Question Author
In reply to all of your very kind answers, the washing machine has always taken in hot water, even when the "tap" connector which attaches to the washing machine hose, was dripping. When the machine wasn't taking in hot water, I loosened the washing machine end of the hose to ensure that the water was getting through & it was. I removed the filter and it was spotless, and I have checked the hose and there aren't any kinks in it so I have decided to change the hose for a smaller one to see if that makes any difference, but many thanks for all your answers, they are all really helpful so I can't really pick a "Best Answer"