Not a gret idea. ) L1 l/ G& G) M" {7 H" j% r0 j$ p8 r+ q f4 P# e
Hot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe.+ z0 [9 n7 W* K
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Beside,furnace hot water coil is made of metal. Some of it will come into the hot water.