it's the TRVs that some properties lack. Consider adding TRVs onto radiators where they are not already present so that you qualify.

Here is a list of standard heating controls that can be chosen in the system. The EPC rating displayed is that which my house achieves with each option chosen. Check out our Case Study 2 for more information of this property.

How the rating changes for your property will differ from this, so always check with an energy assessor to see what rating you will achieve before spending any money:

From no controls at all, to Programmer Thermostat & TRVs gives me an increase of 4 SAP points.

If I already had the Programmer and Thermostat but was missing the TRVs and had those added (which is a much more common scenario), then I would only have a 1 SAP point increase. That single point though could combine with other points to take you over a banding threshold.

With standard heating controls, the flow temperature of the water being pumped around the system is fixed. Control is effected by turning the boiler on and off as the room temperature falls below and then rises above the target temperature you set on the thermostat. This usually leads to the room temperature rising beyond the target temperature and the boiler cycling on and off repeatedly.

There are some advanced heating controls however which adjust the flow temperature of the water being pumped through the radiators and make the boiler slightly more efficient. There are two main ways in which this is possible:

Load Compensation - by taking into consideration the difference between the room temperature and the target temperature set on the thermostat.

Weather Compensation - by taking into consideration the temperature outside the property, compared to the temperature inside.

With load compensation, the flow temperature of the water is generally lower than would traditionally be set with standard controls. Additionally, it is further reduced as the room temperature approaches the target temperature on the thermostat. This behaviour reduces the load on the boiler, avoids overshoot of the target temperature in the room, and prevents the boiler cycling on and off so much. You'll notice the radiators are cooler to the touch and the boiler runs for longer periods of time.

Weather compensation considers the temperature outside the property. The idea is to keep the flow temperature generally low, but to increase it as the heating demand for the property increases when the weather outside is cold. In the winter, with lower outside temperatures, more heat needs to be generated inside the house to maintain a comfortable room temperature. This balances the increased heat being lost through the walls and roof etc. Adjustment is available of a 'Weather Compensation Curve' which controls how the flow temperature varies dependant on the outside temperature.

It is possible to connect Compensator Controls to your boiler and have these recognised in the EPC and get a slightly improved rating. The difference is fairly small, and it relies on the specific heating controls being present in the Product Characteristics Database (PCDB). Additionally, your boiler needs to be on the 'Compatible Boilers' list within the PCDB for that device. Again however, adding this small gain to points from other areas of improvement could take you over a threshold from one EPC band to another.

In my house, I have an Alpha Intec2 28X boiler. I purchased an Alpha Weather Compensation Sensor on eBay for £30 and a second hand Alpha Climatic Controller on Gumtree for £65. I had these fitted by a plumber. Both were available in the PCDF, and it would appear that selecting these in the assessment only increases the EPC rating for my property by 1 SAP point.

The Alpha Climatic Controller is shown here above.

In my case, the devices are not actually listed in the PCDF as being compatible with my specific boiler, even though they are actually compatible, so I am currently unable to select them in the EPC assessment for my house.

More information on my particular boiler and controls are available here: Case Study 2 and also here: Resolve PCDB Issues.

More information about choosing a suitable compensator controller is available on our Case Study 1 page where we look to improve the EPC rating on a property with a Worcester Bosch 30i ErP boiler.

Again, always obtain advice from a local Energy Assessor about what improvement in rating could be achieved by changing the heating controls in your property before spending any money. Their advice will enable you to make an informed decision.

For heating controls on storage heaters, we'll cover this in our page about High Heat Retention storage Heaters.

Click here to return to our 'Improve Your EPC' main page, and see if there is another way you could improve your EPC rating.