Thanks again madlabs,
Great advice on coils and wear on them. I haven't seen stainless tubing in my shopping, except for the flexible type that would probably wear fast. I was thinking of originally placing the coil in the chimney but went the easy route. I can always remove the coil now and make a larger one if need be, as well as change the location of the coil. As is when it is running hot and making about 2 liters per minute of hot water I don't mind waiting 2 hours that it takes to fill the tub with hot enough water. Of course 4 liters per minute would be ideal and maybe take less than an hour to fill it.
I'm just trying to make a simple Japanese style outdoor bath as cheaply as possible for relaxation and for a backup for my electric hot water if we have future problems with the grid or skyrocketing electric rates here.
Here is a simple but expensive boiler fired unit
http://www.auvelcraft.co.jp/rotenburo/I'm not interested in the tub, but the boiler unit, they cost 4-500$ or so. So I was hoping to do something like it for much less money. I'm up to a bout 110$ now. The above linked unit is non-electric and must work on thermosiphon effect. As you can see the two hoses are rather wide. Also I don't like having the boiler so close to the tub, seems smoky and messy.
The blue tub I have is 120liters but needs about 100liters if you count the displacement of the bather.
I also have an extra full sized tub of about 200liters if things become successful.
Ideally I want to have 40C/100F water temps give or take.
I tried out my small drill powered pump that cost about 10 dollars today. All was going well till I realized the impeller is packed with a kind of petroleum jelly...ugg, greasy water.
I'll have to go with the fish tank water pump. Something like one of these cheapies,
http://www.marinedepot.com/powerheads_pumps_taam_rio-ap.html Unfortunately the cheapest types are fully underwater pumps. Don't like the idea of sitting in a tub with a 100Volt appliance plugged in and beside me IN the water, yikes. Should be safe if I don't chew on the wire or something
Does an in-water pump sound crazy or dangerous to you guys?
johnE