As a family-run business of over 40 years, Newark Cylinders has a wealth of knowledge when it comes to answering commonly asked questions on hot water cylinders, thermal stores, buffer vessels, and more.
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“Header tank” is a term usually used for the cold water storage tank, positioned at the highest point of a vented, primary heating system.
The term “feed & expansion tank” is also commonly used for the cold water storage tank. However, this is usually for tanks within secondary hot water systems, rather than heating systems.
In both cases, the tanks accept cold mains water via a float valve, fill and keep their systems topped up with water, and absorb additional water volume from their systems when it expands through heating.
A vented hot water cylinder is a traditional hot water storage system that operates at low pressure, fed by a cold water storage tank typically located in the loft. Unlike unvented cylinders, they don’t connect directly to the mains, so they don’t require a G3 qualified installer to fit.
For a full overview of how they work and whether one is right for your property, see our vented cylinders guide.
Buffer Vessels only hold non-potable, primary water and don’t supply any hot water to taps or showers.
They can serve many different purposes within heating systems, including:
This may include storing heat generated by heat sources which aren’t always available, such as solar and solid fuel burners. Once the heat has been stored, it can then be drawn off for heating purposes, on demand, throughout the day.
Some heat sources require a system to have a minimum volume at all times, to prevent cycling of the heat source in the event that some parts of the system are isolated from the rest.
A buffer vessel can be utilised to store heat from an uncontrollable heat source and then extracted on demand, to heat a cylinder which wouldn’t usually accept heat from an uncontrollable heat source (like an unvented cylinder).
Our service doesn’t include recommending the correct product designs for our customers’ jobs, so the effectiveness of their use within a system should, therefore, be determined by a competent installer.
A buffer vessel stores primary heating water and acts as a central point of heat within a system. It can store heat from sources such as heat pumps or solar, which can then be drawn off on demand throughout the day. For more detail, visit our buffer vessels product page.
A header tank sits at the highest point of a vented heating or hot water system and keeps it topped up with water via a float valve. It also absorbs the expansion of water as it heats up, preventing pressure build-up within the system.
For a full overview, see our complete guide to header tanks.
A feed and expansion tank is a small cold water tank, usually located in the loft, that feeds water into a vented heating system and accommodates the expansion of water as it heats up. It works in a similar way to a header tank, though the term is more commonly used in the context of primary heating systems rather than hot water systems.
For more detail, see our complete guide to header tanks.
A thermal store is a cylinder designed to store large quantities of heat energy until it’s needed. Unlike a standard hot water cylinder, it delivers hot water to taps and showers via a high surface area coil, meaning mains pressure water is heated on demand as it passes through. You can find out more on our thermal stores product page.
Contrary to semi-popular belief, they are not just vertical cylinders laid down. Horizontal cylinders are specially designed cylinders whose features are positioned in such a way that they can be laid down and still operate correctly.
Technically none, as a Calorifier is just a more definitive name for a hot water cylinder. However, within this industry, the term “cylinder” is often used to loosely refer to any cylindrical water storage vessel, including Thermal Stores and Buffer Vessels.
“Calorifier” is, however, usually used to describe hot water cylinders which are for marine applications and large industrial applications, while “cylinder” is used more for domestic hot water (DHW) applications.
A direct cylinder heats water using an internal heat source, such as an immersion heater, whereas an indirect cylinder is heated by an external source, such as a boiler or heat pump, via a coil inside the cylinder. For a full breakdown of the differences, see our guide to vented and unvented cylinders.
A calorifier is a type of hot water storage vessel that heats water indirectly via a heat exchanger coil, through which hot water or steam from an external source such as a boiler or engine is circulated. The term is most commonly used in marine, commercial, and industrial applications.
For a full explanation, see our marine calorifier page.
A calorifier can occasionally be misspelled as ‘clorifier. This is an easy mistake to make due to its pronunciation being ‘c-lor-uh-fyer’. The word partly comes from the Latin word for heat – calor.
A combination cylinder (often referred to by us as a “combi”) is the exact same principle as a vented cylinder, but its cold water tank is built onto the top of the hot water storage section (as opposed to being situated somewhere above, such as on a shelf or in a loft space).
They are designed as a space-saving unit, removing the need for a separate header tank.
Immersion heaters are electrical components that are inserted either from the top or side of a cylinder to efficiently heat water. This process closely resembles the way a kettle functions to heat water.
Due to their (usually) low power outputs though, it can take much longer for immersion heaters to heat a cylinder than it would if heat sources such as heat pumps or boilers were used.
“Thermal mixer” is a partial abbreviation of “Thermostatic Mixer Valve” and describes any valve whose job it is to regulate the temperature of the water that is being delivered to the property’s taps and showers.
It does this thermostatically, so as hot water enters the valve, it will detect the temperature of that water, and adjust itself to let in the amount of cold water that would be necessary to reduce that temperature to the desired level.
We supply mixer valves with all of our thermal stores, as the water tends to be relatively hot as it leaves these types of cylinders, so reducing the temperature is necessary to ensure that no one gets scalded.
