When we moved in, the house was fitted with remotely switched storage heating plus a wet electric boiler providing hot water and partial and ineffective central heating. There was also a burned-out solid fuel stove in the kitchen and a log-burning stove in the living room.
Generation: We chose an integrated system design that uses a centralised storage in a thermal store for both central heating and hot water, with input from a Ground Source Heat Pump (GSHP), Solar thermal panels and a new wood-burning stove with back boiler in the kitchen. We have retained one extant stand-alone log-burning stove and plan to install another in the new living room. We chose a borehole geothermal system over a ground loop as the latter stop working when the ground temperature at circa 1m depth falls too far: on several occasions we have had our mains water freeze in pipes that are 1.5m down, with air temperatures as low as -24°C. The overall system does now work – albeit still requiring work, but only after extended problems with the original contractors, MMAXX Ltd of Cumbernauld and their Managing Director, Neil McFarlane, who despite their MCS and REAL accreditation, proved incompetent, ineffective and uncaring. Their MCS certificate was subsequently suspended following a complaint we made to the BRE. It’s worth noting that MMAXX attempted to block their suspension by claiming that the BRE inspectors were corrupt and colluding with us. Nice one.
The thermal store and the twenty tonnes or so of screed laid downstairs provide for an effective storage system for the heating. The thermal mass of the property also provides significant buffering of temperature change.
Delivery: Downstairs we have installed a multi-zone manifold controlling the wet underfloor heating system, with extra loops for heated towel rails and a heated cupboard for drying outdoor clothes. Upstairs, where we wished to minimise disturbance to the original floor, we have opted for low-volume, low-temperature fan-assisted radiators designed for use with renewable energy systems. These are supplemented by log-burning stoves, one of which also feeds the thermal store. Heating control is provided by a combination of networked NEST learning thermostats and programmable individual thermostats with an external weather sensor to calibrate the heat pump.
The end result though is that we have a completely heated house, at design temperatures of 19-21°C, with an annual total electricity bill of around £2,500, compared to our first year’s bill of over £3,800 to heat less than half of the house (and that rather poorly). That’s also with electricity tariffs now nearly double what they were in that first year. Heated volume is around 700m3, with a heated usable floor area of about 280m2.