Central heating pipe installation

As the heated water from the boiler is fed along the pipe, natural convection hot water rises causes the heated water to rise into the radiator displacing cooler water back into the pipe. A major disadvantage of this arrangement is that the first radiator gets hotter than the second one etc. In principal the number of radiators which can be fitted to a single pipe loop is unlimited, but the more radiators fitted, the greater the cooling between the first and last radiators.

These systems are often used in industrial buildings where the loop pipe may be extremely large, the systems can still be found in older domestic premises but they are generally old installation and are not considered efficient. This system is more efficient than the single pipe loop. The heated water from the boiler is fed to one side of every radiator the feed pipe while the other end of each radiator is connected to a separate common return pipe.

This means that the temperature of the water entering each radiator is more or less the same so each radiator should heat the local environment by the same amount. A pressure relief valve or automatic by-pass valve is connected between the feed and return pipes, this allows the pump to circulated the water from the boiler if all the radiators should be shut off.

Because of the restriction of flow imposed by the radiators, the number of radiators is limited basically by the size of circulating pump. A standard pump for domestic use will probably be able to supply up to 12 radiators.

Another limitation is caused by the size of the pipework - normally the main pipes to and from the boiler are large at least 22mm and smaller pipework 15mm is branched off to feed a number of radiators. The number of radiators which can be fed through these 15mm pipes will depend upon the length of the 15mm pipe runs - the longer the run, the fewer radiators. The illustration above shows two branches each feeding two radiators. The micro bore system uses normal pipework for the feed from the boiler to manifolds and from manifolds back to the boiler on the return side.

From each manifold, small pipework normally 8mm is connected to a number of radiators. The radiators give off the heat from the water to warm the room, and the cooler water then passes back to the boiler for reheating. This sort of central heating system is by far the most common type in use. The most usual form is the twopipe system. Boiler: Can be gas, oil, or solid fuel. May be freestanding or fitted into a fireplace as part of a room heater. Flue: The easiest solution to the problem of flues is to fit a balanced flue boiler.

This is a cheap method of getting a flue and is easy to install. You must be able to mount the boiler on a suitable outside wall — see the drawing. You cannot get balanced flue solid fuel boilers. The alternative is to use a conventional flue boiler, which needs a proper chimney. An existing chimney can be used, but unless this was built after about , it will almost certainly need lining.

Lining is easy for a gas boiler — a lightweight flexible stainless steel liner can be used. More complicated linings are needed for other boilers. Pump: Forces water around the system, and means that you can use small diameter pipes.

Get one with valve fittings on either end, not plain unions: it makes it easier to remove the pump for repair or replacement. Flow pipe: Takes the water from the boiler to the radiators. Return pipe: This takes the water back to the boiler, and is connected in branch runs identical to the flow pipes. Radiator: The usual form of radiator in the UK is the panel radiator: a large panel of steel with channels in it through which the water flows. The basic version is the single panel; other types are the single panel convector or high output radiator, which has extra fins welded on to it; the double panel radiator; and the double panel convector radiator.

These variations give increasingly more heat output for a given surface area — or to put it another way, occupy less wall space for a given heat output. Convector: An alternative to a radiator. The heating element is enclosed in a box and heating is purely by convection.

These are very compact. Most have an electric fan to increase the output — but fans can be noisy. Skirting heating: A type of convector heater, which gives a very good heat distribution, but long lengths are needed.

Valves for turning radiators on and off, and for balancing the flow of water to each heater so that it will heat the room correctly. Feed and expansion cistern: UK systems are normally open to the atmosphere: if there is a fault and the water boils then it can easily expand or boil away without causing an explosion.

The cistern receives its water from a ball valve connected to the rising main. To provide an easy passage for any steam to escape, the system also has a vent pipe connected to the boiler. Domestic hot water dhw : The boiler usually also heats the hot water using an indirect copper hot water cylinder. This works in much the same way as a radiator — inside the cylinder is a coil of pipe, connected to the boiler by feed and return pipes called primary pipes.

