All in power is about 17c per kilowatt hour here in our area of eastern Canada. No argument for younger guys if they can somehow get a geo thermal setup in service cheap enough. Cost versus reward at my age of 73 is just not there.

Locally we are still learning about heat pumps.Too many people seem to have unreasonable expectations. At a certain temperature going on an alternative heating system seems about the best strategy.

I toyed with a design change that might make some sense. Basically another fluid line in the outside condenser. At a certain temperature or defrost call our well water is circulated through the self draining line when no flow is present. Then returned to the well. It could both defrost and provide some additional heat to scavenge from the water.

There are some problems about just how cold the well water might become but on average since the flow is not that great and of a constant nature it may keep the well water well above freezing.

After I work out all the math and if it seems practical. I might approach a manufacture of the heat pumps we buy to build a special condenser for me.

You cannot return the same water to the same well as is the case of a true geo thermal unit but hopefully my calculations might allow this on a single well setup.

This was just something I thought of yesterday. So it will take a little time to totally discount the ideal. Many things I consider are impractable. Yet some work out well.

This one is going to depend on how many btus can be scavenged from the well periodically. Without getting it too cold. Remember the flow rate is relatively small and the volume is also. A small control system and pump is both cheap and inexpensive to operate. Although a small new feeder line from the well is required plus a return.