Just had the diaphragm replaced on a Ravenheat RSF 82ET due to no hot water trouble is i now have hot water but it takes an age to come through any tap when boiler is in DHW mode. When it is in DHW / CH mode the hot water is almost instant. When its on DHW only the radiators are all getting hot first. Could it be that the problem was also the diverter valve as well the diaphragm. The diaphragm definitely needed changing though as it had perished.