Dripping from hot water cylinder

keithsav

Hi,

We have a boiler that heats up our water and central heating, the hot water is stored in a traditional copper cylinder in the airing cupboard. Whenever the water is heated, there is a dripping of water from the top of the cylinder into a pipe that leads outside.

This seems to have gotten worse and I'm wondering what to do next ! When I turn on a hotwater tap, the dripping stops temporarily.

Anybody offer any help or advice please ?

Thanks,

Keith

robowen

You sure it's from a pipe on the cylinder and not from the feed tank in the loft ??

rob

grumbler

keithsav wrote:

Whenever the water is heated, there is a dripping of water from the top of the cylinder into a pipe that leads outside.

robowen wrote:

You sure it's from a pipe on the cylinder and not from the feed tank in the loft ??

Sometimes in old modernised houses feed tank or expansion tank could be found in the same airing capboard above the cilinder. Hot water could drip from the pipe leading outside from the expansion tank. To stop this you can just adjust water level in the expansion tank.

one-non-blonde

grumbler wrote:

Sometimes in old modernised houses feed tank or expansion tank could be found in the same airing capboard above the cilinder. Hot water could drip from the pipe leading outside from the expansion tank. To stop this you can just adjust water level in the expansion tank.

This is exactly the problem I discovered I had recently (after posting on here begging for help re. my dribble!). The water escaping was warm because it was being heated by the hot water cylinder below the feeder tank and wasn't coming from the hot water system at all as I had presumed. The ballc*ck was hitting the lid of the tank (which was just a home-made sheet of hardboard that had warped) and as a result the valve was remaining open. I just took the lid off the tank and the problem stopped, or else I believe you can bend the rod holding the ballc*ck down to lower the water level.

keithsav

Thanks for the replies,

We don't have an expansion tank in the loft - it's a direct system, I think it's the pressure/temperature relief valve on the cylinder. Although the temperature of the water isn't that high when the dripping starts and I can't see why the pressure would build up that much (allowing for the expansion of the hotter water).

Does anybody know if it's normal to get some 'waste' in this kind of setup - It seems reasonable that the pressure would increase a little as the water expands ?

Again, any help/advice gratefully received !

Keith

robowen

Is there a big red pressure vessel on top of this cylinder ?

keithsav

Hi,

Not on top of this cylinder, it's a Honeywell pressure and temperature relief valve, from what I can tell. There is a grey 'dial' on it, if I turn this, it releases some water - I'm wondering if this has failed slightly and is letting water out as soon as the pressure starts to rise due to the heating of the water and expansion.

Keith

ila

Keith

We had this problem a while ago and the valve had failed and needed to be replaced. It was pretty obvious on ours, there was quite a torrent of water coming out so it had failed completely, but I think you could well be right that yours has partially failed, in which case it would expect it to get worse with time (I'm no expert though)

robowen

Apart from the possibility of the valve failing, you may have a faulty pressure vessel.

The large pressure vessel is used to take up the expansion of water as it gets hotter. If it fails and the diaphram allows water to fill the vessel completely, the only way out for the water is through the pressure relief valve.

If you don't have a red pressure vessel on top or somewhere near your cylinder, then you might have an internal baffle type cylinder where the pressure changes are dealt with internal of the cylinder.

Is there a name on the cylinder ?

roger56

There are basically two types of cylinder, the older system which uses a loft tank, a tank above the cylinder (eg in the airing cupboard) or more recently some cylinders have integral non pressure tanks as an integral part on top of the cylinder.
If you have one of these, check that the ball valve washer is stopping the water once the tank is full. (Hint, check if the tank water level is close to the overflow pipe, if it is slightly bending down the ball valve arm will stop the level in the tank reaching the overflow pipe level. If leaking continues, then replace the ball valve washer, it's probably suffering from old age!).

If you have a pressure vessel (red/blue sealed spherical tank on top) then it really is best to get professional help to fix as you have a pressurised system. Often you can see leakage in this type of system if you look in the tun disk which should be close to the cylinder (tun disk - that's a bit of pipe with an opening and a brass dish to see water flowing - kind of difficult to describe by words!)

keithsav

robowen wrote:

Apart from the possibility of the valve failing, you may have a faulty pressure vessel.

The large pressure vessel is used to take up the expansion of water as it gets hotter. If it fails and the diaphram allows water to fill the vessel completely, the only way out for the water is through the pressure relief valve.

If you don't have a red pressure vessel on top or somewhere near your cylinder, then you might have an internal baffle type cylinder where the pressure changes are dealt with internal of the cylinder.

Is there a name on the cylinder ?

Rob,

No name or manufacturer on the cylinder, it's coated in some kind of insulating material. We do have a large red pressure vessel, it sits between the mains inlet and the hot water circuit and looks something like a large red football and looks to have a pressure relief valve on top (it has a red cap on it) - is this what you mean ?

Do you know if there's a way to see if this has failed ? There is a pressure gauge on it, but the dial is in the 'green zone', even when the water and/or heating is on.

Thanks for the help so far,

Keith