Dripping overflow pipe when HW heating-any help appreciated!

[busylizzie]

Hi...first post to this site (and I'm just a girl!) so please go easy!

The overflow pipe from large header tank in our loft always drips when the hot water is being heated-never when just the CH is on. Turning on the HW taps fixes the drip till the tank fills up, then it starts again! It just started doing this a few weeks ago (on investigating I discovered that the piece of Kitchen counter(!) that the previous owners had been using as a lid had fallen into the tank, along with a load of fiberglass insulation that I guess they were using to insulate the tank!?)

Anyway-removed the debris, fitted a proper lid and jacket but ever since then have still got this drip when the HW is on...All I can gather from my DIY book is that possibly we have a leaking heat exchanger in the HW cylinder. Don't have a clue what that means! Am I completely on the wrong track? Would it be easy to fix? Could it have have been caused by what I found in the loft tank?

Also, while up there I had a look in what I assume is the CH Feed and Expansion tank-and it's empty apart from an inch or so at the bottom! Ball valve low-but doesn't open, even when I fiddle with the tap! I don't know enough about any of this to know if that's normal or not!? CH seems to be working fine but I really wanted to treat with scale/rust inhibitor and thought that was the route to go, but not really sure how to go about that now!

Any ideas gratefully received!!!!

 

[B.O.B DOLE]

sticking ball valve may have something to do with it

 

[Expertboy]

Firstly i always respect a woman

I would double check it's not the ball valve which is over filling the tank when you shut the water off, run the hot taps and then bend the arm down slightly. As for the heating tank if the ball valve is jammed i would recommend replacing it (turn the mains off first ) because after all the water has emptied out of this tank you will start to get problems.

 

[busylizzie]

Thanks for your help but I think I have managed to confuse things! When I said that the overflow 'always drips when the hot water is on' I meant when the HW is being heated...not when the actual taps are on...sorry!! Turning on the taps always stops the dripping, until the tank has filled up-then it starts again!! Any ideas?!

 

[Expertboy]

Thanks for your help but I think I have managed to confuse things! When I said that the overflow 'always drips when the hot water is on' I meant when the HW is being heated...not when the actual taps are on...sorry!! Turning on the taps always stops the dripping, until the tank has filled up-then it starts again!! Any ideas?!

If you are not heating your hot water does the overflow drip, at all?

 

[busylizzie]

Hiya,

No...not at all!

(Also...thanks for letting me know about the feed and expansion tank-I'll top it up until I can change the ball valve!)

 

[jobloggs]

First the F&E tank. Water level should be a couple of inches above the outlet (feed) pipe which itself is an inch or so above the bottom. Check this because if not then system will empty as suggested by previous post.

If you push down the ballcock as far as it goes and no water comes out then ballcock needs fixed/replaced. If however ball is floating rather than hanging loose water should come out when pushed down. You then need to adjust the float arm (bend if brass rod).

As far as main tank overflowing is concerned: What may be happening in your case is that the water levels in the two tanks are about same height when the HW is not being pumped and nothing happens. Once the HW is on i.e. pumped, the pressure in the heat exchanger coil inside the cylinder rises. If there is a pinhole in the coil water is forced out of the coil into the cylinder which is fed by the cold water tank. If no taps are opened the water level will rise and overflow.

All this means that you are losing water from your heating circuits and if there is a problem with your ballcock on the F&E the system will empty quite quickly. Need to get all this sorted out asap. Avoid using boiler until you are sure system is full and being fed. Pinhole can wait a while but not too long. (more expensive fix)

 

[Expertboy]

First the F&E tank. Water level should be a couple of inches above the outlet (feed) pipe which itself is an inch or so above the bottom. Check this because if not then system will empty as suggested by previous post.

If you push down the ballcock as far as it goes and no water comes out then ballcock needs fixed/replaced. If however ball is floating rather than hanging loose water should come out when pushed down. You then need to adjust the float arm (bend if brass rod).

As far as main tank overflowing is concerned: What may be happening in your case is that the water levels in the two tanks are about same height when the HW is not being pumped and nothing happens. Once the HW is on i.e. pumped, the pressure in the heat exchanger coil inside the cylinder rises. If there is a pinhole in the coil water is forced out of the coil into the cylinder which is fed by the cold water tank. If no taps are opened the water level will rise and overflow.

All this means that you are losing water from your heating circuits and if there is a problem with your ballcock on the F&E the system will empty quite quickly. Need to get all this sorted out asap. Avoid using boiler until you are sure system is full and being fed. Pinhole can wait a while but not too long. (more expensive fix)

beat me to it