Boiler problems.

Hi,
I've got a problem with my central heating. The pressure has been dropping daily in the last few weeks and we've had to keep topping up the system.I looked everywhere and couln't find a leak anywhere. This constant topping up has caused 'kettling' in the system and now there is water dripping from underneath the boiler. Its a closed system. I'm hoping its just a loose feed pipe or something simple. I'm also worried the kettling might have cracked the heat exchanger which will then cost me a fortune! I'm planning to take a closer look when I get home from work this evening. Has anyone else had experiences similar to this? If so what was wrong?

I'd check the boiler internal's in around the combustion chamber/heat exchanger. What type of boiler is it? How old is the boiler? Have you noticed water dripping from under the boiler before. If you have water dripping from under the boiler. Is this actually through the boiler base cover? If so you have a leak in the boiler. Possible a leaking heat exchanger?

Just replaced a leaking heat exchanger in a Mynute 14SE boiler, Boiler was 6 years old. Wasn't until I opened the front cover, that I observed a pool of water. A pin hole leak in the heat exchanger was the cause. It damaged the insulation on the combustion. Repalced the heat exchanger and combustion chamber and all okay again.

Thanks for the reply, megapixel. I had a closer look when I got home last night. When I took off the cover I noticed a pool of water and the insulation was saturated, crack in the heat exchanger was the problem. Same as your own experience. At least I know whats wrong now so I'll get that sorted.