Backyard Aquaponics
A place to discuss aquaponics

how high would such a siphon operate to though.

As it's only being used as a heat exchanger ,, use poly pipe and copper as you want and no risk of hurting them fesh:)

Woops, did some research, thermosiphon would work as a chiller only Warm water rises, through panel, cools, and sinks back to tank..... no real height restriction afaik vb

unless the heater was below the fish tank...

Chappo - what is that post in response to?

3 replies before mine,,,
"MMMM , some compression fittings on the ends, copper pipe up to the roof solar panel, nice warm fishies. Thermosiphon

I was saying , could even used poly pipe up to the solar panel ( perhaps copper panel)as the water never comes in contact with the fish

copper or poly being cheap I would probably actually go poly

I've seen thermo siphon water heaters but they require a tank above the panel. As water cools in the tank or cool water is introduced to the tank, it flows down and enters the bottom of the panel and pushes the hot water up out of the panel into the tank. You draw hot water from the top of the tank for use and make sure the the input of cold water to the tank is at the bottom. The fittings going down to the bottom of the panel are near the bottom of the tank and the fitting coming back up to the tank from the top of the panel is usually part way up the tank. No pumping involved in the actual water heater. The cold water pressure from the house is all that is needed to work this design.
this is kinda the set up for a domestic solar hot water heater in an area that doesn't get enough freezing weather to damage the panel.

Such a system would not really work in reverse (for chilling) without having a bunch of extra plumbing to reverse direction.

I'm not sure one could get a proper thermo siphon (to much height) going directly from an open fish tank. I think I would require a somewhat closed system for that to work.

I expect that a small (25') wort chiller coil won't show drastic heating or cooling in such as use as this but My real intention is just to take the edge off the really cold nights for the fish. This system would only be a supplement to putting a cover over the entire system area, adding a bit of insulating material over and around the grow beds and sticking the dryer vent in under the tarp of the main section of the covered system. (We only got two nights this past winter that would have required such actions.)

I suppose it would be interesting to know how much a certain temp/volume of water could impart through such a coil.

The other side of all this, was wondering about using say a pool heater as a radiant chiller at night in the summer but I wonder if using it as a heater to power an ammonia bottle ice maker might be more energy efficient and could provide cooling directly during the hottest part of the day when it would most be needed. (Steve might be able to shed light on this.)

Does anyone have any calculations to back this up?

The formula is as follows,.....,

http://en.wikipedia.org/wiki/Heat_transfer_coefficient

Need inside and outside pipe diameters for calculation.

And the following shows how VERY bad stainless steel is as a heat conductor.
http://hypertextbook.com/physics/thermal/conduction/

Another thought,,,copper ,aluminium and pastic are considered a non no because of contamination worries, Silver although a good conductor is a little expensive,,,but what about just ordinary mild steel??? Cheap,better conductor than stainless and any tainting of the water would be iron , something AP'ers generally lack.
Just a thought.

That's a pretty good idea Chappo!

Just make sure that the plain steel is something cheap enough to be replacing since it may rust out. That could be an issue if small holes rust out and you wind up with contamination of the system water with the solar heater liquid. That I suppose is the main reason to use stainless, it is corrosion resistant. As I remember the aluminum coil I saw said for temporary use or use in non-corrosive environments. Any salt in an AP system makes it a corrosive environment for many metals.

yep,agree. Seems that stainless is the best compromise,just need a lot of it to make up for its poor thermals. Can't realistically see myself wanting to constantly be checking the steel pipe and worrying about leaks.

A 2 mm thick steel pipe in AP water will last about a fortnight - I have (used to have) some bits of steel pipe in the water No iron deficiencies in my plants lol

I think some people fill tube with sand to help with bending and stop the tube collapsing in on itself...