Even though our Winter is almost over and Spring is just in front of our Door, I thought some info for Radiant Systems is still appropriate as specially in the time of Spring and or Fall a Floor Heating System is really shining. Nothing better than walk or relax in a room where one has a Radiant Floor Heating System installed.
I want to point out that I attained most of my information from the Radiant Panel Association. The Office of Larry Drake (Executive Director of the Association has been very supportive, not only for this article also for all my needs when installing Radiant Flooring Systems for my Clients.) And at every installation, I was involved with, was a big success.
HYDRONIC RADIANT SYSTEM - Slab on Grade
Radiant tubing is embedded in cement. The tubing is typically attached to metal mesh with plastic ties. A four inch slab is most typical. The tubing is best placed in the middle of the slab. Full under-salb insulation is recommended for most residential application. Slabs have a very large thermal mass, which stabilizes temperature swings but slows response. This method is recommended whenever a slab is poured. Estimated Assembly R-value:R-0.69 - R-1.0HYDRONIC RADIANT SYSTEM - Thin Slab on Subfloor
Radiant tubing is attached on top of subfloor with approved staples or plastic clips. A thin Slab of gypsum-based cement or cent is poured over the tubing. Typical slabs are 1.5inch thick when using 1/2inch tubing, but may be as thin as 1.25inch thick when using 3/8inch tubing. Gypsum cement is lighter than cement, but a little less conductive. Estimated Assembly R-value:R-0.69 - -1.0
HYDRONIC RADIANT SYSTEM - Hanging or attached below Subfloor
Radiant tubing is hung or attached to the underside of the joists in an airspace with insulation below. This requires higher water temperatures and has more limited heat output than other systems. It is often used for retrofitting when access from below is possible. Hanging systems have more even joist cavity temperatures than when pipe is attached in contact with subfloor joists. Estimated Assebly R-value:R-1.7 - R-2.2 (pipe + 3/4inch plywood only)HYDRONIC RADIANT SYSTEM - With Plates below Subfloor
Radiant tubing is attached to the underside of the joists with metal plates to diffuse the heat. Insulation is recommended below the plates. This has higher water temperatures and more limited heat output than above subfloor systems, but plates make it more effective than hanging pipe from under joists. It is often used for retrofitting when access to joist space is available. Estimated Assembly R-value:R-1.3 - R-1.8 (pipe + 3/4inch plywood onlyHYDRONIC RADIANT SYSTEM - Structural Radiant Subfloor with Aluminum & Grooves
Pre-manufactured 1.125inch thick panels have grooves for tubing and an aluminum sheet bonded to the board. In this case, the pre-manufactured panels serve both as the structural subfloor and as the channel into which the tubing is installed. The aluminum sheet makes the system accelerate rapidly and spreads out the heat. Tubing is installed 12inch on center in the grooves. Estimated Assembly R-value:R-0.6HYDRONIC RADIANT SYSTEM - Boards with Grooves and Metal which are attached to top of Subfloor
Several varieties currently exist. One board has metal on the bottom and another on the top. Both serve to spread the heat laterally. Normally they are glued and screwed or stapled to the top of a wooden subfloor. Under some conditions the may be attached on top of existing slabs. These are modular systems with straights and end pieces that are assembled to make a channel for pipe. Different products use different pipe sizes. Estimated Assembly R-value:R-0.75 - R-1.1 depending on product.HYDRONIC RADIANT SYSTEM - Sandwich Method with or without Plates on Top of Subfloor
Typically, 1inch x 4inch x 3/4inch sleepers are attached to the top of the subfloor and pipe is placed in between the sleepers with or without the addition of the metal plates. The metal plates typically cover about 80% of the pipe, adding significantly to the even dispersion of the heat. Estimated Assembly R-value:R-1.1 - R-1.5 depending on product and platesELECTRIC RADIANT SYSTEM - Embedded Cable or Mat
The electric cable, mesh or mat is encapsulated by embedding it in a 1/8inch to 2inch mud bed or in thinset mortar on top of the subfloor as required by the National Electric Code. It is available as a low or line voltage for warming or heating. Higher output systems utilize wider spacing and require a thicker embedding layer. When only floor warming is desired, the system is controlled by a floor temperature sensor. Heating systems are usually controlled with a thermostat, often in combination with a floor sensor. Different systems and embedding thicknesses allow for a variety of floor coverings. Check with manufacturer for limitations and recommendations regarding flooring goods. Estimated Assembly R-value:R-0.3 - R-1 depending on embedding layer.ELECTRIC RADIANT SYSTEM- Self regulating Mat or Cable
This type is formulated so that as the temperature of the mat or cable goes up, the resistance increases, which limits the heating output to a fixed temperature. Some may be embedded in a mortar layer or used directly (as recommended by the manufacturer) under a wide variety of floor coverings. Estimated Assembly R-value:R-0.3 - R-1.0 depending on layer.ELECTRIC RADIANT SYSTEM - Film Type installed from Below
With the film type product, elements are printed with a conductive ink and embedded in a film of plastic. Current products are line voltage. These systems have higher resistance to heat transfer than embedded systems since the heat must travel through an airspace and the subfloor. They must be installed with an airspace. Estimated Assembly R-value:R-1.7 - R-2.2 (pipe and 3/4inch plywood only) The listed Assembly R-values are illustrative estimates only and do not include the R-values of the floor coverings, which must be added to determine total system R-value. Note: Insulation is usually required under radiant heating systems. The Radiant Heating System Design should be designed and installed by qualified professionals.
Posted by Admin at 06:04 PM. Filed under: Floor Coverings •
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