Vitodens 100 losing pressure

[Neil T]

Hi all,
Got a customer with a vitodens 100 boiler that needs topping up at least 2 times a day. I topped it up and over 15 mins noticed it had dropped just under 1/4 bar. All rad valves dry and rads bled. Could it be expansion vessel?
I'm not gas safe but would like to steer customer in right direction ie boiler issue and not pipework so he can get engineer in if needed.
Thanks

 

[Neil T]

Update: lost about 1/2 bar over 45 mins with boiler not running.
No signs of water anywhere on pipework, as I said, rad valves dry and no air I rads. Any ideas?

 

[Darren Jackson]

1 - Could be a split hex, is the condensate constantly running?
2 - Could be faulty PRV letting by, Is the PRV outlet dripping outside?
3 - Could be a leak on hidden pipework under floors etc,
or (but unlikely if losing pressure when not in use)!
4 - Exp Vessel needs recharge or replace.

All possible scenarios require a GSR to find and fix.

 

[king of pipes]

You obviously have a leak somewhere its just a process of elimination as Darren has pointed out and will require a Gas Safe Engineer to fix cheers kop

 

[ShaunCorbs]

Viessmann have a combined prv and condense so have a look at the condense outlet

But I would isolate boiler and see if the pressure drops least you know where you stand

 

[Neil T]

Cheers lads.
There is no visible water from condense or prv outlets. Didnt isolate boiler though as you suggested shaun, just cos i didn't want to waste anymore of theirs and my time as I still wouldn't be able to do anything about it. So I've let customer know it's a probable boiler issue and told him to get engineer in.
With your help I've managed to rule out a couple of things for him anyway.
Thanks again

 

[ShaunCorbs]

Any pipework in concrete? If you know ?

 

[Neil T]

No, there is a solid floor in kitchen but pipework runs through a partition wall to there.

 

[townfanjon]

Viessmann have a combined prv and condense so have a look at the condense outlet

But I would isolate boiler and see if the pressure drops least you know where you stand

Dont forget the early ones had usual arrangement, changed at the start of the WB 1C if memory serves

 

[townfanjon]

Asuming the loss is not via system , Its a fair bet its the vessel .

 

[bright spark]

Has anyone mentioned the cylinder coil yet. Could isolate coil too.

 

[Darren Jackson]

Has anyone mentioned the cylinder coil yet. Could isolate coil too.

I Could be wrong but I think the 100 is a combi so no cylinder.