very good idea. I found a bigger idea. I will build this system on a large scale in the future and I want to supply a city with hot water. co2 free city by crypto miners. let the mining companies realize that the future of the district heating service is in their hands. 
Before going full scale city, start with the neighborhood.
There are countries that have their electricity bills skyrocket, a neighborhood crypto mining to heat their homes might be a money saver.
It may not be profitable but cutting cost by some significant enough % is better than paying in full.
Now, if you are making money from mining then you can compete with the price of heating services.
Feasibility study and small scale first hehe.