I have the usual problem of a dripping expansion relief valve on the cold supply to an unvented cylinder, which is shortly to be replaced (the valve) by a G3 plumber. What made it worse is that the drip (which has become an almost continuous dribble) tends to run down the inside of the tundish rather than dropping straight down, and has leaked between the (supposed) seal between the tundish and the 22mm pipe below. Ceiling below now marked and paint bulged away from woodwork. The nut securing the tundish to the pipe is tight. It's a cheapo-looking plastic job, 85mm high. Can someone recommend a better tundish, please?