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Heat pump accessories — the kit that makes a system more efficient

Thermostats, cylinders, valves, WiFi controllers and filter kits — recommended kit for a new or existing air source heat pump.

The accessories that matter most for a heat pump are a smart thermostat (to shift running to cheap off-peak electricity), a heat-pump-ready hot water cylinder, a magnetic filter to protect the heat exchanger, and an anti-freeze valvefor external pipework. Below are our picks, with live Amazon & eBay prices.

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Smart thermostats

Programme around cheap off-peak tariffs and cut heat-pump running costs.

Google Nest Learning Thermostat (3rd gen)

Most popular

The most popular smart thermostat in the UK. Auto-schedules around your routine and pairs with the Nest app — a solid companion for heat-pump control.

Hive Thermostat Mini

Best value

British Gas's simple, reliable smart thermostat. Easy scheduling and remote control — good value and frequently bundled in deals.

Tado Smart Thermostat V3+

Best for heat pumps

Designed with heat pumps and low-flow systems in mind. Its open-window detection and weather-based load shifting cut waste better than most rivals.

Hot water cylinders

A well-insulated cylinder is essential for efficient heat-pump hot water.

Indirect unvented hot water cylinder (200L)

A properly sized, well-insulated indirect cylinder is central to an efficient heat pump — 200L suits a typical 3-4 bed family and reduces boiler cycling.

Pre-plumbed heat-pump-ready cylinder (250L)

Pre-plumbed cylinders mate directly to air source heat pumps with a large coil for faster reheat and better SCOP-influenced efficiency. Check MCS sizing.

Hot water cylinder insulation jacket

Budget

A cheap, effective upgrade that cuts standing heat loss and keeps the tank hot with the lower-flow heat pump output.

Anti-freeze & system valves

Protect the outdoor unit and balance the heating system in winter.

Anti-freeze valve / thermostatic drain valve

Protects outdoor pipework and the unit from freezing when unused in winter. Essential for many external heat pump installations.

WiFi controllers

Control every room and schedule remotely from your phone.

WiFi smart energy monitor/controller plug

Opt-in

Monitor the heat pump's live draw and shift running to off-peak hours. A cheap 'set and forget' way to cut year-round costs.

Filter kits

Magnetic and inline filters protect the heat-pump circuit and warranty.

Magnetic filter (e.g. Fernox/Sentinel type)

Warranty essential

Captures magnetite and sludge that would otherwise clog the heat-pump heat exchanger. Many installers make one a mandatory condition of warranty.

System filter kit / installation filter set

A complete magnetic + strainer filter kit protects the pump, keeps the system efficient and is required by most manufacturers to validate the warranty.

Prices shown are typical guide prices at time of writing. Product links are affiliate links to Amazon & eBay — we may earn a small commission at no extra cost to you. Always confirm the correct model and size with your installer before buying.

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Heat pump accessories FAQs

FAQ

Heat pump accessories frequently asked questions

What accessories does a heat pump need?
The essentials are a smart or programmable thermostat, a well-insulated hot water cylinder, a magnetic filter to protect the heat exchanger, and often an anti-freeze or system valve for external pipework. A WiFi controller lets you schedule around cheap off-peak electricity.
Can I use my existing thermostat with a heat pump?
Often yes, but heat pumps run most efficiently with a weather-compensating control or a thermostat designed for low-flow systems (like the Tado V3+). A standard boiler thermostat may not optimise an ASHP, so check with your installer before keeping your old one.
Is a new hot water cylinder really necessary?
For most heat pump installations, yes — a heat-pump-ready cylinder with a large coil reheats efficiently at the lower flow temperature an ASHP uses. A typical cylinder adds £1,000–£2,500 to the install cost, but it's essential for an efficient and reliable system.
Do magnetic filters cost extra or are they included?
A magnetic filter is often a separate charge of £40–£90 for parts, though many installers quote it as a mandatory line item. It captures magnetite that would otherwise clog the heat-pump heat exchanger and is required by many manufacturers to validate the warranty.
Are the accessory links here affiliate links?
Yes — some of the product links to Amazon and eBay are affiliate links. That means we may earn a small commission at no extra cost to you if you buy. Prices and stock are the retailer's and change frequently.
Sources & cited data