steam in the summer!

Bearno

I have 4 years old Burnham (Gas)steam boiler and Burnham tank.

when the thank asking for hot water boiler works to the point that generats steam which we don't need in summer time.

I have replaced the Honeywell Presuretrol ( L404F367)and the also Honeywell Board R8845U. Both unites are New.

I also took off the pigtail pipe and the elbow that attaches to presuretrol clean both they are totaly open.

I set Main presur on 1 and the differential to 1.5 for steam.

the thermostat on tank is set on 115 and the differential on almost 10.

the room thermostat is set on almost to 60 .

Problem: when some one talkin shower the boilere kicks and it runs to the point that the radiators in the house start making hissing noise and warming up.

Any idea how to solve the problem?

Thanks