15psi 213°F not too big a diff.Under pressure ... water has a higher boiling point ... just like higher elevation, atmospheric pressure cause water to have differing boiling temp ...
Cars for instance have a pressurized cooling system ... the radiator cap is usually set to hold 15 psi ... this allows over 212 degrees without boiling ... "anti-freeze" (coolant) also increases the boiling point chemically ...
my elev is 211°F