Quick guide to plumbing & heating regulations 2023

Transparent check mark over compliance related icons and words handwritten on white papers

In late 2021, the UK Government’s Department of Levelling Up Housing and Communities (DULHC) announced a whole host of changes to existing building regulations and that they would be introducing several new documents, too. These changes later became official in June of 2022.  So, we thought it would be useful to keep plumbing and heating professional up to date with our handy guide to the new plumbing and heating regulations 2023.

But before we get started, here are a few need-to-knows.

  1. While the DULHC sits across all of the UK, these changes, so far, only affect England.

  2. If construction on a project began before the changes came into effect, i.e. June 2022, that project doesn’t need to comply to these regulations so long as it is completed before June of 2023.

  3. Changes were made to documents Part F (ventilation) and Part L (dwellings). The changes that will affect plumbing and heating fall entirely under Part L.

  4. The two new documents, Part O and Part S, focus on overheating and charging electric vehicles respectively. However, seeing as Part S doesn’t affect plumbers at all, we’re not going to focus on it here.

So, what’s changed?

Let’s start with Part L (dwellings). Heating engineers best pay attention, as one of the biggest changes in Part L is to flow temperatures.

Section 5 of Part L states, that a heating system’s flow temperature cannot exceed 55°C and, in fact, should be below this temperature if possible. This is to cater to the new condensing boilers, which don’t work as intended if they are receiving water hotter than 55°C.

However, to ensure that the system is heating efficiently, it is important that the system is balanced evenly. This means using lockshield valves if radiators are installed, or by using the manifold flow meter adjustment on underfloor heating systems, which will ensure that all areas are evenly heated.

In addition to this major change, there are a number of further changes in Part L that affect plumbing and heating installations overall.

Keep a camera in your toolbox for fitting circulation units

You can wave goodbye to exposed heating pipes in new build properties. In fact, in order to prevent heat loss on heating and hot water supply pipe work, all primary circulation pipes, including those underneath floors or between walls, will need to be insulated, as stated in paragraph 4.24 and 4.25. Additionally, this prevents heat transfer on flow and return pipework that run parallel to each other. It’s all about efficiency these days, the more heat you lose the harder your boiler has to work after all.

In fact, the only area that this change does not affect, is one metre off every pipe from storage systems of hot water, whether this be boilers, unvented hot water cylinders, or where pipes go into a wall or floor. Similarly, if an existing boiler or hot water storage unit is upgraded or replaced, exposed pipes will require insulating too.

Additionally, both paragraphs state that you must submit photos of the insulated pipework to Building Controls, to prove that the pipes have in fact been insulated, so have your cameras at the ready.

Infrared Thermal and real Image of Radiator Heater and a window on a building

55 is the magic number for installers in 2023

Heating efficiency is a fittingly hot button topic amongst the new changes in the new plumbing and heating regulations 2023. In fact, the previously mentioned section 5 focuses solely on this issue. The majority of these changes relate back to the new 55°C limit placed on flow temperatures, for example paragraph 5.10 asserts that all pipework and emitters (meaning underfloor heating, radiators, etc.) should be “appropriately sized” to allow heating systems to sufficiently heat the house, whilst flow temperatures remain below 55°C. While not an out and out rule, this basically means that underfloor heating should be installed in new builds, as traditional radiators cannot operate as effectively at this lower temperature.

The plumbing and heating regulations 2023 do however mention, that if, when installing a new boiler in an existing property for example, the temperature cannot get below 55°C whilst heating the home efficiently, then you have to get it to the lowest temperature possible.

An overhaul on heating control standards

Similarly, all wet heating systems in new builds with a floor area of 150 square meters or more, should have at least two independently controlled circuits; one for heating and one for hot water, and that all system controls should be wired. Therefore, when space heaters or hot water are not in use, the appliances and pumps themselves are turned off, too. Furthermore, paragraph 5.16 determines that domestic hot water circuits supplied from a hot water store, should have a time control that is independent of other space heating circuits and an electronic temperature control, too. So be sure to double check the next time you’re at your local plumbing and heating merchant or stockist.

In fact, any primary hot water circuit for domestic hot water or heating system should have fully pumped circulation, when this is compatible with the heat generator. Similarly, paragraph 5.20 states that, when upgrading a boiler, you must fit a thermostatic radiator valve on every radiator except for areas where individual  room thermostats are installed. This used to just be a recommendation; however, it has now been changed to a regulation for 2023 and must be carried out.

Part L – the one for all plumbers

The final change to Part L that affects plumbers is paragraph 8.8.

This paragraph determines that before a new heating appliance such as a radiator or underfloor heating system is installed, all central heating and primary hot water circuits must be thoroughly cleaned and flushed of debris. This is to make domestic central heating systems comply to British Standards 7593.

It further means that all new boilers will require their water to be checked and cleaned if needed, a magnetic filter to be installed, as well as an inhibitor to ensure that the water’s PH levels are kept correct, and that the system does not cause corrosion.

Not only do these systems need to be commissioned correctly, but there also needs to be evidence of this being the case – so, it is safe to say that the days of free boiler quotes are firmly in the past.

Bleeding radiator wearing blue gloves

What’s Part O all about?

Moving on to the new document, we have Part O, and while there’s only a handful of points affecting plumbing and heating, those points do get complex quickly, so pens and paper at the ready.

Part O affects multiple occupancy buildings, meaning houses, flats and apartments, student accommodation, and care homes, and includes shared communal areas such as concierges, however, it doesn’t affect hotels.

Secondly, Part O specifies two ways to meet the new overheating standards, which are called the simplified method and the dynamic thermal modeling method (DTM). There are more in-depth details in the document itself, but in summary the simplified method looks at glazing and free areas, whilst the dynamic thermal modelling method takes a more detailed look at the building as a whole, and is generally much more of an undertaking than the simplified method.

But how does Part O affect plumbers you ask?

Well, Part O states that the simplified model of conforming to overheating regulations is not suitable for multi-unit buildings with significant horizontal pipework in communal heating or hot water systems, and that the pipework should be distributed vertically to minimise heat gains to corridors. With a vertical distribution the simplified method can be used.

So, thinking about which way to lay pipework beforehand so that you can save time and use the simplified method of compliance, is going to be an important consideration in these multi occupancy situations.

Regulations are constantly being updated and keeping track of them can be a challenge. We hope that this blog can act as a great resource to keep track of all the ins and outs of plumbing and heating regulations for 2023.

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Richard Bateman

Product Marketing Manager Plumbing and Heating

About the author

A highly experienced and passionate professional, I have over 15 years' experience as a commercial and domestic plumber and hold NVQ Level 3 qualifications from City and Guilds

Since joining RWC in 2015, I began as a technical engineer, utilising my extensive knowledge to provide exceptional support. Currently, I am thrilled to be working with the marketing department as a Product Marketing Manager. 

This role allows me to combine my technical background with a keen eye for market trends, ensuring that RWC's products meet the evolving needs of the industry. With my wealth of experience and commitment to excellence, I am proud to serve as a spokesperson for RWC, sharing our innovative solutions and contributing to the growth of the plumbing and heating sector.