Over Flow Pipe Works OK but where's the water coming from?

Spook_ie

OK not a plumber so lead me gently.

Situation two tanks in attic one for taps/shower/toilets etc. another smaller one for the oil fired central heating, both circa 1995 vintage. Each with an overflow to outside wall.

The overflow from the central heating is constantly dripping at a rate of a mop bucket's worth every 8 hours or so,

Now the problem, as a layman I would assume that the excess water must be coming from the tank inlet but when I manually empty the header tank down to a reasonable level ( below the overflow ) I can't see any water coming into the tank, but even so, I have replaced the ball valve on a just in case basis to no avail.

The only other way I can think of water feeding the drip is some kind of cross over from the hot water cylinder to the indirect coils, any ideas on how I can check this? or any other ideas?

Thanks

Wearb

Is the surface level of big tank higher than surface of smaller tank ?

Spook_ie

Wearb wrote: »

Is the surface level of big tank higher than surface of smaller tank ?

Yeah, probably about foot or two in difference of water levels

Wearb

Well if you’re certain that it’s not coming out of the ball valve of the little tank then it’s almost a certainty that the coil is holed.

Just check that the over flow of the larger tank isn’t playing a part in the problem.

Spook_ie

Wearb wrote: »

Well if you’re certain that it’s not coming out of the ball valve of the little tank then it’s almost a certainty that the coil is holed.

Just check that the over flow of the larger tank isn’t playing a part in the problem.

I'm 99% sure, I have replaced the ball valve as mentioned as a "just in case" scenario.

I suppose if I can get the family not to run any water off the attic tank for a while then I should see a similar rate drip into the main tank as is coming out of the overflow, or am I being too simplistic?

Just check that the over flow of the larger tank isn’t playing a part in the problem.

Not sure how it would or could?

Wearb

If you tie up the ball valve in the large tank (or otherwise stop water entering), then using a bathroom tap, drop the surface levels to the same level. Leave a couple of hours without using any water, the overflow should stop. Btw you will need you heating off and mostly cold for this.

On the other point, I have seen the overflow from the bigger tank going into the smaller tank and the smaller tank overflow then doing both.

Avatar MIA

I see a plumber and a new hot water tank in your future.

Spook_ie

Wearb wrote: »

If you tie up the ball valve in the large tank (or otherwise stop water entering), then using a bathroom tap, drop the surface levels to the same level. Leave a couple of hours without using any water, the overflow should stop. Btw you will need you heating off and mostly cold for this.

On the other point, I have seen the overflow from the bigger tank going into the smaller tank and the smaller tank overflow then doing both.

`

Nah two separate overflow pipes to outside wall.

Not sure if I can drop the surface level sufficiently but I'll have another nose in the attic Monday when there are less people in the house, short of that I guess it's calling in a plumber to change the hot water cylinder or see if they have any ideas?

Thanks for the ideas so far.

John.G

Quote:

"Just check that the over flow of the larger tank isn’t playing a part in the problem."
"Not sure how it would or could? "
"Each with an overflow to outside wall."

If the coil is leaking then the ball cock should be making up for it from the BIG tank, check late at night or first thing in the morning when there is no use of domestic water and see if there is a dribble of water into this tank.

Spook_ie

What's the ballpark going rate for replacing an indirect hot water cylinder anyway?

Spook_ie

John.G wrote: »

Quote:

"Just check that the over flow of the larger tank isn’t playing a part in the problem."
"Not sure how it would or could? "
"Each with an overflow to outside wall."

If the coil is leaking then the ball cock should be making up for it from the BIG tank, check late at night or first thing in the morning when there is no use of domestic water and see if there is a dribble of water into this tank.

