Does anyone know about using antifreeze in a hydronic heat system? We are going to be gone in winter and don't want to worry about our cement slab freezing up! I thought maybe RV antifreeze. Any advice will be appreciated. Thank You.

Dear Saraknows Two types of anti-freeze may be used: EYTHYLENE GLYCOL,used in automobiles,has desirable properties but is toxic.Its use may be prohibited when system water/glycol solution is in contact with potable water source such as a tankless heater. PROPYLENE GLYCOL is used in the food industry and is practicaly non-toxic.Its use is permitted where tankless heaters are used.When anti-freeze must be used,inhibited propylene glycol is recommended.There is more information given in TECHNICAL TOPICS NO.2A.available from the NATIONAL HYDRONICS INSTITUTE,35 RUSSO PLACE,BERKELEY HEIGHTS,N.J 07922 Hope This Helps