my halstead best 50 keeps loosing pressure?

because its going out the overflow (pressure relief valve)outside as you said,????

your 3 bar safety valve has opened up either due to yourself over pressurising the boiler or due to a fault like below. now the valve isnt shut 100% due to dirt or similar and is allowing system water out.

boiler cold--guage around 1-1.5bar
boiler with heating on for 15 mins--guage around 2-2.5bar
(normal operation)

if cold is correct then with heating on pressure guage rises to 3+bar then expansion vessel needs recharged or replaced.

just mentioned cos 2 sometimes related.

iain
June 2008