General Plumbing

Hot Water Cylinder Installation

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When replacing an old hot water cylinder, it should be possible to obtain a good match of cylinder connection positions so that pipework modifications are minimal, but in some cases it will be worth labelling the pipes so that you know how to reconnect them. Take care when changing the cylinder to ensure that the walls of the new unit are not damaged when attaching the pipes — they are very thin and are easily damaged.

When removing the old cylinder, turn off the electricity supply before disconnecting the immersion heater (if fitted). Then turn off the water supply and dram the cylinder, using the drain valve at its base, not forgetting the heating circuit from the boiler with an indirect system. The latter will have a drain valve near the boiler. If the cylinder has no drain valve, the only solution is to siphon out the water, using a length of hose inserted through the boss in the top. Once the cylinder is empty, the pipes can be disconnected and it can be removed.

If the cylinder is fitted with an immersion heater, remove this and transfer it to the new cylinder. Being made of copper, the old cylinder will have some scrap value, so it will pay you to look for a scrap dealer who will take it off your hands.

Hot Water Cylinder Installation

1:- A cylinder full of water will weigh a considerable amount, so i must be supported by a firm base. If you are installing a cylinder in a completely new location, stout battens spanning the joist run will help spread the load and also allow air to circulate around the bottom of the cylinder. If you are replacing an existing cylinder, make sure that its support is strong enough to take the weight of the new cylinder.

2:- Fit a compression connector to the top of the cylinder for the feed and expansion pipe, wrapping its threads with two or three layers of PTFE tape to ensure a watertight seal. Tighten the connector in its boss with an adjustable spanner. It may be necessary to turn the cylinder to align the connector and pipe, but this may make other connections difficult, so be prepared to make changes to pipe runs.

3:- With the position of the feed and expansion pipe adjusted as necessary, connect the pipe to the connector in the top of the cylinder. Slip the capnut and olive of the connector onto the end of the pipe and tighten the capnut onto the fitting with an adjustable spanner. Don’t over-tighten the nut, as this may cause a leak to develop. Take care not to dislodge the cylinder, either, as this may strain the connection.

4:- The cold water supply enters the hot water cylinder at the bottom. Identify the boss in the side of the cylinder, then wrap the thread of the connector for the supply pipe with PTFE tape. Again, two or three layers should suffice. Screw the connector into the boss by hand. Then, finally tighten it with an adjustable spanner. If necessary, extend the supply pipe to the boss position.

5:- Rather than attaching the supply pipe directly to the cold feed connector, fit a drain valve to it, aligning the spout so that you can easily push a hose onto its end. This will allow you to drain the cylinder if the need should arise some time in the future. Then connect the supply pipe, making sure the compression connector is tight. Also ensure that there is a servicing valve on the supply pipe so that the system can be isolated easily

6:- With an indirect system, check the connectors for the boiler flow and return pipes, making sure that they are tight in their bosses. Then run in the pipes. If the cylinder has a boss for an immersion heater, fit the heater, adjust the thermostat, and reconnect the wiring. When all the connections have been made, refill the system by restoring the water supply and inspect the connections for signs of leakage.

Instantaneous Water Heaters

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Most modem hot water systems rely on a boiler to supply both hot water and central heating, but there are still many properties where hot water is supplied instantaneously through a multipoint gas or electric heater, or a single-point unit such as the familiar Ascot.

Instantaneous Water Heaters

In fact, the modem combination boiler is essentially a multipoint unit with the addition of a central heating function. Hot water is supplied on demand, often temporarily cutting off the heat to the central heating in the process. However, there are many instances where the use of a water heating unit, separate from a central heating system, will provide an economical and practical solution to a hot water need. This is particularly the case where the ‘point-of-use’ is remote from the rest of the hot water system. The most common point-of-use electrical unit is, in fact, the instantaneous electric shower , and exactly the same installation criteria apply to

the over- or under-sink water heater as to the electric shower. The only difference with the under-sink unit is the need for special taps and valves to deal with the expansion of water. In the over-sink water heater, expansion takes place through the spout, which must always remain open, the water flow being controlled on the inlet side. In the case of under-sink heaters, control is provided by the tap on the outlet, which prevents expansion in that direction.

There are gas instantaneous water heaters available, but since any work on gas appliances may only be carried out by a competent CORGI-registered installer, they are outside the scope of this book.

Sink-based, point-of-use electric water heaters are designed for hand washing and similar activities, and units range in power from about 3kW to over 7kw, the latter being a typical power rating for an electric shower. The electrical installation also follows the rules that apply to electric showers.

Hot Water Supplies

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In most cases, domestic hot water is supplied from a storage cylinder, the water being heated by a boiler or electric heating elements in the cylinder itself. Over a period of time, the cylinder may no longer meet your needs for a variety of reasons: it may have become corroded and begun to leak; it may have insufficient capacity for a growing family’s needs; you may prefer to fit a modern, properly insulated version in place of an unlagged type; or you may be changing the hot water system from direct to indirect, or vice versa.

