HIU Repair & Heat Interface Unit Engineers Tooting

In most developments the HIU inside the flat is the leaseholder's or landlord's responsibility, while the network up to the unit belongs to the building owner. Our test results make the boundary clear.

Annually. The strainer clean and plate check are what prevent the sudden loss of hot water that most HIU call-outs are about.

Yes — we carry common plate sizes and can source model-specific plates quickly, then re-commission and record flow temperatures after fitting.

An HIU should generally be serviced once a year, following the manufacturer’s instructions and any requirements from your heat network operator. Regular servicing helps identify blocked strainers, sticking control valves, leaks and poor temperature control before heating or hot water fails. An engineer checks operation, cleans serviceable components and tests heating and hot water performance. Report fluctuating temperatures or leaks rather than waiting for the annual visit.

An HIU, or heat interface unit, transfers heat from a communal heating network into an individual home’s heating and, commonly, hot water supply. It usually uses heat exchangers and control valves rather than burning gas inside the property. The exact arrangement varies: some units provide hot water only, while others serve both radiators and taps. If several flats lose heat simultaneously, the problem may be with the shared supply rather than an individual HIU.

An HIU service is a planned inspection and maintenance visit for a heat interface unit, which supplies heating and usually hot water from a communal heat network. The engineer checks for leaks, tests temperatures and controls, inspects valves and cleans strainers where required by the manufacturer. They also assess heat transfer and investigate unusual pressure or flow behaviour. Work involving the communal supply may need coordination with the building’s heat network operator.

Do not attempt to service a gas boiler yourself; use a Gas Safe registered engineer. Servicing involves safety checks and work that can affect combustion, flue integrity and gas tightness. You can check the displayed pressure, look for visible leaks and follow the user manual for permitted tasks, such as adjusting controls. Do not remove the boiler casing or disturb internal components. An HIU also needs competent servicing, despite generally having no gas burner.

The cost of a full boiler service depends on the appliance and the work included, so request a service-specific quote rather than using a repair price as a guide. For a gas boiler, the service should follow the manufacturer’s instructions and include relevant safety, combustion and operating checks by a Gas Safe registered engineer. Ask whether cleaning, seals or replacement parts are included, and ensure any additional work is agreed before it starts.

Boiler cleaning does not have one standard cost: the scope depends on the boiler’s condition and whether you mean routine servicing, internal component cleaning or flushing the heating system. These are different jobs, so ask for a quote that clearly states what is included. A Gas Safe registered engineer should assess any internal cleaning needed on a gas boiler. Cold radiator patches or noisy operation do not, by themselves, prove that a full system flush is necessary.

Yes, a boiler should normally be serviced every 12 months, in line with the manufacturer’s instructions. Annual servicing checks safe operation and helps spot deterioration before it causes a breakdown; it may also be a condition of the manufacturer’s warranty. A gas boiler service should be carried out by a Gas Safe registered engineer. If you notice leaks, unusual noises or repeated pressure loss, arrange an inspection rather than waiting until the next service.

A domestic boiler typically lasts around 10–15 years, although its condition matters more than its age alone. Water quality, installation standards, usage and regular servicing all affect lifespan. Frequent breakdowns, corrosion or unavailable spare parts can make replacement more sensible than another repair. An HIU is different from a boiler: it transfers heat from a communal network rather than burning fuel, so boiler lifespan estimates should not automatically be applied to it.