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Re: Source for 7.5W, non-thermostatic heaters

> Date: Wed, 6 Jan 1999 13:29:22 -0500
> From: "James Purchase" <jpurch at interlog_com>
> Subject: Source for 7.5W, non-thermostatic heaters
> Karen Randall mentioned recently the use of small, 7.5 Watt heaters (w/o
> thermostat). I remember several years ago when she initially mentioned the
> use of these items as one possible method of causing a very slow circulation
> of water within a substrate.
> But WHERE do you obtain such small heaters? I can't see any such item listed
> in the online catalogues of any of the aquatic mail order houses. anybody
> have any idea of a current source?

I have usually found them at WalMart, of all places! Watch it though.
They are made as cheaply as their selling price, and are, IMHO, a major
hazard in a tank. The tube is *not* Pyrex, or even glass. It is thin
polyethylene-looking stuff.

From experience, I know the wire-wound resistor inside can melt through
it with spectacular results. The sand inside may not always keep the 2K
10W resistor far enough away from the plastic. It really helps if you
keep it submerged, too. ;-)

It would be better to do it DIY, if you are at all handy. A 12V 1A
transformer (wall-plug kinds are cheap) and a 20 Ohm 10W resistor in a
real Pyrex tube full of fine sand, vinyl sealed, would be safer, IMO.
The vinyl used for coating pliers handles should work nicely.


Wright Huntley, Fremont CA, USA, 510 494-8679  huntley1 at home dot com

Liberalism is totalitarianism with a human face.
                                  Thomas Sowell