500 Litre buffer tank or vessel
Our 500 Litre buffer tank or 500 litre buffer vessel, is a hot water buffer tank normally used to store heating hot water or increase the heating system’s hot water volume. This energy is retained for later use and results in fewer but longer heating cycles for the heating system with our buffer tanks or accumulator tanks.
500l buffer tank for a heating system
This 500L buffer tank can be used on various heating systems, but is often used in conjunction with renewable heating systems such as biomass boilers or low carbon systems such as ground source heat pumps or air source heat pumps.
Air source heat pumps
For a heat pump to operate at peak efficiency, our buffer tank, also known as a buffer vessel, ensures minimal compressor run times and minimum water flow rates. For air source heat pumps, a buffer is necessary because it supplies the defrosting energy for the heat pump. If a heat pump is the only source of heating, it is also possible to integrate an electric immersion element to provide additional heating as needed to our multi port buffer tanks.
Specification of our buffer tank or vessel
Specification of our 500 Litre buffer vessel or 500l buffer tank

Out 500L buffer vessel or tank – overall height 1,770 mm, overall diameter 850 mm with insulation – 650 mm diameter with insulation removed.
Tank storage capacity – 500 Litres
Height – 1,770 mm
Diameter with Insulation: 850 mm
Diameter without Insulations: 650 mm
Product insulation is polyurethane – 50 mm insulation
The insulation is removable – which allows you to get the buffer tank through a standard doorway access
Our 500l buffer tank is a great quality product at a great price
Buffer tank weight – 108 Kg when empty – 508 kg when full with hot water
8 x connection tapping’s – 40 mm (1 1/2″ ) female bsp – designated “KP” on the above drawing
4 x Thermometer or sensor pockets – 15 mm (1/2″) female bsp – designated “T” on the above drawing (sensor pockets are 1/2″ female threaded)
1 x Air vent eliminator or safety valve tapping or bsp safety connection – 40 mm (1 1/2″) female bsp- designated “OZ” on the above drawing
Full port dimensions off the floor for our FH16.500NB-O which is the 500 Litre model product is listed in the following data chart
Buffer tank maximum working temperature – 95 Degrees Celsius
Buffer tank maximum working pressure – 3 Bar
With plenty of tapping’s this 500L buffer tank can be fitted with additional immersion heaters as a backup or top-up heat source.
This 500L buffer tank is manufactured from mild steel, so corrosion inhibitors must be used with this product.
Download the Flexiheat UK 400 to 600 Litre heating buffer tanks vessels brochure
Should you require another capacity or volume buffer tanks or a higher working pressure, then we do a full range of buffer tanks which are listed on their dedicated webpage.
Applications – hydronic heating systems
Our 500l buffer tank can be used with heat pumps, log fired boilers, gasification boilers, wood pellet boilers, or even traditional gas or oil boilers, Flexiheat UK offers a variety of multi-port buffer tanks and accumulator tanks.
Sizing criteria for a 500l buffer tank
Here are some guidelines on sizing for our 500L buffer tank
Air source heat pumps or ground source heat pumps: approximately 25 litres per kW of heat pump output (recommended by BS EN 14511 for defrosting of the heating system).
Wood pellet boilers: a minimum of 10 litres of tank volume for every 1 kW of boiler output.
Solid fuel boilers: a minimum of 30 litres of tank volume for every 1 kW of boiler output.
Wood chip boilers: a minimum of 12 litres of tank volume for every 1 kW of boiler output
Gasification boilers / log fired boilers: a minimum of 50 litres of tank volume for every 1 kW of boiler output.
Thermal storage tank or vessel 500 Litres capacity
If you require more product information, availability, technical support , check stock levels, delivery times or get prices on our 500 Litre buffer tank or vessel for heating hot water, then please don’t hesitate to get in touch. Contact our sales service team on 01202 822221 or use our email contact form via the contact tab above to message us. Connect with us on Facebook or Twitter for our latest products updates and special product price deals.