drlclyde where do you get those?

COASTROAD Hearth & Patio A big flame means you're burning a lot of gas, which can be quite dangerous. The trick here is to get proper gas diffusion up through the media, in this case, stones. For an application like this, there are square-shaped burners designed to fit the opening nicely. "Off-the-shelf" solutions do not typically address the challenges of a custom application like this.

Your local fireplace expert should be able to help you with this. There are codes and guidelines to go by when designing something like this. There are even differences depending on whether you are using natural gas or liquid propane. This is not really a do-it-yourself project.

You can find your local expert by going to the National Fireplace Institute website: http://nficertified.org.

If you need further help, let me know and I can probably give you some direction.