I top my boiler(Saunier duval SD620F) up every day to have found out it is leaking from the over flow pipe outside and would like to know what spare part i should be buying to rectify the problem.It won't even last a full night for the central heating to come on in the morning without screeching when timer operates.

Kevin thompson, February 2008

I have this problem and am sick of everyone scratching thier heads and not solving it.
What was the final outcome. My boilerman says the pressure is right on the exp tank??

david, September 2008

No parts required. The exansion tank on the back of the boiler needs repressurizing. The boiler, is not absorbing the extra volume created when the heating water expands. You have to drain the expansion tank and refill with air. bicycle pump required.

bendan, February 2008