Comment: I have it facing southerly it

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I have it facing southerly it

I have it facing southerly it's also next to the house and the rocks will have my clay soil as as mortar and I will have a green house over it in winter. The water in the tank also acts as heat sink. My goal is to not have to use a heater.. But yeah you are right if you are using a tank heater outdoors in winter insulation on the outside of the thermal mass would be best.

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