Reddit reviews Wrap-On Pipe Heating Cable - 3-Feet, 120 Volt, Built-in Thermostat, Low Wattage - 31003
We found 1 Reddit comments about Wrap-On Pipe Heating Cable - 3-Feet, 120 Volt, Built-in Thermostat, Low Wattage - 31003. Here are the top ones, ranked by their Reddit score.
BUILT-IN THERMOSTAT - Turns the cable on at 38 degrees F and prevents frozen pipes to -50 degrees F - Simply wrap on, insulate and plug in. Insulation sold separately.PRESS-TO-TEST BUTTON - Exclusive feature to test cable before or after installation.ENERGY EFFICIENT - Uses up to 65% less energy at 2 watts per foot vs other cables at 7 watts per foot.USE ON ALL RIGID PIPES - PVC, CPVC, copper and metal pipes.MADE IN THE USA
External pipe heater(needs insulation around it but this might be simplest/cheapest solution):
https://www.amazon.com/WRAP-Pipe-Heating-Cable-Built/dp/B0002YWM2I
Inline heaters:
https://www.lowes.com/pl/Whirlpool-tub-air-bath-heaters-Bathtub-shower-parts-Plumbing-parts-repair-Plumbing/4294644663
Electric Tank Heater(should use 1.1kw to heat 12 gallon 68f->105): https://www.amazon.com/American-Standard-CE-12-AS-Electric-Water/dp/B01IEJ1PWK/
Although these devices are advertised as AC I'm 99% certain you can use them with DC, as long as they don't have components other than the heating element. Just be mindful to not go over the rated voltage, with 48v DC it might have ~43% the heating wattage
Not sure if you'd want to drain the end-shower product into the tank heater as from what I've seen the end product of a shower loop isn't pure