its nothing to do with the modureg it doesnt matter what voltage is going there you are completely on the wrong path with that, the modureg only comes in to use once the boiler has lit its like an accelerator on a car for want of a simpler explanation
Not really the whole story.
Nearly all boilers ignite with about 2/3 the total power!
Biasi boilers ignite at 6 mB out of a total of 10.5 mB on their older boilers!
A typical mod coil operates between 6v and 17v. The Biasi thus moduates between 1.5 mB and 10.5 mB with an applied voltage of 6v - 17v.
Tony