16-12-2013, 02:20 PM
It is supposed to be pressurized, water expands when heated, so that's perfectly fine by itself.
Problem is if it gets so high that the cap starts to spit out water, or if you get air-pockets in the system which disallows the water to flow properly, hence overheating.
Problem is if it gets so high that the cap starts to spit out water, or if you get air-pockets in the system which disallows the water to flow properly, hence overheating.