Will fitting a tap aerator cause a problem with my boiler?

Any combination boiler should have enough safety devices to ensure that the restrictive nature of the aerator does not damage the appliance. The fact behind this is that a tap can actually be more restrictive than an aerator on the outlet, should the tap only be opened a fraction (itself a method of eco flow control) this can show an even reduced flow than the aerator offers.

If you are in any doubt please consult a professional plumber.