The hot water from the boiler flows through the coil, heating the water in the cylinder; this is drawn off at the top through secondary pipes to the hot taps. The cylinder is refilled through a feed or makeup pipe from the cold water cistern, and as with the boiler, there is a vent pipe for safety. Usually, the dhw primary circuit is operated by natural gravity flow — the water circulates without the need for a pump. This is simple, but requires large diameter pipes and a careful layout — with the cylinder more or less directly above the boiler.

It is neater, and means you will be able to re heat the water quickly. Microbore: Most systems use smallbore tubing — rigid pipes down to 15mm diameter. For some of the piping to the radiators, you could use instead microbore tubing. This is smaller in diameter 10mm, 8mm and 6mm so looks less obtrusive if you fix it to wall surfaces; it uses clips like those for electric cables, too, which are simpler to fit than normal pipe clips. It is also flexible to some extent, so you may find it easier to thread under floorboards and through walls.

You can use it for the final branch run to each radiator unless the radiator is very large in much the same layout as an ordinary system, but main runs will still need to be the larger smallbore pipes. Alternatively, you can use a different sort of layout, in which radiator branch pipes all run to a single central point, rather than joining up along the way.

At this point, the microbore pipes all join up in a single fitting called a manifold which is connected to the boiler. Control system: All boilers have a boiler thermostat to prevent overheating. But you need other controls if you want to keep fuel bills as low as possible. Control systems to provide economical running can become very complex — and the danger might be that you spend much more on the controls than you would save in lower fuel bills. Most people, however, would appreciate a timer — sometimes called a programmer — which will switch on the boiler or the pump depending on the design only when you want heating.

Besides controlling time, you also need some way of controlling temperatures. The usual way is by a central room thermostat —this is sited usually either in the hall or living room and can be preset to a particular temperature; when the room reaches this temperature, the heating in the whole of the house goes off.

Much more flexible, but more costly, is to fit each radiator with a thermostatic radiator valve to control the temperature in each room individually.

The simplest control for hot water is a thermostatic valve that fits in the primary pipe work and cuts off the flow whether pumped or gravity whenever the temperature of the water in the cylinder rises above a preset limit.

With gravity flow systems, this is the only control usually fitted — water is otherwise heated whenever the boiler is not switched off. If you want independent control of the hot water timing, you will have to fit motorized valves in the primary pipework, and check that the timer you use is capable of controlling all the components independently.

As long as the outside of a house or even an adjacent room is colder than the room you are considering, then heat will flow out of it — and to stop the room growing cold you have to supply heat to it at the same rate. The rate of heat loss varies, partly depending on how cold it is outside, and how warm you want it to be inside.

So the first step in the heat loss calculation is to decide inside and outside design temperatures. If you want a costeffective heating system, it is important to pick both temperatures carefully. If you choose too high an outside temperature, then your heating system will not be able to warm rooms properly in the coldest weather, and you will have to top up.

Design temperatures depend on nominal outside temperature and personal preference for inside temperatures for each room You cannot normally fit hot water controls of any type to a solidfuel fired system. If you do want to do this, you will need to fit a special, and rather complicated system. If you use a designandsupply firm, they may be able to arrange for the work to be done. An oil boiler needs a large oil tank and fuel delivery line. Ask your local authority about the regulations governing the position of an oil tank and the fire safety regulations involved.

For a solid fuel boiler, you will have to provide a bunker. Proper design is not a haphazard process but involves careful and systematic calculation taking account both of your needs and the limitations of any system. This is normally divided into four stages. If you want a cost effective heating system, it is important to pick both temperatures carefully.

If you choose too high an outside temperature, then your heating system will not be able to warm rooms properly in the coldest weather, and you will have to top up with some other, perhaps more expensive, form of heating.

If ydu choose too low a temperature then the system will be bigger than it needs to be. With excess heating capacity for most of the year and it will be more expensive to run. Many of the same considerations apply to inside temperatures — if they are too low, you will feel cold: if they are too high then your system is bigger than it needs to be.

