To All Concerned.
Lately I have found a lot of confusion regarding the proper coolant in all Aqua-Hot /Hydro-hot heating systems

      Below is a direct respond fron  Aqua-Hot

   PROPLENE GLYCOL, BOILER BASE ANTIFREEZE, -100F; G.R.A.S. APPROVED
AQUA-HOT SERIAL #s 03-725 to 03-733; 03-751;03-761 and from 03-774 on...
Hydro-Hot Serial #s03-586 to 03-590: 03-590; 03-618;03-619 and from 03-653 on...


1 Gallon; MSX-300-270; MIX 50/50
1 Qt; MSX- 300--275 Mix 2 part distilled water to 1 part Antifreeze
Thanks
Orman