How Does Radiant Heat Work ?

Are you wondering how does radiant heat work when it is in the floor? Radiant floor heat isn't very complex.

What happens is a floor heating system is installed under the finished floor. Energy is delivered to the system which in turn heats the floor. The floor "radiates heat" throughout the room and the entire home. There are multiple different ways to create radiant floor heat.

Warmboard Sample cut out.

How Hydronic Radiant Heat Works

For larger surface areas, hydronic heat is usually used. One way to use hydronic heat is to install it in a subfloor. The picture to your right is called "Warmboard." This is an aluminum covered subfloor. Aluminum is used for hydronic heat because it is a great conductor.

The tube is the most important part though. This tube is called PEX. It is a specially constructed material designed to carry warm water from a boiler, through a tubing circuit and then back to the boiler.

As the warm water circulates under the finished floor, the aluminum heats up. This aluminum radiates heat into the finished flooring. The finished flooring could be any surface you choose including wood, tile, laminate, or even carpet. The floor will radiate warmth throughout the room. The floor will be warm to the touch. (Imagine a nice warm tile floor when you get up in the middle of the night. It's amazing!)

Aluminum Plates holding PEX on the bottom of a sublfoor

In other cases where the subfloor has already been installed, you can still strap the PEX tubing underneath. The tubing circuit is installed between the joist. Aluminum flashing plates are attached to the subfloor, and these plates have a trough for the PEX tubing to rest in.

This system isn't as efficient as the Warmboard, but you have to install Warmboard as you build the home. You would have to tear out the entire subfloor and all the finish flooring if you wanted Warmboard on an existing home. The picture to the right is from a home that was retrofitted with hydronic radiant floor heat.

How does radiant heat work when it is used in concrete? The heated water still flows through PEX tubing in this system. The big difference here is that this PEX tubing is embedded in the concrete. You lay down the tubing circuits first. Then you pour concrete over the PEX tubing. The concrete hardens and then you have a floor that you can cover up with any finish surface you desire. Some people opt to leave the floor as concrete, especially for business or factory applications.

How Electric Radiant Heat Works

How does radiant heat work with an electric system? The concept is the same, but you have to lay down electric wires or an electric mat underneath the finished flooring. The picture on the right shows Thermofloor being installed under Tile. When the electric radiant heating system is in place, energy radiates through the wires. These wires heat up the floor, and then the floor radiates heat throughout the room.

An advantage that electric has over hydronic is it can be used in small applications. You can install a small mat in a bathroom and program the unit to heat up at specific times during the day. This makes electric heat cost efficient.

There is some lag time for any radiant floor heating system. If the floor is cold, and you want the room to heat up, first the floor temperature must be heated up higher than the air temperature. Once the floor reaches a higher temperature than the air, the floor radiates heat into the air and into anything that comes in contact with it. If you are standing on a radiant heated floor, it actually radiates heat directly into your feet. Have you ever noticed how cats will sometimes sit directly on a heating register to be in direct contact with the heating source. With radiant floor heat, the entire floor radiates warmth. It creates an indescribable comfort.

The increased comfort level, and the improved efficiency of radiant floor heat make it a great choice for any home. The feeling is hard to describe. You have to experience it first to truly understand how does radiant heat work.

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Related Articles

Hydronic - Radiant Water Heat
Electric Radiant Floor Heat

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