Telford Tempest 300L Heat Pump Cylinder with 50L Integrated Buffer

Description

The Telford Tempest 300L pre-plumbed tank-on-tank heat pump cylinder combines a 300 litre Duplex stainless steel hot water store with a 50 litre internal buffer in one insulated white casing. Built for air source heat pump systems, it delivers mains pressure hot water and is suited to large homes and light commercial properties with substantial hot water demand.

It arrives pre-plumbed and pre-wired with the heating circulation pump, 3-port diverter valve, magnetic heat pump filter and filling loop already fitted, plus a 3kW immersion heater, remote expansion vessel and unvented kit. That cuts on-site pipework, keeps installs tidy, and is backed by a lifetime warranty on the inner vessel.

300L

Nominal Capacity

50L

Internal Buffer

3 m²

Coil Area

3kW

Immersion Heater

2020 mm

Height

Lifetime

Vessel Warranty

What is in the box: Factory-fitted on the cylinder: heating circulation pump, 28mm 3-port diverter valve, 28mm magnetic heat pump filter, filling loop with gauge, air vent, tundish, 22mm inlet control group, 1/2 inch 7 bar temperature and pressure relief valve, wiring centre, high limit stat, domestic hot water sensor and 3kW immersion heater. The remote expansion vessel and the unvented component kit are supplied with the cylinder.

Space and floor loading: Fully loaded, the 300L weighs 404 kg. Check the floor loading before positioning, and note the 2020 mm height. Telford notes that sizes may change due to ERP standards, so confirm dimensions for tight spaces.

Valve configuration: The cylinder is supplied with a 28mm 3-port diverter valve, and Telford shows an optional 2-port valve configuration. Confirm the arrangement your heat pump and controls need before ordering.

Important Safety Information: Unvented cylinders are covered by G3 Building Regulations and must be installed and commissioned by a competent, suitably qualified person. The temperature and pressure relief valve and tundish discharge must not be altered or blanked off.

Key Features

Pre-plumbed and pre-wired

Arrives with factory-fitted pipework, wiring centre, heating circulation pump, 3-port diverter valve, 28mm magnetic heat pump filter and filling loop with gauge, so installers connect the heat pump and the water supplies rather than building the primary circuit from scratch.

Integrated 50 litre buffer

A 50 litre buffer store built into the same casing adds system volume for the heat pump, helping reduce short-cycling without a separate buffer vessel or the wall space it needs.

Duplex stainless steel vessel

The inner vessel is Duplex stainless steel, offering superior corrosion resistance, and is backed by a lifetime manufacturing warranty on the inner container.

Large heat pump coil

A purpose-designed coil with a large surface area maximises heat transfer at the lower flow temperatures heat pumps run at, for fast reheat and efficient operation.

Mains pressure hot water

Supplies mains pressure hot water with high flow rates, and ships with an unvented kit, a 22mm inlet control group, tundish and a 7 bar temperature and pressure relief valve.

3kW immersion back-up

A factory-fitted 3kW immersion heater (240V) provides back-up heat if the heat pump is unavailable or additional capacity is needed, with a high limit stat and domestic hot water sensor fitted for control and protection.

Technical Specification

General

Brand

Telford

Range

Tempest

Product code

TSMI300/50/HP/PP/WB2

Type

Pre-plumbed unvented heat pump tank-on-tank cylinder with internal buffer

Nominal capacity

300 litres

Internal buffer store volume

50 litres

Vessel material

Duplex stainless steel

Case finish

White steel case, fully insulated

Dimensions and Weight

Overall height

2020 mm

Diameter

580 mm

Empty weight

110 kg

Full weight

404 kg

Thermal Performance

Primary coil surface area

3 m²

Standing heat loss

2.22 kWh/24h (92 W)

Energy efficiency class

C

Pressure

Operating pressure

3 bar

Maximum incoming supply pressure

12 bar

Temperature and pressure relief valve

7 bar, 1/2 inch, factory-fitted

Heating, Connections and Controls

Immersion heater rating

3kW @ 240V, factory-fitted

Hot water draw-off

22mm

Inlet control group

22mm

Return connection to heat pump

28mm

Heating return

1 inch BSP female

Thermostat pocket

12mm

Pre-plumbed circuit

Heating circulation pump, 28mm 3-port diverter valve, 28mm magnetic heat pump filter, filling loop with gauge, air vent and tundish

Controls and sensors

Wiring centre, high limit stat, domestic hot water sensor

Valve configuration

3-port diverter valve as standard, optional 2-port valve configuration

Drain

1/2 inch drain

Warranty

Inner container

Lifetime manufacturing warranty

Components and parts

2 years

Compare the Tempest Pre-Plumbed Sizes

Model

Capacity

Height

Coil area

Empty / full weight

Standing loss

170L

170L + 50L buffer

1315 mm

2 m²

79 / 247 kg

1.94 kWh/24h

200L

200L + 50L buffer

1430 mm

3 m²

88 / 282 kg

1.85 kWh/24h

250L

250L + 50L buffer

1780 mm

3 m²

98 / 344 kg

2.00 kWh/24h

300L (this model)

300L + 50L buffer

2020 mm

3 m²

110 / 404 kg

2.22 kWh/24h

Frequently Asked Questions

What does the 300L Tempest cylinder include?

The Telford Tempest 300L pre-plumbed cylinder (TSMI300/50/HP/PP/WB2) includes a 300 litre indirect vessel with an integrated 50 litre buffer, factory-fitted pipework and wiring centre, heating circulation pump, 28mm 3-port diverter valve, 28mm magnetic heat pump filter, filling loop with gauge, air vent, tundish, high limit stat, domestic hot water sensor, 3kW immersion heater, remote expansion vessel and an unvented kit.

What is the integrated buffer for?

The 50 litre buffer store sits inside the same casing and adds system volume for the heat pump primary circuit, so you do not need to fit and pipe a separate buffer vessel. It is part of the pre-plumbed unit and is sized by Telford for this range.

Do I need a separate expansion vessel or unvented kit?

No. The remote expansion vessel and the unvented component kit are supplied. The expansion vessel is remote rather than internal, so allow wall space near the cylinder to mount it.

How much space and floor loading should I allow for the 300L?

The cylinder stands 2020 mm tall with a 580 mm diameter and weighs 404 kg when full (110 kg empty). Confirm the floor can carry the full weight and allow room around and above the cylinder for the pipework and servicing. Telford notes that sizes may change due to ERP standards, so confirm dimensions for tight spaces.

Is this cylinder suitable for an air source heat pump?

Yes. The Tempest heat pump range is designed for use with an air source heat pump as the main heat source. Check your heat pump manufacturer's cylinder requirements, particularly coil area against the heat pump output, before specifying.

Can it be configured with a 2-port valve?

Telford's datasheet shows a 28mm 3-port diverter valve as standard, with an optional 2-port valve configuration. Confirm the arrangement your heat pump and controls require before ordering.

Who should install it?

Unvented hot water cylinders must be installed by a competent person in line with G3 Building Regulations, with the electrical connections completed in line with BS 7671 and notifiable under Part P where required. Follow Telford's installation manual and commission the safety devices.

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Room Dimensions

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Height (in m):

Room Type

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Glazing Type

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Double Glazed

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External Walls

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Insulation Level

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Average

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