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A safety group is a simple valve. When set to a certain value, it is triggered in case of overpressure inside a storage water heater. A slight flow during the heating phase is normal. On the other hand, if the flow is large and continuous, the group is involved and must be changed.

Water heater: replace a safety group

Practical advice

● Look for a model close to the original one. If the groups are too dissimilar, you will have to modify the cold water supply, sometimes in a rather important way.
● Operate the safety valve once a month by turning the operating knob in the direction of the arrow. Water flows into the siphon, thus avoiding seizing of the valve.

The intervention concerns a gas water heater on the ground. Like the electric models, it is obligatorily equipped with a group of safety whose functions are here located on the top of the apparatus. This does not change its operation. The group is joined to the balloon by a horizontal pipe on which it is screwed. Its side inlet is fed by the cold water pipe in copper tube Ø 14 with ball shut-off valve and connection by collar flared in 20 x 27. The small siphon, screwed to the base of the group, collects the water flow to the heater and discharges it through a copper tube Ø 16.

Choose the replacement group

Before any disassembly, visualize the damaged group to find on the market an identical or fairly similar model, in accordance with standard NF 36-401. Consider the relative position of the inlet and outlet, and the diameter and threading of these ports, often 20/27 (3/4 ").The operating knob to test the proper functioning of the device must be accessible.
● The new group is quite similar to the old one. For a few euros more, this model is an improved version, equipped with a ceramic valve seat avoiding scaling.

Disassembly

After shutting down the water heater and closing the two hot and cold water valves in the system, remove by unblocking the 20 x 27 bushing nut from the knocked-out collar. Do the same for the outlet that flushes the water out of the siphon. Unscrew and remove this one.
● The body of the group has a hexagonal print. Loosen it with an adjustable wrench or claw to disengage it from the male elbow ending the connection tubing to the water heater.

Winding

It is carried out in the reverse order of disassembly, again sealing the connections. Coat the male part of the elbow lightly with the joint compound, then wind tightly on the thread, in a clockwise direction, a few strands of tow. Screw the exit of the group that remains suspended, before proceeding to its equipment.
● Reconnect the water inlet to 20 x 27 and tighten the flare collar socket after inserting a flat fiber gasket or, better, a Teflon gasket. A small difference in the positioning of the inlet between the old group and the new one can be compensated by slightly bending the copper supply pipe.
● When the siphon is cleaned, screw it in place. Finally, reconnect the drain line by placing a flat gasket and moderately tightening the flare collar.
● To put back into service, slowly open the hot and cold water valves. Check for leaks and then warm up the balloon. After a while, a slight flow will occur in the siphon.

Description of the water heater

Description of the water heater

On this water heater, the functions are located at the top. on the right, the arrival of cold water. on the left, the departure of hot water. The safety group is mounted on a double bent tubing.

Unscrew the collar of the beaten collar...

Unscrew the collar of the beaten collar...

After shutting down the water heater and closing the shut-off valves, unclamp and unscrew the flanged collar bushing at 20 x 27. It serves as a connection connection to the water inlet pipe Ø 14 mm.

... and the siphon drain pipe

... and the siphon drain pipe

Do the same for draining the siphon. Generally PVC, it is here in copper. It crosses the wall to evacuate the water produced at each heating (3% of the capacity).

Unscrew the group

Unscrew the group

The group is suspended from the terminal elbow of the connection pipe. Unscrew it and remove it with a wrench or claw by acting on the upper hexagonal imprint.

Compare old and new group

Compare old and new group

The new group corresponds well to the old one. At the top, the female connection to the water heater. On the right, the supply with stop valve. On the left, the valve. Bottom, the connection to the siphon.

Seal the male part...

Seal the male part...

Coat the thread of the male part of the connection elbow with sealing compound. Pull a few strands of tow in a doll and wrap them tightly on the threads, in a clockwise direction.

... and the female part

... and the female part

Also coat the female part of the group with paste and screw it on the prepared connection to the tow, first by hand and then with the key. The tow has some resistance to tightening.

Screw on the siphon bowl

Screw on the siphon bowl

Screw the siphon bowl back to the base of the unit. Reconnect the cold water supply and drain by placing a flat fiber seal on each flanged collar. Tighten energetically with the key.


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