Risk of freezing! Pem32 or 40?

[Bjober]

I am in the process of bringing water into the mountain cabin. So far, we've been showering and using the toilet in a separate building on the property. There's a pump system there that makes noise and causes disturbances. Approximately 25m suction line with a heating cable. Now I'm planning for a new well as close to the cabin as possible. The cabin is left unheated, so the idea is to have a submersible pump in the well and to drain the water back into the well when the cabin is closed. When we're at the cabin, I expect not to need to use the heating cable. Good insulation for the piping in. Water has the fantastic property of being heaviest at +4°C, which (hopefully) means that it moves in the pipe if it starts to freeze. I think warmer well water circulates up.

Now to the actual question. Is it better with Pem 40 than Pem 32? Does it significantly reduce the risk of freezing?

With the solution we have today, we use electric heating for about 2-3 hours until the suction hose has thawed, and then it stays on the whole week we're there. I've tried turning it off, but it freezes.
25m x 30w doesn't cost so much that you go bankrupt, but I'm thinking that if you can make it smarter and more efficient from the start, why not. That's why I plan to operate without a heating cable.

 

[BSOD]

Water that is 3C is lighter than 4C. This means that as it approaches the freezing point, the cold water will end up on top and freeze. It will not self-circulate as you wish.

 

[Bjober]

That's true. Then the question is what temperature you have at the level above and below the freezing point. Maybe rising ice crystals carry warmer water down?

 

[Daniel 109]

The difference in density between 0-degree and 4-degree water is very small, and in the wrong direction. So disregard circulation due to temperature difference.