Re: flea bay tankless water heaters.
The batch heaters are stupidly simple. They aren't real reliable since the depend on the weather, but for me it works.
The long and the short of it is that it's just like leaving a garden hose out in the sun all day. You know that nasty rubber tasting blast of 120 degree water you get when you go to get a drink because you're parched? The batch heater I want to use will be the same idea.
Basically I'm just going to build an insulated box about 8 inches tall. The bottom of it will be lined with a thick steel plate as a h*ector on the cover so I can use it to focus some more light on the box.
So...supply line runs up from the bus into a check valve and then the box. It will sit in there until I open the hot water tap at which point it will drain some nice hot water (hopefully) for me while refilling the coil from the supply line. It isn't going to work well on cold days and by 4:00 am it might be a bit cold to take a shower, but the building supplies for the operation are cheap (aside from copper) and it should suit my needs fairly well.
My quick and dirty calculations lead me to believe that 100 feet of 1 inch i.d. tube should get me just over 4 gallons of hot water at any given time. That's comparable to most RV water heaters though the recovery time will of course be less. On the otherhand, it is cheaper by a long shot and can supplement any later heating system I use.