Flat bottom tubs and flexwatt

[hungba]

The racks I have made in the past has always been with tubs that had tiny little "bumps" under each corner, or an edge on the bottom, such as the floor is raised approximately 1/8 of an inch off the flexwatt. I always wanted to find completely flat bottom tubs like vision tubs, but none available in my country.

I finally found completely flat bottom tubs last week. However, I am now a little hesitant to use them.

1) I read that the flexwatt may have small areas where there is uneven heat making a hot spot, thus if it were flat against the tub, it would transfer these hot spots to the tub, whereas the layer of air would even it out. Is this true?

2) I have asked before about constantly reading about needing a "air gap" for the flexwatt to "breathe", though have never recieved a satisfactory answer as to why. They say that heat can build up on the tape, but I don't see how this can happen as the thermostat would switch it off at the set temperature whether it is from the tape switched on, or "build up". Once it is off, it may take longer to dissipate the heat into the tub, but how can it heat up further to dangerous levels when off? I use failsafes for all my thermostats by the way, and if we are talking thermostat failure anyway it's going to overheat regardless of a tiny air gap or not. So thermostat failure is a different issue.

3) If I want to put something over the flexwatt to protect from scratches, what non metallic sheets can I use? Can I use vinyl films? Contact paper? Or cut something like the material off of those clear office files/folders?

By the way I don't have access to a router or table saw, so I can't recess a grove for the heat tape. I it really is bad to sandwhich it, it would be easier to find a way to lift the tub up than to bury the tape down.

Thankyou.

[bcr229]

You definitely don't want the tub rubbing on the heat tape. There should be a slight air gap between the tub and the tape.

I've had to consider this also for a rack design for bigger tubs than 41-qt for when my BRB's grow up; fortunately I have a few years. I was looking at rigid foam board available at office supply stores. It's almost 1/4" thick, fairly sturdy, and you can cut it into strips a few inches wide. Put it along the edges of each rack shelf for the tub to ride on, with the heat tape or FlexWatt between it.