[Colmsport]

Thought I’d ask if there’s any friendly plumbers on here that could perhaps share some insight into an issue that we’re trying to get resolved at home.

Currently under a British Gas service contract & so far they’ve not been able to rectify the issue & we seem to be on a constant path of spending money on new ‘ideas’ but without actually solving the problem...

House is about 5 years old, Worcester green star boiler & an unvented water cylinder.

Noticed just after we moved in (about 3 years ago) that an overflow pipe was occasionally dripping outside. BG engineers who completed the annual service advised it was a condensate pipe & nothing to worry about.

Dripping gets worse & I decided to do my own ‘internet’ research, found out that it wasn’t a condensate pipe (as it’s copper) but actually a pipe from the upstairs airing cupboard where the hot water cylinder is - the tundish was constantly dripping & exiting out of this overflow pipe.

Internet research suggested that a tundish dripping constantly was potentially a dangerous issue so BG engineer called out. Identified that the expansion vessel was knackered (as couldn’t get any pressure into it) so swapped it out.

This stopped the tundish from dripping, but within a couple of days it returned, although not as constant as before. BG engineer called out again, blamed it on a weakened combination pressure valve (maybe caused by the expansion vessel failure. The combination valve was then changed.

Then we started to get loud vibration noises through the pipes, when the hot water was drawn but only when turning the hot water tap on upstairs & when the hot water was on. BG engineer called again, this time reckoned the flexi from the bottom of the recently swapped expansion vessel was too long & restricting pressure from expansion vessel. This was sorted by a much shorter flexi & extending some 22mm copper pipe.

Still have the problem. BG engineer comes out & fits a pressure gauge on the cold water supply to water cylinder to see what water pressure is doing. We’ve noticed that when we have the noise, when the hot water is drawn, the pressure drops & fluctuates massively before settling down. Also noticed that during the day the pressure is steady at about 2.75 bar, but it seems to increase overnight to around 3.25 bar to 3.5 bar, which I believe is what is causing the noise.

Next suggestion from BG engineer is to fit a 22mm pressure reducing valve on the mains inlet. Happy to spend the money to do it but it feels like we’re not getting to the bottom of it...

I’ve turned the water pressure down on the stopcock but still happens. Thought that if I did this I could ascertain whether a pressure reducing valve would solve the issue. But it hasn’t...

No problem with the BG engineer, he’s been brill, but starting to lose confidence a bit.

Everything was fine before the new expansion vessel was fitted, but we did have a dripping tundish...

If there is a plumber on here that would have some ideas, it would be hugely appreciated!

Cheers!

[JD6]

I think EvilDrPorkChop is a heating engineer/plumber who knows his stuff.

I have had a pretty dreadful experience with British Gas in the past, and this sort of issue on an unvented system sounds very worrying to me.

[EvilDrPorkChop]

Originally Posted by Colmsport

Thought I’d ask if there’s any friendly plumbers on here that could perhaps share some insight into an issue that we’re trying to get resolved at home.

Currently under a British Gas service contract & so far they’ve not been able to rectify the issue & we seem to be on a constant path of spending money on new ‘ideas’ but without actually solving the problem...

House is about 5 years old, Worcester green star boiler & an unvented water cylinder.

Noticed just after we moved in (about 3 years ago) that an overflow pipe was occasionally dripping outside. BG engineers who completed the annual service advised it was a condensate pipe & nothing to worry about.

Dripping gets worse & I decided to do my own ‘internet’ research, found out that it wasn’t a condensate pipe (as it’s copper) but actually a pipe from the upstairs airing cupboard where the hot water cylinder is - the tundish was constantly dripping & exiting out of this overflow pipe.

Internet research suggested that a tundish dripping constantly was potentially a dangerous issue so BG engineer called out. Identified that the expansion vessel was knackered (as couldn’t get any pressure into it) so swapped it out.

This stopped the tundish from dripping, but within a couple of days it returned, although not as constant as before. BG engineer called out again, blamed it on a weakened combination pressure valve (maybe caused by the expansion vessel failure. The combination valve was then changed.

Then we started to get loud vibration noises through the pipes, when the hot water was drawn but only when turning the hot water tap on upstairs & when the hot water was on. BG engineer called again, this time reckoned the flexi from the bottom of the recently swapped expansion vessel was too long & restricting pressure from expansion vessel. This was sorted by a much shorter flexi & extending some 22mm copper pipe.

Still have the problem. BG engineer comes out & fits a pressure gauge on the cold water supply to water cylinder to see what water pressure is doing. We’ve noticed that when we have the noise, when the hot water is drawn, the pressure drops & fluctuates massively before settling down. Also noticed that during the day the pressure is steady at about 2.75 bar, but it seems to increase overnight to around 3.25 bar to 3.5 bar, which I believe is what is causing the noise.

Next suggestion from BG engineer is to fit a 22mm pressure reducing valve on the mains inlet. Happy to spend the money to do it but it feels like we’re not getting to the bottom of it...

I’ve turned the water pressure down on the stopcock but still happens. Thought that if I did this I could ascertain whether a pressure reducing valve would solve the issue. But it hasn’t...

No problem with the BG engineer, he’s been brill, but starting to lose confidence a bit.

Everything was fine before the new expansion vessel was fitted, but we did have a dripping tundish...

If there is a plumber on here that would have some ideas, it would be hugely appreciated!

Cheers!

