Heat Interface Unit (HIU) Repair Specialists in London

24/7 HIU engineers for servicing, repairs and planned maintenance across London.

Who we are

Welcome to HIU Experts, a specialist team providing HIU servicing, repairs, parts replacement and commissioning across London.

We support apartments and residential blocks, working with homeowners, landlords and managing agents for reliable Heat Interface Unit (HIU) maintenance and fast breakdown response.
Our engineers diagnose and resolve common HIU faults such as no hot water, heating failure, leaks, pressure issues and temperature instability. We are manufacturer-trained and follow recommended procedures to keep your system running safely and efficiently, helping maintain a consistent heating and hot water supply.

HIU Experience

Satisfied Customer

Parts Replaced

Emergency Support

What we do

Our Most Popular HIU Services

HIU SERVICE

HIU servicing in London for communal and district heating systems.
We carry out strainer and filter cleaning, operational checks, temperature and pressure testing, and provide written findings following a manufacturer-recommended approach to help minimise breakdowns and maintain reliable performance throughout the year.
Our servicing helps improve efficiency, extend component lifespan and identify developing faults before they result in loss of heating or hot water.

BOOK HIU SERVICE

HIU REPAIRS

Need HIU repairs in London? We diagnose and resolve common Heat Interface Unit faults in residential blocks and apartments, including no hot water, no heating, leaks, pressure loss and fault codes.
Where suitable, we offer fixed-price repair options for typical faults and confirm component costs before installation. We aim to restore heating and hot water quickly while keeping communication clear throughout the visit.

FIX MY HIU

HIU REPLACEMENT

HIU replacement for properties connected to communal and district heating networks.
We safely isolate and remove the existing unit, install the replacement HIU, recommission the system correctly and verify performance for heating and hot water operation.
We also provide installation documentation and advice regarding manufacturer warranty periods, depending on brand and model.

REPLACE MY HIU

THERMAL STORES & CYLINDERS

Some flats use a thermal store or cylinder system rather than a heat interface unit.
We diagnose operational faults, carry out servicing and repairs, and replace components where required to restore consistent hot water and heating performance.
Following attendance, we provide clear findings and recommendations so the system continues to operate reliably.

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Common HIU Problems We Fix

If your heat interface unit stops working, these are the typical faults we repair in London apartments:

No hot water from HIU
Heating not working
HIU losing pressure
HIU leaking water
Hot water temperature unstable
Fault codes / display errors
Blocked plate heat exchanger
Loud noises from the HIU
Radiators are cold, but hot water works

Faulty HIU plate heat exchanger in London flat Blocked HIU strainer, causing no hot water Leaking HIU valve repair

Why Choose Us

Experienced Professionals

Our experienced HIU engineers bring years of hands-on expertise in diagnosing and resolving heating and hot water issues, delivering reliable, high-quality service across London.

A man in a high-visibility vest at night for the Heat interface unit repairing

24/7 Emergency Services

With 24/7 emergency support across London, we respond quickly to critical HIU faults, minimising disruption and restoring system performance without delay.

Affordable Pricing

We offer competitive pricing without compromising on workmanship, ensuring excellent value for every service we deliver.

Customer Satisfaction

Our dedication to outstanding customer service has built a strong reputation for reliability, reflected in the positive feedback and repeat clients we proudly serve.

London’s Leading HIU Experts

Reliable, Specialist HIU Services Across Greater London

We provide expert Heat Interface Unit servicing, fault diagnostics, component replacement and commissioning across London. Our engineers follow manufacturer guidelines and industry best practice to maintain system integrity, optimise efficiency and extend equipment lifespan.

From resolving no-hot-water and pressure-loss issues to full HIU replacement and recommissioning, every intervention is carried out with technical accuracy and documented findings. Our goal is not just to fix faults, but to ensure safe, stable and long-term heating performance for residential developments and communal systems.

By working closely with homeowners, landlords and managing agents, we ensure clear communication, transparent recommendations and work completed to industry standards on time and with full accountability.

