permanently dripping overflow

[stevejd58]

I'm not sure if this is the correct forum as you will see below.

I have a multifuel gravity system with an electric immersion heater in the cylinder.

The external overflow has a constant drip all year round.
I've been in the loft where there are x3 tanks, the largest I assume is the main cold storage tank and the one of the two smaller for the fire/boiler and one for the immersion.
I've tried adjusting the levels of the tank with the outside overflow, even replaced the ball valve.

I must admit to being puzzled by this.
I want to see if this is a simple fix or something I need to pay a plumber to sort.

Fire is a Charnwood LA 50B

this is the layout of the tank connections

 

[Best]

Take a look with a torch inside the tank, where the cold feed pipe connects near the bottom. Or it might be easier to isolate the mains supply & syphon the water out of the tank & take a careful look at the connection. If you see any water coming up & into the tank, then you probably have a hole in the coil of the cylinder & unfortunately need it all replaced. What make is the cylinder?

 

[Best]

I should have added that if it is the cold storage tank overflowing it could also be mains water going through & mixer tap or mixer shower somewhere. A faulty monobloc sink mixer could have a pin hole in its casting & allowing the higher pressure mains to enter the lower pressure hot pipe & into cylinder & then up the cylinder feed to the bottom of the cwt.

 

[happyflyer]

I should have added that if it is the cold storage tank overflowing it could also be mains water going through & mixer tap or mixer shower somewhere. A faulty monobloc sink mixer could have a pin hole in its casting & allowing the higher pressure mains to enter the lower pressure hot pipe & into cylinder & then up the cylinder feed to the bottom of the cwt.

Wow Best,

That would be an unusual one even for an Old baldy git, I would have never thought of that

 

[Best]

Wow Best,

That would be an unusual one even for an Old baldy git, I would have never thought of that

Yes, I have seen a few brand new taps doing this. Monobloc taps have very close water channels. I remember one man having overflow problems with new Ballvalve fitted etc until a guy said it then must be the copper cylinder coil & fitted a new cylinder. Problem still there & he asked us what it could be. When we asked what other work he had got done prior to all this, he said a new monobloc mixer on a basin....
A check valve on the hot pipe to tap would solve this obviously.
I came across a job that the people were threatening to sue the idiot plumber for charging a lot of money 4 times to repair a ballvalve on cwt. I went to it & saw a haze of warm water entering the cwts at cyl feed. 2 new taps had been fitted previously by same plumber - a deck mixer in garage & a monobloc on kitchen sink. I turned hot supply off & disconnected hot pipe at sink monobloc & mains water was coming out of hot tail. New mixer sorted it.