What I don't understand is why go to the trouble of arranging for Hot water and the extra running cost, purely for a supple hose and frost protection only?
The extra running cost is more than compensated for by ease of working (which translates to speed)
For example, NPower (my supplier) charges 15.7p per kwh of electricity. So heating a tank of water using 3kw for say 8hrs only costs (£0.157 x 3) x 8 = £3.77 per day.
If easier to handle hoses saves you just 2 minutes per hour, and your hourly rate is £25, if you work for 6 hours you have saved £5.
And (in my humble opinion) supple hoses saves MUCH more than 2 minutes per hour, and that's to say nothing of how much more pleasant using warm/hot water is over cold.
As for frost protection, the cost of replacing frozen-up gear (not to mention the lost work time) will be many times more than the cost of heating water overnight during the winter.
Also, that power usage is tax deductible, so the running cost is actually 20% less than I stated above (or 40% if you're a higher rate tax payer)