tap water too hot and can't get heating on without hot water

[johnlon]

Total newbie.

Symptoms
- My hot water cylinder is too hot.
- The rads never get really toasty
- The lever on the cylinder diverer value never moves and seem to be floppy - no resistance
- The lever on the heating divertor moves when the heating comes on

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I'm guessing the diverter valve to the cylinder isn't closing to force the water round the heating circuit and both the cylinder and house circuits are open at the same time, even when I just want heating.

This accounts for the cylinder getting really hot even when the cylinder thermostat has reached its target temp.

I'm guessing the cylinder thermostat isn't the problem because the cylinder diverter valve lever never moves at all even if I turn off the system.

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Can someone confirm whether I'm on the right track.

Also assuming it is the cylinder valve thats stuffed, do I need to completely replace the valve and/or is there some partial repair I can do, and how do I tell which?

If I can repair this myself then does anyone have info on how?

The Cylinder value is a Danfoss HPA2.


Thanks loads John

 

[45yearsagasman]

Start by removing the two screws and remove the powerhead from the body.Check that the spindle moves freely.You should be able to move it by hand.If siezed then you can either replace the internals or replace the whole valve.Your make of valve is not that reliable and are prone to siezing.Service kits are available for these valves but require a drain down or system bung if you know how to do that.

 

[johnlon]

Hi when you say remove the two screws do you mean the two I can see right now on the white casing or do you mean two inside the unit?

If I remove the two white screws on the casing will the whole unit come off the unterlying brass work?

Re 'bung' - don't know about that.

Thanks

 

[Gasop]

Start by removing the two screws and remove the powerhead from the body.

Start by isolating the electrical supply

 

[johnlon]

Thanks for the advice.

The mechanism came off easily.

I can see the valve is definitely seized up.

Looks like I need help.

Thanks