Vaillant Lockout

[rellio]

Hi All

Help please!

I have a Vaillant 824E Turbomax.
When it is running in 'constant' with heating and hot water on it is fine - pressure 1 to 1.5 bar.
If I switch heating off it gradually loses pressure for about 4 hours then locks out with code F.28 (note not F.22).
If I recharge to about .5 bar and turn heating back on (water no problem) it rapidly gains pressure back to normal.

If I turn heating off then wait until pressure down to about .5 bar, then turn heating back on it gains pressure again back to normal.

Installer and Vaillant engineer have visited and replaced expansion vessel and pressure release valve but problem still remains!

Any ideas please???

 

[Agile]

I would still question whether the EXV has been correctly precharged with air ( or nitrogen in the case of Vaillant! )

Tony

 

[gas4you]

I thought F28 usually pointed to no gas, as in the gas valve failing

 

[Gasguru]

Normal pressure is about 1 to 1.5 Bar with the boiler OFF and the radiators COLD. Ideally with the radiators hot pressure should be not much more than 2 Bar. Repair the leak.

 

[rellio]

Thanks Folks

I'll consider those three options - EXV not correctly charged / gas valve failure / leak in system (though I've checked all the rads and joints I can see - which means lifting floorboards I guess!)

 

[rellio]

Normal pressure is about 1 to 1.5 Bar with the boiler OFF and the radiators COLD. Ideally with the radiators hot pressure should be not much more than 2 Bar. Repair the leak.

Gasguru

If there is a leak:

1. Why, when I switch off the heating and allow the pressure to fall to .5 or less, does the pressure then rise again to the original reading when I switch the heating back on? If water had leaked from the system wouldn't it be unable to get back up to pressure?

2. If there is a leak why does the pressure remain constant when I leave the heating on ( it will maintain pressure for days on end providing I don't switch the heating off

Sorry if I'm being dense!!

 

[gas4you]

I think you have 2 problems, leak and gas/ignition fault.

Are you sure that your filling loop is fully turned off?

When water is heated, its volume increases, hence the pressure rise.

 

[rellio]

I think you have 2 problems, leak and gas/ignition fault.

Are you sure that your filling loop is fully turned off?

When water is heated, its volume increases, hence the pressure rise.

Thanks Dave - that makes sense.