HIU Installation & Replacement London

New HIU installation in London

A new HIU installation starts with the network, not the unit. We confirm the available primary flow temperature and differential pressure, then set out the connections, isolation, strainers and metering so the unit can be serviced later without draining the riser. The unit is mounted, connected to the heating circuit and domestic hot water, wired to its controls and heat meter, flushed and commissioned. We record flow and return temperatures, hot water flow rate and keep-warm settings so performance can be checked against the design in future.

• HIU installation London for new-build and refurbishment
• Connections set out for future serviceability
• Heat meter and controls wired and tested
• Commissioning figures recorded at handover

HIU replacement

Replacement makes sense when a unit is obsolete and spares are no longer produced, when the body or exchangers are leaking, or when a block is suffering repeat failures on an early-generation design. Most replacements are completed within a day per flat: we isolate at the riser, remove the old unit, adapt the pipework where the new unit has a different footprint, fit and commission the replacement and leave heating and hot water working before we go. Where a whole block is being changed we programme flats in sequence to keep disruption and riser isolations to a minimum.

• Obsolete and unsupported units replaced
• Pipework adapted where footprints differ
• Single flats or phased whole-block programmes
• Old unit removed and recycled

HIU replacement cost — what drives the price

Cost depends on the unit specified, whether the replacement is like-for-like or needs new pipework and a different footprint, whether a heat meter and controls are being reused or renewed, and access — a cupboard in a hallway is quicker than a ceiling void. Volume matters too: a phased block programme is priced very differently to a single flat. We survey first, then issue a fixed written quote covering the unit, installation, commissioning, removal of the old unit and the handover record, so there are no hourly charges to track.

• Fixed written quote issued after survey
• Like-for-like swaps priced lower than reconfigurations
• Block programmes priced per unit across the scheme
• Quote includes commissioning and removal of the old unit

Sizing and selecting the right unit

An oversized HIU wastes network capacity and raises return temperatures; an undersized one leaves residents with poor hot water at peak times. We size on the dwelling's actual heat loss and hot water demand — number of bathrooms, simultaneous draw-off, the primary flow temperature available and the differential pressure at that point in the riser. Selection then weighs indirect versus direct arrangements, plate exchanger duty, control type and, importantly, the availability of spares and the local service support behind the brand.

• Sized on heat loss and simultaneous hot water demand
• Checked against available primary temperature and pressure
• Control strategy and keep-warm mode specified
• Spares availability and long-term support considered

Working with communal and district heating systems

Units are only as good as the network they sit on. Before installing, we check return temperatures across the scheme, because high returns are the usual reason a communal system underperforms and a new unit alone will not fix them. We set keep-warm and control parameters to suit the network, coordinate riser isolations with the site team and residents, and where the wider system is at fault we say so rather than swapping units that were never the problem.

Brands we install

We install and replace units from all the mainstream manufacturers used on London schemes, including Danfoss, SAV Systems, Evinox, Alfa Laval, Caleffi, Giacomini, Heatweb, Altecnic, Watts and Armstrong. Brand-specific pages set out the service and spares position for each — see our Danfoss HIU and SAV Systems HIU engineers for the units most often found in London blocks. If the existing unit is unsupported we will recommend the closest practical replacement for the pipework already in place.