Side Tank Heater

I just bought a new heat pad and the instructions said that it is preferred(it doesn't say by whom specifically) if the heater is mounted to the side of the tank as suppose to underneath.
Does anyone actually do this? and what is the difference or advantage/disadvantage?

Thank you! Unfortunately, I do not have your answer but my snake's enclosure is on the ground so I can't use under the heater pads. I have also been wondering about side heat. At least on one side.

What type of reptile is the heater for, I've always kept mine under the tank, my boa seems to enjoy this after she has eaten a big meal, she will lay above the heater to warm up her belly. I have never used one on the side of the enclosure so I cant really compare the 2.

Side tank heating is generally aimed more at arboreal species that don't stay on the bottom of the tank.
What brand of heater are you talking about?

It really depends on what you are housing. They say on the side is better, because there is a small chance it could damage whatever furniture the tank is sitting on and they don't want to be liable for it.

If you have a burrowing animal, put it on the side. Most animals burrow to keep cool and the could get burns if they burrow too far down.

If you have a tree dwelling, you can do bottom or side, but I feel more heat goes into the tank if its on the bottom, and less gets lost into the room.

I'm not sure about ground dwelling. Again, I think it depends on what you are keeping in there, and what your substrate is.

If your goal is to use it for raising the ambient temperature. It is much more effective underneath as the heat will rise uniformly. Mounting on the side it would require much more wattage to project the heat very far.

Thanks for your help,
The heater is for my corn snake, and so I really don't know what would be best.
Here's the set-up:
Right now I'm using aspen substrate, he does like to burrow, he never digests his food on the warm side (he's stays on the cooler side), and he does stay on the ground all the times only climbing at night. I don't have a thermostat (I've yet to find one), I use a heat lamp during the day, and the brand of the heater is Repti Therm.
Any suggestions on which side to mount it on would help.

Someone with a corn will chime in.

I get my thermostats online at HerpSupplies.com - Reptile Supplies, Vivarium, Reptile Accessories, Reptile Habitat, Reptile Lighting, Zoo Med, Reptile Supply, Lizard Supplies, Reptarium, Rep-Cal, Flukers, Reptile Bedding, Fresh-Air Habitat, Reptile Heat Pads
For a cornsnake I would put the pad on the bottom of the tank. The repti therms are for either side or bottom mount. It is suggested that you use the enclosed rubber feet to raise the tank up so that there is some airflow under the tank.
If you are worried about the heat discoloring furniture you can put a piece of styrofoam insulation under it.

I use Under Tank Heater and have aspen in my enclosures.

Putting the pad on the side is great for burrowing snakes like milk snakes and even my corn snake seems to like it.