Telford Tempest Indirect Horizontal Heat Pump Cylinder 170L 200L 250L 300L 400L 500L

The defining feature of this range is its horizontal orientation. Where headroom is insufficient for a 1.5–2 m+ vertical cylinder, the Tempest Horizontal sits on two supplied cradles and uses length rather than height to store volume. This makes it the natural choice for loft spaces, under-eave plant rooms, integral garages, and any installation where floor-to-ceiling clearance is limited — a scenario that is increasingly common in heat pump retrofits where the airing cupboard has been repurposed.

A standard indirect boiler cylinder typically has a coil of 1–1.5 m². The Tempest Horizontal HP features a purpose-designed coil of up to 3 m² (3.3 m² quoted by some distributors for the 200 L+) — more than double — to compensate for the lower flow temperatures delivered by an air or ground source heat pump. Larger coil area = faster heat transfer even when the primary circuit is operating at 35–50 °C rather than the 60–80 °C typical of a boiler.

Telford's Tempest flagship range is manufactured from Duplex stainless steel with walls up to 40% thicker than some competing products. Duplex combines the corrosion resistance of austenitic stainless with the strength of ferritic grades, delivering a vessel that handles aggressive water chemistry and mechanical stress across decades of service. The 316L grade stainless-steel 22 mm compression fittings and coil match this premium standard throughout.

Every size includes a factory-fitted 3 kW immersion heater at 240 V, ready for connection to a time switch or smart controller. This serves two purposes: it provides electric back-up heating when the heat pump is in defrost or maintenance mode, and it enables anti-legionella pasteurisation cycles by heating the cylinder above 60 °C periodically — a requirement under HSG274 for some occupied buildings.

Every cylinder ships with the complete G3 unvented kit: inlet control group (including 3 bar PRV), acetal tundish, dual probe thermostat (dual high-limit stat), factory-fitted T&P relief valve (7 bar / 90 °C), 2-port motorised valve, remote expansion vessel with wall-mounting bracket, and — uniquely for a horizontal cylinder — two mounting cradles so the cylinder can be sited directly from the box without sourcing separate supports.

The Tempest range is WRAS approved, confirming suitability for connection to the UK mains water supply. As an unvented indirect cylinder, it delivers full mains-pressure hot water to all outlets simultaneously — no pump required, no gravity-fed trickle — matching the performance expectation of modern heat pump installations where underfloor heating and efficient domestic hot water are specified together.

For hybrid installations combining a heat pump with solar thermal collectors, or for those wishing to retain a gas or oil boiler as a supplementary heat source, Telford offers a twin-coil variant of the Horizontal HP. The second coil serves the boiler or solar circuit independently of the heat pump primary circuit. Contact us to confirm availability in the required capacity.

The inner stainless-steel vessel carries a lifetime manufacturing warranty — one of the strongest guarantees in the UK market. Controls and components carry a 2-year guarantee. This warranty is transferable if the property changes hands. Terms and conditions apply; always retain the installation paperwork and Benchmark Commissioning record as evidence of compliant installation.