new AFCO radiator

[TMat]

I just got my new afco radiator, it's a double pass with a built-in heat exchanger. A very nice piece. I was looking at the instructions and it says "A good surge tank placed in line with the overflow will insure integrity of the cooling system throughout the heating and cooling cycles."



I've never seen this before, I've seen an overflow or surge tank alone but not the 2 together. Anyone, familiar with this. Is the surge tank just to catch the overflow so it doesn't end up on the ground?

[chevyhector]