Whatever the reason for installing a new cylinder, it may be a useful exercise at this time to assess if the hot water system performs as well as you require. If it does not, you can take the opportunity of installing a cylinder system of improved performance (mains pressure, for example), and remove the cold water cistern from the loft.

Hot Water Supplies

The Surrey flange

A device designed to draw off hot water from a relatively air-free position, just below the top of the hot water cylinder, is known as the Surrey flange. Hot water supply to the shower, or for any other critical use, comes via a centrally-mounted draw-off tube, which is offset to one side of the main outlet from the cylinder. The flange allows trapped air and water vapour to vent from the cylinder through the expansion pipe, and not to be dragged into the shower supply, where it could disrupt thermostatic control, etc.

Another advantage is that the position of the inlet helps to maintain flow, and hence shower water temperature when other hot outlets are also being used.

The flange simply fits into the top outlet of the hot water cylinder. With the water drained to below the cylinder head, all that is necessary is to remove the top connection, insert the flange, and reconnect the pipe. No special tools are required other than the correct spanners.

Immersion heaters

Immersion heaters perform two roles in the supply of hot water. They can either be used as a supplementary source of cylinder water heating when the main boiler is not required, or they can be the only form of storage water

heating, taking advantage of reduced electricity tariffs. In the supplementary role, normally only one immersion heater (either single- or dual-element) is fitted to the cylinder. When used as the primary source of heat, however, two or more horizontal immersion heaters are installed. The lower element is normally wired up to operate during off-peak tariff times, while the upper heater is wired for peak-rate top-up duties during the day.

Long, single or dual elements may be mounted to the top of the cylinder, while short, single elements are likely to be mounted horizontally near the base. Since only the water above the lowest point of the element will be heated, it is important that any heater projecting down from the top is of the correct length to heat the whole cylinder. Also, it must not foul either the heating coil or any corrosion-inhibiting anode fitted within the cylinder.

Dual elements may also be wired for off-peak heating, the long element for off-peak tariffs, and the shorter element for peak daytime use. Separate wires from the control switches should be used for each heater.

Each immersion heater must be fitted with a thermostat, which should be set at 60°C. This temperature provides water that is hot enough for domestic use without the danger of excessive scale formation in hard water areas.

Installing a Stop valve

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When extending an existing plumbing system, or installing a completely new system, it makes sense to fit valves of one form or another to the various pipe circuits so that they can be isolated for maintenance and repair work. These can be installed at the same time as the new pipework. However, many old plumbing systems may not have valves to control the various pipe circuits, which means that the entire system must be out of action while any work is carried out. This is far from satisfactory, so at the first opportunity you should remedy the situation.

In some cases, even the rising main may not have a stopvalve to shut off the water supply inside the house, which is something that should be attended to as a matter of urgency. Faced with a major leak, on a cold, wet night, the last thing you will want to do is scrabble about in the dark, looking for the cover of an underground valve that may be under water itself.

The step-by-step illustrations show the installation of a stopvalve and associated drain valve to an existing rising main, but the techniques can be used for installing any type of valve with compression joints. The job is quite straightforward, but it relies on the slight flexibility of the pipework to allow the valve assembly to be sprung into place between the cut ends. To make this as easy as possible, the pipe should be released from any clips in the immediate vicinity. Alternatively, a short length of pipe can be fitted to the valve, with a straight solder fitting slid over the end. This assembly should be fitted in the gap in the pipework, and the solder fitting slid over the joint between the two pipes and soldered in place.

Installing a Stop valve

1:- If the stopvalve is to control the rising main, the water supply should be turned off at the water authority’s stoptap on the supply pipe to the property. Then you can assemble the stopvalve and a drain valve on a short length of pipe. The drain valve should be just above the stopvalve when installed, so that the system above can be easily and completely drained whenever necessary.

2:- It is essential to fit a stopvalve the right way round, otherwise it will not be able to do its job properly. An arrow will be cast into the body of the valve to indicate the direction of the water flow through the valve. Another clue can be gained from the shape of the valve body below the handle: it tapers away in the direction of flow. A gate valve can be fitted either way round; it will accept flow in either direction.

3:- Make sure that the short pipe between the stopvalve and drain valve is inserted fully into each fitting and that the capnuts are tight. Then decide where on the rising main you want to fit the assembly and hold it alongside. Use a pencil to mark the amount of pipe that must be removed from the rising main. A shoulder formed on the body of each valve will give an indication of the cutting point.

4:- Make sure that your pencil marks are accurate. Then carefully cut through the rising main pipe at the points marked. You can use a junior hacksaw, as shown, a small pipe cutter or a ratcheting pipe cutter if you have one. With the last two, you are guaranteed a square end to the pipe, whereas if you use a saw, you must take extra care to cut it squarely. A piece of tape wrapped around the pipe will help.

