Lynn,

 

what is the 10% anti-freeze for?

!0% seems very low to do any serious "anti-freezing".

Is there a different purpose behind?

 

Thomas J.

Each pound of pressure (pressure cap) raises the boiling temp three (3) degrees.

Then a 20 PSI cap is about 60 degrees. The 10% increases boiling temp (about) 30 degrees (76/1000).

 

The 10% reduces freezing temp to 27 degrees. 

 

Check out the data on an antifreeze jug.

 

Lynn E. Hanover