Re: Temp. controlled DIY heat cables

>I am working on building a set of DIY cables for my 55 and was looking for a
>way to improve the recommended low wattage design that is so common.  I
>figured that the ideal is to have the cables provide all the heating in the
>tank, thus maximizing the convective flow and warmth of the substrate.  My
>plan is to take a 300 Watt Otto compu-therm heater and hook the supply for
>the transformer up to the control box instead of the otto heater.  Voila,
>instant probe and controller.  The cost of it is $30.00, which is less than
>I would have paid for another heater to make up the difference in the
>required wattage and a timer to control the intervals on the cables (if it
>would have ended up being necessary).
>Has anyone tried this?  Is there any reason why this wouldn't work?

I don't know if the controller is capable of handling the inductance
of the transformer.  It is possible that the controller will be damaged.

A high-power tansformer that delivers 200+ watts at 24 volts will be
expensive.  The cost will be above $100, even if you order through the
mail.  You may be able to pick one up for a reasonable cost at an
electronic junkyard.

Also, a high-wattage substrate heater will remain off during the
summer, depending on where you live.  A low-wattage system could be
left in operation year-round.

>It seems like I am not the only one looking for suitable cables to use.  I
>was looking at the cables designed to melt ice off of the eves of houses and
>out of the gutters.  They are waterproof obviously, but I didn't know much
>else about them and didn't want to spend $26.00 to learn that they wouldn't
>be usable (my insulation sucks, so the heat from my house melts my snow and
>ice- no use for them their.)

What is the wattage, and how long is the cable?  For instance, if you
want a 25 watt 24 volt system, you need a cable that is rated at
approximately 500 watts at 110 volts.  Ideally, it should be about 20
feet long if it is to work in your 55 gallon tank.