Buffer vessels from Flexiheat UKFlexiheat UK

 Buffer Vessel /Buffer Vessels

Buffer vessels from Flexiheat UK

Buffer vessels are used a variety of water systems, be it domestic hot water (DHW), heating (LTHW), and or even process applications such as chilled water. The basic concept or function of buffer vessels is to heat the vessel during low demand periods and then release the heat during high demand periods, thus as such they are also called a thermal store. For chilled or cooling water applications – the reverse is applicable to the buffer vessels.

Stored heat energy / hot water storage products

Their purpose is to collect heat from one or more heat sources and store it for later use as part of a heating system. For example for a heating buffer vessels – the heat energy produced by a heat pump (air source heat or ground source heat pumps ),biomass boilers or even renewable energy sources such as solar hot water systems , might be kept in a buffer tank and then drawn out as needed to heat a wet heating system, such as an under-floor heating or radiator space heating system

An open vented buffer can be used to manage an uncontrollable heat source, such as a solid fuel boiler (pellet boilers biomass, wood burning stoves etc), without requiring the same level of safety precautions as unvented systems require as the heated water can expand into the feed and expansion tank since the buffer vessel is open to the atmosphere.

You should not used mild steel thermal storage tanks, as an open vented system is susceptible to introducing air into the heating water, and cause corrosion and damage to the mild steel vessels – thus you should use glass lined vessels or stainless steel vessels products

Buffer tanks product construction

We can manufacture these buffer vessels in various materials – mild steel , glass lined mild steel or stainless steel dependant on your requirements and capacities. All vessels can be fitted with an immersion heater or heaters as backup or supplementary energy sources to the range of vessels we offer.

Boiler buffer vessel – heating

Because biomass boilers pellet,log or wood chip – will  take longer to heat up than a gas boiler, a buffer vessel with a stored water temperature of 70 to 80 degrees C is installed to give instant heat. Boilers,biomass boiler in particular benefit from running longer and achieve maximum efficiency while heating the vessel, whilst staying off for longer between heat cycles.

The heating buffer vessels are the ideal solution for storing hot water in reserve for rapid and efficient supply, whether you’re short on boiler power or have a high peak demand.heating buffer vessels;biomass boiler;boilers

The vessels are manufactured in mild steel,copper is not required as its heating water, and therefor a suitable corrosion inhibitor must be used on a buffer vessel for heating solution.

We offer products from 300 to 10,000 litres in capacity , with a maximum operating temperature of 95°C , and a maximum operating pressure of either 6 or 10 Bar, in mild steel, enamelled mild steel, or even stainless if so required.

Benefits Benefits of buffers in heating systems from Flexiheat UK

Stratification –  The hydraulic circuit’s temperature can be stratified using the various temperatures available thanks to the inlet and outlet hydraulic connections positioned at varying tank heights.

Anti – condensation –  When using biomass heat generators (wood, wood chips, pellets, etc. ), it can operate as an anti-condensation circuit, ensuring that the manufacturer’s requirements are followed. These tanks allow you to comply with rules that demand the use of buffer tanks in conjunction with heat generators in some countries.

Partitioning – In addition to separating the hydraulic circuits between primary and secondary, it is possible to expand both the primary heating by connecting additional energy sources.

They can utilize renewable energy sources such as solar, via an indirect coil to help heat the system.

buffer tanks for heat pumps;cylinders buffer vessels; heating;heat pump buffer


With options of vertical low, vertical extra-low or even customized dimensions to suit site installation requirements.

We offer ErP “A” energy rated buffer vessels – From 50 litres to 500 Litres capacities in accordance with the European Directive 2009/125/EC. These are designated the “Q” range .You can download the full brochure here –

Tank Q Buffer Vessels Brochure 50 to 500 Litre ErP “A” energy rated – Flexiheat UK

Or the range of heating hot water storage buffer vessels from 800 to 5,000 litres in capacities, in plain mild steel, galvanized mild steel or even stainless steel.

Buffer Vessels – 800 to 5,000 Litres “Hot” range Brochure – Flexiheat UK

Domestic hot water buffer vessels / domestic hot water storage tanks

Our domestic hot water buffer vessel product range can also be called domestic hot water storage tanks. Historically these used to be manufactured from copper , but due to the fact that copper vessels can’t take as much pressure as stainless steel manufactured buffer vessels, stainless steel units have taken the market in the stainless steel copper argument

Also copper is not as durable as stainless steel, as copper is more prone to stress and crevice corrosion. Copper solutions for a thermal store / thermal energy vessel are also subject to the copper commodity prices which can fluctuate wildly these days. Stainless steel prices used to be a lot more than copper , but these days the price of stainless steel products is a lot closer to copper products , these factors, mean copper buffer vessel’s are less competitive in terms of long-term product installed life cycle costs.

domestic hot water buffer tank;hrs hevac aquafumo

We do a full range of stainless steel or glass lined mild steel domestic hot water buffer tanks from 200 to 5000 litres in capacity in a vertical or horizontal configuration.

Domestic hot water tanks from Flexiheat UK;hot water buffer tank


domestic hot water storage tanks dimensions from Flexiheat UK; products hrs hevac

With options of vertical low, vertical extra-low or even customized dimensions to suit site requirements, and optional accessories such as a magnesium anode or an electronic anode for the enamelled versions – stainless versions don’t require any protection.

We can also supply larger volume units and bespoke units in enamelled mild steel, stainless steel at special request.

hydraulic equipment – tapping’s and dimensions

technical detail of our DHW buffer tanks from Flexiheat UK; hrs hevac aquapiv

Both types can be fitted with immersion heaters connected, for either direct top up or emergency back up of the hot water systems, we can manufacture or supply the immersion heaters in various heat / energy outputs to suit the system requirements for the thermal store. Or supply units that can utilize renewable energy , via an indirect coil to heat the hot water systems capacities.

Download the domestic hot water storage vessels -TAH-TA Flexiheat Brochure

Energy saving insulation

We supply energy efficiency class leading B or C ErP insulation rated buffer products to comply with the building regulations and European Directive 2009/125/EC

Chilled water buffer vessels – Steel

Chilled or cooling water services cylinders buffer vessels are used to assist chillers in air conditioning systems to avoid excessive chiller cycling and temperature control issues, and low water volume systems may require additional buffer capacity installed as a solution.

These products are available with the options of either a perforated central divider plate or multiple flow dividers -which helps reduce fluid mixing and convective turbulence due to temperature differences in the chilled water. They also ensure the reduction of compressor start-ups of the chillers.

chilled water buffer tanks

With standard products from 100 to 5000 litres in capacity ,with rigid or anti-condensation polyurethane insulation.

Dimensions of our chilled water storage tanks Flexiheat UK

hydraulic equipment – tapping’s and dimensions

technical detail of our chilled water tanks Flexiheat UK

We can also supply a range of buffer vessel for chilled water products above 5000 litres in volume, and bespoke units at special request.

Download the Flexiheat VT Chilled Water Buffer Vessels Brochure

Should you require more product information, availability, technical support or prices on our complete range of buffer vessels – for heating or chilled water then please don’t hesitate to speak or call us – contact our sales service team on 01202 822221 or use our email contact form via the contact tab above to message us.