Domestic hot water Copper Cylinders by Gledhill

Direct....  Indirect.... Combination..... Solar....  What does this mean? Click on your question below -

....It all depends where the cylinder gets it's heat from.

Please note: Information contained on this page is intended to assist with your understanding of cylinders and terminology. It does not represent a definitive description of each and every product available. If in any doubt, please call for assistance - we will be pleased to help.

A DIRECT CYLINDER

The diagram shows a 'direct' cylinder with two side mounted immersion heaters.

Please note: Variants may include:

• a side mounted single immersion heater boss
• a top mounted single immersion heater boss
• one side mounted and one top mounted heater boss
• two side mounted heater bosses
• more than two heater bosses

You should specify the number of heater bosses you require and their desired position. The diagram is only intended for the purpose of explanation. Immersion heater elements are not normally fitted or included in the price of a cylinder and should be specified if required.

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Indirect cylinders may be fitted with immersion heaters as a supplementary heat source, but they are still known as 'Indirect'.

An Immersion heater boss may be fitted through the top of the cylinder. You should specify your requirement. Immersion heater elements are not normally fitted or included in the price of a cylinder and should be specified if required.

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Where the property is unable to accommodate a header tank (for example in an apartment or flat) the header can be accommodated literally on top of the cylinder and is built into the unit. The cylinder therefore combines the 'header' and the 'storage' elements and becomes a COMBINATION cylinder.

Note: The output water pressure from a combination cylinder is often poor due to the small distance (head) between the header, the cylinder and the outlet (i.e. A tap).

Combination Cylinders may be Direct, Indirect or Economy 7. They simply combine the header function.

Immersion heater elements are not normally fitted or included in the price of a cylinder and should be specified if required.

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The 'solar coil' is a particularly high efficiency heat exchanger designed to add as much of the relatively low solar gain.

Solar coils may be added to standard cylinders to supplement energy input.

Also see:

• TORRENT RE Solar mains pressure hot water cylinder
• SUNSPEED Solar gravity fed hot water cylinder

Renewable energy systems (such as solar, heat pumps, geothermal etc) are becoming popular. However, it continues to be relatively expensive to install - albeit you recover the cost over the long term.

Many discerning householders are now fitting cylinders that are 'solar ready' in order that future addition of a solar (or any other renewable energy) system will present minimal disruption and eliminate the need to change major hardware - enabling an easily expandable system.

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Economy 7 cylinders are available as direct and indirect models.

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Configuring or Specifying a Cylinder to your own design

To fully configure a cylinder to your requirement also see information about heat exchangers -

• British Standard
• Condencyl
• Designing a cylinder to meet your specific needs

Gledhill cylinders are fitted with a 30mm jacket of rockwool insulation (with the exception of the Economy 7 models that have a 60mm jacket).  At your request it is possible to have a 60mm thick jacket fitted to any cylinder - greatly enhancing the performance of the insulation and improving economy.

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In simple terms, this translates to the gauge (thickness) of copper used in construction. Do not confuse a gravity cylinder with mains pressure or unvented cylinders.

Connection of mains pressure water to any cylinder designed for a gravity feed can be extremely dangerous.

Grade 1 - Can withstand a 25 metre head of water

It is possible to supply a gravity cylinder that will withstand a 31 metre head. This is achieved by doming the bottom of the cylinder. These cylinders sit in a ring mount. Please specify the working head of the system into which the cylinder will be installed.

A normal domestic cylinder  is usually a Grade 3. (All prices quoted on this website refer to Grade 3 cylinders unless otherwise stated)

INSULATION

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Insulation is absolutely essential on a 'hot water' cylinder. It is ridiculous to consider heating a large volume of water only to let it go cold again. Many older properties will indeed have an un-lagged cylinder, but their owners are simply burning money each and every day as they warm the water then allow the heat to escape. It is almost a blessing when an old cylinder fails, as the replacement will invariably arrive lagged and go on to demonstrate the difference in efficiency over the following years.

But the term 'insulation' can be a little misleading. Many manufacturers try to utilise the spray-on properties of a polyurethane foam as a quick (if not entirely clean or green) and cheap method of apply an insulating layer to the body of a cylinder. Indeed, there are so many about these days that one could be excused in thinking this is a best or only way the job might be done. But no, it is simply the cheapest, easiest, quickest way. But chemical foam insulation is not all it's cracked up to be.

Studies have revealed that chemical foam insulation can lose up to 40% of its efficiency in a relatively short period of time as it oxidises through repetitive cycles of warming and cooling. So the advantages of using such a material (namely cost and convenience for the manufacturer) result in eventual waste to the end user. But of course, you are now the owner of said object and unlikely to have the means to check efficiency, so as the problem goes unnoticed up go your running costs.

The foam utilised to insulate cylinders is similar in composition to the foam that used to be used in furniture, yes the stuff that gives off noxious and lethal fumes in the unfortunate event of a fire, so the potential repercussions are worthy of serious consideration.

All Gledhill cylinders are fully insulated to British Standard using a premium insulation based on the mineral rockwool.

When you chose to change your cylinder opt for the natural premium choice - Flexilag.

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