ideal mini

[mikegas]

hi the above boiler is rising to 3 bar then discharging through prv, suspected expansion vessel so i depressed schrader valve on the vessel to see if the diaphragm had split but no water came out, so does this mean it just needs re charging or can the diaphragm stretch causing the same fault meaning i need to replace expansion vessel. any advice please

 

[wnjswozo]

check filling loop,might just be open a midges,
isolate heating circs on boiler,empty,recharge to 1 bar,see how you go on

 

[mikegas]

checked filling loop, only rises when heating demand. Do you need to leave an end open somewhere so water or air can be discharged whilst charging vessel? also do you know if the diaphragm can stretch giving the same symptoms of a split diaphragm?

 

[oldplumber]

Discharge the radiator system pressure via a doc, not the prv in the boiler. then take a pressure reading on the shraeder valve and see if the expn vessel needs topping up, morally around .5 bar check your mfi for exact setting. just cos no water escaping doent mean expn vessel charged correctly

 

[wnjswozo]

the diaphram is designed to stretch so far,but wont go like a balloon.
do as i say above,you need to drain boiler only,there will be a drain off on boiler itself. you dont need to drain the full system.close drain off then re,pressrize to 1 bar
you,ll see pressue gauge on boiler start rising when you pump it up,then a 1 bar ,take off pump,open circs to boiler ,if nessesary,fill to 1.5 bar with filling loop.must drain boiler

 

[mikegas]

the diaphram is designed to stretch so far,but wont go like a balloon.
do as i say above,you need to drain boiler only,there will be a drain off on boiler itself. you dont need to drain the full system.close drain off then re,pressrize to 1 bar
you,ll see pressue gauge on boiler start rising when you pump it up,then a 1 bar ,take off pump,open circs to boiler ,if nessesary,fill to 1.5 bar with filling loop.must drain boiler

ok so if theres no water coming out of the valve on vessel then the vessel cannot be faulty and it only needs charging? also for future if i ever need to replace a vessel and cust chooses external vessel rather than replace existing would i just connect onto either the flow or return?

 

[oldplumber]

return would be the easy norm, try t'ing onto the filling loop pipework, saves cutting into the return

 

[mikegas]

Ok thanks for all the replies

 

[Billy Bob Bob]

ok so if theres no water coming out of the valve on vessel then the vessel cannot be faulty and it only needs charging? also for future if i ever need to replace a vessel and cust chooses external vessel rather than replace existing would i just connect onto either the flow or return?

its failed,a recharge may work but i would put a new one in also safety valve if its opened it tends to not re-seat

 

[mikegas]

its failed,a recharge may work but i would put a new one in also safety valve if its opened it tends to not re-seat

Thanks gas man. I did replace prv i also re charged the vessel and filled system to 1.5 bar, the pressure did rise to 2 bar but very slowly but customer had to be somewhere so i couldnt wait to see if the pressure continued to rise so maybe i will need to replace vessel tomorrow. In what way do the vessels fail other than diaphragm splitting?

 

[Billy Bob Bob]

rarely the casings split but it would flood the place its normaly the diaphragm

 

[aggis]

Always worth checking the supply tube/pipe to the expansion vessel as can be blocked on any boiler. Therefore if blocked & you have repressurize the exp vessel & the system will still blow off!

 

[Billy Bob Bob]

Always worth checking the supply tube/pipe to the expansion vessel as can be blocked on any boiler. Therefore if blocked & you have repressurize the exp vessel & the system will still blow off!

good point, neutral point in sealed system

 

[RoryD]

checked filling loop, only rises when heating demand. Do you need to leave an end open somewhere so water or air can be discharged whilst charging vessel? also do you know if the diaphragm can stretch giving the same symptoms of a split diaphragm?

All you have to do is hold the PRV open as you pump the vessel to 0.75bar, this allows water to displace.... job done!