We Service All Major HIU Brands

Customer Feedback

What Our Clients Say About Us

We needed urgent HIU repairs in our apartment block in East London. The team arrived on time, diagnosed the issue quickly, and had everything running smoothly within a few hours. Polite, professional, and very reasonably priced. Highly recommended

Maria Walton

East London

From start to finish, the engineers were fantastic. They installed a new Heat Interface Unit in our flat in Croydon and the job was done perfectly. Clean, efficient, and friendly—everything you want in a tradesperson

Jose Hines

Homeowner, Croydon, South London

We compared a few quotes before choosing this company for our district heating system maintenance in Kent. Not only were they competitively priced, but the quality of service far exceeded our expectations. Excellent value for money

Karen Murphy

Facilities Manager, Kent

HIU FAQs

A Heat Interface Unit (HIU) is a compact heat exchange system installed in properties connected to a communal or district heating network. Instead of having an individual boiler, the HIU transfers heat from a central plant room to provide domestic hot water and heating within the property. It contains components such as a plate heat exchanger, control valves, sensors and pressure controls to regulate temperature, flow and system safety. Proper servicing ensures the HIU operates efficiently, safely and reliably.

Noise from an HIU can be caused by several issues, including trapped air in the system, incorrect flow rates, worn or sticking control valves, pump vibration, pressure imbalance, or scaling within the plate heat exchanger. In some cases, noise may also originate from the communal heat network rather than the HIU itself. A proper diagnostic check is required to identify whether the issue is hydraulic, mechanical or related to system settings, and to prevent further wear or performance issues.

The most common HIU issues include no hot water, heating not working, pressure loss, fault codes on the display, temperature fluctuations, and leaks from valves or internal components. Our engineers carry out a full diagnostic assessment to determine whether the fault is within the HIU itself or related to the wider communal heat network.

Heating and domestic hot water are controlled separately inside the HIU. A fault may affect one circuit only. Common causes include actuator failure, blocked filters, incorrect flow rates, sensor issues or thermostat settings. A full diagnostic check confirms the exact cause.

Frequent pressure drops may indicate an internal leak, expansion vessel issue or pressure relief discharge. Avoid repeatedly topping up the system without diagnosis, as this may worsen the problem. Contact an engineer for proper inspection.

HIU repair costs depend on the type of fault, required parts and diagnostic time. Minor issues such as blocked strainers or valve adjustments may be resolved quickly, while component replacements (e.g. actuators, sensors or plate heat exchangers) vary in cost. We provide clear pricing before any work is carried out and confirm parts costs in writing.

Yes. Annual HIU servicing is recommended to maintain performance, improve energy efficiency and reduce the risk of unexpected breakdowns. Regular servicing also helps protect manufacturer warranty conditions where applicable.

A typical HIU service includes:
Inspection for leaks and corrosion
Cleaning strainers and filters
Pressure and temperature checks
Expansion vessel pressure testing
Valve and actuator testing
Flow rate verification
Performance testing for heating and hot water
Written service report with recommendations

Yes. We provide fast-response HIU breakdown services across London. Priority is given to properties with complete loss of heating or hot water. Sharing the HIU brand and any fault code helps speed up diagnosis.

We regularly service and repair HIUs from leading manufacturers including Danfoss, Caleffi, KaMo, Evinox, Switch2, KVM, Vital Energi, Rhico and others commonly installed in London apartment blocks.

Replacement may be recommended if:
The unit is over 10–15 years old
Major components repeatedly fail
Spare parts are no longer available
Efficiency is significantly reduced
We provide honest advice based on condition and cost comparison.

Yes. We provide planned HIU servicing programmes for residential blocks and managing agents, including scheduled annual servicing, bulk bookings and detailed reporting for compliance records.

We cover Greater London and the surrounding areas. Contact us with your postcode to confirm availability.

Most diagnostic visits take 45–90 minutes. Minor repairs can often be completed during the first visit, depending on parts availability and access conditions.

Reliable Servicing, Repairs & Fast Breakdown Response

We provide expert Heat Interface Unit (HIU) servicing, fault diagnosis and repairs across London. Whether you’re experiencing no hot water, heating failure, pressure loss or fault codes, our engineers respond quickly to restore your system safely and efficiently.
With hands-on experience across leading HIU manufacturers, we ensure all work is carried out to high technical standards, minimising downtime and preventing repeat breakdowns.

Book A HIU Service