F&E attic tank filling, overflow dripping

Gryzor

hey there

Have an issue with the overflow on my F&E tank dripping when heating is on.

I've emptied water (~6 litres)from the tank down to the level that the ball valve kicks in multiple times, and within 4-5 days it's filled back up again.

Last thing thing I did was remove the ball valve and bend the arm, so it reduces the level down another 4-5 inches in the tank, still an inch or two above the F&E pipe (About 10 ltrs to reach overflow). That was 6 days ago, and the water level is climbing again, I'd say it'll be dripping this evening or tomorrow at the latest.

1) Open System
2) Overflow only drips when heating is on.
3) Have confirmed it's not coming out of either of the two vents
4) 99% sure the ball valve is not leaking, but am going to replace anyway

If it was a pinhole in the cylinder worm, it'd be dripping all the time, right?

noel100

Having the same problem

Joe1919

I have seen the situation where the heating vent pipe blows and circulates hot water back into header tank when radiators are turned off or circulation pump is turned up too high or cylinder balance valve (if fitted) turned down in hot press and this can cause a change in tank water level.
But if you checked the vent pipes with system running, this may not be the case.

I fitted a new ball valve lately and it was intermittently leaking. I dismantled and discovered a small bit of white nylon was sticking out and slightly covering the small round rubber disk, so preventing a good seating. I broke it off and it worked ok afterwards.

PS Another situation I came across was where the cold feed going to ball valve was unsupported and was causing the tank to warp by pulling down on the tank wall and rising the ball valve and causing overflows. We used stiff wire (opened-up coat hangers) to support weight of cold feed off the rafters and this worked and adequately supported the cold feed and stiffened up the tank wall at ball valve.

Dtp1979

Is the water level in your tank lower than the water level in the large tank?

Gryzor

Joe1919 wrote: »

I have seen the situation where the heating vent pipe blows and circulates hot water back into header tank when radiators are turned off or circulation pump is turned up too high or cylinder balance valve (if fitted) turned down in hot press and this can cause a change in tank water level.
But if you checked the vent pipes with system running, this may not be the case.

I fitted a new ball valve lately and it was intermittently leaking. I dismantled and discovered a small bit of white nylon was sticking out and slightly covering the small round rubber disk, so preventing a good seating. I broke it off and it worked ok afterwards.

PS Another situation I came across was where the cold feed going to ball valve was unsupported and was causing the tank to warp by pulling down on the tank wall and rising the ball valve and causing overflows. We used stiff wire (opened-up coat hangers) to support weight of cold feed off the rafters and this worked and adequately supported the cold feed and stiffened up the tank wall at ball valve.

I tied some small plastic bags around the bottom of both the vents, and left them overnight. Nothing but a bit of condensation in them the next day dispite the water level having rose ~2 inches..

I'll change the ball valve this weekend and see if things improve.

Dtp1979 wrote: »

Is the water level in your tank lower than the water level in the large tank?

F&E is lower.

Dtp1979

Gryzor wrote: »

I tied some small plastic bags around the bottom of both the vents, and left them overnight. Nothing but a bit of condensation in them the next day dispite the water level having rose ~2 inches..

I'll change the ball valve this weekend and see if things improve.



F&E is lower.

Chances are the coil in your cylinder is leaking.

Joe1919

Dont forget that water expands when heated (approx 4%) so it would be normal for the level in the expansion tank to rise as the system heats up. So its important to allow for this when fitting the new ball valve by setting the water level a good few inches below the overflow level. (often by bending the brass arm)

Gryzor

Ball valve replaced, we'll see how it goes...not confident tbh..

Is there situations where a pinhole or joint crack in the cylinder coil could be opened by the heat of the system, and close again when things cool down. Could this explain the dripping only when the heating is on??

Dtp1979

Gryzor wrote: »

Ball valve replaced, we'll see how it goes...not confident tbh..

Is there situations where a pinhole or joint crack in the cylinder coil could be opened by the heat of the system, and close again when things cool down. Could this explain the dripping only when the heating is on??

Yes that's exactly it

John T Carroll

Gryzor wrote: »

I tied some small plastic bags around the bottom of both the vents, and left them overnight. Nothing but a bit of condensation in them the next day dispite the water level having rose ~2 inches..

F&E is lower.

Gryzor wrote: »

Ball valve replaced, we'll see how it goes...not confident tbh..

Is there situations where a pinhole or joint crack in the cylinder coil could be opened by the heat of the system, and close again when things cool down. Could this explain the dripping only when the heating is on??

Its not clear to me at any rate if the heating was on during the night as well. If so then it may be possibly that the hot water is backing up the feed and expansion pipe without overflowing from the vent pipe?. Its probably against regs now but I have never seen a F&E tank lower than the main tank, in my own house it was originally perched on top of the main (zinc coated) steel tank.

Gryzor

John T Carroll wrote: »

Its not clear to me at any rate if the heating was on during the night as well. If so then it may be possibly that the hot water is backing up the feed and expansion pipe without overflowing from the vent pipe?.

I have new water getting into the system though (~15ltr in 5 days), it has to be coming from somewhere. Even after replacing the ball valve the level in the F&E tank is rising..only other place it can get in is the cylinder??

John T Carroll wrote: »

Its probably against regs now but I have never seen a F&E tank lower than the main tank, in my own house it was originally perched on top of the main (zinc coated) steel tank.

Thought the F&E should be lower?

Joe1919

You could turn off or blank off the main supply to tank ball valve (which should be easy enough) for a few days to make absolute certain that the water is not coming via ball valve.

John T Carroll

Gryzor wrote: »

I have new water getting into the system though (~15ltr in 5 days), it has to be coming from somewhere. Even after replacing the ball valve the level in the F&E tank is rising..only other place it can get in is the cylinder??

Thought the F&E should be lower?

Yes I'm pretty sure that it should be lower now, certainly not higher from a H&S point of view as you dont want rust inhibited/rusty water leaking into the hot water cylinder via the cylinder coil.

As you say above the cylinder coil seems a likely culprit, you can do a relatively simple test even with the boiler running..... make sure that there is no draw off from the cold water tank or the hot water cylinder anywhere and then just crack open a tap until the make up just starts to dribble into the cold water tank and then shut it, as soon as the dribble stops tie up the ballcock for a few hours and then release it and see if it makes up, if you can keep it tied up for 4 hours then it should make up around 0.5 Litres based on the leakage rate of ~15 Litres in 5 days.

Gryzor

John T Carroll wrote: »

As you say above the cylinder coil seems a likely culprit, you can do a relatively simple test even with the boiler running..... make sure that there is no draw off from the cold water tank or the hot water cylinder anywhere and then just crack open a tap until the make up just starts to dribble into the cold water tank and then shut it, as soon as the dribble stops tie up the ballcock for a few hours and then release it and see if it makes up, if you can keep it tied up for 4 hours then it should make up around 0.5 Litres based on the leakage rate of ~15 Litres in 5 days.

I like it, hadn't thought of that approach, thanks!