Higher Speed = More Heat?

[mike65]

Hi

I have noticed my ventalation/heating system (non a/c) is pretty feeble when it comes to hot air unless I get moving! At tickover from a cold start there nothing much happening, then hit the loud peddle and the flow of air is greater and the heat comes through much better, but this is also true when the engine has warmed fully (though to a lesser extent).

Can anyone tell me why?

Mike.