Confused and frustrated by flexwatt

OK here's the deal. I got tired of stacking bins and all that, and because of the setup of my snake room, I don't really have room for a rack. For the snakes that I have in sterilite bins, I mounted a few wire shelves on the wall. Not a traditional rack, no, but it works.

I haven't moved all of the snakes that will go there onto the shelves yet because I'm still trying to figure out what kind/how much Flexwatt to buy to be efficient. The bins that I'm using are 14" wide by 22" long. There are two bins per shelf, butted up against each other on the short edge.

Which setup sounds better with the flexwatt?
1) One 4" strip of flexwatt running the length of the shelf along the long edges of the tubs.
2) Two 1' long pieces of 11" flexwatt. One under each bin.

I think setup #1 sounds easier and less cluttered with wires, but would that leave enough of a cool area?

http://i14.photobucket.com/albums/a3...exQuestion.jpg

The second question that I have is... which has the potential to get hotter: 4" or 11"? 4" runs off of 8 watts/ft and 11" runs off of 20 watts/ft, so it seems like the 11" would, in the event of thermostat failure, get hotter than the 4". On the other hand, the wattage density for 4" is .17 w/in^2 rather than a density of .15 w/in^2 for the 11" flexwatt.

Thanks!

I'm going to suggest you do what I do. Speak directly to Rich at Reptile Basics. Either call him or email him with your drawing and questions. What that man doesn't know about flexwatt isn't worth knowing.

Here's his FAQ about flexwatt....

http://www.reptilebasics.com/Flexwatt-FAQ-sp-4.html

Here's a direct quote from that FAQ about the differences in how hot 3" and 11" flex gets and why....

Quote:

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Ok, so how come 3"/10 watt gets hotter than 11" heat tape? Which is "safer"?

The maximum surface temperature of heat tape is determined by something called "wattage density", not width. The wattage density is how many watts of power is consumed by a unit of heat tape (usually a square foot or square inch). The higher the wattage density, the higher the potential heat output. With the heat tape widths generally used in reptile applications square inches makes the math a little easier.

For instance-

3"/6watt= .17 watts/sq.in.
3"/10watt= .27 watts/sq.in.
4"/8watt= .17 watts/sq.in.
11"/20watt= .15 watts/sq.in

You might see something interesting here. The 3"/6watt and the 4"/8watt are essentially identical in output. You may also notice that the 11"/20 watt actually has the lowest wattage density of the group! There are a lot of misconceptions about heat tape out there, especially in forums, about which is "safer" or "hotter" and so on. Here are the facts.

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That's the page I've been looking at, but it's also the only credible place where I've seen wattage density mentioned. On the other hand, you have Jeff Ronne of Boaphile saying things like this:

Quote:

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1. The most important thing that needs to be discussed is using the appropriate product for the application required. As discussed elsewhere on the site Boaphile Plastics always uses the lowest wattage possible Flexwatt to create the thermogradient needed for your herps. This means at no time will Boaphile Plastics install the 20 watt per lineal foot 11" wide material in the sub floor of a cage as this is overkill. No pun intended. The lower wattage material used by Boaphile Plastics is 21.5" wide and less than half the wattage per square inch of the 11" - 20 watt per foot material. This will give you the nice safe warm area required for your herps.

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According to the Reptile Basics website, the 11"/20 w/ft material is the lowest wattage density available. See why I'm confused??? lol

I don't know how they get it, but they do have lower wattage flexwatt. The 20watt 11" is by no means overkill. I'm having a hard time getting it to keep the temps up properly, it's just not putting out enough heat, gonna have to go with more on the other side.

All things being equal with heat output...which setup seems to be best above? I'd rather do the 4" strip simply because it's only one connection per shelf rather than two, but I don't know if it would supply enough of a cool area.