Attached is the setup in a utility cupboard. The condensing pipe from a boiler was fitted 15 months ago and I have not had any problems. I decided to investigate a bad smell from the washing machine which I've discovered is from the waste outlet pipe. The pipe has been cleaned but I noticed for the first time after moving boxes that the horizontal waste pipe appears to flow at the wrong angle, presumably because the boiler fitter altered the waste angle when trying to fit the condensing pipe fittings. Is it just force of water from the washing machine that allows it to escape?
Thanks.