I think if it heats it's own heat storage chamber it is better, then you only need to have a cut-off to stop thi miner at max working temp. It probably already has this circuit and putting it on a separate heat storage vessel still gets cooled as water is drawn from the hot taps.
Any other solution creates complications with the heat dissipation mechanism or uses power, or could lead to the miner running too hot.
This is not for miner cooling. It’s just to have hot water even if the tank heater has been off, or ran out of hot water.
In my region, people have small water heater tanks with a wall switch to turn it off to save energy.
Problem is, when forgetting to turn it on hours before use, there’s no hot water when needed.
So, i guess the obvious answer then is to have inline heater downstream of the heater tank.
The issue is that the miner has to turn off if it's too hot. Already heated water is effectively heating the miner. Heat shortens the lifespan of the device.
It is more complicated, but two systems, one that directs the flow through to the normal heating vessel, and have it's heater dial down so it let's the miner provide a baseline and a secondary flow path to a radiator with fan once the water temp rises above the optimal max for the miner.
Or to integrate the thermostat controls so it turns on the miner at low temp ranges and flips to the resistive element is the tank when it passes a threshold, then the miner is baseline and the element is backup and tops off to reach max.
