Noisy valve for cold storage tank

basill

It`s driven me mad for some time (years) now, when I use water from the plastic loft storage tank its ok until the last few minutes as the ball valve is closing. It makes an awful SH SH SHHHHH noise for several minutes until the tank is finally refilled, I `m sure it must be audible in my neighbours houses as well but they have not said anything
There is history with this tank, it used to make a very nasty loud humming/buzzing noise which shook the pipes throughout the house as the valve was closing as well. I found this was caused by the tank side flexing as the valve closed. I have braced the pipe to a convenient joist, the tank itself will not allow side to side movement and the brace prevents horizontal movement and that noise is now history. I have replaced the valve with a similar part. I have also drained the system and ensured it refills from the bottom up to try and remove air from the top of the system.
I`m at my wits end and I`m hoping some of you can think of a cure?

TIA

Basill

gromituk

Try a Torbeck or a Flowmaster valve. These are either fully open or fully closed. However, although the Torbeck doesn't close instantaneously, I have had problem with oscillations. It may be due to my particular water pressure and pipe layout.

moneysavingplumber

The most effective cure for water hammer is usually a mini-expansion vessel fitted along with a double check valve, immediately after the mains stopcock within the property, check valve first and then the vessel. Torbecks and equilibrium valves don't always solve the problem, although in some circumstances they do. Pressure reducing valves can also help if the problem is related to high mains pressure.

basill

If I`d stayed on the forum I would have seen your almost instant replies!

I don`t think its related to pressure as winding the stopcock almost closed has no effect on the noise so I`ll try one of the suggested valves.

Cheers

B

moneysavingplumber

Winding down the stopcock won't reduce the pressure, just the flow rate. The closing action of the ball-valve can cause the jumper to vibrate in the mains stopcock causing the resonating sound. If the pressure is genuinely too high then a proper pressure reducing valve is necessary, reducing the flow rate can exacerbate the problem.

fazz

I slightly reduced the flow thro' my mains stopcock, this solved my "howling" cold water ball valve, and the "sound like a jet engine" toilet flush refilling!

Martini

moneysavingplumber wrote:

Winding down the stopcock won't reduce the pressure, just the flow rate. The closing action of the ball-valve can cause the jumper to vibrate in the mains stopcock causing the resonating sound. If the pressure is genuinely too high then a proper pressure reducing valve is necessary, reducing the flow rate can exacerbate the problem.

Surely it does reduce both the flow and the pressure until the float valve closes.
Then the pressure in the pipework will equalize at the mains pressure either side of the stopcock until the float valve opens again.
I hope that makes sense!
Although I do agree with your cure!

moneysavingplumber

Martini wrote:

Surely it does reduce both the flow and the pressure until the float valve closes.
Then the pressure in the pipework will equalize at the mains pressure either side of the stopcock until the float valve opens again.
I hope that makes sense!
Although I do agree with your cure!

Glad we agree on the ultimate cure!

If you have ever come accross a blocked water main or one with a cranked down valve, when you open a tap the water bursts out at high pressure and then slows because the flow rate is reduced, but the static pressure is the same. As a ball valve closes and the flow rate slows further, it will allow the working pressure to catch up again, there again increasing the risk of the noise problem. Cranking down valves where pressure is excessive can often cause a high pitched whine as the water is forced through the smaller opening at high pressure, which can be worse than the original water hammer.