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.

 

[Nobblers]

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.

The schematic in the instruction manual shows the EV connected directly to the combination valve, which is what he has done.
The combination valve is made by Reliance, but unfortunately I cannot find the model, to confirm what the inlets & outlets are for.
Should the EV have been connected to one of the outlets on the left instead?

 

[Nobblers]

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.

I have checked the plumber's registered operative id number online, and can confirm he is qualified for G3.

 

[ShaunCorbs]

Should be from the black plastic blanking plug one

 

[Nobblers]

Should be from the black plastic blanking plug one

Thanks to you and all the others who have helped me with this, Scott_d especially. I really appreciate it.

I've gone back to him to tell him the EV connection needs moving. Will the cylinder need draining while he re-routes the EV pipe?
How long should it take to fix? I will let you know the outcome.

 

[ShaunCorbs]

Doesn’t matter how long as you won’t be paying for it under 2 hours in reality though

 

[Nobblers]

Response from plumber: The expansion vessel can connect to either side I believe as it is past the none return valve but if it is still leaking I think I will tee into the 22mm pipe below the multifunctional valve. If it still happens after that it would have to be a faulty expansion tank.

 

[Nobblers]

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.

Nice one 👍

 

[EvilDrPorkChop]

Response from plumber: The expansion vessel can connect to either side I believe as it is past the none return valve but if it is still leaking I think I will tee into the 22mm pipe below the multifunctional valve. If it still happens after that it would have to be a faulty expansion tank.

He's wrong, as if that was the case you'd get back feeding from the hot (Cold feed to cylinder) down the balanced cold.

 

[Ricky]

He's wrong, as if that was the case you'd get back feeding from the hot (Cold feed to cylinder) down the balanced cold.

I agree with the above, if you are going to connect into the multi block it has to go into the connection on left hand side (photograph) not the top right, as said previously that is for the balanced cold water, it is before check valve, partially blame manafactures as their installation instructions are not clear on how to connect to the multi block,