I have a washing machine which is connected to the hot and cold water supply. When filling the machine for a 40 or 50 degree wash it does not draw hot water from our combi boiler. However, carried out a rare 90 degree wash the other day, and it did. Does the machine heat up the water sufficiently at a lower degree wash or is there another reason for this? Our water pressure is fairly high, so this isn't the problem.