Diesel Heater for Back-up heat during long grid failures?

[Xringer]

Originally Posted by Robl

External heat sources like monobloc ashp, or pipes that might freeze up, could be protected from frost damage with an anti freeze valve. Its just a valve at the lowest point in the plumbing, that opens a bit when the temperature falls below 3C or so, to prevent freeze damage. Once it’s opened, slightly warmer water is present, and it will close again for a while. Link to one below.

https://www.seconrenewables.com/heat...lve-7537-p.asp

Those valves would work in many systems and don't require any operator input.
I like the idea, but if they are installed at the 'lowest point', that means in the basement, near the uninsulated slab.
Where the winter slab temperature is 40 to 50 degrees F. Thanks to the Geothermal effect of the ground water table etc.
So, the valves would never get cold enough to open. The water pipes to the bathroom, kitchen and the forced hot water loop (upstairs) in the bedrooms would freeze up and split open.
The only pipes I'm worried about freezing are the pipes that are at least 5 feet above the basement floor.

I once used a small ASHP hot-water heater in the basement. It made a LOT of very cold air, while making our hot water. I was afraid it would make the basement very cold during the winter.
But, it was never able to lower the room temperature enough to notice.
Geothermal heat from the floor is very stable.
In the summer that ASHP kept the basement air less humid. I was sorry to see that system go..