Low-carbon heating for Muswell Hill Sustainability Group members
Group Buy North London is working in partnership with Muswell Hill Sustainability Group (MHSG) to help members lower their carbon emissions and take meaningful climate action. Through this group-buy scheme, MHSG members can access high-quality, fixed-price air source heat pump installations with significant savings.
The scheme combines secured group-buy pricing, clear technical design, and independent quality assurance — bringing together the collective purchasing power of the MHSG community whilst maintaining the highest standards. All installations are delivered through an allocated installer from the RetrofitWorks Co-operative of contractors and installers, operating within the Co-op's Quality Assurance Framework. This ensures consistent standards, independent oversight, and clear accountability providing consumers with confidence and peace of mind.
Your Heat Pump — Baxi HP40 Range
Baxi is a trusted British heating manufacturer with over 150 years of experience, producing heating systems since 1866. The HP40 range is designed specifically for UK homes and climate conditions, offering reliable, efficient heating even in the coldest weather.
Technical Specifications
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Baxi HP40 - Full Manufacturers Technical Specification
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Key Features
- Monobloc design — Single outdoor unit with no refrigerant pipework inside your home, simplifying installation and reducing maintenance requirements.
- DC inverter technology — Automatically adjusts output to match your home's heating demand, improving efficiency and reducing energy consumption.
- Cold climate operation — Engineered to operate reliably down to −25°C ambient temperature, ensuring consistent heating throughout British winters.
- Low GWP refrigerant — R32 refrigerant has a significantly lower global warming potential than older alternatives.
- Compact footprint — Single-fan design saves space compared to twin-fan units, making installation suitable for a wider range of properties.
What's Included
Every Group Buy North London heat pump package includes: Complete System Package Baxi HP40 air source heat pump (5–13 kW, sized to your home) UK Cylinders heat pump-compatible hot water cylinder (150–300 L) Replacement radiators (5–8 depending on system configuration) Smart heating controls Room-by-room heat loss assessment and system design MCS-compliant installation and commissioning System volumiser or buffer tank for optimised performance Handover pack, certificates, and warranties Warranties & Aftercare Your installation is protected by comprehensive warranty coverage: Coverage Duration Heat pump manufacturer warranty 7 years Hot water cylinder manufacturer warranty 25 years Cylinder parts warranty 2 years Installation workmanship warranty 2 years Annual service reminders — Your Installer can set up service reminders to help you maintain your system and protect your warranty coverage.
Your Heat Pump Package Prices
Heat pump Size Typical home type You pay (after BUS Grant) 5 kW Small Smaller homes and flats from £4,038 8 kW Medium Typical 2–3 bedroom homes from £5,133 11 kW Large Larger family homes from £5,493 13 kW X-Large Large homes with high demand from £5,817 Important: The heat pump sizes shown above are illustrative of secured group-buy prices. Final system size, configuration, and price will be confirmed following your technical home survey and design review. Prices vary depending on hot water cylinder size and number of radiators included. A full price list for all system configurations is provided in Appendix C upon request. Heat Pump Sizes 5 kW — Small Typically suitable for smaller homes and flats with lower overall heating demand. Compact, efficient systems commonly installed in smaller properties. 8 kW — Medium Typically suitable for most 2–3 bedroom homes, including terraced and semi-detached houses. This is the most commonly installed heat pump size across Group Buy North London. 11 kW — Large Typically suitable for larger family homes with greater space heating and hot water demand. Provides additional capacity whilst maintaining efficient operation. 13 kW — X-Large Typically suitable for large homes with higher overall heating and hot water demand. Designed to comfortably meet the needs of larger households. Note: Final heat pump size is always confirmed following your home survey and heat loss calculations.
Your Hot Water Cylinder
Your package includes a British-manufactured heat pump cylinder from the UK Cylinders range. These specialist cylinders feature an oversized primary coil for efficient heat transfer from your heat pump, ensuring rapid hot water recovery. Capacity Typical suitability 150 L 1–2 bedroom homes, smaller households 200 L 2–3 bedroom homes, average households 250 L 3–4 bedroom homes, larger households 300 L 4+ bedroom homes, high hot water demand The right cylinder size for your household will be confirmed following your home survey. Key features: Cylinder Specifications 545 mm diameter (all sizes) Duplex stainless steel construction 50 mm CFC-free insulation 3 kW backup immersion heater included Market-leading high-efficiency primary coil Cylinder Warranty & Installation Warranty Coverage Cylinder warranty: 25 years (manufacturer) plus 2-year parts warranty If you don't currently have a hot water cylinder (e.g. you have a combi boiler), your installer will work with you to identify a suitable location. Full technical specifications are provided in Appendix D.
Additional Options & Costs
The standard package includes 5–8 radiators depending on your system size. Additional items can be added at fixed prices if required following your home survey. Additional Radiators If your home requires more radiators than included in your package, these can be added at a fixed price. Price: £200 per radiator Includes supply, installation, and Thermostatic Radiator Valve (TRV). Pipework Trunking Premium external trunking to conceal and protect heat pump pipework. Provides a neat, professional finish and protects pipes from weather damage. Price: £250 Converting from a Combi Boiler If you currently have a combi boiler and no hot water cylinder, additional work is required to install a cylinder in a new location, connect heating and water pipework, and wire the immersion backup heater. Price: £600 Note: All additional costs will be confirmed in your final quotation following the home survey. There is no obligation to proceed until you have reviewed and accepted your complete quote.
YOUR INSTALLER & NEXT STEPS
Your Allocated Installer: Sustain Homes
Sustain Homes is rated 4.8 out of 5 on Trustpilot based on 750+ reviews
Sustain Homes is an awarding winning low-carbon technologies installer with extensive experience delivering air source heat pump installations across London and the South East. The company focuses exclusively on renewables projects and has a strong track record working in the types of homes commonly found across North London.
Sustain Homes has supported multiple group-buy schemes and brings significant experience in delivering high-quality installations at scale whilst maintaining excellent customer service.
As a member of the RetrofitWorks Co-operative Sustain has completed RetrofitWorks' full installer vetting process. All installations are delivered in line with our Quality Assurance Framework, providing oversight of technical design, installation quality, customer experience, and issue resolution.
Accreditations & Recognition
MCS Certified
Microgeneration Certification Scheme
TrustMark Registered
Government Endorsed Quality
RECC Member
Renewable Energy Consumer Code
Certified B Corporation
Verified social and environmental standards and value creation for impact driven businesses
RetrofitWorks Co-operative Member
Vetted & Approved Contractor. Governed by RetrofitWorks' Quality assurance standards and code of practice
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