Not a gret idea. + l: b# K, |2 m* e- V* V' E 3 r6 f r% Y* X6 b& gHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe. # P& b* v. X" s( T( ?* L/ A( ^* `1 e" F8 ~% ?& a* X! q. X5 U0 u
Beside,furnace hot water coil is made of metal. Some of it will come into the hot water.