home made hot water heater

davidh

davidh

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the super titewad in me wants to make a small, inline water heater so I can heat the 30 feet or so, of pex tube that I have weaving around in the concrete floor of my sauna. I know, its a sauna but, it gets freezingars cold here and the floor really never gets as warm as i'd like it to be for at least 4hours of firing. by then im done with the sauna.
camper antifreeze in the line, maybe a very small low volumn pump and the heating element from an old water heater installed in a 3" or 4" pipe about a foot long and of course well insulated.
maybe I would not even need the pump. the farmers gravity fed all the radiators in my house in days of old. . . hummm, that would be even less cash outlay.
ive looked around at tankless waterheaters, they say very little about how they would function unless there was active water, and not to hot or not too cold for an inlet and even the cheapest I've found would be near $100.
I even have a timer switch that could be used in the a/c line so I wouldn't forget to shut it off.

and on the same subject, would a single element from a water heater even operate at 110v. a/c ? I have a couple of those, but they do make 110volt ones.

just something to knaaw on a bit. . . any opinions ? ? ?
 
Not knowing a single thing about water heaters except for having watched Mythbusters and replaced my own, I would make sure there's no chance you could build up pressure in the system.
 
I am no expert so I will deffer to anybody that knows what they are talking about. That said, a couple of thoughts: I think it is convection that you are thinking about and for that to work, I think the heat source needs to be a few feet below the cold side. Any resistance heater will run fine on lower voltage. Power is V**2 / R so you will get 1/4 the watt draw with half the voltage. In other words, a 3000 watt heater on 240 volts will put out 750 watts on 120 volts. I would build in some sort of over temp protection and a pressure release valve. You should be able to scrounge those off an old hot water heater.

Brian
 
Why not a small 5Gal water heater and a small pump? could turn the pump on when you want the floor warm (or 20 mins before you get in). The rest of the time it just keeps the 5 gals hot. Make sure its got an 'open air' overflow tank, and you wont build any preasure...

Shouldn't be too expensive...

P.S. a hot tub heating tube is really nothing more than an electric water heater element in an aluminum tube... but the circuitry to keep it from melting itself is complicated.
 
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Not sure if this would work on 110v but if an element is available I don't see why not.

Here is a link showing a system with an in line heater element heating domestic water that you could adapt to your needs http://www.willis-renewables.com/immersion-how-it-works.htm

I have this system in my home as a summer standby for when our range cooker is not alight, the water almost boils around the element and the thermo syphon effect is almost instant after switching on.

I'm no expert, just my opinion, but as long as the system you design is not pressurized and a thermostat is installed it should be safe.....the only problem that may arise is if you are in a hard water area the pipes could get blocked with lime scale in time and you would need to address that.
 
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David
Hove a look at the RIMS Tube on the Home Brew Talk site. What you want to do has been done and they have some very nice controls to help manage the temp of the floor. If you have an issue finding it PM me and I will link you to it.

Bob
 
Years ago, I used to see those projects in Mother Earth News.

Maybe you can get hold of the old designs, from some old issues.
 
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