Preparing radiators

Most radiators have four tapped inserts for the connections, one at each corner - these are for:

  1. The 'tails' for the control and lockshield valves.
  2. A bleed valve at one end at the top of the radiator.
  3. A blacking plug for the unused insert.

It is usually easier to fit these parts before the radiator is hung on its mounting brackets.

As supplied, the radiator will normally have blanking plugs fitted to the tapped inserts to avoid the ingress of dirt and muck into the radiators, leave these plugs in place until it is time to fit the connectors/plugs.

Radiator valve tailsNormally the bleed valve and the blanking plug will be supplied with the radiator.

The 'tails' for the valves are normally supplied with the valves which will need to be purchase separately. You will need one radiator valve (either a manual or a thermostat type) plus one 'lockshield' type which may incorporate a drain off point - having a 'lockshield' with a drain off point will enable you in future to isolate, drain and remove the single radiator without having to drain the whole system.

Fitting the 'tails'

To fit the tails for the valves, dismantle then from the valve bodies. If the both valves are of the same make, the 'tails' will probably be interchangeable, but check, if the 'tails' are not interchangeable, make sure that you can identify which 'tail' fits which valve. Some 'tails' will have external 'flats' where a spanner can be applied for tightening, other 'tails' may have an internal square or hexagonal hole where a suitable metal bar or Allen key can be inserted.

Fitting lower radiator connectorWrap several layers of PTFE tape onto the thread of each 'tail' in turn and screw it into the appropriate tapped inserts in the radiator.

  • For single pipe systems the control valve should be fitted in the upper insert of the radiator at the boiler end, while the lockshield valve should be fitted in the lower insert at the opposite end.
  • For two pipe systems, the tails for both the control valve and the lockshield should be fitted in the lower inserts, the control valve for connection to the 'flow' pipe from the boiler, the lockshield for connection to the 'return' pipe.
  • For micro-bore systems, the position of the tails is the same as for the two pipe system unless a combined flow and return valve is used (not very common these days), in which case, the valve tail needs to be fitted to one of the lower inserts and an additional blanking plug will be required.

Fitting the bleed valve and plugs

Fitting upper radiator bleed plugThe bleed valve is fitted to one of the top inserts and the remaining insert(s) are fitted with plain plugs.

Wrap several layers of PTFE tape onto the thread of each bleed valve/plug in turn and screw it into the appropriate tapped inserts in the radiator.

The method used to tighten the valve/plug will depend upon the make, some have external flats, where a spanner can be used, others have an internal shaped aperture which will accept a square or hexagonal drive. Take care when tightening these valves/plugs not to damage the surface especially where they have a chrome plated finish.

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