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Interesting Heaters


  1. Fishmas list - heater
    by Earle Hamilton <ehami/> (Fri, 5 Dec 1997)
  2. VisiTherm heater construction
    by jimh/ (Jim Hurley) (15 Jan 92)
  3. comment on beginner FAQ
    by "Lisa Procter" <lmprocter/> (Mon, 20 Sep 1999)
  4. retraction of comment on beginner FAQ
    by "Lisa Procter" <lmprocter/> (Mon, 20 Sep 1999)
  5. RE: yeast CO2 and heater rant
    by "Chin See Ming" <chinseeming/> (Mon, 12 Mar 2001)

Fishmas list - heater

by Earle Hamilton <ehami/>
Date: Fri, 5 Dec 1997

Those of you that take AFM may have read my article on aquarium heaters.  
At the end of the article I described my "ideal" heater which would have 
a variable wattage.  A week ago I was contacted by some folks who had 
read the article and they sent me a prototype for evaluation.  At the 
risk of sounding like their PR dept let me just say if you want the 
ultimate aquarium heater, this is it.  It holds the temp to within 0.1 
degree F (which of course is beyond any value that the fish require).  
What is more important is that it will work for any size tank. I tested 
their heater (200 watts) in a two gallon tank and it reduces wattage as 
the tank temperature approaches the set point.

The element is encased in metal that is safe for marine tanks.  The case 
acts as a tank ground probe so you save at least $15 on buying a ground 
probe.  Being solid state there are no bimetal strips or contact points.  
There is a separate temperature sensor.  The whole ball of wax can be had 
for about $65 including shipping.  Call 1-800-215-2936.  Temzone inc.

George, even you who has everything doesn't have one of these things.  
For the person who has everything or thinks they do, the Temzone variable 
watt heater would make a great stocking stuffer.

- --Earle Hamilton from northern Michigan where coral once grew

VisiTherm heater construction

by jimh/ (Jim Hurley)
Date: 15 Jan 92
Newsgroup: rec.aquaria

I had a 150W VisiTherm break when I accidentally let
the tank sump drain and then refill. The heater was on
and the water cracked the glass.

Taking this opportunity to disassemble it, I was a bit
disappointed. I thought it would have some 'high-tech'
components, but it is just like most other heaters
I've seen.

The set screw adjusts tension on a bimetallic switch.
Apparently they have good material control, because there
is nothing to suggest that the heater will maintain the
indicated temperature just set. That is, there is no
temperature sensing elements in there, just the bimetallic strip.
The air temperature in the glass tube causes the
bimetallic strip to warp as it gets hotter. The set screw
applies a biasing force on the strip.

There is a small ceramic magnet that keeps the bimetallic strip
attached longer than normal. This adds some hysteresis to
the system and also helps keep the contacts clean, I guess, by
the natural brushing action of the warpage.

The glass tube seal was via a soft compressed rubber compound
that was hard to remove, but wasn't glued to the glass. I guess
it was compressed well-enough to ensure a long life.

I can't see any way this heater can fail in the ON state.
The most likely failure might be contact wear or corrosion.
I would have expected some spark suppression capacitor
across the switch.

The LED is turned on when the switch connects. The heater voltage
is dropped down by a large resistor and applied to the LED, so
you have a positive indication of heater voltage, but not current.
If the heater wire breaks, the LED could still come on.

The glass, while very thin, was remarkable tough. I had to whack it
several times sharply with a hammer to shatter it. Too bad the
response in open air is so slow or it would have shut off more
quickly before it self-destructed. The plastic parts seem to be very
durable. All wiring was cleanly done. There seemed to be little possibility
of shorts or other hazards.

"I'll bet any quantum mechanic ... would give the rest of his life 
for a chance to fool around with this gadget"  -  Forbidden Planet
Jim Hurley -->  ...!ames!ultra!jimh  (408) 922-0100
Ultra Network Technologies / 101 Daggett Drive / San Jose CA 95134

comment on beginner FAQ

by "Lisa Procter" <lmprocter/>
Date: Mon, 20 Sep 1999
To: <faq/>

First of all I want to say this is a great FAQ and I really appreciate
having this resource.
Second of all (no offense intended) I want to disagree with you on a minor
point involving heaters.  You said:

>Submersible heaters are the better design, as they can be placed
horizontally along the tank's bottom. This helps keep tank temperature
uniform (heat rises), and prevents the heater from becoming exposed while
doing partial water changes.

I totally agree that submersible heaters are best, but when it comes to
water, heat doesn't rise.  When heated air rises, it's because gasses in
general expand when heated, taking up a larger volume and therefore becoming
less dense.  Many liquids and solids also expand when heated, but not water.
Liquid water is virtually incompressible and does not change volume or
density at all when the temperature is changed; it just turns to steam
and/or evaporates faster.

Nevertheless there are plenty of good reasons to locate a heater
horizontally at the bottom of a tank.

Once again thanks for all the work you've put into this FAQ.  It's a great

Lisa Procter

retraction of comment on beginner FAQ

by "Lisa Procter" <lmprocter/>
Date: Mon, 20 Sep 1999
To: <faq/>

I think I'd like to amend my previous comments about how water doesn't
change density with temperature.  I went and tested the density for
different temperatures of tap water.  Lo and behold, the density changed!
Slightly.  So I guess I was wrong.

Here's my data, if you're interested:

Temp                      Density
(deg C)                   (g/mL)

12                           1.001
24                           1.000
38                           0.998

Lisa Procter

RE: yeast CO2 and heater rant

by "Chin See Ming" <chinseeming/>
Date: Mon, 12 Mar 2001


Here what I see on the Visi-Therm intruction sheet.  It says "Water level 
must be maintained at the water level mark near the top of the heater."  
Figure 1 on the sheet illustrates that instruction.  Another illustration 
shows the heater in a vertical position with the dial above the water line 
and a YES written next to it.  Another part of that same illustration shows 
the heater in a horizontal position completely underwater (the position I 
was planning to install my heater) with a NO next to it.

However, another part of the instruction sheet say "VISI-THERM is a 
submersible aquarium heater."  (which comports with the language on the box 
and on Aquarium System's website).

As I am, at bottom, wont to take the easy way out, I decided that I'm not 
going to sort out what Visi-Therm is trying to communicate to me and bought 
a replacement Ebo-Jager:-)) I also decided NOT to read the Ebo-Jager 
instruction sheet . . . ;-))


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