We take the hassle out of finding a local heating engineer and help make your annual HIU service cost less.
Here’s two options for getting your annual HIU serviced with a local heating engineer.
Book pronto
for just £78 (inc vat)
Book in advance
and save up to £24
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I recommend Boiler Booker in a heartbeat!
Before getting onto a group booking I have (almost) never serviced my boiler, mostly because it seemed daunting. With these guys, I didn't have to search for hours and wait for a myriad of quotes..
Edgar
⭐️⭐️⭐️⭐️⭐️
Great service!
Boiler stopped working on the Wednesday night and Tom came out to see us the next morning a 9am.
He fixed the problem in no time and provided great advice on maintenance…
Kwoky
⭐️⭐️⭐️⭐️⭐️
A great and affordable service
Simple to use website and making the booking was easy. Very happy, will definitely use again next year.
James
HOW BOILERBOOKER WORKS
We take the hassle out of finding a plumber or heating engineer and help make your service cost less.
Click ‘book now’ to get dates that suit you.
Pick a date with a 5* rated HIU heating engineer.
The more bookings in your postcode on the day, the less you pay.
Let your neighbours know about the group bookings: the more bookings in your postcode on the day, the less you pay.
WHAT’S DONE ON A HIU (HEATING INTERFACE UNIT) ANNUAL SERVICE?
We advise all service engineers check the below during your HIU service. The most important part of the service is to make sure any debris captured in the strainers are removed. If left, debris can affect how well the unit works, especially if debris is found in the control, balancing or regulating valves.
The heating engineer will provide their own company’s annual service sheet for your records.
Here’s an example checklist for servicing an HIU:
Check with you first that you’re not experiencing any problems
Isolate the HIU at the lever ball valves and remove and clean the strainer filter media.
Replace filter, reassemble the strainer, open the lever ball valves and check for leaks
Check the motorised valves are operating - ensure 100% shut down of flow
Assess heating volume flow rates and re-set as required
Check hot water volume flow rates and re-set as required
Check the operation of the differential pressure controller and vent impulse line
Check operation of installed controls
Boiler casing checked to see it’s properly sealed. Replacement seal, if needed (charged separately)
Complete documentation of maintenance sheet
Replace cover to HIU
Note: additional parts and labour may be charged extra.
Before any annual service, we recommend you ask the engineer for their ID and qualifications, when they arrive. The local engineer is the provider of the annual service. BoilerBooker is not responsible for any part of the service.
CLEANING THE STRAINER
Your HIU strainer collects debris from the system over time, so cleaning it during the annual service is vital. Keeping it clear helps maintain good water flow, reliable heating, and efficient operation.
To keep your heat interface unit running efficiently and protect your home's heating system, two simple maintenance checks make all the difference: keeping the strainer clear and ensuring inhibitor levels are correct.
5 reasons why strainer cleaning and inhibitor checks are critical in a district heating system:
1. Protecting your HIU from costly damage The strainer acts as your HIU's first line of defence. District heating networks can carry debris, scale, and sediment through the pipework — if the strainer becomes blocked, this material can reach the heat exchanger and internal components, causing damage that is expensive to repair and entirely avoidable.
2. Maintaining your heating and hot water performance A clogged strainer restricts the flow of water through your HIU, meaning your radiators may take longer to heat up and your hot water may run cooler than expected. Regular cleaning restores full flow and keeps your home performing as it should, especially during the colder months when you need it most.
3. Preventing corrosion throughout your system Inhibitor is a chemical treatment that protects the internal components of your heating system from rust and corrosion. In a district heating system, if inhibitor levels drop too low, metal pipework, valves, and the heat exchanger itself can begin to corrode — leading to leaks, reduced efficiency, and ultimately, premature system failure.
4. Keeping your energy bills in check A partially blocked strainer or degraded inhibitor forces your HIU to work harder to deliver the same level of heating and hot water. This inefficiency shows up directly on your energy bills. Simple, regular maintenance keeps the system running at peak efficiency and your costs where they should be.
5. Protecting the wider district heating network Unlike an individual boiler, your HIU is connected to a shared network serving many homes. A neglected strainer can release debris back into the communal system, and low inhibitor levels can contribute to corrosion that affects the network as a whole. Keeping your unit well-maintained is not just good for your home — it's a responsibility to every property connected to the same system.
Frequently asked questions
Why do I need to get my HIU serviced?
Getting a regular service will help identify any problems early on so you can maintain your HIU performing at its best for longer. As you’re on a district heating system it helps everyone on your network to get the HIU serviced and the filter cleaned. Which is why we created thr group bookings.
It’s also recommended by the manufacturers of the expansion vessels that you get your HIU checked regularly.
What is an expansion vessel?
An expansion vessel is a small tank used to protect closed water heating systems and domestic hot water systems from excessive pressure. The tank is partially filled with air, whose compressibility cushions shock caused by water hammer and absorbs excess water pressure caused by thermal expansion.
Will my HIU work better after the service?
Once your HIU has been checked it should be working to its optimum capability.
Why might my HIU not be working as well as it should?
If you live in a hard water area, this water quality makes it harder for your HIU to perform at its best. Having an annual service will help identify any damage this hard water is causing early on.
What is BoilerBooker?
BoilerBooker is a marketplace for independent local plumbers and heating engineers to provide annual boiler and hot water cylinder services at a lower cost for customers. The service is provided by the local heating engineer. BoilerBooker is not responsible for any part of the service. Please read the Terms & Conditions here.
How do the group bookings work?
We always try to get as many people on a booking as possible to make it cost effective for both the customer and heating engineer.
How do I pay the heating engineer?
You pay the heating engineer directly, once the service is complete. You can pay by cash, card or bank transfer.
Can I get a hot water cylinder service at the same time?
Yes, the engineer can service your hot water cylinder at the same time as the HIU service.
Who carries out the annual service?
The local independent heating engineer is the provider of the annual service. Before any annual service is carried out, we recommend you ask the engineer for their ID and qualifications.
BoilerBooker is not responsible for the service provided. BoilerBooker is neither a buyer nor provider of services offered for sale. We are neither a principal nor agent in a buying transaction. Please read our Terms & Conditions for more information.