Header water tank float valve confusion

ThisIsWeird

Apodemus said:

On a connected issue - isn't the water level in that tank a bit high (if your CH is cold)? I don;t know if it is, but I'd always set mine lower than that to provide plenty of elbow room; as your system heats up, expanded water is fed into that tank via its lowest pipe, and the level will rise to a max level. You don't want that 'highest' level to be too close to that overflow, I don't think.

I believe it is the header tank for the domestic hot water system, not a CH header tank,  So the fill level looks to be correct.

Thank you.

ThisIsWeird

k1rkyc said:

Thank you for your reply!

I asked the plumber if I could turn the valve outside the tank slightly to stop the water filling so quickly but he said he wasn't allowed to as he's water board approved?!

The noise seems to be the cold water from the tank re-filling the hot water tank below it. It's very loud, and then just towards the end when the arm of the valve moves up, it's a little louder again!

With regards to a knocking/hammer noise, YES! we have recently noticed that! We don't have any way of knowing what our water pressure is, but we had to turn the cold water valve down under the kitchen tap as it was too powerful! our mains stop cosk is behind the toilet so not sure how a PRV would fit?

If this is the domestic CWS that supplies the hot cylinder, then it wouldn't be a good idea to tweak down the isolating valve. Tbh, it isn't a good idea anyway - it's not a proper fix, and could lead to other issues. It was just in case a gentle tweak would sort the noise, without affecting the actual flow by much, but it's best left alone.

It does sound like the drone you get when the pressure is too high, and the sheer force of the flowing water sets the rubber washer vibrating, or sometimes if the ballcock isn't anchored properly so, again, can vibrate.

A Part 2 ballcock differs only by having its water outlet on its top - so needs a plastic upside-down U tube to aim it back down at the water - and that the ball is mounted on an adjustable slider so doesn't need the actual arm to be bent to find the correct level! There is no 'reason' why these differences would affect the noise, but every valve is marginally different, and one might just not resonate so much as another.

From what you also describe, I would guess that excessively high pressure is the actual 'cause'. Test: when it next 'drones', try turning on the cold kitchen tap. Does the drone stop?

The cold water valve under the kitchen sink, does that supply only the kitchen sink? If you turn down the stopcock behind the toilet (unusual place), does that also shut off the kitchen?

k1rkyc

It's more like a very high level whoosh and it sounds like too much water is trying to fill up the tank too quickly..... I guess that we haven't noticed it until now as the old one was so worn and full of limescale maybe?! It's just SO loud and embarrassing when people are here

Unusual is our house! haha Yes, it's only supplying the kitchen sink, and yes it shuts off the kitchen when it's off.

Also, the valve he's fitted says 'high pressure' on it - could that be why?

ThisIsWeird

k1rkyc said:

It's more like a very high level whoosh and it sounds like too much water is trying to fill up the tank too quickly..... I guess that we haven't noticed it until now as the old one was so worn and full of limescale maybe?! It's just SO loud and embarrassing when people are here

Unusual is our house! haha Yes, it's only supplying the kitchen sink, and yes it shuts off the kitchen when it's off.

Also, the valve he's fitted says 'high pressure' on it - could that be why?

I'm not so familiar with 'whooosh', except when conversations go over my head :-(

If it's literally the sound made by the incoming jet of water hitting the water already in the tank, then perhaps tweaking down the isolating valve to the ballcock is worth trying? But, you'd need to ensure it isn't turned down to the point where the tank cannot refill fast enough to cope with demand. So you'd need to note what that demand is by, say, turning on a main hot and cold and checking the CWS level doesn't fall faster than it can be kept topped up :-)

'High pressure' is the correct ballcock, because that is what your system appears to be.

I don't follow what you say about the main stopcocks. Is it that the one under the sink only shuts off the sink? And the one behind the toilet shuts off the whole house? If so, a PRV - should you decide to fit one after further tests - would go after the 'toilet' one.

Apodemus

k1rkyc said:

ThisIsWeird said:

k1rkyc said:

Hi everyone! We recently had issues in the loft where the header tank valve was dripping. We had a plumber come and replace it, and although he said it was sorted, it was still dripping. He fitted the part in a rush and we didn't feel confident with him so we asked another plumber to come. He said we needed a different type of float valve as the one fitted was meant for a toilet, not a header tank....... 

He's since fitted what he assures us is the correct type, and the dripping has stopped, but the noise when the hot water taps are used and the tank filling up is awful. It's 10 times louder than it used to be! We've asked him again and he's basically said there's nothing he can do......

Here's what he's fitted. Can anyone please tell me if this is correct and if it's supposed to sound like a plane is departing the runway each time we use any hot water?! Thank you!

From what you describe, you are not suffering from the noise of the water landing in the tank, but from the new valve resonating from the force of the water passing through it - classic 'foghorn' :-)

So, adding a plastic tube - which you seemingly shouldn't anyway - is unlikely to fix it. 'Plumb' gave you a good list of options to try.

As an initial step - since you really should do this anyway (and is another reason why you shouldn't invite that plumber back) is to buy the 'by-law' kit, which has a lid (which I hope will fit neatly - but might not), and insulation jacket (no harm in having two), and ballcock (two is alwasy good) and other bits that you are unlikely to use (I think they prevent insects crawling up the overflow pipe and in to your tank?!)

There is a chance - not very high - that fitting a snug lid could help as it may dampen or change the resonant frquency of the bc. Also worth trying - as it's easy - turning down the isolating valve as this will reduce the flow to the bc, and even the pressure to it until it's nearly fully off. This might work, but you'd need to ensure the bc still passes a healthy flow.