5:- The most difficult part of the job is springing the stopvalve/drain valve assembly into the gap between the cut ends of the pipe. First slide the olives and capnuts of the fittings onto the ends of the pipe; you can tape them out of the way. Then slacken the capnuts holding the fittings to the short piece of pipe. With everything loose, and a bit of effort, you should be able to spring the valves into place.

6:- Tighten each capnut in turn, setting the positions of the valves as required; the stopvalve handle should face away from the wall so that you can turn it off easily without skinning your knuckles on the wall. With everything tight, and both valves closed, restore the water supply and check the joints for leaks. If all is well, open up the stopvalve to supply water to the rest of the system.

Types of Valve

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There are several types of valve other than taps:

• The stopvalve (or stopcock) is fitted on the rising main, and may incorporate an integral drain valve. The internal pattern of this valve is similar to a tap, with a spindle, jumper and washer. Unlike a tap, it usually has compression fittings at each end, and is marked with arrows to indicate the direction the flow of water must take through the fitting.

• A gate valve contains a ‘gate’, or paddle, which is raised or lowered by a spindle to control the flow, Usually by turning a wheel handle. It should be kept in the fully open position (or just slightly closed to prevent jamming), and may be fitted either way round. Again, compression fittings are standard.

• A ball valve has a ball with a hole in it to control water flow. It needs only a quarter turn from fully open to fully closed, and is usually fitted with a lever handle that clearly shows whether the valve is open or shut. In the fully open position, this valve provides a full bore opening, which offers less resistance to flow than other types of valve.

• A servicing valve is a form of ball valve, but is usually turned on and off with a screwdriver in a slot, or a knob or short lever, such as is common on washing machine valves. Servicing valves should be fitted before all taps to allow easy maintenance, and to allow easy system balancing, which is important on mains-pressure and unvented systems.

All of these types of valve rarely give problems. Gland

packing can fail in time, and can be replaced in the same

manner as that of ordinary taps. Washers rarely fail.

With the exception of ball valves, all are prone to sticking in the open position, simply because they are not moved often enough. Stopvalves and gate valves should be turned off and on regularly, if only a few turns, to make sure they do not seize up. They should be left a quarter-turn closed after being opened fully. This won’t affect flow, but should prevent sticking in the future.

If a valve does jam, a little penetrating oil or spray should be applied, repeatedly if necessary, until the valve is free. Undue force should not be used; it may damage the valve, or even the pipe.

Types of Valve

Above right Quarter-turn ceramic disc mixer with pull-out spray.

Centre right The Speedfit tap connector allows for simple hand

tightening to provide a leak-proof seal.

Right A ‘%in stopvalve showing typical signs of leakage from the gland around the shaft, together with a chrome-plated 15mm stopvalve for exposed positions.

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Fitting and Replacing Taps

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Taps are fastened to sinks, baths, basins, etc, with washers and nuts. In the bathroom, they may have mastic between the body of the tap and the fitting instead of a washer or gasket, with a plastic or rubber washer underneath. Sink pillar taps are usually fitted with a plastic or rubber washer/gasket above and a ‘top hat’ washer underneath.

In either case, the nut must be tightened with a special basin spanner, designed to reach up behind the sink, basin or bath. This spanner is also used to turn the nut on the tap connector fitting. Alternatively, proprietary fittings, such as the Speedfit tap connector, may be used. These need only be tightened by hand.

With sink, bidet and basin mixer taps, the tap tails are often plain pipe. These allow push-fit fittings to be used as an alternative to the conventional compression or soldered fittings.

Fitting and Replacing Taps

For ease of fitting, flexible connectors can be used, or lengths of plastic pipe. Alternatively, flexible corrugated copper tube connectors can be used, but these must be handled with care. Do not flex or bend them more than once, otherwise they may crack and leak.

To replace or fit new taps, the water supply to both t~ps must be turned off and the pipes drained. The old taps should be disconnected from the supply pipes (use an old towel to mop up the water that may spill from the broken joints). After removing the old taps, clean away any old mastic from around the tap holes, taking care not to damage the surface. Then fit the new taps, with their washers in the correct positions. Reconnect the pipes to the taps (adjusting the length if necessary), and restore the water supplies.

Above left Two-hole bath/shower mixer.

Left High-neck kitchen pillar taps.

Improving Taps Appearance

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An inexpensive way of improving the appearance of old taps is to use a conversion kit to replace the cross-head and easy-clean cover with a shroud head, which simply fits on to the top of the spindle. Sanitaryware manufacturers produce ceramic tap heads, colour matched to their suites, but these may only fit their own ranges of taps, so check before buying.

Improving Taps Appearance

General Plumbing

Hot Water Cylinder Installation

Instantaneous Water Heaters

Hot Water Supplies

Installing a Stop valve

Types of Valve

Fitting and Replacing Taps

Improving Taps Appearance

Catagories