Under floor heating, or radiant heat, is a method of heat transfer from below the floor covering material, to the surface of that material, and into the room. It’s a process known as thermal radiation.
It can be hydronic (water) or electric. Electric systems draw low amps and are perfect for retrofitting smaller areas, particularly bathroom floors, shower floors, and even shower benches. Hydronic systems are are more complex, excellent in large areas, and better suited as an addition to a major renovation project.
Let’s start with the benefits of radiant heat in general, as it applies to both systems.
For starters it works very efficiently. More efficiently than any other type of heat. According to research it’s 25% more efficient than a typical forced hot air system. You aren’t just heating the air, you’re heating everything from under the floor and up. It warms everything in the room thus creating thermal mass, which is great for the retention of heat.
Radiant heat distributes the heat in a room evenly. There are no cold spots or hot spots in a room since everything is warmed. In the winter, floors always seem to be cold, especially tile. You can walk around in bare feet with radiant heat all winter long. For comfort, radiant again is the leader.
When compared to forced hot air systems that incorporate a blower with vents, radiant does not spread allergens, dust or viruses throughout your home. It also does not create hot spots like forced hot air does. And compared to traditional baseboard heat, radiant does not leave cold spots as baseboard is known for.
Breaking down the two systems we start with hydronic. It all starts at the boiler, or a hot water tank, that goes to a manifold system which in turn that warmed water is then sent through a loop of tubing. Each loop can be a “zone” and controlled independently. Similar to zones with traditional heating systems, whereas there may be one, two, three, or more thermostats that control certain areas, or rooms. With hydronic radiant heat it’s easier to incorporate multiple zones working off one system. It’s extremely efficient, and as noted above it heats evenly, without hot or cold spots, and brings comfort to another level in the cold months.
Many improvements have been made to hydronic systems over the years making them very popular in new construction and in major renovations. The downsides to hydronic radiant heat do exist however. First is the difficulty to incorporate it into existing construction. Although it’s not impossible, it is a major project. Retrofitting it into existing homes creates an increase in height which may not be acceptable in some cases. There are systems that can be installed under the subfloor to alleviate that concern but on multi level homes that requires tearing out ceilings for the floor above.
Next is the cost. It’s more upfront cost for material and labor, so it’s not for everyones budget, but the benefits and cost savings to run the system over its lifespan create a positive return on your investment.
Electric radiant heat starts at your electric panel, typically on a dedicated or isolated breaker. Power is brought to a room through a typical switch box to which a thermostatic controller is wired. Leads off of that controller go down the inside of the wall, inside of conduit, and into the room under the flooring through a cold splice which turns into heating cables which are placed under the flooring as well. Electric radiant heat is less complex to install than hydronic and is well suited for existing structures. From our experience, they are an excellent addition to a bathroom renovation, not to replace the existing heat source, but to compliment it. Theres nothing quite like getting out of the shower onto a warm floor. It will create a more even heat experience, similar to hydronic, in the room. Also when your bare feet are warm the rest of your body feels warmer.
Similarly there are some downsides to electric radiant as well. The most obvious would be the cost to run the system. On a large scale, as an only heat source, it’s not an economical choice. Especially in cold climates combined with high energy costs, as is the case in NY.
Second is the upfront material and install cost, again. Although electric radiant systems are not extensively costly, they are a moderate upfront cost so it’s worth noting here. As with hydronic radiant, electric radiant also requires a competent installer.
In conclusion, radiant heat is an excellent choice. Hydronic radiant heat, in our opinion, is the absolute best in class choice for a primary heat source. As a secondary, or complimentary heat source in a bathroom, bedroom, kitchen, or other area, electric radiant heat systems are an excellent choice. We’ve had the pleasure of working with both. In fact, we install electric radiant heat systems in 75% of the bathrooms we renovate and our clients love it. It’s a game changer when your bathroom floor is toasty warm. We even install them through the bathroom right onto the shower floor. The added perk there is not only the shower floor being warm, it’s the fact that the shower floor and all the grout joints completely dry out between uses. In addition, we’ve also put it under the stone of a shower bench. Imagine how the feels when you sit down in the shower…
Hopefully this information helps you make an informed decision if you are considering radiant heat in your next project. We almost exclusively install Schluter Systems Ditra Heat systems in our projects for electric radiant. We have a lot of experience with their system and it’s considered amongst the best, not only by us, but by industry standards. It also has an excellent waranty and speaking from tons of experience, it outperforms all the other electric radiant systems. You can do additional research on that system here: Schluter floor warming