By Kolyn “Coach” Marshall No matter where we go these days it seems as if there’s always someone trying to upsell us on something. Truth is, the art of upsell is nothing new. Walk into a fast food restaurant and you’re asked if you want to super-size it. Go to the theater and you’re asked Read more
Radiant Floors
By Kolyn “Coach” Marshall
No matter where we go these days it seems as if there’s always someone trying to upsell us on something.
Truth is, the art of upsell is nothing new. Walk into a fast food restaurant and you’re asked if you want to super-size it. Go to the theater and you’re asked if you want to make your popcorn a combo deal. Heck, even Amazon’s in on the program.
Ubiquitous upsells can be awfully annoying, especially when it’s something you know a lot about. But, what if it’s something you know nothing about? Or, better yet, didn’t know to even ask?
This last question is where I find a lot of potential radiant buyers. They simply don’t know enough about what’s out there to ask.
This is where you—Neighborhood Radiant Installer—come into play.
It’s your opportunity to throw out the option of radiant floor heating or snowmelting. Sounds easy, right? Well . . . sort of. In order for you to be able to effectively talk about radiant, it can be helpful to know what there is to talk about.
Understanding the want
Depending on the audience, say, home or a business owner, the want or need may vary. For homeowners, they may want to be more comfortable. There’s a factor of efficiency or cost savings, but those are typically secondary to comfort. People really don’t like being cold.
Comfort, however, takes on many forms. But, as the Neighborhood Radiant Installer, it’s important to know what comfort means. One aspect is keeping the room temperature between 68 and 70 degrees. The other facet is knowing how occupants interact with the interior space. The key driver for comfort is floor temperature.
Ever step out of the shower onto a cold tile floor? In that instant it’s pretty easy to connect to what cold is. Oddly enough, our feet dictate our comfort more than air temperature. It’s the main reason why we have slippers and wool socks. If our feet are warm we feel warmer.
So the easiest way to feeling comfortable is to keep the floors from being cold. Radiant heat does that with most radiant systems maintaining a floor temperature between 75 and 85 degrees.
Business owners tend to have a slightly different goal in mind. Their focus is more on customer safety, especially when the weather turns cold and the freezing rain and snow start to fall. Or: employee satisfaction, a great incentive in retaining, and attracting, employees.
As for safety, injuries due to slips and falls plague business owners constantly. It’s a seasonal risk, and source of concern.
Radiant snowmelting systems help keep walkways, parking lots, and access ramps ice and snow free all winter long. This means no more early morning labor; shoveling snow is a thing of the past. No more chemical ice melt. This alone eliminates another key concern: icemelt tends to get picked up by customer’s shoes and tracked inside, eventually taking its toll on the floor.
The upgrade package
So a spark is struck. Warm floors are something that wasn’t expected but is now very much wanted.
How are these once cold floors now warmed? There are two main ways to provide radiant floor heat: hydronically with water, or through electric resistance.
Hydronic systems rely on tubing being installed in the floor and connected to a heat source. Tubing options range from PEX, to PE-RT, to EPDM rubber. Tubing is connected to a series of manifolds, then those manifolds connect to a boiler, or other equivalent heat source.
If the area to be heated is small, say only a kitchen or bathroom, then an electric product may be best; these use electrical resistant wire or cable to generate heat. Wire is embedded in a lightweight concrete or thinset generally under tile or other masonry material. One of the advantages of electric is there is no need for a mechanical room and no need to physically run piping back through a home or facility. Electrical installations tend to be less invasive but also tend to be reserved for smaller areas.
With both electric and hydronic systems there are options for controls and thermostats. Most of today’s systems incorporate some form of connectivity feature, giving remote access to users.
Delivering the Goods
Congratulations Neighborhood Radiant Installer! The Enlightened Customer has decided to go with the radiant upgrade. Now what?
Now it’s time to figure out how to get all those tubes and wires where they’re supposed to go.
Hydronic tubing is generally installed in one of two ways, either in a concrete slab or under a frame floor. In a concrete slab, tubing is typically 6, 9, or 12 inches on center with the tubing approximately 2 inches down from the top. In a frame floor, the tubing is secured to the subfloor, often with heat transfer plates. These plates secure the tubing (usually PEX or PE-RT) to the subfloor while providing good conductive heat transfer to the floor.
Electric systems are installed in a similar fashion to hydronic slabs with the difference being the wire is generally installed on top of the floor in ½ inch thinset with tile or other stone material as the finished floor covering. An electric system is then connected a controller or thermostat.
Both hydronic and electric systems then operate in the same way any forced air system does. The controller or thermostat is set to the desired temperature and the system operates automatically.
Satisfied Customers
So how does our Neighborhood Radiant Installer know the system is working as expected and the customer is happy? It’s simple: our Honorable Customer won’t be able to stop talking about the most comfortable heat they’ve ever experienced.
Becoming the go-to radiant expert is the best way to keep the future looking warm and bright.
Kolyn “Coach” Marshall, based in Springfield, Mo., is Systems Engineering Manager at Watts Radiant.
Radiant floors have long been popular in new construction and retrofit projects. In the face of huge popularity, growing success and satisfied customers, it’s difficult to criticize radiant floor heating technology. When radiant floors are installed well under the proper circumstances, radiant floors are among the most comfortable and efficient means of distributing heat in Read more
Radiant floors have long been popular in new construction and retrofit projects. In the face of huge popularity, growing success and satisfied customers, it’s difficult to criticize radiant floor heating technology.
