| Domestic Cylinders Explained
- The terminology |
| DIRECT, INDIRECT, COMBINATION, ECONOMY 7, SOLAR, CYLINDER GRADES |
|
Domestic hot water Copper Cylinders by Gledhill |
| You may find the terminology used to
describe a hot water cylinder a little confusing. 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 is heated by a source
located within the cylinder - such as an electrical immersion heater. Because
the Immersion Heater is heating the water 'directly' the cylinder is called a
'Direct Cylinder'. In a direct cylinder there are no other external heat
sources. The diagram shows a 'direct' cylinder with two side mounted immersion heaters. Please note: Variants may include:
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. |
|
|
|
|
| An INDIRECT CYLINDER | |
| Although heat is imparted to the cylinder by an
internal heat exchanger, the heat source is actually remote - such as a gas
boiler, solar panel, wood burning stove, Aga etc. etc.. It is therefore deemed
that such a cylinder is 'Indirect'. 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. |
|
|
|
|
| COMBINATION CYLINDERS | |
| A gravity-fed household copper cylinder is
supplied typically from a tank sited above the cylinder - often
located in the loft. The higher above the cylinder, the greater the 'head' of
water and hence the higher the gravity pressure. (Please refer to Section on
Grades of Cylinder to understand more) 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. |
|
|
|
|
| SOLAR CYLINDERS | |
| This is a cylinder that has been configured
to accept solar energy. Cylinders we provide can often have an additional
'solar coil' fitted in order to add solar energy to the cylinder when
available. 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:
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. |
|
|
|
|
| ECONOMY 7 Cylinders | |
| An Economy 7 cylinder is designed to
exploit 'off-peak' electricity. Because you are heating your cylinder
overnight it is important to not to loose the stored heat. Economy 7 cylinders
are therefore fitted with an extra thick jacket of insulation - typically 60mm
thick, as opposed to the 30mm jacket on a standard cylinder. Economy 7 cylinders are available as direct and indirect models.
Configuring or Specifying a Cylinder to your own design To fully configure a cylinder to your requirement also see information about heat exchangers - 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.
|
|
|
|
|
| Grades of cylinder | |
| Domestic Cylinders are available in three
grades. The grades refer to the pressure of water they can withstand from the
header tank (the pressure created by the height of the header tank above the
cylinder). 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 |
|
| Grade 2 - Can withstand a 15 metre head of water | |
| Grade 3 - Can withstand a 10 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) |
|
