Alfa 240 E – Diverter valve leaking

[Zehroni]

This diverter valve has two sections, the bigger section facing you as you put the control penal down is connected the valve main body via an Allan key screw (this is the DHW one). There is a pine goes in and out depending when there is a demand for domestic hot water and this is where the water is coming from. It only leaks when there is a demand for DHW.
My question is
Do I have to replace the whole valve or just the diaphragm if the DHW section. It is about 4 inches in diameter.

 

[Agile]

If the leak is at the front where it operates the switch then there is a gland which can be replaced.

Tony

 

[Zehroni]

Tony, many thanks for the reply.
The leak is not at the Front where it operate the switch, it is in the opposite side to it, from behind. I thought there might be a small O ring to replace, but could not fine one when I creaked open an old one. it is sealed by the diaphragm itself. That is why I think changing the diaphragm might solve the problem rather then replace the whole valve. But I need your expertise and advice to decided.

 

[45yearsagasman]

If it's leaking at the back of the diaphragm housing then it needs a new seal which is contained in a service kit still readily obtainable. Changing the diaphragm will not cure the leak as there is water both sides. Apologies for butting in.
Be sure about where the leak is from as the main seal in the valve body is also prone to failure.

 

[Zehroni]

Thanks Pete, you are right. I opened the back gland (which is slightly smaller then the front one mentioned by Tony) and could see there is a small O ring washer. I believe this washer is damaged not the main seal in the valve body, because the boiler pressure is not affected i.e. the pressure stays at 1 bar (cold) despite it is losing nearly a liter of water a day.

 

[ChrisR]

Change the diaphragm and pin while you're there. Scale/roughness wears the O ring. All in the right kit.