No Heating in a Canary Wharf Flat (HIU)

October 24, 2026 Emergency Repair

Project Overview

Location	Canary Wharf, east London (E14)
Call-out	Emergency — no heating in a flat
System	Heat interface unit (HIU) on a communal heating system served by plant room boilers
Fault found	Heating thermostats dead with no display; building’s communal boilers not running
Work completed	Fused supply checked, thermostat batteries replaced, time set and the HIU heating call proved working

The Challenge

We were called out to a flat in Canary Wharf with no heating. The flat has no boiler of its own: heat comes from boilers in the building’s plant room, through a heat interface unit (HIU) in the flat. On arrival the heating thermostats were dead, with nothing on the display.

With a communal system there are two halves to check — the flat’s own controls and HIU, and the building’s central plant. The job was to find out which half had failed, fix what could be fixed in the flat, and give the resident a straight answer about the rest.

The Solution: Revive the Controls and Prove the HIU

We checked over the system, including the fused supply to the heating. The power was fine, so we turned to the thermostats. Fresh batteries brought the screens straight back on, and we set the time so the heating programme would run correctly.

With the thermostats calling for heat, the heating valve in the HIU opened and the heating call came on. That proves the flat’s side of the system is working: the heating will come through as soon as the main boilers in the plant room are running again.

Programmable room thermostat with its battery cover open in a Canary Wharf flat with no heating — The flat’s heating thermostat — dead with no display until new batteries were fitted and the time reset

Why Flats on Communal Heating Lose Heat

When a flat on a heat network goes cold, the fault can be in the flat or in the building. Checking in the right order saves time and avoids paying for parts that are not needed:

Dead thermostats: Battery-powered thermostats stop calling for heat when the batteries run out, so the HIU never opens its heating valve — a two-minute fix that is easy to miss.
Power to the controls: A blown fuse on the heating supply stops the thermostat and HIU controls working, which is why the fused spur is checked first.
The HIU heating valve: If the valve opens when the thermostat calls, the flat’s controls and HIU are doing their job.
The plant room: If the heating call works but no heat arrives, the communal boilers are the problem — and that sits with the building’s management and their heating contractor.

Heat interface unit in a utility cupboard in a Canary Wharf flat on a communal heating system — The flat’s HIU — its heating valve opened as soon as the revived thermostat called for heat

The Repair Process

System check: We checked over the heating system in the flat, including the fused supply to the heating controls.
Thermostat batteries: The batteries in the heating thermostats were changed and the screens came back on.
Time set: The thermostat clock was set so the heating programme runs at the right times.
HIU proved: The HIU heating valve opened and the heating call came on, confirming the flat will heat once the plant room boilers are running.

Electrical tester and Testo case laid out beneath a heat interface unit during a no-heating diagnosis in Canary Wharf — Testing the fused supply and controls at the HIU before looking any further

The Results

The flat’s thermostats are working again and the HIU responds to a heating call, so nothing in the flat needs repairing. The resident knows the remaining problem is the building’s communal boilers, which the building’s team expect to have back on by Tuesday — and that their heating will come back with them.

Recommended Follow-Up

Contact the managing agent: Speak to the building’s management agency and the company repairing the building’s hot water, who have said the heating will be back on Tuesday.
Our tip — spare batteries: Replacing thermostat batteries once a year avoids the same call-out next winter.

No Heating in a Flat — Questions

Why is there no heating in my flat with an HIU?

Check that the thermostat has a display and fresh batteries, and that the fused spur for the heating is on. If the thermostat is calling for heat and the HIU still gets nothing, the problem is usually the building’s communal boilers or pipework rather than your flat.

Can you fix an HIU if the building’s boilers are off?

We can test and repair the HIU and controls in your flat and confirm they are working, as we did here. The central plant room is normally the responsibility of the building management and their contractor. See our HIU repairs service for faults in the unit itself.

Do you cover Canary Wharf?

Yes. Talis covers Canary Wharf and east London, including nearby Greenwich, Stratford, the City of London and Southwark. For a plant room job, see our emergency plant room repair in Westminster.