Pressure & Water Bangin

[Lectrician]

I fitted a new electric shower recently. It was replacing the mixer-type shower onthe wall. I capped the hot supply, and used the cold pipe to feed the shower, and altered the plumbing in the loft to give this pipe mains pressure.

All worked fine, and as expected.

In the last few weeks we have had the water authority replacing pipes etc on our estate, and they have now finished.

Since then, it appears as if we have a higher pressure....?

Everytime the shower is started or stopped (solenoid), the pipe feeding it bangs.

Everytime the washing machines solenoid operated, the pipe feeding it bangs, different pipe, different floor.

Same problem with the toilet - It has one of the quick fill valves which stop suddenly.

So, my missus thinks it is me with the shower.......but I think the pressure has been increased? Adjusting the main stop tap makes little difference, except for reducing the flow considerably!

Could I get the waterboard to check, or do I need to look at a pressur reducing valve? Would this be ok with a mains pressure shower?

Current setup is mains water to kitchen, utility, and to fill cold water tank and cent heat header tank in loft (also tees in loft to new shower). Bathroom has tanked cold water, and HW from cylinder. Cylinder is heated by a standard boiler, gravity system. Sent heat is pumped, and taked heat from cylinder via a coil (I think).

Thanks for any advise!

 

[Softus]

Everytime the shower is started or stopped (solenoid), the pipe feeding it bangs.

You probably have an unsupported pipe somewhere.

Everytime the washing machines solenoid operated, the pipe feeding it bangs, different pipe, different floor.

You probably have an unsupported pipe somewhere else.

Same problem with the toilet - It has one of the quick fill valves which stop suddenly.

!

do I need to look at a pressur reducing valve?

Yes; or clip the unsupported pipes to something solid.

Would this be ok with a mains pressure shower?

Yes, as long as you set the pressure above the minimum value specified by the shower manufacturer (commonly 1 bar).

If you buy a PRV then you'll get a pressure gauge that will allow you to see the prevailing mains pressure.

 

[Lectrician]

Thanks - but I would like to point out that all the pipework has been in situ for 20yrs, and has been fine for the 15yrs! It seems to be due to the works in the street.

The shower is using an original pipe, although the pipe was for tanked pressure originally.

 

[Softus]

Thanks - but I would like to point out that all the pipework has been in situ for 20yrs, and has been fine for the 15yrs! It seems to be due to the works in the street.

This just means that it's a 20-year-old installation fault that's been waiting to be noticed, and that it's been provoked into being a nuisance.

 

[simond]

I suggest you fit a shock arrestor.

This is a small expansion vessel with an air bladder. When the higher flow/pressure causes a shock wave when suddenly terminated (eg: solenoid valve in shower - I assume your shower turns the water off with a switch rather than twisting a knob) the arrestor damps the wave and silence is preserved.

 

[Softus]

... and if you get regular spots and zits, don't worry about changing to a healthier diet, simply cover up the symptoms with a dab of face cream or some such. Lovely job.

 

[simond]

So there you have it;

You could upgrade your pipework.
Or fit a shock arrestor, and risk spots and zits.


I have a similar dilemma each time I hanker for a kebab. The kebab normally wins. Let us know how you get on, Lectrician.

 

[timbalcombe]

similar problem, wher the bleedin hec do you purchase one of these water hammer arrestors?
My ggogle search ended me up here.

 

[doitall]

plumbcenter should keep shock arresters for potable water

 

[ChrisR]

Are there any "dead legs" in the CW main? These can trap air after work's been done, which causes banging.

Here's an arrestor - connect it through an isolating valve and you can alter the effect.
http://www.bes.ltd.uk/products/graphics/11355.gif

Merchant local to me carries smaller ones, about 100mm long and 25mm diameter.

 

[simond]

Mira showers demand you fit this type of thing to their Excel thermo mixers when connected to a combi.

It appears they are worried about the expansion in the HW side of the combi causing their shower valve to become difficult to operate...... Now this IS a case of Softus' scenario with the zit cream.

Needless to say you don't get the expansion vessel with the Mira shower kit, and have to source it yourself.

 

[Softus]

Mira showers demand you fit this type of thing to their Excel thermo mixers when connected to a combi.

I take yout point, simond, and I sense there isn't as large a chasm between us as once there was, but, to be ever the pedant, Mira can't make a demand, merely make the installation of a thingy a condition of their warranty.