Central Heating Parts


The pump, or circulator, should be fitted with isolating valves on each side. These can then be simply shut down to isolate the water and allow the pump to be removed without having to drain off circuit water.

It does not greatly matter if the pump is installed in the flow or in the return line of the circuit. A pump mounted upstairs, in a conventional system with a feed-and-expansion cistern, might, in some cases, when first started, surge water into the storage or make-up cistern.

This will not happen if it is fitted in the return pipe.

Do not install the pump in the lowest part of the circuit as this can encourage the formation of sediment. To avoid a situation where the pump again may discharge water via the safety pipe into a cistern, the cold-feed connection and safety pipe should both be on the same side of the pump.

Sometimes, and usually initially when live air is still present in the water, there can be considerable noise from the pump. Most pumps have a vent button, which, when operated, should reduce or cure this.

Expansion cisterns

Expansion cisterns should be located about lm higher than the main cold-feed cistern and should be connected either close to the boiler heating return connection or into the primary return pipe of the gravity system. Expansion, or safety pipes should be in 22mm-bore pipe and taken over the cistern in a gentle curve-but clear of the water.

Hot cylinders

Provided the water content of a thermostatically controlled small-bore system does not exceed about 136 litres, a self-priming hot-water cylinder can be used. However, these must not be used on solid- fuel systems without thermostatic control, either on the cylinder or on the boiler, since if the water boils, the two waters will mix. The system operates on the principle of an air bubble which separates the primary (heating) and secondary (draw-off) waters. If used on a pumped-primary circuit, the separating air bubble would be pumped out. A special high-recovery cylinder or one accepting a microbore element (direct cylinder) should be used in the latter case.


A lockshield and a handwheel valve are usually fitted at either end of a radiator. Aesthetically, these look best at the bottom, but if it is physically easier to fit them to the inlets at the top of the radiator, such as on a drop-pipe system, you can do so.

Some types of radiators have the valves built in. Valves may not be necessary at every point on skirting convectors, beyond a balancing valve for the circuit, where a single-pipe series-loop arrangement is used.

A radiator can be easily removed, simply by shutting down both the valves and uncoupling the lock nuts. With care, the water displaced can be collected in a strategically placed bucket.


The tops of radiators (or the bottoms in the case of top-entry pipework) are blanked off. An air-release valve is usually fitted at one end of the radiator, though in the case of top-entry connections, the air release valve may be found in pipework in the loft.

Blanking fittings and air-release valves are threaded. These are wrapped with PTFE tape and screwed in with a spanner.

The air vents are simply opened with a key to allow the release of entrapped air, which collects at highest points in systems.

Conventional steel-panelled radiators are hung on brackets fixed securely to the wall. Since radiators are fairly heavy once charged with water, ensure that the fittings, and the fixings are adequate.

Some radiators possess more than two brackets, but this depends on the size.

To fix, mark and check the position of the brackets carefully. Radiators are usually located about 150mm from the floor at the base. Some makes allow slight adjustment on the fixing brackets to enable accurate horizontal alignment.

Where possible, fit radiators below windows, some 75mm below the sill, because these are the room cold spots. Windows are areas which cool surrounding air and create turbulence or draughts.

However, convenience of installation should govern your final decision on the position of radiators. Convected dust above wall-hung radiators may tend to discolour the wall surface. This can be remedied by fitting a shelf about 75mm above the radiator and projecting 25mm to 50mm forward. Where you have uneven walls, a piece of foam rubber can be mounted on the wall face of the shelf.

The effect on transmission of heat when radiators are painted with ordinary paint is very small. Special radiator paint can be used. However, metal paints, such as aluminium or bronze, may reduce the overall emission of heat by up to 15 per cent.

10. November 2011 by admin
Categories: Featured, Handyman Tips | Tags: , , , , , , , , , | Comments Off on Central Heating Parts


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