Triple Coil Ultra-Efficient 400 Litre Unvented Cylinder from Heat & Hot Water Cylinders – Reduce Energy Costs with Overnight Electric Tariffs and Solar

SKU: HH-D-393
Availability: In stock

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£1,952.58 EXCL. TAX

£2,343.09 INCL. TAX

Customer Notice: These cylinders are sent direct from the manufacturer - please call us on 01691 888595 to confirm lead times and delivery charge

In stock


Smart Energy Solutions: 3-Coil design maximizes energy efficiency & optimizes heating options.

Help heat your home economically by integrating your existing Solar PV or Solar Thermal.

Take advantage of reduced heating cycles and backup heating support with a versatile Heat & Hot Water Cylinders unvented cylinder.


400L Three-Coil Unvented Cylinder with 24L Potable expansion vessel & 28mm Hot & Cold Connections

Comes with 1m2 DN25 Bottom Input Coils (Solar), 2m2 DN32 Middle Input Coils & 1m2 Top Output Coils with 28mm 2-port zone valve for middle input coil (for when connected to a boiler) & high limit stat.

*Delivery to Mainland UK Only – Delivery in 14-21 working days *
Please Note Returns On This Item Will Incur A 25% Re-Stocking Fee And Must Be Returned At Your Cost via A Pallet Service With Insurance
Cylinder Dimensions:  1575mm x 690mm
Why buy a Heat & Hot Water Cylinders Unvented Cylinder?
  • Increase or maximise the use of cheaper overnight or flexible electric tariffs
  • Increase or maximise the use of your Solar PV or Solar Thermal to include some heating instead of just battery storage or hot water
  • Reduce the runs cycles or run time of your primary & most expensive, component of your heating system
  • For heating of towel rails or designated areas in your home during the Autumn or Spring time when you don’t want or need much
  • Use any PV export to help warm your home
  • Help reduce reliance on or the need for heating fuel deliveries
  • Back-up heating option when your primary heat source breaks down
  • Low energy buildings that then have a heating option simply by installing a hot water cylinder that isn’t limited to the energy going down the drain
For more information, please visit

This Cylinder comes with:

  • 24L Potable Expansion vessel
  • 28mm Hot & Cold Connections
  • Unvented Kit
  • Esbe VTA323-DN20-35-60 Thermostatic Mixing Valve 35C – 60C for the DHW draw off
  • Esbe VTG141-20-55 Manually Adjustable 4-way Thermostatic Mixing Valve for blending down the Top Output Only Coil to the required temperature. Please Note : The cooler the set temperature, the longer the kWhr’s supplied to the heating / heated circuit.
  • Pump for the load side of the 4-way blending valve. Pumping to either your Radiator/s, Towel Rail/s or UFH manifold. You will need the appropriate size pump valves.

A better hot water cylinder by design!

These cylinders are manufactured by 3rd generation hot water cylinder manufacturers’, with heritage and history dating back to 1967. Their manufacturing and engineering team are unrivalled in the industry, their state-of-the-art manufacturing base and processes underpin the lifetime 25-year warranty on Heat & Hot Water Cylinders.

Heat & Hot Water Cylinders care manufactured to the highest British Standard EN 12897:2006

More than a hot water cylinder.

Heat & Hot Water Cylinders unvented cylinders are different from standard hot water cylinders that are only designed, and capable of, providing hot water for bathing, showering & washing.

Like a battery, but storing thermal energy or heat.

These cylinders are unvented hot water cylinders, with the added ability to be able to provide heating via a patent-protected output coil at the top of the cylinder. Heat & Hot Water Cylinders are not Thermal Stores, although they do store thermal energy or heat.

Top output only coil.

Heat & Hot Water Cylinders are installed exactly the same way as you would install a standard unvented hot water cylinder.

The controls are intended so that the top output only coil only works between your chosen temperature band, ensuring there will always be enough hot water for the day.

Via the 4-port blending valve & pump, the top output-only coil is to be connected to the heating circuit you want to supplement. The cooler the 4-port Esbe valve is set at, the longer the kWhr’s of use.


In the UK, all unvented hot water cylinders have to be Pasteurised to help protect against Legionella. Pasteurising at 50C will take around 2 hours to kill any legionella present. Pasteurising to around 60C will kill any legionella present even quicker, however, the higher the temperature the water in the cylinder is taken to, the greater the heat loss, especially if the water isn’t going to be used. With a Heat & Hot Water cylinder, that excess temperature after the Pasteurisation process can then be used to heat a towel rail or two via the Output Only Top Coil.

Please Note : These cylinders are presented and sold on both Nominal and Actual volumes, for example, the 200litre 2-coil cylinder, because it has the additional extract / output coil, the actual water storage volume is a little reduced. The NOMINAL volume without coils is 200litre, the ACTUAL volume with coils is slightly reduced at circa 189litres. This slightly reduced volume applies to all of our cylinders due to the extra coil.

Further information and schematics:

Heat & Hot Water Cylinders Mechanical Schematic

Heat & Hot Water Controls

Tesla T-Smart Hot Water Cylinder Thermostat

Thermostatic Mixing Valve

Additional information

Weight52 kg

Manufacturers Code