exspansion vessel

[desrob]

why would you put one of those small shock absorber type exspansion vessel on the incoming cold supply to a combi boiler,water pressure not excessive,no unwanted noise prior to been fitted.any other reasons,please enlighten me?

 

[Bartdude]

Water meters and check valves can stop the expansion of hotter water into the water main. This can cause the pressure to increase which can affect the boiler,washing machines etc.The vessel protects the boiler from this pressure build up.

 

[desrob]

but surely all back flow preventive measures from appliances etc, are in place and i;ve never heard of the incoming mains getting hot enough to exspand,sorry mate but am i missing some thing here or have you miss understood

 

[Bartdude]

Mixer taps,showers and the like are points where the hot and cold supplies can cross to one another. That can cause a temperature rise and therefore expansion. In reality the amount of expansion in a water main would rarely cause problems and I think manufacturers mention it to cover themselves for an out of the ordinary situation. Worcester have it here

Greenstar 37CDi Supply requirements - Worcester, Bosch Group UK installer site

 

[Reg Man]

Expansion vessel on incoming main to combi's and water heaters are a common requirement with MI's, but this is rarely adhered too.

 

[SafeGasInstall]

i think also to prevent hammering effect

 

[desrob]

yes it;s all there ,never came across it before and think it highly unlikely, but you never no,thankyou.

 

[gasmarc]

you use to get them in some boilers ,a little metal ball abit bigger than a tennis ball, regarding fitting valves etc , some manufacturers specify pressure reducing valves , which i still dont fit , but I have heard from an instructor where thames water managed to burst a load of combis on the same street apparently there were a few different vans down the road that day, And there is also an issue where the insurance firms wont pay out if this happens