Temporary leak into tundish when boilers fires up

[Nobblers]

Hi. I've just had my unvented hot water cylinder replaced. Works fine, apart from a slight trickle into the tundish when the boiler comes on after a period of inactivity for about 10 mins, which then slows to a drip and stops. He replaced the expansion vessel, all valves etc with new parts during the installation. The installer's been back to check the expansion vessel pressure, and other aspects, but can not find any fault, so he's leaving it as is. Is that a reasonable thing to do? Is there any way to narrow down what's causing it? E.g downstairs mixer tap on unbalanced supply?

 

[ShaunCorbs]

No shouldn’t drop or dribble when heating best to get ideal eg the manufacturer out

 

[Nobblers]

No shouldn’t drop or dribble when heating best to get ideal eg the manufacturer out

Will Ideal charge for that service? What is the most likely cause of the leak?

 

[ShaunCorbs]

Should be under warranty as it’s new

 

[Scott_D]

Which pipe is the white expansion vessel connected to?

 

[Nobblers]

Which pipe is the white expansion vessel connected to?

Expansion Vessel pipe is on top right, above the 4.5 bar PRV/SRV as shown in the photo. The temporary trickle/drip into the tundish is cold / tepid. Turning off the cold water supply has no effect on it, when it happens.

 

[Scott_D]

Expansion Vessel pipe is on top right, above the 4.5 bar PRV/SRV as shown in the photo. The temporary trickle/drip into the tundish is cold / tepid. Turning off the cold water supply has no effect on it, when it happens.

It’s in the wrong place
Was the installer G3 qualified?

 

[Nobblers]

It’s in the wrong place
Was the installer G3 qualified?

Thanks. I haven't asked him if he has G3. I took it as a given, as AFAIK, it's illegal to install a domestic hot water cylinder if you don't have G3. Would you be willing to post concrete evidence that the pipe is in the wrong place - otherwise he could say that's just your opinion, when I go back to him? Where should the EV pipe go? Assuming the EV pipe is in the wrong place, how would that explain the temporary leak into the tundish when the boiler comes on in the morning?

 

[EvilDrPorkChop]

Yeah as @scott_d says expansion vessel is connected in the wrong place. Should be tee'd off the cold feed to cylinder, it's currently in the balanced cold connection of the combination valve.

 

[Scott_D]

The vessel is not in the correct place to take up expansion.
The installation manual will give you concrete evidence.

An easy mistake to make but best to check they have the correct qualification.