The car is a 1996 306 D Turbo
I noticed today is that the heat from the centre dashboard vents is hot, whereas the heat from the side vents, windscreen and footwell is luke warm, bordering on cold. As it's my wife's car, I don't drive is that often. Last winter, I was driving and thought the heater wasn't very warm. The next day, I changed the thermostat, it still wasn't much better. Then I flushed the heater matrix out backwards and it still seemed the same. I've bled the system properly and used a header tank, so there's no air lockage.
Can anyone shed any light on this before the weather starts getting cold Cheers Neil