My Coldwater tank in the loft (a Polytank) is dripping from the overflow.
I have assumed it was a leaking float valve and replaced it yesterday. I
have also set the float to it's lowest position, to try and get the water
level down a bit.
To my dismay it is dripping again! There is one other pipe which feeds into
the top (I think it is from the hot water tank?) but as far as I can see
there is no water coming through. If there was, what would the cause be?
Could I have been unlucky and bought a second faulty float valve?
I would be grateful for anyone's thoughts as there seems to be no logic to
Thanks in anticipation,
I suffered the same symptoms with a system that turned out to be a split in
the heat exchanger coil inside the Hot Water cyclinder. This was allowing
the indirectly heated hot water system to feed in to the primary heating
system thereby adding water to it which ended up in the header tank. To
check for this, iscolate the feed to your header tank and see if it fills
up, it may take a day or so to notice the difference. Cure inthis case is
new hot water cylinder I'm afraid :o(
Be aware that condensation can cause overflow and other pipes to drip.
If you have e.g. hot water getting into teh tank, it will cause hugh
humidity in teh space above teh water, and if the outside air temp is
low, condesnsation will form and drip out.
The key thing to check is if the water level is up to the overflow pipe
or not, if not its condensation. Otherwise something is (over)filling
Gavin Gillespie wrote:
The only things to cause water to come out of the over flow are the tank
filling up too much, or a faulty ballvalve.
I would say your replacement ballvalve is faulty.
Check the washer seating, adjust the fill height or replace it
1. Did you replace the actual ball? If not, is the old one leaky and so not
floating properly? (Been there, done that one!)
2. Does the water shut right off when the ball is floating? Even a slow
trickle or drip can cause the tank to overflow in time.
3. Overflow from HW system- is there a pattern. Does it leak after the HW
has been heating?
4. If the CH header tank is higher than the main tank, you could have a leak
in the heat exchanger coil in the HW tank. (This doesn't apply of the CH
header tank is lower.)
5. Is the overflow from the CH header tank routed to drain into the main
tank (very naughty but seen it done).
6. Hole in the roof letting rain in. (seen it happen with a tank with no
The other pipe is probably the vent/overflow. Test it by taping a
single sheet of bogroll over the end - if it breaks while you're away,
then water's coming out. Fix /that/ by turning down the CH pump.
It's possible, or the fitting was wrong, or that the pressure is too
high and you've not fitted the twirly reducer valve, or that the mount
is insufficient and the water's pushing the wall out at the fixing, or
that you've simply not adjusted it Ok.
Is the ballvalve dripping? Empty the tank enough to start a normal
fill sequence and watch and wait.
If the pressure is very high, get a bigger ballvalve. I tried about
half a dozen different valves for a field trough where the pressure
overnight soared to stupid levels (sometimes bursting joints). Only by
fitting a larger sized ball and valve (designed for a high capacity
tank, the ball was three times the size of a standard one). You might
get away with just a bigger ball to counteract the pressure forcing it
Simon Avery, Dartmoor, UK
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