Not a gret idea. @& T5 g- I( p6 Y/ E3 L0 t: ? ' t- D& Y4 e6 D' ?( l7 rHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe. * q) y- _2 c7 g0 z4 M8 K' s" [/ ~- i4 |& L1 J
Beside,furnace hot water coil is made of metal. Some of it will come into the hot water.