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Gas Combi to ASHP - Making sense of survey results and proposal.

IRMartini · 2024-04-24T10:00:23Z

Hi Everyone, I’m Ian and recently joined this forum as I’m in the process of switching from a gas combi to ASHP. I did a little intro a few days ago but I’ve now got my heat lose survey and proposal from my chosen company and I’m trying to understand the results and what is being proposed. Although I understand how a ASHP works at a block diagram level I do not at the moment understand specifics. Can I ask anyone willing to take a look at the below details and give me their honest opinions and advise please. I do realise this is a rather long post and that I don’t really know what I’m even asking!? As this is so new and different from anything I’ve every done before but thank you to anyone who takes the time to read and respond I really do appreciate it. House details:Detached property, 155m2, South East Shropshire near BridgnorthGood loft and cavity wall insulation, Double glazed and PV system.Gas usage approx. 13,000kWh per yr. **EDIT** HEAT LOSSArea M2 - 151.39Power (W) - 7047Energy HP (kWh) - 19281 ***** HEATING ANNUAL HEAT DEMANDDemand kWh/yr 19281Heat supplied by HP, excluding auxiliary heaters kWh/yr 19281Seasonal Coefficient of performance SCOP SCOP 3.84Electricity consumed by HP, excluding auxiliary heaters kWh/yr 5021Renewable heat supplied by HP kWh/yr 14260 WATER HEATING ANNUAL HEAT DEMANDDemand kWh/yr 5619Heat Supplied by HP, excluding immersion heater kWh/yr 5619SCOP of HP in Hot water mode SPF/SCOP 3.34Electricity consumed by HP, excluding immersion heater kWh/yr 1682Renewable heat supplied by HP kWh/yr 3937Remaining heat, supplied by immersion heater kWh/yr 156Electricity consumed by HP, including immersion heater kWh/yr 1838 PROPORTIONS, ENERGY CONSUMPTION, AND PERFORMANCEProportion of heating and water heating demand provided % 100by heat pump (excluding auxiliary/immersion heaters)Capacity @ design conditions kW 8Renewable heat kWh/yr 18196Electricity consumed by HP kWh/yr 6703(excluding auxiliary/immersion heaters)Electricity consumed by immersion (supplied as part of HP) kWh/yr 156HP combined performance SCOP SCOP 3.65Star Rating / Flow Temperature 4 / 45°COutside air temperature -3.46°C RUNNING COSTS (Based on Calculations)Cost per unit of electricity for HP p/kWh 25Cost of electricity for HP £/yr 1715(including auxiliary/immersion heaters) The only thing that stood out from the above for me was the heating demand seemed rather high compared with my gas usage, but looking at the room by room heat loss calculations they are based on all rooms at 21deg except bedrooms at 18deg, where we have the living room thermostat set at 18 which we often up it to 19 on an evening and weekend and occasionally 20 but that only seems to happen when I’m not looking! I’ve no idea about hot water demand? there are 4 of us in the house and 3 of us shower everyday and 1 teenage boy who might average 2 a week if we are lucky! PROPOSALTo supply and install an 8KW high temperature Samsung Air source heat pump with R290 refrigerant.To connect heat pump to a RCBO size to be confirmed.To Supply and fit communication cables between heat pump and plant room.To run 2 X 28mm pipes from plant room to heat pump.To supply and fit 250 litre Joule Cyclone unvented hot water cylinder1 x 3 KW immersion heater for legionella purge installed as standardSupply and install a 50 litre stainless steel volumiser or buffer tankConnect heat pump to hot water tank and heating circuits.To fill and flush the whole system and fill with 30% inhibited glycol.To carry out all associated electrical work.To commission system.To provide handover pack which will include building regs certificates for the heat pump and the cylinder, an MCS certificate for the system and all warranty certificates.Eco-Wright energy offer annual servicing and the opportunity for the owner to take out a service contract I havn't copied everything into this post there is additional hot water demand calculations and the individual room and radiator calculations and i've trimmed the boave to try and keep it to the point. COSTSRadiatorsLabour £600New Rads £2,106.96Extras10m Rhau pipe £730HeatPump £11,971.72Sub Total £15,408.68BUS Grant -£7500Site Survey -£300Total £7,608.68 As I said above any thoughts, recommendations and what the above actually means and how I interpret it would be...