Radiant heat in concrete slab installation

For many shops or garages, one zone is adequate. Keep in mind that a zone is different than a loop or circuit of tubing. You may have only one zone but there can be 4 or 5 circuits of tubing within it. You may decide that those areas should be at different temperatures and will want to zone it as such. You then order QK to cover the shop space and QK to cover the storage area which allows for 2 heating zones when you get ready to install the mechanical system.

If you have questions or are unsure about which kit to order, we do provide free design assistance. You can call us at Your email address will not be published. This will leave two vertical pipes sticking up above slab level…your supply and return lines. They are fully accessible, untouched by concrete, and protected from possible damage during future construction. The photo above on the right shows a different job with the slab manifold buttoned up and ready for the pour.

Note the fiberglass insulation stuffed around the tubing. Scraps of foam, newspaper, or rags will also serve to keep concrete from flowing into the box and touching the copper manifold. This system was pressure tested at 50 psi, but lost about 3 psi after hours.

This is common and results when the air cools in the tubing, especially overnight. However, if the pressure drops more than 5 psi over the same time period, check for leaks. Most often, the connections simply need tightening.

This well keeps the connections visible and accessible, but safe from damage during future construction. If the tubing were sticking up out of the slab, the chances of harm coming to the exposed PEX pipe are much greater. Notice also how the pressure test kit bridges the supply and return side of the manifold. This temporarily creates a closed loop, allowing the system to be pressurized.

When the manifold is ready for final connection to the heating system, the test kit is either cut off or unsweated, leaving only the two vertical supply and return pipes sticking up above slab level. This is especially true when the concrete company creates a long hose by coupling together shorter sections with a heavy steel fitting that can crush or puncture the tubing. That way you can use the box to shield the wall behind it from the effects of the torch.

With a single zone in a very large slab it is usually better to gang together multiple slab manifolds and spread them over the zone rather than create a single monster manifold that forces all the circuits to begin and end in one location. This more spread out approach eliminates the unwieldy cluster of stacked tubing that is the inevitable result of the single mega manifold.

Though not the easiest way to manifold slab circuits, occasionally an installer will run the return side of a slab circuit adjacent to the supply side. In other words, instead of having all the supply ends on one side of the manifold and all the returns ends on the other, the tubing will alternate across the manifold like this: Supply, return, supply, return, supply, return, etc. We normally come across this approach when the tubing has been installed alone, i. Obviously, this situation can present some difficulties.

This forces the plumber to blow air into tube 1, and then determine from which of the other tubes it escapes. Hopefully, the plumbing person has a handy air compressor available. This is not only tedious for the plumber, but potentially embarrassing for onlookers with vivid imaginations. So, the above is an example of what we call a front to back design manifold. It manifolds supply red ball valves and return lines adaptors only that have been installed side by side.

The point is, Radiant Floor Company can accommodate any circuit arrangement for any slab zone. Fact: Melting snow and ice with radiant heat consumes a staggering amount of energy.

Only a massive, and very expensive, solar powered snow melt system would avoid this almost embarrassing fossil fuel consumption. However, having said that, some special situations can make snow melt justifiable. One of our customers, for example, used snow melt to keep a set of outside concrete steps, on an attached apartment, safe for his 81 year-old mother.

Another customer bought a house and discovered during his first winter that, thanks to poor design on the part of some contractor, dangerous ice sheets formed on heavily traveled areas around his badly graded driveway. In these situations, the need for safety justifies the enormous energy consumption and expense of radiant snow melt.

First , always install a 6 mil polyethylene vapor barrier, then insulate as much as possible under and around the snow melt area. Snow melt is difficult. Direct the energy toward the task of melting the snow instead of leaking thermal energy into the ground or to the surrounding air. The vapor barrier prevents moisture from migrating up from below and stealing heat from the tubing. Second , use a spring timer to activate the system instead of a thermostat, slab sensor, or some high-tech snow detection system.

The spring timer itself should be fed power via a standard light switch. Some customers take the further step of wiring a light bulb into the same circuit to give the operator a visual indication that the snow melt is operating.

Again, these are simple, effective ways of preventing the snow melt system from ravaging your energy bill. Third , as indicated by the drawing below, always encase the radiant tubing in a compacted sand bed and always pump cold water through the tubing while applying the asphalt. This will literally prevent the tubing from melting.

The compacted sand increases the thermal mass of the system for maximum performance and also protects the tubing from damage during application of the asphalt. Without the proper topping, the melted snow simply absorbs into the unsealed driveway and leaches heat away from the radiant tubing. In effect, the snow melts into microscopic puddles of water instead of flowing away from the driveway.

Of course, this scenario assumes that the system is capable of generating enough heat to evaporate a driveway of saturated asphalt. Not likely. Even a well designed snow melt system would have to squander energy twenty-four hours a day to pull that off. A snowmelt parking area and driveway, well graded for drainage. Fourth , if possible, in the case of new construction, orient driveways and walkways to take advantage of natural solar radiation.

This may include removal of selected trees to prevent shading or adding a dark shade of integral dye to a poured concrete driveway. Warm heat distributed with forced-hot-air systems is uneven. Most of the heat rises to the ceiling. With radiant floor heating in concrete, the heat is concentrated at the floor making you feel comfortable at a lower thermostat setting and will eventually rise to heat your entire house. To get it professionally installed at the "higher end" of the spectrum, it can cost you thousands of dollars, especially if you are getting it installed for your entire house.

If you are looking to save some money, you can try to install it yourself, so you don't have to pay for someone's time and labor, only materials. As you can see, we pour many concrete floors with radiant heat installed, especially since we live in Maine and deal with very cold winters. I'd say we pour at least 1 concrete floor with radiant heat, weekly.

I've been on a lot of job-sites and poured a lot of concrete floors where radiant heat is being installed. Personally, I would hire a professional to do the installation of the pex tubing instead of trying to do it myself. These are all things I feel are best left to someone who is trained to install radiant heat in concrete floors.

Once the concrete is poured there's no going back and trying to change something if it's not working properly. Here's a concrete slab we're getting ready to pour with the radiant heat installed professionally.

Notice the styrofoam going up the edge of the slab to reduce heat loss. This is one step I see left out of a lot of radiant installations. I do think concrete floor heat is a great way to go. If I were building a new home I would install it in all my concrete floors. If you're thinking of installing you're own radiant heat floors, you can buy your pex tubing right from Amazon. This pex tubing is for good for light commercial and residential applications.

The simple answer to that is YES , especially if you're re-modeling and installing new tile, carpet or wood flooring. But there are some things you have to take into consideration.