Not a gret idea. 6 {+ H& e5 y9 i) O4 m % i2 T i( h. W& Y2 c1 Y$ CHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe.. `4 K! y. `2 I" ~: u
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Beside,furnace hot water coil is made of metal. Some of it will come into the hot water.