Sounds like you have an air lock in the heater, needs bleeding. From cold check and top up coolant, run engine without coolant cap put heater control to hot, watch the fluid level, will rise then fall suddenly when the thermostat opens, top up coolant and put the cap back on, later when the engine has cooled down again, check coolant level. Hope this helps.
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Sounds like you have an air lock in the heater, needs bleeding. From cold check and top up coolant, run engine without coolant cap put heater control to hot, watch the fluid level, will rise then fall suddenly when the thermostat opens, top up coolant and put the cap back on, later when the engine has cooled down again, check coolant level. Hope this helps.