The pipes in the house on both sides of the 6 inches that goes thru the wall should be a conduit for heat more than anything else should it not? The idea of not insulating or rather insulating one side seems strange to me. Is this a best guess, or qualified advice?
Why should it be strange. Heat moves from the warm area to the cold area. Insulation's job it to stop the movement. While you don't want heat to leak out of the house, you do want it to reach the pipe in the wall. Insulate the cold side. The only source of heat if the pipe is insulated is the water itself. If that is not enough to sustain it above 32F or 0C, the pipe will freeze. . I'd not rely much on the pipe itself to conduct enough heat.
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