There's even tricks like dismantling the bc - easy to do in situ, but don't drop any bits into the tank - and coating the rubber washer with silicone grease - I've done that successfully a few times, and it's often enough to dampen the vibration and prevent it building up to a resonance.

I think, other than that, it'll require a bc-off job to add a stiffening plate to the side of the tank, in which case you might as well replace the bc with the correct P2 type (and give it a good silicone-greasing first).

Do you have any other noise issues with your plumbing? And 'hammer' or knocks when you turn taps and toilets on and off? I wonder if your water pressure is a bit high, so you might benefit from having a Pressure-Reducing-Valve fitted after your mains stopcock? (But only if you are noticeably above 3 bar).

On a connected issue - isn't the water level in that tank a bit high (if your CH is cold)? I don;t know if it is, but I'd always set mine lower than that to provide plenty of elbow room; as your system heats up, expanded water is fed into that tank via its lowest pipe, and the level will rise to a max level. You don't want that 'highest' level to be too close to that overflow, I don't think.

Another solution could be to fit a 'Torbeck' type valve, but I don;t know if these are allowed in these tanks? If they are, these operate in a completely different way, and shut off 'instantly', so leaving out the partially-closed resonating part.

ThisIsWeird said:

k1rkyc said:

Hi everyone! We recently had issues in the loft where the header tank valve was dripping. We had a plumber come and replace it, and although he said it was sorted, it was still dripping. He fitted the part in a rush and we didn't feel confident with him so we asked another plumber to come. He said we needed a different type of float valve as the one fitted was meant for a toilet, not a header tank....... 

He's since fitted what he assures us is the correct type, and the dripping has stopped, but the noise when the hot water taps are used and the tank filling up is awful. It's 10 times louder than it used to be! We've asked him again and he's basically said there's nothing he can do......

Here's what he's fitted. Can anyone please tell me if this is correct and if it's supposed to sound like a plane is departing the runway each time we use any hot water?! Thank you!

From what you describe, you are not suffering from the noise of the water landing in the tank, but from the new valve resonating from the force of the water passing through it - classic 'foghorn' :-)

So, adding a plastic tube - which you seemingly shouldn't anyway - is unlikely to fix it. 'Plumb' gave you a good list of options to try.

As an initial step - since you really should do this anyway (and is another reason why you shouldn't invite that plumber back) is to buy the 'by-law' kit, which has a lid (which I hope will fit neatly - but might not), and insulation jacket (no harm in having two), and ballcock (two is alwasy good) and other bits that you are unlikely to use (I think they prevent insects crawling up the overflow pipe and in to your tank?!)

There is a chance - not very high - that fitting a snug lid could help as it may dampen or change the resonant frquency of the bc. Also worth trying - as it's easy - turning down the isolating valve as this will reduce the flow to the bc, and even the pressure to it until it's nearly fully off. This might work, but you'd need to ensure the bc still passes a healthy flow.

There's even tricks like dismantling the bc - easy to do in situ, but don't drop any bits into the tank - and coating the rubber washer with silicone grease - I've done that successfully a few times, and it's often enough to dampen the vibration and prevent it building up to a resonance.

I think, other than that, it'll require a bc-off job to add a stiffening plate to the side of the tank, in which case you might as well replace the bc with the correct P2 type (and give it a good silicone-greasing first).

Do you have any other noise issues with your plumbing? And 'hammer' or knocks when you turn taps and toilets on and off? I wonder if your water pressure is a bit high, so you might benefit from having a Pressure-Reducing-Valve fitted after your mains stopcock? (But only if you are noticeably above 3 bar).

On a connected issue - isn't the water level in that tank a bit high (if your CH is cold)? I don;t know if it is, but I'd always set mine lower than that to provide plenty of elbow room; as your system heats up, expanded water is fed into that tank via its lowest pipe, and the level will rise to a max level. You don't want that 'highest' level to be too close to that overflow, I don't think.

Another solution could be to fit a 'Torbeck' type valve, but I don;t know if these are allowed in these tanks? If they are, these operate in a completely different way, and shut off 'instantly', so leaving out the partially-closed resonating part.

The noise seems to be the cold water from the tank re-filling the hot water tank below it. It's very loud, and then just towards the end when the arm of the valve moves up, it's a little louder again!

It would probably be good if you could differentiate the sounds from your hot water cylinder and the sounds from your header tank.  What, if anything, has changed about the water entering the hot tank?  Surely the pressure from header tank to hot tank can't have changed, unless the pipe run has been altered?  

ThisIsWeird

Yes, it would help to know just what this sound is. Could you take a short clip using your phone and use a third-party site to post it on? Imgur, YouTube, and I'm sure there are many others.

The solution will completely depend on the cause.

Section62

grumbler said:

If a 'tube' is made from soft plastic film, you can pump water through it, but It's impossible to suck water back.

This has been found to be not the case in practical use - in particular as the plastic hardens with age it can be stiff enough to allow some backflow of water.

Anyone old enough to remember plastic drinking straws may also remember chewing or bending them so they were no longer rigid.  If you then sucked on the straw hard it would collapse and no drink would come out.  But it was possible - if you sipped slowly - to carry on drinking using a damaged straw, so long as the flow rate was low enough.

The golden rule with potable water is not allowing it to become contaminated with stored water.  Hence the use of air gaps or check valves. The plastic film 'tubes' simply don't give an adequate level of protection against backflow - and hopefully they will vanish from plumbing systems over time.

Meanwhile, fitting any kind of rigid or semi-rigid 'tube' to a valve filling a stored water tank is an absolute no-no.