Reptile & Amphibian Forums

Several years ago I used some racks with back heat, two strips of 11 inch flexwatt. In my opinion it did not work well. The rack material was 1/4 inch plastic. I lost a lot of heat out of the back of the racks. I resolved the issue by attaching 2 inch rigid insulation on the back and sides of the rack. Since then I have switched back to belly heat. I need to change the heating on one of my racks from belly to back heat. So this time I thought I would place a piece of rigid insulation across the back of each shelf on the inside. Each shelf is deep enough that the boxes would still slide in all the way. I want to place a 1/4 inch thick, 3 inch by 24 inch piece of rigid insulation at the back of each shelf. Then I would glue or tape reflectix to the surface of the rigid insulation. Then I would tape or glue my 3 inch flexwatt to the reflectix. What I'm trying to do is prevent any heat from going out the back of the rack or even heating the back panel. I want the insulation and reflectix to cause the heat to radiate forward toward the boxes.
Have any of you ever done this type of setup?
Are there any issues with glueing or foil taping the flexwatt directly to the reflectix?
I have seen flexwatt sandwiched between two layers of foil tape and it induced a current onto the tape and would shock you if you touched it. So I just want to make sure the same problem will not come up with the reflectix.
Thanks
John Q

I want to place a 1/4 inch thick, 3 inch by 24 inch piece of rigid insulation at the back of each shelf. Then I would glue or tape reflectix to the surface of the rigid insulation. Then I would tape or glue my 3 inch flexwatt to the reflectix.

Are there any issues with glueing or foil taping the flexwatt directly to the reflectix?

There are a couple of issues with this approach. One is that by taping the flexwatt directly to the Reflectix you are allowing the heat to pass through the first layer of foil by conduction. Reflectix and similar products block radiant heat but not conductive heat.

The second is that you'll lose the heat sink effect of the back of the rack.

So you're better off if you attach the flexwatt directly to the inside of the rack and directly to the back. The more direct contact with the back of the rack the better. Then loosely wrap the back of the rack with Reflectix, creating a slight air space between the outside back of the rack and the first layer of foil.

If you want to use the rigid insulation board you're still better off attaching this to the outside back of the rack.