Gareth Ash, Marketing Manager at Danfoss, offers his quick guide to the key changes in Part L 2022 when it comes to electronic heating controls.

With significant updates to Approved Document L for use in England due to come into force in June it’s important for heating professionals to understand the implications for their business and ensure compliance. The new Building Regulations will see an uplift to existing energy efficiency standards that impact new build homes and some existing dwellings. So what’s changed?

Heating controls and zones
Let’s start with an overview of the main changes that installers need to know as far as effective heating controls and zoning are concerned:
1. Where technically feasible, Part L 2022 will mandate the installation of heating controls such as TRVs.
2. For wet heating systems in new dwellings with a floor area of 150m2 or greater a minimum of two independently controlled heating circuits should be provided.
3. Such systems should also ensure a minimum flow of water to avoid short-cycling.
4. System controls should be wired so that when there is no demand for space heating or hot water the heating appliance and pump are switched off.
5. In addition to the above, for heating systems in new dwellings, or when a heat generator such as a boiler is replaced in an existing dwelling, each room should be provided with thermostatic room controls. These should be capable of being used to separately adapt the heating output in each room served by the heating appliance. Needless to say, there is no need to install thermostatic room controls in rooms/zones without heating in new or existing dwellings.
6. In brief, these standards may be satisfied by providing any of the following:
– A thermostat in a room that the heating circuit serves and an individual thermostatic room control for each heat emitter, such as a TRV, on all heat emitters outside the room that contains the thermostat. As with previous guidance, TRVs should not be used in the same room as the reference thermostat.
– Alternatively, installers can fit an individual room/heating zone thermostat or fan coil thermostat for each room or heating zone.
– Or an individual networked heat emitter control for each emitter can be installed.
7. Installers should also be aware that under Part L 2022 it may be justified to control a heating zone rather than individual room in, for example, a single-storey open-plan dwelling in which the living area is greater than 70% of the total floor area. This could also apply where two adjacent rooms have a similar heating requirement, such as a kitchen and utility room. In such cases these should be considered as a single heating zone.

Missed opportunity?
Although fitting TRVs has now become standard practice for many heating professionals, official recognition of these controls in Part L 2022 is still very welcome. However, Danfoss believes that excluding mandatory system balancing from this regulatory update is a missed opportunity. We appreciate that when using traditional balancing methods this process can be time-consuming, resulting in extra cost for the customer, but there are benefits when combined with effective control. Tests conducted independently at the Salford University Energy House showed that without both control and balancing boilers will operate in condensing mode for around 5% of the time, whereas with, it’s closer to 80% of the time. Furthermore, a correctly balanced system offers improved consumer comfort.

Time saving
The new Danfoss RAS-B2 Dynamic Valve addresses some of the issues associated with system balancing. The valve’s built-in differential pressure controller ensures that pressure drops over the valve remain at a constant level, which means flow through the valve is maintained at both full and partial loads. Also, using the Danfoss Installer App the RAS-B2 can ensure a lower return temperature, thereby optimising condensing boiler efficiency. And because pre-setting of the desired flow is done on the valve, rather than on the lockshield, it is estimated that this could save installers up to two hours of working time.

Further guidance available
We hope this quick guide to some of the key changes in Part L 2022 relating to heating controls is helpful but installers can seek further guidance from the Danfoss team if required. Whilst we know that change can be a challenge, perhaps installers should see this as an opportunity to update their knowledge and skills, not only to ensure compliance, but also to help consumers faced with soaring energy prices to make heating their homes more efficient.
For more information go to