Inside design temperatures are largely a matter of personal preference. Many designers use these temperatures:. The calculations will also take into account the materials from which the house is built —some are better at retaining heat than others. And insulation will affect this, too — see The benefits of insulating. As a general rule, the best positions for radiators is on external walls, preferably underneath windows — this gives the best heat distribution in the room, especially around the window area.

However, there may not be enough room under the window for a normal radiator of sufficient heat output. In this case, the designer will normally opt for one of the higher output types. Where there definitely is not space under the window for any type of radiator, another position on an outside wall can be tried — perhaps alongside the window: or the radiator could be split into two, one half on each side of the window.

Only if all these approaches fail should radiators be placed on inside walls. In a large room, or a long one such as a through lounge, you should use two or more radiators to give a good heat distribution.

The best pipe runs are as short as possible —taking into account the construction of the house. Where possible, pipes underneath floors should run along the joists rather than across them. Doors, and to a lesser extent, walls and fitted furniture may mean the pipes have to make detours, and branch runs may have to be connected rather differently from the layout that appears to make most sense.

Having sorted out what appears to be a sound and realistic pipe layout. It is then necessary to calculate the sizes of pipes needed. Choose too small a pipe, and it will not be able to carry enough heat to the radiators to provide the required design heating load — no matter how carefully the radiators are sized, the room could be too cold.

Too large a pipe would be wasteful of materials, and is more difficult to install. In most cases, sizing small bore piping is not too difficult: 15mm pipe is usually big enough for all but the largest main runs nearest the boiler. For these runs, and for pipes leading to the hot water cylinder, 22mm or 28mm pipe is used. Sizing a microbore layout can be more difficult, partly because there are more main pipe sizes to choose from. The pump has to be capable of pushing water quickly enough round the circuit to supply the heat required, and powerful enough to overcome the resistance of the pipes themselves.

Pumps are usually variable head: they can be set to provide a number of different flow rates. If you use a design consultant, they will come round and take full details of your house and.

Your requirements. But if you take the cheaper option of using a mailorder firm, and you want them to do a good job of designing your central heating system, you must give them all the help and information you can. You need to draw up a plan of the various floors in your house, together with details of its construction, level of insulation and so on, decide what sort of a system you want, and tell the firm of any particular requirements you have.

The firm should supply you with squared paper to draw out your plans, and a questionnaire to fill in, but to make sure you tell them everything they need to know, follow this checklist:. This means the cleaning agent travels through each radiator pipe and gets rid of excess in the power flushing machine, such as sludge. There is not a fixed time for the cleaning agent: it's done after most of the sludge has been removed, ensuring good flow. Not Helpful 4 Helpful 6.

Is it OK to install the pipes from the boiler to the radiators at ceiling height in a bungalow? Pipes that go from the boiler to the radiators are best if they travel beneath the floor boards to ensure that there is no danger of a gas leak or coming into contact with the pipes while they are hot. However, tubing carrying heated waters from the boiler to radiators can be above the floor if preferred. In this case, place all delivery pipes above in the ceiling cavity and then have 'droppers'' going to each individual radiator.

All returns are in or under the floor. Try to stay away from pumps and make full systems to thermosyphon. Not Helpful 21 Helpful 6. Should there be a bleed valve in the loft to de-air the central heating system? Fred Daggs Missus. Systems need an expansion pipe, leading from the highest point in the delivery side of the system.

The end of that expansion tubing should return the radiator waters back into the header tank. That way, the pH of the waters can continue to be ok after being treated with a rust inhibitor not automobile anti freeze Any air bubbles in the system hopefully should reach the highest point in the system and then travel up and out into the ceiling cavity.

Any dripping waters will return into the system which in turn, keeps the rad's system full. The heater tank size should be reasonably generous and have its own fresh water supply, which is operated by a ball cock valve. Not Helpful 0 Helpful 0. Include your email address to get a message when this question is answered.

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