Hot water tank overflow

[liamb]

I have a Thorn Appolo boiler which feeds a hot water tank for the central heating and hot water. There is an overflow pipe from the hot water tank which has been dripping constantly whenever the tank is hot. (is this an indirect system?)

What do I need to do to stop the dripping?

 

[oilman]

This does not make sense. Normal vented HW tanks do not have an overflow, Un-vented tanks do, but there is a fault causing the dripping.


We need to know more about your tank, type, make, size, age, anything.

 

[liamb]

I may have been confused, there are two overflow pipes; one from the small tank above the hot water tank and another overflow pipe somewhere between the two tanks. This one is dripping constantly whenever the hot water is switched on.

The hot water tank is old, I would say at least 15 - 20 years and feeds both the central heating and the hot water.

How do you know if a tank is 'vented' or not?

 

[Bahco]

I am a bit confused here
To clarify,which pipe is actually overflowing? Is it the one leading from your cylinder vertically and terminating above your cold water cistern.
If so this is your open vent which allows for expansion of heated water.
Or could it be the overflow pipe from your cold water cistern leaking to outside .
Rereading your post you may have a primatic system which is supplied by only one tank in loft .
Please check and report back with as much info as poss