HIU Service & Repair Cost in London (2026 Guide)

HIU Annual Service Cost

An annual HIU service from Collide Group starts from £120 per unit. This includes a full 30-point inspection and service covering strainer cleaning, plate heat exchanger assessment and descale if required, actuator and valve testing, flow and temperature verification, expansion vessel pressure check, and a written service report.

The service price includes all standard labour. Parts replaced during the service visit (such as a strainer mesh or small seals) are included. Major component replacement — such as a plate heat exchanger or actuator — is quoted separately if required following the service inspection.

HIU Repair Cost

HIU repair starts from a £120 callout fee, which covers the engineer's travel, diagnostic time and first-visit labour. If parts are required, these are quoted transparently before any work is carried out — you will always know the full cost before you approve the repair.

Common HIU repair costs in London (2026):

All prices are inclusive of VAT. We never charge hidden extras — if the repair cannot be completed on the first visit (e.g., a part needs to be ordered), we will not charge additional callout fees on the return visit for the same fault.

HIU Installation Cost

A full HIU replacement installation — supplying and fitting a new unit, commissioning, and disposing of the old unit — starts from £1,950 for a standard residential replacement.

Factors that affect HIU installation cost include:

• Brand and model: Premium brands such as Danfoss, Caleffi or Alfa Laval carry higher unit costs than entry-level alternatives. We will specify the most appropriate unit for your building and budget.
• Access and location: HIUs installed in awkward cupboards, high-rise flats requiring equipment hoist, or locations with limited working space take longer to install.
• Pipework modifications: If the existing pipework connections are not compatible with the new unit, or if the pipe runs need extending or rerouting, additional pipework cost will apply.
• Commissioning: All installations include full commissioning — setting flow rates, temperatures and controls to the building specification — and a handover report.
• Secondary circuit powerflush: We often recommend a powerflush of the secondary circuit at the time of a new HIU installation. This adds cost but significantly improves the performance of the new unit and extends its life.

For a precise installation quote, contact us with the make and model of your current unit (if known), the building address and floor, and any specific requirements. We aim to provide quotes within one working hour.

HIU Powerflush Cost

A powerflush of the HIU secondary circuit — which clears sludge, scale and debris from the radiators and underfloor heating pipework — starts from £250 for a standard residential installation.

A powerflush is typically recommended when:

• Installing a new HIU (to protect the new unit from debris in the existing system)
• Radiators are cold at the bottom or not heating evenly
• The secondary system has not been flushed in several years
• Dark, discoloured water is present in the system

The powerflush price varies depending on the number of radiators, the length of pipework runs, and the level of contamination. A combined HIU service and powerflush is available at a reduced package price — ask for details.

Bulk HIU Servicing Contracts

For property managers, housing associations and estate management companies with multiple HIUs across a building or portfolio, we offer annual bulk servicing contracts from £95 per unit (minimum 10 units).

Bulk contracts include:

• Coordinated access scheduling with residents
• Individual written service reports for each unit
• Block-level summary report suitable for compliance records
• Priority response for emergency repairs within the contracted portfolio
• Annual review meeting with account manager

Contact us to discuss a servicing contract for your building or portfolio.

What Affects HIU Repair Cost?

Beyond the type of repair required, several factors influence the total cost of an HIU repair in London:

• Brand: Parts for less common or older HIU brands can be expensive or difficult to source. We carry common Danfoss, SAV and Switch2 parts as standard on our vans, reducing wait times and costs for these brands.
• Age of unit: HIUs over 12–15 years old may have obsolete parts that require refurbishment or substitution. In some cases, replacement of the entire unit is more cost-effective than sourcing a legacy PCB or heat exchanger.
• Parts availability: Some brands source components from Europe or further afield. If a specific part needs to be ordered, this adds to the repair timeline and may affect the total cost.
• Access difficulty: Units installed in confined spaces, behind fixed furniture, or requiring specialist access equipment take longer to work on.
• Emergency vs. scheduled: Same-day emergency callouts are prioritised and priced accordingly. Scheduled repairs during standard working hours (Monday to Friday) are typically lower cost than out-of-hours emergency responses.

Is HIU Repair Covered by Home Insurance?

This is one of the most common questions we receive, and the answer depends entirely on your policy:

• Standard home contents insurance: Almost never covers HIU repair. HIUs are part of the building's heating installation, not your personal contents.
• Buildings insurance: May cover HIU repair if the policy includes mechanical and electrical breakdown cover. Standard buildings-only policies typically do not. Check your policy schedule for “mechanical/electrical breakdown” or “home systems” cover.
• Home emergency cover: Policies specifically designed for emergency home repairs (sometimes sold as an add-on to buildings insurance) often cover HIU failure. Policies typically require that the unit has been regularly serviced — an unserviced unit may not be covered.
• Leasehold buildings: In many leasehold blocks, the building insurer holds a policy that covers communal and individual heating installations. Check with your managing agent or freeholder.

If you believe your repair may be covered by insurance, we can provide a detailed invoice and engineer's report to support a claim. Contact us for more information.