Too much pressure in your new expansion vessel. They come from factory set at 3.0 bar, it may have slightly more in. It should be set 0.2 bar below your dynamic pressure, that'll be the pressure when you're drawing water off. However it isn't always as straight forward as that. You could try letting some air out of the expansion vessel yourself down to around 2.5 bar (You'll need a pressure gauge to test and you'll need to isolate the water to the cylinder and let the pressure off to get the correct reading in the vessel)

But that's what your issue is.

TBH I never like them when they are piped up with a Flexi, and although you can still have this issue you do find it's more common when the expansion vessel is piped up on a smaller pipe (I.E. Flexi or 15mm copper). They should be done in 22mm and taken from the cold intel to the cylinder (Not the combination valve as many do)

JD6 Thanks for the heads up.

Hope that helps.

[isleaiw1]

Originally Posted by EvilDrPorkChop

Too much pressure in your new expansion vessel. They come from factory set at 3.0 bar, it may have slightly more in. It should be set 0.2 bar below your dynamic pressure, that'll be the pressure when you're drawing water off. However it isn't always as straight forward as that. You could try letting some air out of the expansion vessel yourself down to around 2.5 bar (You'll need a pressure gauge to test and you'll need to isolate the water to the cylinder and let the pressure off to get the correct reading in the vessel)

But that's what your issue is.

TBH I never like them when they are piped up with a Flexi, and although you can still have this issue you do find it's more common when the expansion vessel is piped up on a smaller pipe (I.E. Flexi or 15mm copper). They should be done in 22mm and taken from the cold intel to the cylinder (Not the combination valve as many do)

JD6 Thanks for the heads up.

Hope that helps.

I have no idea what any of that means but I do know you are very generous in your advice!

[Colmsport]

Originally Posted by EvilDrPorkChop

Too much pressure in your new expansion vessel. They come from factory set at 3.0 bar, it may have slightly more in. It should be set 0.2 bar below your dynamic pressure, that'll be the pressure when you're drawing water off. However it isn't always as straight forward as that. You could try letting some air out of the expansion vessel yourself down to around 2.5 bar (You'll need a pressure gauge to test and you'll need to isolate the water to the cylinder and let the pressure off to get the correct reading in the vessel)

But that's what your issue is.

TBH I never like them when they are piped up with a Flexi, and although you can still have this issue you do find it's more common when the expansion vessel is piped up on a smaller pipe (I.E. Flexi or 15mm copper). They should be done in 22mm and taken from the cold intel to the cylinder (Not the combination valve as many do)

JD6 Thanks for the heads up.

Hope that helps.

Really appreciate you taking the time to respond, thanks.

Might have a go at this myself.

In isolating the water to the pressure vessel - would this be as simple as turning the water off at the stopcock & running a tap to empty the pipes? Or will I have to activate the pressure valve on the combination valve?

You’re right with regards to the plumbing of it though - the flexi originally went to the combination valve, but when replaced the BG engineer took a 22mm copper pipe from the top of the combination valve which now terminates to a shorter flexi about 12” long.

Thanks again for your help 👍

[EvilDrPorkChop]

Originally Posted by Colmsport

Really appreciate you taking the time to respond, thanks.

Might have a go at this myself.

In isolating the water to the pressure vessel - would this be as simple as turning the water off at the stopcock & running a tap to empty the pipes? Or will I have to activate the pressure valve on the combination valve?

You’re right with regards to the plumbing of it though - the flexi originally went to the combination valve, but when replaced the BG engineer took a 22mm copper pipe from the top of the combination valve which now terminates to a shorter flexi about 12” long.

Thanks again for your help 👍

Yes your easiest way is to turn your stop tap off, and open your HW tap at the lowest point (Usually kitchen sink) and let it run off. You don't need to touch any pressure relief valves.

When you say the new pipe from the combination valve, is it actually coming from there or a pipe after this? Have you got some photos of the alterations they've done - probably easier to see it.

[Colmsport]

Chaps,

Just wanted to say a big thanks, especially to EvilDrPorkChop for the advice.

Just a bit of an update, the noise this morning was horrendous when the hot water tap was running in the main bathroom so decided to have a crack at the advice above.

The expansion vessel was charged at about 3.2 bar, with water pressure on the gauge at about 2.8/2.9 bar. Reduced it to around 2.5, which to be fair was quite a lot of air from the valve.

I’ve now had the water on & have drawn hot water upstairs & all is well. Previously it would make a noise when the hot water was on. Hoping that this will be the end of it now, but the real test will be in the mornings, but feeling pretty confident at the moment!

Thanks again, really do appreciate your help!

[EvilDrPorkChop]

Originally Posted by Colmsport

Chaps,

Just wanted to say a big thanks, especially to EvilDrPorkChop for the advice.

Just a bit of an update, the noise this morning was horrendous when the hot water tap was running in the main bathroom so decided to have a crack at the advice above.

The expansion vessel was charged at about 3.2 bar, with water pressure on the gauge at about 2.8/2.9 bar. Reduced it to around 2.5, which to be fair was quite a lot of air from the valve.

I’ve now had the water on & have drawn hot water upstairs & all is well. Previously it would make a noise when the hot water was on. Hoping that this will be the end of it now, but the real test will be in the mornings, but feeling pretty confident at the moment!

Thanks again, really do appreciate your help!

Find yourself a good local engineer that comes recommended in future that'll look after you and bin British Gas off The contracts that these big companies offer aren't usually worth the paper they're written on, and the engineers aren't always great - I'm sure there's some very experienced guys who work there but it's the luck of the draw.