My halstead best 50 keeps loosing pressure. I top up the system but the pressure goes within 30 minutes. The overflow pipe outside keeps dripping. I have checked the radiators/pipework for leaks but cant find any.

Paul Hagan, June 2008

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