Venting from a loft overflow Q.

[adders]

1) Boiler make / model (gas or oil)
Gas - Myson Orion

2) What is / is not happening
two tanks in the loft, a hot water tank in the airing cupboard & a boiler on the ground floor.

one of the overflows for the tanks just drew my attention to the loft, so I went up to see if the ballvalves were stuck. both tanks were an inch below the overflow pipes

Where did the overflowing water come from? (I suspect another pipe which joins the overflow pipe.
Incidently the tank is now warm - could it have been warm water venting from somewhere into the overflow & thus into the 'cold' tank?


3) Has ANYTHING else been done / changed recently
No

4) When did it (problem) start
Last night 6-ish

5) When does it happen? eg, heating coming on or going off
1 event

6) Anything else you feel may be of relevance
sadly - no

 

[ArtfulBodger]

Which tank is overflowing? you should have a small one with filthy, black disgusting water in it and a larger one whose contents should be marginally less filthy - at least at the top!

 

[adders]

its the larger, cleaner tank - the other one has crud growing on the inside (surely that can't be healthy).

HTH

 

[ArtfulBodger]

So, it's your cold water tank. Under normal circumstances it should only get warm if the open vent from your HWC is, well, venting. Have you recently turned the HWC stat up to a very high temp?

However, there is the possibility that your HWC coil has ruptured and water from the CH side is finding its way into you CWC, if your hot water (and maybe cold) water starts running discoloured. There's lots on this forum on this.

Anyway, the first thing I would try is to adjust your ball valve to drop the water level down by at least 3 or 4 inches and monitor it from then on, especially when the heating is on. Oh, I'm assuming that you've checked to see if there is absolutely no letting by when the valve should be closed.

 

[adders]

So, it's your cold water tank. Under normal circumstances it should only get warm if the open vent from your HWC is, well, venting. Have you recently turned the HWC stat up to a very high temp?

nope. we've not altered anything

However, there is the possibility that your HWC coil has ruptured and water from the CH side is finding its way into you CWC, if your hot water (and maybe cold) water starts running discoloured. There's lots on this forum on this.

I'll keep an eye on it

Anyway, the first thing I would try is to adjust your ball valve to drop the water level down by at least 3 or 4 inches

Done

and monitor it from then on, especially when the heating is on. Oh, I'm assuming that you've checked to see if there is absolutely no letting by when the valve should be closed.

there is nothing coming from the BALL valve when it's closed - do you mean that one?

OK, as you appear to be using a version of english I'm not entirely conversant with I've highlighted the incoherent bits of your post in blue.
Would you be kind enough to translate?

Is this an expensive thing to fix?


EDIT ok is HWC = hot water coil (whatever that might be) & STAT is theromstat.
Gosh, this is quite a learning curve...

 

[ChrisR]

Level in the big tank would normally be the few inches below the overflow, but the small tank should only fill to about 4" deep.

Which tank's water level is the higher one - from the floor?

 

[adders]

smaller tank is higher

edit: due to understanding your post... duh

the larger, lower tank was the one that was overflowing
the higher smaller tank is also next to full, but is not overflowing.

 

[brumylad]

so the smaller tank is raised off the loft floor on a platform of some kind

 

[Slugbabydotcom]

My 2p worth :-

but the small tank should only fill to about 4" deep

Just to add to it and accelerate learning curve

Smaller tank should be about a third full when cold to allow the expansion of water when the system heats up. Bend the arm down carefully or adjust it.
Water increases by up to 1/20 extra volume when heated so if you have 20 gallons in your system the other gallon 'created' needs somewhere to go hence the term expansion tank.

Theres usually a tell tale mark so that you can identify when a tank has been overflowing

 

[felix]

Hot water in your storage tank??? A leaking cylinder coil could do this but you'd have to push a lot of water through that leak before hot stuff started coming up the cold feed. If that's the cause why isn't it running now?

I suspect another pipe which joins the overflow pipe.

If this comes from the small tank, is it possible that water ran backwards into the big tank (warming it up) before making its way out of the overflow? And if it's not from the small tank where exactly does it come from????

 

[adders]

& I thought this would be simple...


the 2 tanks are not visibly connected.
they have independent overflow pipes.
the small tank is raised off the loft floor on a platform.
the larger, lower tank, which is nearly full of clean water has a T joint in to it's overflow pipe. the T joint into the overflow pipe is approx. 4-5 inches below the level of the water in the tank & 6inches below the level of the overflow point.