No Hot Water
in Flat London
Woken up to no hot water in your flat? You're not alone — it's one of the most common callouts we receive across London. We'll get you sorted today.
Why Is There No Hot Water in Your Flat?
No hot water in a flat is a genuinely disruptive problem — especially on a cold London morning. It's frustrating, uncomfortable, and if you have young children or vulnerable people at home, it can be urgent.
Flats present a unique problem that houses don't: most modern London apartment buildings don't have individual boilers. Instead, they use a centralised communal heat network — and your hot water comes from a device in your flat called a Heat Interface Unit (HIU).
Important: This Is Usually Not a Boiler Problem
If you live in a flat or apartment in London, there is almost certainly no boiler in your property. Your building is served by a communal heat network, and your hot water is produced by a Heat Interface Unit (HIU) — a compact unit typically located in a cupboard inside your flat.
Many engineers unfamiliar with HIUs will misdiagnose the problem, waste your time, or — worse — tell you there's nothing wrong because they can't find a boiler fault. Our engineers are specifically trained on HIU diagnosis and repair.
The HIU connects your flat to the building's communal heat circuit and uses a plate heat exchanger to produce domestic hot water on demand. When it fails, you lose hot water — even though your heating may still work fine (the two circuits can operate independently).
This also explains why searching for a standard "boiler repair London" service can lead you to the wrong type of engineer. You need someone who understands HIUs — and that's exactly what Net-Plumbers provide.
Common Causes of No Hot Water in a Flat
Blocked Plate Heat Exchanger
Scale and debris build up inside the PHE over time, reducing or cutting off hot water flow entirely. This is the most common HIU fault in London flats.
Faulty HIU Valve
The domestic hot water valve inside the unit can stick, fail, or lose calibration — preventing hot water from being drawn from the district network.
Sensor & Controls Failure
Temperature sensors, pressure sensors, or the HIU controller board can develop faults that cause the unit to shut down hot water production.
Pressure or Flow Issues
Low pressure from the communal network, or internal pressure imbalances, can prevent the HIU from delivering hot water at the correct temperature.
What Our Engineers Check
When we arrive, we carry out a full systematic diagnosis of your HIU — not just a quick look. Our engineers follow a structured checklist to identify the root cause, not just the symptom.
We also check whether the problem originates within your flat's HIU, or whether it's a building-wide issue with the communal network — which would require escalation to your building management or heat supplier.
Same-Day HIU & Hot Water Repairs
We know that no hot water isn't something you can wait days to fix. Our engineers are dispatched across London 7 days a week, with evening and weekend availability. Most HIU faults are resolved on the first visit.
You Call or Book Online
Reach us any time — 24/7. Tell us your flat location and we'll dispatch the nearest available engineer.
Engineer Arrives Fast
We aim to be with you within 1–2 hours in London. Our engineers carry common HIU spare parts on every van.
Diagnosis & Fixed Quote
We identify the fault, explain what's needed in plain English, and give you a fixed price before any work starts.
Hot Water Restored
Most HIU repairs are completed same-day. All work is backed by a 12-month parts and labour guarantee.
For Property Professionals
Landlords & Managing Agents
If you manage residential flats in London, no hot water complaints require fast action. Delays can lead to tenant disputes, compensation claims, and potential legal liability. We provide rapid-response HIU repairs with full documentation.
- Legal duty to maintain heating and hot water under Section 11 of the Landlord and Tenant Act 1985
- No hot water counts as a Category 1 hazard under HHSRS — act quickly
- We issue a full written report after every visit for your records
- Bulk-discount contracts available for managing agents with multiple flats
- We liaise directly with tenants and building management if required
Related Services
Why Net-Plumbers?
Gas Safe Registered
Reg No: 217785 — fully qualified and insured engineers.
Same-Day Available
7 days a week across all London boroughs.
HIU Specialists
Trained specifically on Heat Interface Unit diagnosis and repair.
12-Month Guarantee
All repairs covered by parts and labour guarantee.
Free Callback
Request a Callback
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or call us directly: 0330 520 1642
No Hot Water in Your Flat?
Don't wait — call now for a same-day HIU repair across London.
Families and vulnerable residents prioritised.