# Building a Hot Tub



## Rhizzlebop (Jan 28, 2009)

I'll admit, I have never done anything like this, but it is a very interesting idea. From my HVAC and plumbing engineering perspective, I'd like to suggest an continuous fired hotwater heater with a small recirculating pump for the water heating and movement. Pipe it in line. You flip a switch, or use a timer to run the pump, and when the burner in the water heater senses flow, it fires the heater and heats the water to your desired temp, say 90F or whatever. If the water heater detects basically 90F coming back to the heater, the burner wont run and you're just circulating with a small, 1/10 hp pump then.

Would be interested to hear others discuss this.


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## Rhizzlebop (Jan 28, 2009)

Skimmy, there doesn't seem to be much action here to get you any answers. Might I suggest you post your question over on Garden web forums as their typically is more action over there.


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## echase (Mar 10, 2010)

Don't forget insulation! 

My cousin built a nice stone & ferro-cement tub around some massive styrofoam blocks. It keeps pretty darn hot long after the heater is turned off.

Someone has to have written a book on this by now. If this an outdoor project you can also use foam blocks into the earth to create walls that will keep the heat from spreading out horizontally.


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