Bettas should not be kept in vases. They can survive in small spaces with no filtration or heating, but that doesn't mean they are happy and thriving. I agree with the comments that suggest you try to find a way for the water to flow through the betta enclosure (maybe a betta enclosure like giantdogg uses?). At the very least, your original idea will keep his vase warm, which is an improvment over his current situation.

The vase is in! Thanks to everyone for the advice. GiantDogg thanks you for your concern, I have left considerable space above the vase for him to grab air. Natalie allow me quell your concerns as well. This is no normal vase. It is easily over a half gallon in size and could very well be over a gallon. It is not one of those horribly cramped pint sized bowls that they sell in the pet store, nor is it an ultra thin flower vase. I will continue looking into ways to get water flowing through the vase (drilling might be hard since you need special drill bits to put holes in glass) but for now, weekly water changed will have to suffice. I will put pics up as soon as i get a chance. thanks again all!

I have done this before with a 2 gallon glass jar in my 55gallon tank. I supported it by stacking it on another large glass jar. It worked really well for my baby Africans, as I had a filter inside of the jar. It did take up like a quarter of the tank though. It was funny to watch my juvy texas and red devil stock the baby africans from the outside. The babies though the Red devil was their mother, and would rush over to meat with him, only to be stopped by a glass wall.

Finally got some pics! My apologies for the sub par quality, had to use my camera phone, but you guys will get the gist of it.

Tekneb, one other thing. Bettas are excellent jumpers. Keep an eye on him. It looks like he could hop into your main tank pretty easily.