we have a combi boiler, it heats the radiators fine and the hot water to sink and basin, the shower wont remain constant temperature and the bath water is only warm why is this?
Mine is like that although not quite as bad as you describe. When I want a really hot bath or to do the washing up, I don't turn the tap on all the way. I think it's bacause there is a limit to the amount of cold water it can heat - the faster the water flow the harder it works to get the water hot. Slow the water flow and the water gets heated sufficiently. I think!