When radiant floors are installed well under the proper circumstances, radiant floors are among the most comfortable and efficient means of distributing heat in most homes. Operating within their capabilities, radiant floors can easily meet the heating loads of well-designed modern structures.
For nearly 20 years I have been installing hydronic-based heating systems. Over the last two decades I have been faced with many situations where radiant floors are either not the best choice for a certain space or heat source no matter how well thought out. However, I have seen many projects where designers have exceeded the capability of the radiant floors and have had to face some harsh realities. Thermodynamics is not just a good idea….it’s the law.
The output of a radiant floor is limited in two ways. First, the maximum surface temperature of a radiant floor is limited to around 87F (about 45 Btu per square foot). If the floor is operated above this temperature, the occupants are likely to complain of uncomfortably hot and sweaty feet.
The second limitation of radiant floors is the amount of energy that can penetrate highly resistant floor coverings, such as certain carpeted and wood floors. Often, these materials limit the actual output to less than 20 Btu per square foot. Unfortunately, these beautiful and thermally resistant floor coverings are often used in the more elegant rooms, with large windows and high heating loads. As a contractor/designer we often must push the limits to meet the load in such spaces. Also, floor coverings are likely to change significantly over the life of the building, leading to the comment “It worked until the owners placed a thick Persian rug over the wood floor”.
How about a radiant floor alternative?
Radiant ceilings can easily operate at surface temperatures up to 100 F, delivering in excess of 55 Btu per square foot. Since ceilings are typically constructed of gypsum based sheet rock, they offer very little resistance to thermal transfer. Unless interior designers regress to the 1960’s and resume putting shag carpeting on the ceilings it’s likely the output of the ceiling won’t change during the life of the home.
In any discussion of radiant ceilings and comfort, there seems to be some ingrained misunderstandings of the concepts. Someone will say that “heat rises, therefore you’ll have a hot head and cold feet”. Not true. Heat doesn’t rise. Hot air rises. In radiant systems objects of mass are heated without heating the air. In fact, there is typically more hot air rising with a radiant floor than with a radiant ceiling. This is because air molecules that come into contact with the radiant ceiling already occupy the highest strata. In radiant floors, the cooler molecules sink and come into contact with the warm floor surface and rise as their density changes with heat, driving the convective forces that cause stratification. Under normal conditions neither radiant floors nor radiant ceilings heat the air to an uncomfortable level like in forced air systems.
Another myth about radiant floors and ceilings involves the surface temperatures that are achieved. Just as the beach sand absorbs the overhead rays of the sun, radiant ceilings warm the floor. There are no cold floors in radiant ceiling projects. You can put a piece of Tahiti in your living room with radiant ceilings.
I also hear radiant ceilings criticized for what is termed “shadowing affects”. This is the belief that legs under tables or desks are shielded from the radiant heat and are, therefore, cold. Radiant ceilings, like floors both radiate and re-radiate. The invisible heat rays emit from the heated surface to other colder unheated surfaces. The total affect of all of this bouncing of energy is very even heat distribution. If a person is seated at a table near an outside wall, there could be some shadowing from above with a radiant ceiling, just as there might be shadowing from below with a radiant floor when seated on a sofa near the outside wall. In most situations, shadowing for radiant ceilings or floors is negligible.
More significant, however is the possibility that objects placed on the radiant floor will impede the flow of energy. Area rugs, and some furnishings such as certain sofas and beds can reduce the usable floor area, increasing the Btu load per square foot and, perhaps, exceeding the system capability. Radiant ceilings are not subject to these types of problems.
Radiant ceilings accelerate fast when needed to meet a big change in heating load. They dissipate energy fast as well. The responsiveness of radiant ceilings makes them excellent for modern controls, placing energy where it is needed when it is needed, and achieving superior comfort and efficiency. Some high mass radiant floors are sluggish in that they take a long time to meet the load.
In modern heating systems too much emphasis has been placed on energy efficiency of the heat plant while wasting energy on poor distribution. This is like putting a Viper engine in a Yugo. Far more heat energy can be salvaged by not wasting it in poorly controlled buildings, than can be achieved by squeezing another Btu per hour out of a heat plant. There are some pretty interesting solutions to heat distribution problems by using radiant floors in conjunction with radiant ceilings. In this way the floors are not required to meet the entire load, yet are conditioned to provide comfortable surface temperatures. The ceilings are heated, where necessary, to take on the severe conditions and give everyone involved the peace of mind that the system will keep up with the heat loss under severe conditions.
Without a doubt, radiant ceilings cost far less than radiant floors. In most cases they cost less than half of a radiant floor. Lower cost means more opportunity. They take less effort to design and install. Radiant ceilings are perfect for retrofit situations. It is very inexpensive and easy to lower a ceiling to accommodate the radiant ceiling, but difficult to raise a floor.
Radiant ceilings are not optimal over a concrete slab placed on the grade of the earth although high r-value flooring can. Radiant floors are best for these situations. I also prefer radiant floors in rooms with smooth surface floors, such as bathrooms where occupants are often barefoot. It is a real nice touch. But when the going gets tough, the heat losses are high and the floor coverings are plush, radiant ceilings cannot be beat.