Commercial Hot Water Cylinders, Calorifiers and Buffer Vessels

A calorifier is a type of indirect hot water cylinder. While both store hot water for use around a building, a calorifier heats water indirectly using another heat source. Usually that is a boiler, heat pump or solar thermal system connected to a coil or heat exchanger within the vessel. Commercial buildings favour calorifiers because they allow the primary heat source and storage cylinder to be sited separately, and because calorifiers can be fed by multiple heat sources simultaneously. 

There is no single right answer to cylinder sizing for commercial buildings. The size you need depends on how many people it will serve, how many outlets are connected, your peak demand periods and recovery time, and how powerful your primary heat source is. Commercial installations are typically sized at somewhere between 30 and 50 litres per occupant for DHW demand alone, but this varies considerably depending on the building type. Kitchens demand hot water throughout the day. Peak demand in a hospital differs greatly from peak demand in an office. 

Adveco can help you specify the right size and type of cylinder for your project. Our engineers carry out a demand assessment as part of the design process. 

Yes. Adveco’s commercial cylinder range includes vessels with both single and dual coils designed for use with solar thermal panels, air source heat pumps and other renewable heat sources. Our ATSB and ATSI commercial cylinders are particularly well suited to hybrid setups where more than one heat source is connected to the same cylinder. The key is making sure the coil surface area and cylinder size are matched to the output of your heat pump or solar thermal system. Our design team can advise on this. 

An unvented cylinder does not have a vent pipe. Instead it is fed directly by the mains water supply, which means mains-pressure hot water at every tap and shower in the building. Unvented cylinders need to be installed by a G3 registered engineer, but they are the recommended choice for most commercial applications where mains pressure is available. 

Yes. Like all hot water cylinders, commercial vessels should be serviced regularly by a qualified engineer. An annual service maintains performance and efficiency and ensures the cylinder stays compliant with water hygiene legislation. A standard annual service will check anode condition where applicable, coil and heat exchanger integrity, safety valve operation and carry out a Legionella risk assessment. Adveco’s warranty service and maintenance contracts cover the full hot water appliance, not just individual components. 

The softer the water, the more potential it has to be corrosive to bare metal. Stainless steel cylinders are extremely resistant to corrosion providing longest life for investment. Carbon steel cylinders provide some protection depending on the quality of the enamel (also know and glass) lining. Where water is soft, but not overly corrosive, these are a sensible lower cost option.   

Cylinders in a hard water area are prone to limescale, especially when water is in continuous contact with high temperature surfaces, such as an immersion. Carbon steel cylinders are the popular option but should be configured as an indirect water heater / calorifier, reducing contact between heating elements and mains water. Cylinders in hard water areas must have regular maintenance to avoid build-up of limescale which actively reduces heating efficiency and can lead to critical damage.