Terry has an old boiler radiant water system and wants to replace it. He had the following question:

The type of installation you refer to is called a "sandwich" because the flexible tubing that carries the hot water is sandwiched between a subfloor and the wood flooring. Sleeper boards are used to create the space between the subfloor and floor. Of course you would want a reflective surface on the subfloor so that you don't have as much heat going into the concrete slab as into your heated room. Some manufacturers make prefabricated panels that include the subfloor, sleepers and tubing.

Here are some things to consider:

• With a sandwich system you in effect are raising the floor by as much as 3 inches or even more.
• These systems must be highly engineered to provide efficient and effective heating. Be sure and study the tubing supplier's application notes carefully, use prefabricated panels, and/or have a pro do the installation.
• If you are going to use the existing boiler, there are fittings designed to transition from copper piping to flexible plastic pipe. Use the ones recommended by the manufacturer of the tubing you choose to use.

Good luck Terry. Please send us pictures of all stages of the installation if you move forward with the project. I am sure it would be helpful to other do-it-yourselfers in the same situation.