Hi
We previously used a small portable but mains powered washing machine, twin tub, top loading. The hardest thing about that was getting the soap out again which used a huge amount of water. The best thing was once that had been achieved the spinner was worth it's weight in gold.
You could connect a hydronic heater to domestic towel rails? That's our plan A, but probably with a washing machine though. I'm assuming a domestic machine will use less than the massive amount the machine above did with us controlling quantities.
In the UK at least you can buy clothes airers with a small 2-300W heater in which are supposed to be much cheaper than a tumble dryer but then fold up, costing very, very little to run. Might be worth investigating? From Lakeland Plastics in the UK anyhow.