watching the video, it seems that the fire chamber is restricted, without adequate air flow, which is something necessary for good, hot combustion and subsequent heating.

It's efficient packaging and storage, all right, but I fear it will do poorly in actual use.

Interestingly enough, our hot water heater is on the blink and service is likely about twenty-four hours away. Oh dear, what shall we do?!! We can still use the microwave, but beyond that, I would crank up the camping and outdoor gear - the two burner camp stove or various canister rigs. For showers, I would go for solar shower bags, which I have used extensively and satisfactorily in the past.

These would be my preference before resorting to heating water over wood fire = it will get the job done, eventually,