A pressure relief valve is a crucial safety component in a heating system. Its primary purpose is to protect the system from overpressure conditions that could potentially lead to serious safety hazards. Suppose the pressure within the system exceeds the recommended levels. In that case, the relief valve automatically releases excess pressure, preventing damage to the components and ensuring the safety of the entire heating system.
Regular maintenance and testing of the pressure relief valve are essential to ensure its proper functioning and to uphold the safety standards of your heating setup.
Single-feed indirect cylinders, sometimes known as “Primatic” cylinders, have several limitations.
Many modern heating systems favour double-feed indirect cylinders, or unvented cylinders, due to their flexibility, compatibility with chemical inhibitors, and fewer maintenance concerns.
No, this is not possible without upgrading your entire system.
While changing your system from a vented cylinder to an unvented system could be costly, having an unvented installation has the potential to be more cost-effective in the long term.
Yes, in many cases, it is possible to retrofit a thermal store into an existing heating system. However, this process requires careful consideration of the system’s compatibility, size, and integration.
It’s recommended to consult with a heating system professional who can assess your current setup, evaluate the feasibility of retrofitting a thermal store, and provide guidance on the necessary modifications.
Retrofitting offers the advantage of enhanced energy efficiency and flexibility in managing various heat sources within your heating system.
We usually work directly with companies who have particular requirements to meet, innovative ideas to incorporate, or restrictive obstacles to overcome. But in many of these cases, we then work with those companies to standardise that bespoke design into their own exclusive range, as it makes them optimal for the majority of their installations.
Compared to designing something bespoke each time, this helps to minimise everyone’s admin costs, the savings from which can passed on, keeping everyone in the supply chain competitively priced.
Learn more about our standardise and bespoke cylinder solutions here.
Neither is universally better; it depends on your priorities. Copper has excellent heat conductivity and natural antibacterial properties, making it a trusted choice for domestic hot water systems. Stainless steel is more flexible in terms of design, highly recyclable, and generally more affordable.
For a full side-by-side comparison of both materials across key attributes, see our copper vs stainless steel guide.
As a general rule, a family of four needs a cylinder in the region of 210 litres for an unvented system, or around 140 litres for a vented indirect system. That said, the right size depends on your number of bathrooms, usage habits, and whether you’re planning for future occupancy rather than just the people living there now.
The Hot Water Association‘s hot water calculator is a reliable starting point for working out the right capacity for your specific situation.
For a 2 bedroom property with a bath or shower, a 150 litre indirect cylinder is typically recommended. For larger properties with 2 bathrooms, you’d generally be looking at 180-250 litres depending on bedroom count and usage.
For a full breakdown by property size, see our Unvented Cylinder Size Guide.
Various factors can assist you with optimising the efficiency of your heating and hot water system.
Read our article on 14 Steps to keep your heating and hot water system otpimised.
You can find instruction manuals for our Aquinox Stainless Steel Unvented Hot Water System and POWERflow Unvented Hot Water System on our Downloads page.
Also on this page, you can find product specification booklets (such as the Heat Geek Mini Store) and data sheets.
If you require help with any of our other products, please contact us.
All of our cylinders are manufactured in-house, which allows us to offer greater flexibility in designs and options for our cylinders.
While other manufacturers offer 25-year guarantees, we feel this is quite disingenuous. This is because it relies on a cylinder being serviced annually. However, with every passing year, it becomes less likely that the homeowner will remember to get the cylinder serviced, and as soon as this is missed, the guarantee becomes void anyway.
We feel that it’s much more valuable for customers to have an honest and transparent 5-year guarantee against manufacturing defects, which doesn’t have any small-print, get-out clauses. We are very upfront that our guarantee doesn’t cover corrosion, stress fatigue, or accidental damage. or any other reason for failure which is out of Newark Cylinders’ control. Besides these reasons, we will fulfil our guarantee obligations.
If you experience a manufacturing defect with any of our products within 5 years of supply, you can be confident that we will work with you vigilantly. We will inspect the product and then repair/replace, and return it with minimal fuss. Our highest priority is to always minimise the downtime for the end user. We will also provide an honest report on what caused the leak, even if it leaves us liable.
For further information, please view our Conditions of Sale.
We are not insured to work anywhere besides our own premises. Determining the correct product for your job is also not part of our service, so we rely on installers to survey your property’s requirements. They can then provide the necessary information to us. Therefore, we are unable to provide on-site assistance.
We do offer trade discounts and credit accounts, however, these are subject to approval after repeat business.
Yes, orders can be collected from our premises in Newark.
We advise discussing this with our Sales team when placing an order.
Brunel Drive
Northern Road Industrial Estate
Newark
Nottinghamshire
NG24 2EG
Find us on what3words:
///detonated.combines.galaxy
Economy 7 (or ‘ eco 7’) is an electricity tariff offering cheaper rates for off-peak hours and more expensive rates during peak hours.
The off-peak duration is for 7 hours, and according to Ofgem, your energy supplier will specify when this 7-hour period is. Although it is often between midnight and 7:00 am.
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