Thought I would just post my recent experience with my Ravenheat Primary CSI which is about five years old, a few days ago grey liquid was pouring out of the bottom of the case, it turned out the condesate drain was blocked somewhere, after a lot of time spent I ended removing boiler from wall and removing the aluminium condensate heat exchanger, the drain pipe at the back of the exchanger was completely blocked, ended up using a hammer and a screw driver to break it out and using a round file to clean the inside if the pipe, in the instructions it says pull the plastic elbow off the aluminiumm pipe, how ? it was so firmly attached to the pipe that I had difficulty removing it even with the boiler off the wall, anyway flushed the exchanger out, cleaned the plastic drain pipe, and the condensate trap and checking the outside drain pipe, reassembled everything carefully and have been rewarded with the greatest sight in the world being a nice steady flow of condensate into the drain, only other fault I have had was the spark electrode so I always keep a spare now.

kevinbswiss, March 2011