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Central Heating Pipes

If you are planning to install a central heating system, or you are replacing large parts of an existing system, the benefits you can expect are more efficient heating and lower heating bills.

An efficient boiler and new radiators will be more cost-effective, but the pipe work should not be neglected; it can have a dramatic effect on the overall efficiency of the system.

It pays to give consideration to the pipe work within the central heating system.

The correct pipe work can have a dramatic effect on the overall efficiency of the system.

If you are using a professional to complete the installation, you should already be in discussion with them about the type of radiators you want, the size of boiler needed for your property, and your family’s hot water requirements.

All of these things will help them determine how much heat output will be demanded from the boiler, and should also be a pointer to the size of pipe required.

There a three common methods for laying central heating pipes in the UK, find out which method your installer plans to use and consider the benefits. Will it suit your property and allow your system to run at full efficiency?


Single pipe loop

As the name implies, this is a single loop of pipe, which runs from the boiler, through each radiator, and back to the boiler.

As the hot water is circulated through the system natural convection occurs and the hot water rises into the radiators and pushes the cold water back into the circuit to be reheated.

A notable drawback of the single loop system is that the first radiator tends to be the hottest, with each radiator down the line becoming progressively cooler.

These types of systems have often been used in large commercial buildings where much larger pipe sizes can be used for the central heating circuit.

They may be adequate for smaller properties with few radiators, but are unlikely to be the most efficient choice for a large property with several radiators.


Feed and return pipes

Feed and return pipes are a pair of pipes that run together to the radiators. The feed pipe carries the hot water from the boiler, and the inlet on each radiator is connected to this circuit. The return carries the cold water from the radiator outlets back to the boiler.

The key advantage to this system is that each radiator will be supplied with water at the same temperature and should be able to heat equally. The system becomes more efficient and the house becomes more comfortable, with a more even temperature throughout.

The radiators will restrict the flow of water through the system when feed and return pipes are used, and the number of radiators, which can be supplied, is directly related to the size of the pump fitted with the system.

An average domestic house should be comfortably served by a single network of pipes, but if your property has more than twelve radiators you should consult your installer to ensure the system they are fitting can adequately cope with the demand.

The systems are commonly installed with 22mm pipe serving the boiler with 15mm pipe branching off that to supply the radiators. The 15mm pipe can cause extra resistance in the circuit, particularly if there are several bends or long pipe runs.

This may need to be taken into account when sizing the boiler and deciding how many radiators to connect to each branch of the system.


Microbore central heating

Microbore central heating systems use small diameter pipe, typically 8mm or 10mm. Standard pipe work is used for the supply and return from the boiler to manifolds, and microbore piping runs from the manifolds to each radiator in the system.

The systems tend to be highly efficient as the smaller pipe contains less water and less heat loss is suffered. It is also much easier to install as the plastic piping can be bent to suit without the need for as many elbows and joints as a conventional system.

The most obvious disadvantage to a microbore system is that the smaller pipe work is more prone to becoming blocked by sludge, debris and limescale. As soon as the circulation in a heating system becomes restricted, the boiler and pump will waste unnecessary energy to supply heat to the radiators.

It may be necessary to develop a regular maintenance plan to keep the system at its most efficient, it is also possible to buy water treatment kits to soften hard water before it enters the system.

Your installer will advise you on the most appropriate layout for your home.

Consult with your installer to achieve the most efficent pipe layout for your home



Installing the pipe work

How the pipe work is installed with your central heating system will be governed largely by the property. In new builds the pipe work is usually laid beneath the floor, rising through holes in the floorboards to supply the radiators.

This is the most common method of laying pipe, but will not be practical in certain situations, such as houses with concrete floors.

An alternative way of arranging the pipe work is to fit it in the joists of the ceiling, and drop pipes down the wall to each radiator.

Although not aesthetically pleasing, another way to fit the central heating pipes is to run them high on the wall at ceiling level, again with drop pipes to the radiators.

Your property will lend itself to the most appropriate pipe work arrangement, and your installer should know exactly what is required to fit the system into your home.


It is easy to focus on the larger components of a central heating system, such as the boiler and the radiators, to make sure you are getting the most efficient products for your budget.

It also pays to give a little consideration to the pipe work within the system, and how it will affect the optimum running of the heating.

When planning the heating system, your installer should make calculations regarding the heat loss in the system, the resistance through radiators and pipe work, the demand for hot water, and various other factors to determine how the heating will work in practice.

The more you can help them with this information, the easier it will be to select boiler, radiators and pipe work.

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