System specification
Vaillant aroTHERM plus 7 kW air source heat pump (R290 propane refrigerant). 200L Mixergy hot water cylinder. Vaillant sensoCOMFORT controller. Wall-mounted outdoor unit on the rear yard wall with rubber isolation pads. 4 radiator upgrades to double-panel K2 in spare bedroom, kitchen, bathroom and dining room. Underfloor heating preserved in extension where original. Whole-house heat loss 6.2 kW at -2°C design day.
Property
3-bed end-of-terrace, c.1905, solid brick walls, partial cavity insulation, EPC D
The Gateshead property is a typical Victorian end-of-terrace — solid brick external walls, partial cavity insulation in the rear extension, EPC band D. The owners had been considering a heat pump for 18 months but were anxious about retrofit complexity and radiator upgrade costs. The trigger was the aging Worcester Greenstar combi (15 years old) needing a 3rd repair in 14 months.
Our Heat Geek-trained heat loss survey took 90 minutes and produced a room-by-room breakdown showing whole-house heat loss of 6.2 kW at the Gateshead -2°C design day. The existing radiator stock was a mix of original 1970s single-panel K1s (too small for heat pump flow temperatures) and replacement double-panel K2s from a 2018 refurb. Four radiators needed upgrading; the living room and main bedroom K2s were large enough to keep.
We specified the Vaillant aroTHERM plus 7 kW specifically for the R290 propane refrigerant (the lowest-GWP option on the UK market — 225× lower than R32) and for the compact footprint that fit cleanly on the rear yard wall. The Mixergy 200L hot water cylinder was chosen for its high-temperature stratification — gives the family of 4 reliable shower availability without oversizing.
The install took 5 working days: day 1 scaffolding + outdoor unit prep, days 2-3 indoor pipework + cylinder + radiator upgrades, day 4 commissioning + customer handover, day 5 reactive snags + filter clean. BUS grant application submitted on commissioning; received £7,500 deduction on the invoice within 4 weeks.
After 4 months of winter operation the heat pump delivered a SCOP of 3.9 — above the design estimate of 3.5 and well above the typical 2.8-3.2 we see from non-Heat-Geek installers. The owners report the house feels noticeably warmer (consistent 21°C in living spaces vs the boiler's peak-and-trough cycles) and the running cost is tracking 38% below the prior gas boiler year on year.
Vaillant aroTHERM plus retrofit on a Victorian terrace is one of our most common project types in Tyne and Wear — there are tens of thousands of similar properties in Gateshead, Newcastle, Sunderland, and South Shields where the retrofit pattern is well-understood and the BUS grant materially shifts the economics.
