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Thermal store OPEN VENTED

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  • Thermal store OPEN VENTED

300 Litre Copper Thermal Store Open Vented Without Header Tank

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Availability: In stock

Regular Price: £1,449.00

Special Price £1,099.00

Quick Overview

300 Litre Copper Thermal Store  - Open Vented Hot Water Cylinder for Stoves with Back Boiler - (Requires a header tank)

Diameter: 540mm including insulation (450 under the insulation)

Height: 1800mm

Capacity: 300 litres

Seperate header tank is required

Internal 3kw electric immersion heater included


1 x Flow and return 28mm boiler connections.
x Flow and return 28mm stove back boiler connections.
1 x 22mm cold and 22mm hot water draw connections to internal coil
1 x Flow and return connections to central heating circuit

Options: Solar Coil 28mm £159 extra  Please ask before ordering
               Additional 28mm tappings £49 extra per pair. Please ask before ordering


What is a Thermal Store?

A Thermal Store is a hot water cylinder, used for storing hot water for domestic consumption and to heat a central heating system, however unlike a traditional hot water cylinder the water within the tank / cylinder is never consumed. Instead of using, or consuming the hot water within the thermal store, it is held as a reservoir of hot water that is used to heat your domestic hot water and your central heating system. The hot water that is held with the thermal store is the same water that is pumped around the central heating system. There are a number of advantages to installing a Thermal Store over a conventional hot water cylinder. 

A Thermal Store will provide mains pressure domestic hot water, without the perils of having an un-vented / pressurised hot water system. This is because the domestic hot water that goes to your hot taps is created from mains pressure cold water passing through a sealed coil within the Thermal Store. The mains cold water is heated by the hot water that surrounds the coil as it passes through the coil

This means that unlike with a conventional vented or un-vented hot water tank, you don't consume or use the hot water in the Thermal Store, and therefore there is no requirement to replace the hot water with cold mains water, which on a convention cylinder then cools the remaining hot water. This means that recovery heat up time is much shorter as the reservoir of water within the Thermal Store is always kept hot, thus making the appliance very efficient.

A further advantage of having a Thermal Store is that you can easily introduce multiple heat sources to combine their resources. For example you can link the thermal store to a gas or oil boiler and a wood burning stove with back boiler and Solar Thermal and a heat pump, therefore using different and alternitive sources of heating to suite the time of year and your preferential requirements. Essentially you can have one, or numerous sources of heat channeled in to a Thermal Store.

In addition you can connect the Thermal Store to more than one heating outlet, for expample you might want to connect to an underfloor heating circuit and to a seperate wall hung radiator central heating system. Thermal Stores work best when they are tall and narrow, against being short and wide, this is because the water in the tank will be hotter at the top than it will at the bottom. When connecting underfloor heating it is preferrential to make the connections lower down the tank, where the water is cooler, because typically speaking underfloor heating is most efficient at arounf 50 degrees. However when connecting wall hung radiators it is preferrential to connect the circuit further up the tank where the water is hotter. 

Thermal Stores are also normally equipped with an electrical immersion heater, to allow electric heating when non of the heat sources are providing heat, or for use as a method of topping up the temperature of the Thermal Store.

How a Thermal Store Works


The water in the cylinder ‘the store’ is heated to and maintained at 76oC by the heat source which can be a boiler, immersion heaters or solar themal (NB Solar Thermal is optional and must be requested when ordering - extra £159).

Cold water at mains pressure is fed through a heat exchanger / coil in ‘the thermal store’ (a high efficiency coil). The cold mains water is heated by the surrounding hot water as it passed through the heat exchanger / coil and is them supplied to the taps at a thermostatically controlled 51oC.

Thermal stores are highly efficient and heat loss is kept to minimum due to the high density CFC free foam installation, meaning minimal heat loss when the thermal store is at rest. This keeps running costs very low because you only heat the water you use. The key to using a thermal store in the most cost effective and efficient manner is to maintain ‘the store’ temperature at a constant 76oC by means of the chosen heat source.This will ensure that ‘instant’ hot water, at mains pressure, is available whenever required; no waiting for the cylinder to heat up.

Thermal stores do not require G3 Building Control Notification and unlike other stored mains pressure systems no special qualifications are required to install the unit.


The water held in a Thermal Store is stored at normal atmospheric pressure, and is topped up by a header tank. Thermal Stores are available with a built in header tank. The header ttank must always be located at a level which is higher than the tallest radiator or under floor heating circuit, otherwise the water would flow back in to the header tank. As an example where the Thermal Store is to be located on the ground floor of a property, with radiators on floors above, the header tank that will feed the Thermal Store must be located seperately from the Thermal Store at a higher level than the highest radiator, but connected to the Thermal Store by connecting pipework. 

Choosing the size of a Thermal Store:

The greater the size of the Thermal Store the more hot water it can store. The greater the volume of stored hot water means the more thermal energy that it will store, which in turn means the less thermal energy you will draw from the store, when you turn on a hot tap or operate the central heating. In other words the temperature of the water within the Thermal Store will cool much quicker the smaller the reservoir of hot water is. Typically speaking a 3-4 bedroom house with 1-2 bathrooms will require a 300 litre Thermal Store.

Please note that we sell all types of flue pipe and fittings. We also offer a free chimney and flue pipe design and quotation service..

Not sure what you need.. Call 0161 439 1400.

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