[Nozon]

Hello

Chemisty seem to be a bit tricky for me, but here is the problem and my take on it. I want to know if anyone can confirm and maybe even give a better explanation on the equillium of the reaction.

Problem /Observation
A electrical kettle containing 53.5 Liter of soft water (Ca++ and Mg++ replaced with Na+) heated up to 8 Bar pressure approx 170°C /  443,15 K become basic - As vapor is removed and new water added the pH increases over time.

Hypothesis
My best guess is that the Na+ ions react with the bicarbonate in the water.
With heat added NaHCO3 -> NaOH + CO2 
The vapor become a little acidic, which can be explained by the CO2 becoming bicarbonate ion which I recall as a weak acid.

But how likely is it that you reach pH 10-11 by heating up kettle water to 170 °C. What I can find it states that it require like 500° C in order to obtain lye (NaOH).