... 1.economical heat system 2.antifreeze function 3.over-time protection 4 .saving energy solar hot water circulation system1, the ... , the hot water will be out ,4,over-time protection function: When the circulation pump running for 30 minutes has ... won’t waste any energy.6, leakage protection function: When the system has a leakage phenomenon, leakage protection function is activated, cutting off the ...