Yet another heating question...

[Max Gfx]

I see this new fish tank heating device that Sylvia's business is selling, but I have one concern regarding part of its design. Why is corrugated stainless steel tubing used for the heat exchanger rather than PEX? I was once told many years ago that you never expose edible fish to any form of metal because they will quickly absorb even the smallest amounts of metal, all metals. Hence, the reason why my wood stove heats water/antifreeze in a 55 gallon drum that has a double coil of thin-wall polyethylene tube (DIG brand drip irrigation supply line) dropped into the barrel that my tank water circulates through.

[Scott Roberts]

The heat transfer rate of PEX is fairly low. I'm not sure what grade of stainless steel CSST is made out of, but as long as it's an appropriate type of SS, then it's fine to be in the water. Most stainless steel grades are quite safe.

[Max Gfx]

I'd be interested in finding out what brand of CSST is safe and try It as a replacement for the 100 foot coil of polyethylene tubing that I currently use as a heat exchanger.

[Scott Roberts]

CSST is made of either Type 304, 316, or 316L Stainless Steel, so in freshwater, any brand should be fine. I did some checking, and Wardflex, Gastite and Proflex state they use type 304. Tracpipe, Parflex, and Diamondback Flexible Gas Pipe only state "300 series SS", so they're probably 304.

[Max Gfx]

Thanks a million for such specific information! I will have to go pick up a spool this weekend and see if it improves the performance of my heating system. I went with the drip line irrigation tubing in the first place because it was thinner than PEX and heat penetrated it much better. Happen to have any remote idea how hot the water would be inside of the CSST used in the system that Sylvia's business is selling? My system is simple and more than likely laughable. My water/antifreeze mix only gets between 115 and 140 degrees. Luckily, my greenhouse is extremely well insulated with both fiberglass and reflective "bubble wrap" insulation, so a little heat goes a long way. I'm just curious as to how hot the liquid inside of their CSST might be. Might give me an idea of how much CSST I will need inside of my drum with the heated water/antifreeze.

[Scott Roberts]

Don't forget to take the plastic coating off the CSST. Are you using propylene glycol  as your antifreeze?

[Max Gfx]

No, plain old automotive antifreeze. I was just going with what I knew wouldn't boil, but also wouldn't freeze. Would have went with propylene glycol, but since that's the primary element used in fog-juice for stage foggers and I know the price of it painfully well, I went with the cheaper alternative.

[Tom Henderson]

If we are using metal in contact with our fish water, it always 316 stainless.  It holds up extremely well.

[Max Gfx]

Well I got a 25 foot coil of Pro-Flex and fittings today, so I got a weekend project. Got a PDF here that says it takes 4x as much PEX as stainless steel to achieve the same result. So I guess I'll see if this works as well as my 100 feet of polyethylene drip irrigation supply line.

[Max Gfx]

I'll be dipped in sh*t...1/4 the length of polyethylene tubing substituted for 1/2" of CSST and I'm actually getting better heat transfer. A mere 25 feet of 1/2" CSST and I am able to actually remove all of the heat in my 55 gallon barrel of water/antifreeze to equal the room temperature. No dead fish yet from metal poisoning, so this might be a good sign. Thought it was funny with the initial test using a 5 gallon bucket of well water. The water went in at 45 degrees and came out at 70 degrees. Didn't take but an hour to reduce 55 gallons of 115 degree water/antifreeze to room temperature of 73 degrees after pumping 600 gallons of fish tank water through it. My tanks and room temperature have completely neutralized now and both hang right at 73 degrees.

[JJ]

I'm looking at building a wood stove heat exchanger. Do you know of any particular brand of CSST that uses type 316 stainless? thanks

Scott Roberts said:

CSST is made of either Type 304, 316, or 316L Stainless Steel, so in freshwater, any brand should be fine. I did some checking, and Wardflex, Gastite and Proflex state they use type 304. Tracpipe, Parflex, and Diamondback Flexible Gas Pipe only state "300 series SS", so they're probably 304.

[Jeff S]

Check this out  
http://www.nybrewsupply.com/beer-home-brewing-equipment/wort-chille...
JJ said:

I'm looking at building a wood stove heat exchanger. Do you know of any particular brand of CSST that uses type 316 stainless? thanks

Scott Roberts said:

CSST is made of either Type 304, 316, or 316L Stainless Steel, so in freshwater, any brand should be fine. I did some checking, and Wardflex, Gastite and Proflex state they use type 304. Tracpipe, Parflex, and Diamondback Flexible Gas Pipe only state "300 series SS", so they're probably 304.

[Zach]

How well does it work? what temp does the water get?