Water Hammer & Shock Arrestors

[Mika]

Dear All,

I have had a new boiler fitted last year (Vaillant TurboMAX 828E), and with that a new Bathroom & Kitchen. Since the new items there's been a 'water hammer' problem that has been around, which has now caused me to act!

I've got 2 ideas....1) Fit a Shock Arrestor or 2) Fit a PRV (Pressure Reducing Valve). The mains pressure in the sealed system seems quite high, and I'm guessing that I need to either reduce it (fit a PRV) or fit the 'arrestor(s)'.

If I fit the 'arrestor' do I really need one for each tap where the cold water is? Or can I fit it in a place where all taps/showers will benefit? Bearing in mind that I cannot get access to the pipes for the shower (concealed behind tiles into the wall), bathroom basin (concealed behind tiles into wall with a non-pedestal type basin), the only access to cold water is at the boiler and kitchen sink.

If I fit the PRV, I have no idea where to fit this, and help here would be greatly appreciated.

Thanks in advance

Mika

[Christian McArdle]

The sealed system has nothing to do with it. The pressure is set by opening the valve until the pressure is as required. Whilst the US happily leave theirs connected to the mains via a pressure reducing valve, us UK types are sensibly precluded from doing so.

However, assuming you have a water hammer part in your water supply section (hot or cold) rather than the primary heating circuit, then indeed, both a PRV and a shock arrestor can help. However, I would measure the static pressure and only fit a PRV if the pressure is above around 3 or 4 bar. Otherwise, shock arrestors it is (or even as well, in the case of a PRV).

You want to avoid using a PRV if the pressure is lower, as it may reduce the flow rate.

The closer to the tap they are, the more effective they will be. You may find that you get away with one in the bathroom covering all outlets. However, if you have a serious problem, you may need one per fitting, fitted closely.

As for fitting one in the kitchen to cover the bathroom, you could give it a go, but you might be disappointed (or might not).

Fit it in the rising mains, preferably after the garden tap (and maybe kitchen tap), but before any bathrooms, laundry appliances and water heating appliances (i.e. combi boilers/heat banks).

Christian.

[bigcat]

ways to ersuce the problem:

replace rubber washers in ballcock/taps, this is the main cause of trouble. turn down flow rate slightly on any noisy ballcock clamp pipes securely to wall where not already fit service valves and turn them down from full just slightly. Put where the vibration is greatest in the pipe. If the pipes are unexposed, mechanically absorbent lagging often stops it, eg carpet offcuts or lagging.

ewe con teal eye dont yous a spall chequer car NT yew?

NT