Heating Interface Units
(HIU / HIUs)
- London Boilers®

London Boilers® is the trading name of Express Gas & Electrical Ltd (EG&E Ltd, based in St Albans, Hertfordshire) serving north London and Hertfordshire for repairing of commercial, industrial and complicated domestic boilers.

Heat Interface Units (Hydraulic Interface Units)

HIUHeat Interface Units (HIUs, or called Hydraulic Interface Units), are widely used in community heating systems, for example a tower block with a central boiler plant room, the energy of heating and hot water is being transferred to each flat by an interface.

An interface can be a model from these three common makes - Akva, Termix and Vital, but they are all based on Danfoss components.

We have experience on Danfoss interface repairs and services. We stock some common parts for them, as most of their parts are from mail orders.

The most components we replaced on HIU repairs are a zone valve (VMT) for central heating and a thermostatic valve (AVTB) or PTC controller for hot water.

This is Danfoss HIU parts supplier in the UK:


These HIUs are not difficult to repair, as they are simpler than gas combi boilers, but their parts are expsensive.