" L8 f9 ^7 P/ c! Q' [1 C& x$ wHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe., c+ J1 s- `/ O" J5 J' v( _
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Beside,furnace hot water coil is made of metal. Some of it will come into the hot water.