Cosy by Octopus vs a standard installer.

The Octopus-branded Cosy offer is a productised installation. A national brand fronts the sales and the aftercare, a survey engineer visits, the price is presented as a single figure inclusive of the Boiler Upgrade Scheme grant, and the installation is handled by a network of trained installers on Octopus paperwork. The proposition is coherence; you buy one thing from one brand, and the same brand is on the phone if something breaks in year three.

A standard installer is a locally-selected MCS-registered heating engineer or contractor. You ask two or three of them for a quote, weigh the designs, and pick one on the strength of the survey rather than the strength of the brand. The proposition is fit; the installer you choose has surveyed your specific house and their design reflects it, not a national playbook.

Neither route is objectively better. The mistake is treating them as interchangeable and then being surprised that the survey depth and the aftercare model differ; they were always going to.

For an owner who values a single point of accountability, the packaged route is genuinely attractive. One brand quotes, one brand installs, one brand answers the phone if the system trips in January. The price is presented net of the grant, which reduces the paperwork the homeowner has to complete, and the tariff proposition (a heat-pump-tuned electricity tariff on the Octopus side) is coherently designed to work with the kit.

For a typical mainstream British house on the packaged route's happy path — a 1930s semi or a modern detached with reasonable insulation, a workable outdoor unit position, standard radiator upgrades achievable — this is a legitimate and often excellent way to buy a heat pump. The design will be capable, the installation will meet MCS, and the aftercare will be traceable to a national brand.

For a house that sits off the happy path — a Victorian terrace with awkward micro-bore pipework, a stone cottage with an unusual heat load, a listed building, a rural site with a borehole possibility, or a homeowner who wants water-based underfloor heating designed rather than substituted for larger radiators — the local specialist is often the better route. The survey will be deeper because the installer will be on site rather than compressing the visit into a national scheduling window, and the design will reflect the room-by-room quirks that a productised offer has to average across.

The other case is homeowners who genuinely enjoy the specification conversation. A competent independent installer will discuss flow temperatures, weather compensation curves, radiator sizing per room, buffer tank versus low-loss header, in more depth than any packaged offer is set up to. If you want to understand the design decisions before signing, you will usually get further with a specialist.

The design flow temperature. A packaged offer will usually target 45–50 degrees; a good specialist will aim for 40 or lower. Every degree lower is roughly two per cent added efficiency for the life of the system, so a ten-degree gap is a twenty per cent running-cost delta the whole time the kit is running.

The radiator schedule. Both routes will upsize radiators to some extent; the interesting question is which rooms and by how much. A schedule that upsizes every radiator by the same factor is a productised answer; a schedule with different factors by room reflects a real heat-loss calculation.

The aftercare contract. Read both. A packaged offer usually includes annual servicing baked into the tariff or the warranty; a specialist may separate service from install. Neither is wrong; know which one you are buying.

The commissioning report. Ask both routes what commissioning documentation you will receive at handover. Anyone who cannot describe the format in advance is a red flag regardless of the brand on the paperwork.