Thanks we'll be nosing in the attic again on Monday but have that nagging feeling this is a new tank

I suppose that the bright side of it is I plumber can fit a larger one for if we ever decide to go power showers instead of electric at some date.

noel100

I put in a check valve in mine. Have the same problem. Did this a temporary fix in place 2 years. Had no issues. Stops the tanks trying to equalizing and no more leaks.
There is a valve going down to the tank filling it turn it off and put a carrot in a bag and force it into tank stop the water filling tank.
Buy check valve €5 cut pipe make sure valve is in the right direction of flow.

Wearb

noel100 wrote: »

I put in a check valve in mine. Have the same problem. Did this a temporary fix in place 2 years. Had no issues. Stops the tanks trying to equalizing and no more leaks.
There is a valve going down to the tank filling it turn it off and put a carrot in a bag and force it into tank stop the water filling tank.
Buy check valve €5 cut pipe make sure valve is in the right direction of flow.

I don’t get this. Could you post a diagram?

noel100

Tried to upload an image doesn't work

Wearb

noel100 wrote: »

Tried to upload an image doesn't work

Upload it to Dropbox or similar and post a link to it.

John.G

Wearb wrote: »

I don’t get this. Could you post a diagram?

Don't think it would be a very good idea to fit a check valve in the feed from the expansion & feed tank as you are now using the vent to take the expansion plus the main tank via the hole in the coil?.

noel100

Well it feed from the expansion tank into the coil at bottom of the tank. I've had no problem. Water will flow to topup coil but stops water equalizing because 2 tanks different heights. Stops over flow to outside. I did this as a temporary measure to get me over winter and it's been fine for over 2 years. I will get around to replacing cylinder but I'll leave the check valve in place. All it does allow water flow one direction.
Sorry for not uploaded image did try but would not work for me.

Wearb

noel100 wrote: »

Well it feed from the expansion tank into the coil at bottom of the tank. I've had no problem. Water will flow to topup coil but stops water equalizing because 2 tanks different heights. Stops over flow to outside. I did this as a temporary measure to get me over winter and it's been fine for over 2 years. I will get around to replacing cylinder but I'll leave the check valve in place. All it does allow water flow one direction.
Sorry for not uploaded image did try but would not work for me.

Unless I misunderstand your setup, your heating water is contaminating your domestic hot-water. That is why i wanted to see a diagram to check it out.

John.G

"but I'll leave the check valve in place."

When you renew the cylinder you will again have two completely different circuits, it would be prudent to remove the check valve as the primary water contents (boiler, rads, coil,pipework, etc) will be able to expand to the F&E tank, this could be 2 to 3 litres each time the boiler heats up/cools down. At the moment you have the hot water cylinder/main header tank via the hole in the coil doing it.

Its a bit surprising that you are not seeing a bit of discoloration, in the hot water at least. Alot of houses had the F&E tank actually perched on top of the main water tank and the first sign of a leaking coil was this discoloration of the hot water.

"it would be prudent to remove the check valve"
To clarify the above, if check valve is not removed, the expansion volume would still go to the F&E tank via the vent, then when the heating system cools down, it would return to the system via the check valve but the water would be aerated and probably lead to rapid corrosion.

Spook_ie

OK got back into the attic when no one was around running the water off and definite drip into the main water tank at about the same rate as the drip from the CH overflow, so looks like getting the hot water cylinder replaced.

Now questions
Is there any advantage of vented systems over non vented or vice versa

Having a vented system as it is now, can it be converted to non vented? if so how easy/hard would it be to carry out?

Any other options?

John.G

In my admittedly little experience of 4or 5 relations systems. Two were unvented and had lots of sludge build up probably because both had auto fill systems, the other 2 or 3 (vented) have some of their original 30 year rads.

Spook_ie

Just an update for all.

Decided in my own mind that it was a cross leak from hot water tank to indirect coils, as heating tank was lower than cold water tank it would siphon into heating tank and out of overflow.

Anyways, called in a plumber and got the hot water cylinder replaced ( put in a larger one at the same time ) and everything is now fine.

Thanks for all contributions and ideas.