Shock arrester or mini expansion vessel

[Flue man]

Fitted a baxi duo tec last week , and the hot water cycle starts , as the cold water is used, spoke to baxi and they said , I need to fit a shock arrester/mini expansion vessel , baxi say this is becoming really common , it's never happened to me before , can this be fitted anywhere on the cold water circuit , even on the capped cold pipe in the cylinder cupboard? Thanks

 

[SimonG]

I would want it as close to the boiler as you can get it.

 

[AWheating]

does the main have a NRV/ meter?

 

[Vee]

Very common with NRC in meter or water softener / combi mate type, I.e nrv.

 

[kris]

It would have to go close to the boiler --between the boiler cold inlet and the closest tee piece.

 

[kris]

I had one a few months ago . Couldnt work out why as no meters , softners or non returns . I fixed it but never knew what was causing it. I put it down to the boiler ( custard bought a glowworm flexicom for about 500).

 

[josh]

I had one a few months ago . Couldnt work out why as no meters , softners or non returns . I fixed it but never knew what was causing it. I put it down to the boiler ( custard bought a glowworm flexicom for about 500).

Sometimes lever type taps shut of quick do it as creates shockwave, I'v been told to fit a NRV then an expansioni vessel after to take the expansion rather than just a vessel. Can't remember the type now but in boilers they've (the newer baxi's anyway) changed the flow switch (think to the turbine type) to stop this problem. Was told that on one of their training days.

 

[lame plumber]

intergas combis can suffer as well from this especially with ceramic taps, as mentioned a shock arrestor cures it normally

 

[happyflyer]

Old rubber washer ball-taps use to cause water hammer before dip pipes came in, water boards would not allow dip pipes they thought it would cause back syphoning, old plumbers used to wipe a branch joint to the ball tap on the gravity tank, this was a short 1/2" lead up stand, this was a mini shock arrester, near to the source , water hammer was caused by waving in the tank, another piece of complete useless information from an old git, long live push-fit and water hammer.