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Drops falling on the tiles, it is a warning sign that indicates that the faucet has had its day... Lack of spare parts, some models are not repairable and must be changed.

Change the tap of a water radiator

Intervene on a coupling tap-radiator without joint

The old faucet is an angled model with a welded inlet (Ø 14 mm) and an outlet coupled to the radiator by a conical bearing assembly.
The male end screwed into the radiator is provided at the rear with a movable sleeve threaded internally. It is equipped at the front with a tapered head which rests on a milling cut out of the tap. The machining of the two parts, male and female in contact, is so precise that, by clamping the sleeve, the connection is tight and requires no seal.
Before disassembly, the installation must be drained.
When changing a valve, the new is supplied with its threaded end screwing into the radiator because the male and female parts were lapped together. We must extract the old part.
The old faucet models have, inside the mouthpiece, two lugs in opposition for the assembly / disassembly. When you do not have the right key, you need to make one from a thick flat iron (8 mm) ground to the file to fit exactly in the indentation. Operated with a wrench (photo 1), the tool presses the pins and unscrews the piece.

Choose a suitable model

The current models are simpler: the tip has inside an Allen key imprint actuated by a male key for disassembly / reassembly. If we compare the two faucet models: old and new, there is little difference. Radiator side is the same, the thread is always 15 x 21 mm. On the water inlet side, the copper tube was directly welded to the valve body. Now the welding is done at the entrance of an elbow which is screwed on the body. Whatever the case, it is recommended to choose a model close to the old one to limit modifications, knowing that it is also possible to install a thermostatic in the same way.

Remove the socket

Remove the socket

Loosen the bushing, the conical part then separates from the inlet of the tap.
Introduce a flat tool that rests on the lugs of the tip.
Loosen by operating the tool with the key.

Coat with joint paste

Coat with joint paste

Prepare the new mouthpiece (15 x 21 mm) by sealing its threads with special joint paste, then tightly wrap strands of tow, enough to cover the fillets.

Screw the new tip

Screw the new tip

The new tip has an internal cavity with hexagon socket (13 mm).
Coat the inlet of the radiator thread with dough, present the end piece, not forgetting the socket and screw with the male key.

Remove the old faucet

Remove the old faucet

The old faucet is joined by welding to the supply pipe.
Heat the torch elbow by protecting the wall with fireproof material.
Pull the element to the pliers.

Clean the connection

Clean the connection

The copper supply pipe (Ø 14 mm) is welded to the tap via an elbow (15 x 21).
Spray a little cleaner inside the Ø 14 entrance.

Weld the pipe

Weld the pipe

Strip the end of the hose with abrasive and comb the tube of the angled fitting, well oriented.
Heat without oxidation and present the solder wire to the joint.
The solder rises by capillarity.

To screw

To screw

Seal the dough and tow as before, then screw the valve onto the elbow fitting.
The vise grip holds the fitting and the key screws the faucet.

Gather the tip and the tap

Gather the tip and the tap

Face the tapered end of the radiator tip and the threaded outlet of the valve face to face.
Join them by threaded sleeve, then tighten energetically.

PRACTICAL ADVICE

• In this job, the most difficult may be to remove the threaded end screwed into the cast iron radiator because of internal rust. Choose the right tool. If necessary, heat without excess by torch.
• The solder was made with solder (tin-lead alloy) which is sufficient (low water temperature, no pressure). It is also possible to perform a strong braze with the torch.


Video Instruction: Change radiator valve without draining.