HIU Repair, Service &
Maintenance London
Professional Heat Interface Unit engineers for flats, apartments, landlords, managing agents and housing associations across London.
We specialise exclusively in HIU repair, servicing and installation — not a boiler company trying to adapt. All makes and models. Same-day available.
Typical HIU units our engineers service across London
HIU Brands
We repair them all
Repairs
Most faults resolved
Emergency Line
Always available
Guarantee
Parts & labour
What We Do
HIU Repair & Servicing Services
Full-scope heat interface unit engineering for residential and commercial properties across London.
HIU Fault Diagnosis
Full diagnostic inspection to identify the root cause — not just the symptom.
Plate Heat Exchanger Repair
Clean, descale or replace blocked PHEs restoring full hot water output.
Control Valve & Actuator Repair
Faulty valves repaired or replaced same-day in most cases.
Sensor & Controller Faults
Temperature and pressure sensor replacement, controller resets and reconfigurations.
HIU Leak Repairs
Locate and fix leaks on primary and secondary circuits within the HIU.
Pump Replacement
Circulating pump failures diagnosed and replaced with compatible parts.
HIU Pressure Problems
Pressure balancing, PRV faults, and expansion vessel issues resolved.
Annual HIU Servicing
Planned preventative maintenance to keep your HIU running efficiently year-round.
Understanding the Problem
What Is a Heat Interface Unit?
A Heat Interface Unit (HIU) is the device inside your flat that connects it to a communal or district heat network. It transfers heat from the building's central system to deliver your heating and hot water — without the need for an individual boiler.
HIUs are standard in modern apartment buildings, mixed-use developments, student accommodation, housing association properties and district heating schemes across London. If you live in a flat built after 2000, you almost certainly have one.
When an HIU develops a fault, it can affect your hot water, your heating, or both. Because most plumbers and boiler engineers have limited HIU experience, faults are frequently misdiagnosed — or worse, dismissed entirely. Our engineers are trained specifically on HIU systems.
Typical HIU installations our engineers service across London
Important: If a standard boiler engineer has told you "nothing is wrong" with your heating system, it's likely because they couldn't find a boiler — not because the HIU is fine. Always use an HIU specialist.
Common Problems
HIU Faults We Fix
Our Process
What Our Engineer Checks
We carry out a structured, systematic diagnostic inspection — not a guess-and-replace approach. Every HIU repair starts with a thorough assessment.
How It Works
Our Repair Process
Call or Book Online
Contact us any time — 24/7 emergency line. We confirm your booking and dispatch an engineer.
Engineer Dispatched
A specialist HIU engineer heads to your property, typically within 1–2 hours for emergencies.
Diagnosis & Fixed Quote
We identify the fault and give you a clear fixed price before any work begins. No surprises.
Repaired & Guaranteed
Most repairs completed same-day. All work backed by a 12-month parts and labour guarantee.
All Makes & Models
HIU Brands We Repair
We carry parts and have experience with all major HIU manufacturers found in London properties.
Don't see your brand? Call us — we repair all HIU makes and models.
Landlords
HIU Servicing for Landlords
As a landlord, you are legally required to maintain heating and hot water for your tenants. HIU failure is a Category 1 hazard under HHSRS. We offer rapid-response repairs and annual servicing contracts tailored for landlords with one or many flats.
- Annual HIU service certificates provided
- Priority same-day response for tenant callouts
- Full written report after every visit
- Multi-property discounts available
- Direct tenant liaison if required
Managing Agents & Housing Associations
Planned HIU Maintenance Contracts
We work with managing agents and housing associations across London to deliver scheduled HIU servicing, reactive repairs and compliance documentation for large residential portfolios. One point of contact, consistent service, transparent reporting.
- Block-wide HIU servicing programmes
- Reactive repair SLAs available
- Compliance and audit documentation
- Dedicated account manager
- Volume pricing for 10+ units
Reviews
What Our Customers Say
"Called at 8am with no hot water. Engineer arrived by 10, diagnosed a faulty DHW valve and had it fixed within the hour. Brilliant."
Rachel S.
Stratford, E15
"Tried two other plumbers who had no idea what an HIU was. These guys knew immediately — blocked plate heat exchanger, sorted same day."
James T.
Canary Wharf, E14
"Managing 12 flats with Evinox HIUs. Net-Plumbers are now our go-to. Fast, reliable, proper documentation every time."
Priya M.
Islington, N1
"HIU was leaking and the heating had been off for two days. Engineer found a split valve seal, replaced it and the system was back up in 90 minutes."
David O.
Elephant & Castle, SE1
Frequently Asked Questions
Why Choose Us?
Gas Safe Registered
Reg No: 217785 — certified and fully insured.
HIU Specialists
Trained specifically on heat interface unit systems.
Same-Day Available
7 days a week including evenings and weekends.
12-Month Guarantee
All repairs covered by parts and labour guarantee.
Free Callback
Request a Callback
Leave your details and we'll call you back within 15 minutes.
or call us directly: 0330 520 1642
Need an HIU Engineer Today?
Call now for same-day HIU repair, service or fault diagnosis across London.
Landlords, managing agents and housing associations welcome.