Heat Interface Unit (HIU) Services
Your HIU not doing its job? We'll sort it.
We service and repair heat interface units across South London and Surrey — all major brands, residential and commercial. Whether you're a resident booking directly, a building manager looking after a whole development, or a developer fitting out new builds, we make it straightforward.
What we cover:
HIU servicing and maintenance
Fault diagnosis and repairs
New HIU installations and replacements
Heat meter calibration and testing
System commissioning and balancing
Emergency callouts
For building managers and developers:
Bulk installations for new developments
Planned maintenance contracts - HIUs and communal plantrooms
Compliance testing and certification
Why us for HIU work?
We actually understand these systems. HIUs aren't just another boiler. We know how they connect to the wider district heating network, which means faster diagnosis and fewer repeat visits.
All major brands covered. Danfoss/SAV, Altecnic/Caleffi, Herz, Evinox, Ideal, Worcester, Giacomini — whatever's in your building, our engineers know how to service and repair it.
Fixed pricing, no surprises. All prices include VAT, labour, and parts. You'll know what you're paying before we start. If we can't fix it, you don't pay.
Enhanced DBS-checked and trauma-aware. Every engineer. We know we're coming into your home, and we take that seriously.
We turn up when we say we will. You'll get a text with a one-hour arrival window before your booking. Book in 30 seconds, pay your invoice in 30 seconds, schedule a repeat visit in 30 seconds.
18-month guarantee on all workmanship. If something's not right, we come back and fix it at no extra cost.
We clean up properly. Shoe covers, protective sheets, and yes — we hoover.
Our service area covers most of London and Manchester - please see the map below and zoom in on your area.
Where we work
Over 1,450 jobs completed since August 2025 across most of London - and since February 2026, we're in Manchester too. Zoom in on the map to find your property.
The map shows exactly where we've been. If you're in our service area, book your HIU service online in 30 seconds. If you're just outside it, give us a call - we can usually make it work.
Recent HIU work
Herz Oxford DHW HIU — Leaking primary valves, Manchester
Resident had a small leak from the primary isolation valve and drain-off valve on their Herz Oxford HIU (installed July 2019). They'd already had several contractors come out to look at it — none were comfortable working on the system. They found us online, sent photos, and we identified the parts needed remotely. Our engineer replaced the primary flushing bypass and ball valve on the primary side. Leak sorted, system tested, no further issues.
Unit: Herz Oxford DHW HIU (2019)
Fault: Leaking primary isolation valve and drain-off valve
Fix: Replaced HERZ primary flushing bypass (1401887) and ball valve (1401990)
Location: Manchester, M15
HIU Service — Preston, Lancashire
Resident had been struggling to find anyone locally who could service their HIU. Local plumbers and engineers only covered boilers and wouldn't touch it. The last contractor who came out mainly dealt with regular boilers and didn't inspire confidence. They searched "HIU engineer Preston," found us near the top of Google, and booked in.
Our engineer carried out a full service on the Giacomini HIU in a block of over 100 flats. The resident was happy enough to share our details on the building's residents WhatsApp group. We've since connected with the block's management company and are looking at servicing more flats in the development.
Unit: Giacomini HIU
Work: HIU service
Location: Preston, Lancashire
Vital Energi HIU Service — London
Routine annual service on a Vital Energi HIU installed in March 2018. Full service carried out - internals opened up, heat exchanger and control valves inspected, all components checked and cleaned. Unit closed up and running as it should. These units are reliable kit but they need regular servicing to stay that way — leave it too long and a small issue turns into a cold flat.
Unit: Vital Energi (2018)
Work: HIU service
Location: London
Evinox HIU Replacement - South West London
Resident's Evinox HIU had failed completely - no heating, no hot water. We attended, assessed the unit, and confirmed it was beyond repair. Within 48 hours we'd sourced, supplied and fitted a brand new Ideal POD I405HWM replacement. Heating and hot water restored. No weeks of waiting, no back-and-forth with suppliers - we handled the whole thing from diagnosis to installation.
Old unit: Evinox (failed) New unit: Ideal POD I405HWM
Work: Full HIU replacement - source, supply and fit
Turnaround: 48 hours from first attendance
Location: Epsom, Surrey
