Foghorn sound when turning on hot water tap after new bathroom installed

Ella_fella

Pretty much as the title says, after having a new bathroom suite installed everytime I turn on a hot water tap either in kitchen or bathroom after a few seconds an extremely loud reverberating fog horn sound is generated which stops after about a minute.

The source of this sound appears to be in the area in the loft above the shower where the cold water pipes run down from.

Have tried turning water off on mains and draining system which doesn't have any effect, have seen suggestions that it's a perished ball valve but this noise only started after the bathroom work was done and the plumber hasn't been anywhere near the loft where I'm sure there is a hot water tank there - am currently running off a conventional boiler.

Any suggestions gratefully received

daveyjp

Water hammer caused by the new pipework.  Adjusting the pressure slightly may stop it, try and adjust while it is making the noise.

Ella_fella

daveyjp said:

Water hammer caused by the new pipework.  Adjusting the pressure slightly may stop it, try and adjust while it is making the noise.

Thankyou. When you say adjust the pressure the only way I can think of doing this is by relaxing or tightening the stopcock under my sink?

grumbler

Water hammer happens when taps or valves are closed sharply, not when opened.

And it's called 'hammer' for a reason - nothing resembling foghorn sound.

ETA: IMO 'foghorn sound' is likely to be some sort of resonance in piping caused by small vibration produced by water passing through some valve

twopenny

Im interested in this post because I get the same thing from one particular toilet at the end of the tank refilling (noise in attic) but not always. Frustrating.

adonis

It is most likely the valve in the loft needs a new washer or the valve replaced,

same with twopenny's post, but that could be the toilet valve.

Sometimes when having plumbing work done it can throw up faults on other parts if they are worn.

Jeepers_Creepers

Ella_fella said:

Pretty much as the title says, after having a new bathroom suite installed everytime I turn on a hot water tap either in kitchen or bathroom after a few seconds an extremely loud reverberating fog horn sound is generated which stops after about a minute.

The source of this sound appears to be in the area in the loft above the shower where the cold water pipes run down from.

Have tried turning water off on mains and draining system which doesn't have any effect, have seen suggestions that it's a perished ball valve but this noise only started after the bathroom work was done and the plumber hasn't been anywhere near the loft where I'm sure there is a hot water tank there - am currently running off a conventional boiler.

Any suggestions gratefully received

Hi Ella.

I'm guessing, from the info you've provided, that you have a 'vented' DHW (domestic hot water) system, in that there's a hot cylinder in a cupboard (surely not up in the loft?!) and a CWS (cold water storage) tank in the loft that's supplying it?

If so, then most likely cause is the ballcock on that CWS in the loft. That bc has a rubber disc in it which the inlet water valve is pressed against as the ball arm rises to shut off the water. These are prone to vibrating for all sorts of reasons - high water pressure, age making them hard or drying out, etc - and the result is a foghorn sound when these vibes are sent down the pipes - they vibe in sympathy.

Quite possibly - quite likely - this had nothing to do with the new bathroom.

You turn on a hot tap, and the hot cylinder begins to drain. Very quickly the water level in the CWS also drops - since this is what's supplying the hot cylinder - and the ballcock also drops as it follows the water level. The valve opens, and water comes in to refill it. This will carry on for as long as you are draining water, and for a short while afterwards (the duration depending on how much water has been taken). That explains the wee delay before the noise begins after running a hot tap, and the fact it carries on for a while after the tap is closed again.

Are you up for checking out your loft?! If you locate the CWS (phew - it's hot up there...), find the cold mains water inlet pipe - it'll be 15mm (almost certainly) and will connect with the tank at one end and near the top. Cool. Is there an isolating valve on that pipe? (Chrome, with a screw slot in the side).

Are you up for removing the lid from that tank to have a gander inside? Great! Get someone to run a hot tap downstairs until the foghorn blows. Now grab the ball arm and gently lift it up so the water shuts off. Does the noise stop? Cool.

If that is the cause, then the cure is a servicing of that ball valve, or even a replacement. If there is an isolating valve (as asked about before) then that makes the job easier as you can stop the flow to it for removal.

Are you up for dismantling the ballvalve and checking that washer? No? Ok, we've found you limit... :-)

One possible reason why it started after the bathroom refit is that your mains stopcock might have been intentionally left partially-closed to reduce flow and prevent that noise. Your plumber, after installing your bathroom, would likely have left it open near-full.

Anyhoo, first thing is to ID whether it is the CWS.

Jeepers_Creepers

The best song in the world which employs a foghorn.

https://www.youtube.com/watch?v=syIUmrSJWAU

I fib - just one of the best songs itw full stop.

Ella_fella

Jeepers_Creepers said:

Ella_fella said:

Pretty much as the title says, after having a new bathroom suite installed everytime I turn on a hot water tap either in kitchen or bathroom after a few seconds an extremely loud reverberating fog horn sound is generated which stops after about a minute.

The source of this sound appears to be in the area in the loft above the shower where the cold water pipes run down from.

Have tried turning water off on mains and draining system which doesn't have any effect, have seen suggestions that it's a perished ball valve but this noise only started after the bathroom work was done and the plumber hasn't been anywhere near the loft where I'm sure there is a hot water tank there - am currently running off a conventional boiler.

Any suggestions gratefully received

Hi Ella.

I'm guessing, from the info you've provided, that you have a 'vented' DHW (domestic hot water) system, in that there's a hot cylinder in a cupboard (surely not up in the loft?!) and a CWS (cold water storage) tank in the loft that's supplying it?

If so, then most likely it's the ballcock on that CWS in the loft. That bc has a rubber disc in it which the inlet water valve is pressed against as the ball arm rises to shut off the water. These are prone to vibrating for all sorts of reasons - high water pressure, age making them hard or drying out, etc - and the result is a foghorn sound when these vibes are sent down the pipes - they vibe in sympathy.

Quite possibly - quite likely - this had nothing to do with the new bathroom.

You turn on a hot tap, and the hot cylinder begins to drain. Very quickly the water level in the CWS also drops - since this is what's supplying the hot cylinder - and the ballcock also drops as it follows the water level. The valve opens, and water comes in to refill it. This will carry on for as long as you are draining water, and for a short while afterwards (the duration depending on how much water has been taken).

Are you up for checking out your loft?! If you locate the CWS (phew - it's hot up there...), find the cold mains water inlet pipe - it'll be 15mm (almost certainly) and will connect with the tank at one end and near the top. Cool. Is there an isolating valve on that pipe? (Chrome, with a screw slot in the side).

Are you up for removing the lid from that tank to have a gander inside? Great! Get someone to run a hot tap downstairs until the foghorn blows. Now grab the ball arm and gently lift it up so the water shuts off. Does the noise stop? Cool.

If that is the cause, then the cure is a servicing of that ball valve, or even a replacement. If there is an isolating valve (as asked about before) then that makes the job easier as you can stop the flow to it for removal.

Are you up for dismantling the ballvalve and checking that washer? No? Ok, we've found you limit... :-)

One possible reason why it started after the bathroom refit is that your mains stopcock might have been intentionally left partially-closed to reduce flow and prevent that noise. Your plumber, after installing your bathroom, would likely have left it open near-full.

Anyhoo, first thing is to ID whether it is the CWS.

Spot on, thankyou

Slinky

We had similar, right racket when running the shower. Turned out to be the valve in the cold water tank in the loft.

Rosa_Damascena

I had similar last year after having two bathrooms installed. It self-resolved within a fortnight and I haven't thought about it since.