Opening a Vaillant Sine 18 T3TWF H to repressurize the PV

[jsimas]

Hi,

My Vaillant's pressure is going to zero overnight with all the symptoms that match the FAQ entry "REPRESSURISING THE PRESSURE VESSEL".

The procedure seems pretty straightforward and I would like to try it. I need to open the left hand side of the boiler but before I start unscrewing things I wonder if someone can tell me how do I remove the cover?

 

[kevplumb]

View media item 17253
View media item 17252

 

[jsimas]

Hi,

That is fantastic! A big thanks (And I pressed the thanks button too, of course).

Cheers,
Simas

 

[Agile]

You should only remove screws "d" on the first diagram.

NOT the four screws on the second which are for the combustion chamber which you should not remove.

Once the left panel is off the valve is clearly visible.

You must first test it by pressing the middle and making sure that only air comes out. Water means its failed.

The follow the FAQ instructions. Its essential that the repressurising is done with the system open to atmosphere.

In the case of just THIS model I recommend about 0.8 Bar of air pressure and a system presure of about 1.2 bar cold.

Tony

 

[jsimas]

Hi Tony,

Thanks for that, you say:

>You must first test it by pressing the middle and making sure that only air comes out. Water means its failed.

I also saw that in the FAQ. Does "failed" mean that the whole part must be replaced?

Simas

 

[kevplumb]

I also saw that in the FAQ. Does "failed" mean that the whole part must be replaced?

yes or fit a remote one on the boiler return

 

[Agile]

Test it first before you get excited.

I have never found one of those which had failed.

I have a spare used one in the store.

Tony

 

[jsimas]

Hi,

Again, thanks for your help but I could not figure out how to remove the cover. I was able to loosen the bottom left screw and the cover is indeed loose at the bottom but I don't have access to the top screw as it is behind the front cover which I cannot figure out how to remove.

Any suggestions are welcome and I wonder if there is someone in or near Bristol that knows about these boilers and wants to fix this for me. It needs servicing anyway.

Simas

 

[kevplumb]

as it is behind the front cover which I cannot figure out how to remove.

it pulls off

 

[jsimas]

Does it pull out as in my direction when I am facing the boiler?

I pulled it out, up, down, the works... and all the covers move with the front cover. Maybe I need a more confident pull ?

 

[kevplumb]

pull it towards you as you face the boiler

 

[jsimas]

Got it! The problem is that the access is not brilliant but now that I was certain I used a screwdriver to pull it of and it worked.

Thanks again and I am having another go at repressuring the PV later today.

 

[jsimas]

Hi,

I just wanted to thank you guys for the helpful posts. I managed to remove the cover, find the PV valve and, after bleeding out the system, top up the PV to 0.8 Bar. A bit of a nerve wrecking experience but looking back quite an easy procedure. The pressure indicator is now rock solid at 1.2 Bar whereas it used to go up and down a lot from cold to hot.

I still have problems with some of the radiators but I will leave that for another day and post.

Cheers,
Simas