Ravenheat CSI85(T) Boiler?

This boiler was fitted in January 2006.

The problem I have is if the central heating is NOT on and I want to run some hot water, I have to wait over a minute for the water to start getting warm, then it eventually reaches the temperature that it's set at.

However, when the central heating is ON and I go to run hot water, I'm getting scalding water through immediately and it takes over a minute and a half before it cools down to a temperature that you can actually put your hand in. I've lost count of the number of times that I've burned myself on it.

I've called out the guy from the Council (it was them that installed it) several times and he tells me that there's nothing wrong with it - that's the way it's meant to work. But this must surely be dangerous? What if a kid puts their hand under the tap when it's like this? They could get serious burns.

Anybody else with this type of boiler have the same problem?