General Treatment Products, Inc. Residential Glycol Feed Systems automatically maintain pressure in the loop by adding glycol solution to make up for losses which occur due to bleed / relief valve leakage or evaporation. This compact Glycol Feed Package is design for home radiant heat systems, small boiler's and snow melt packages. Coupled with an optional mounting bracket, makes this price effective, durable glycol feed system is perfect for use in the home.