Small pocket of air trapped in a stub of pipe? Aka a water hammer arrestor?
Pressure sensistive bypass will spring shut after the transient, possibly making the hammer worse. Water hammer does not behave how one might expect. The sudden pressure build up caused by the interia of the moving water needs to be dissipated/absorbed by something.
I actually measured the volume required to fill my new CH system of a new combi and 14 radiators.
I simply read the water meter, then filled the system via teh filling loop until I achieved correct system pressure.
I then re-read the water meter and subtracted the previous reading.... Came out to 83 litres.
(The manual was saying if system volume > 100 litres, an expansion vessel would be needed)
In message snipped-for-privacy@mid.individual.net>, Roger Hayter snipped-for-privacy@hayter.org writes
Ok but where does the boiler output go? Stop the pump and it would lock out on over temperature surely.
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Hopefully a pressure sensitive by-pass would restrict the pressure rise. I may have miss-described the boiler relief valve opening.
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My suggestion was having a valve open a bypass pipe, and after a second or so operate the diverter. No need to stop the pump.
In message snipped-for-privacy@mid.individual.net>, Roger Hayter snipped-for-privacy@hayter.org writes
OK. That should work. I may try the valve first as the plumbers fitted one! Sadly in the wrong place!
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name and Shame him !
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