at 190bhp maybe you just need a bigger rad??

is it a 1.6 CVH or is it ZVH? - i hear ZVH's can have head gasket issues

if youve recently emptied the water system you could have an airlock...

could be a number of things.

just a thought aswell, not sure how the pipes go but make sure that both the water pipes going to the heater matrix are coming from a T piece...
basically what i mean is, if you turn the heaters to cold, its not going to stop it circulating to somewhere else!