| Radiant Heat and Pex Tubing Glossary |
Refers to the portion of PEX Tubing in a Radiant Heat Loop that is actually in the space being heated. It is equal to the total loop length minus the leader length. A radiant heat product that controls the valve of an individual manifold loop. These controls are wired to the thermostat and will open or close the valve depending upon when heat is needed. The actuators come in fast opening motorized versions and slower opening thermal versions. Aquapex is potable water PEX Tubing, made by Uponor Wirsbo. The Tubing is most commonly used for PEX Plumbing applications, but may also be used for Radiant Heat Applications where no ferrous materials are present. A bend support is used in Radiant Heat and PEX Plumbing systems to make turns with PEX Tubing. The bend supports are sold in plastic, PVC, and metal. The PVC bend supports are designed for exiting concrete slabs. An acronym for British Thermal Unit, it is a measure of the amount of energy needed to raise the temperature of one pound of water by one degree fahrenheit. Many of the heat related items in the Hydronic and Radiant Heat industry are measured in BTU's, BTU per hr, or BTU per sq. ft. A term used for two tees used in a hydronic system to separate a primary(heat source) loop from a secondary (distribution) loop. A boiler that takes advantage of the condensing gases that accumulate in a boiler. This type of boiler makes use of the extra heat that is created when the gas turns to liquid. This liquid is very corrosive and therefore the boilers are created to withstand corrosion. A pattern used to lay out PEX Tubing in a Radiant Heat System. This pattern is most often used when there are no exposed walls, or in a Snow Melt System. This pattern allows for even heating throughout a floor space. Counter-flow is not recommended for rooms with one, two, or three exposed walls. When a pump such as a Taco Pump, does not have any flow of water coming to it. The pumps' motor continues to spin without any water and eventually burns out. A standard that is often mentioned when referring to PEX Tubing. This is a measure of the ability of PEX Tubing to prevent oxygen diffusion. DIN 4726 is a German Standard, which all of the oxygen barrier PEX and PEX-al-PEX on PexSupply.com meet. This standard says that no more than .1 milligrams of oxygen will enter a system per liter of water in the system per day. A Radiant Heat or other hydronic heating system in which the radiant panel and the heat source are connected directly to each other. This is the simplest piping strategy possible. Refers to a type of oxygen barrier that is commonly used in PEX Tubing. EVOH stands for ethylene vinyl alchohol, this compound prevents oxygen diffusion. This compound is bonded to the PEX during the manufacturing process. A control used in a Radiant Heat or other hydronic heating system that centers the supply water temperature around a single number when heat is called for. This temperature is often referred to as the target temperature. A board placed over a slab, thin-slab, quik trak, or other form of heat source prior to placing tile down. This board is commonly seen in Radiant Heat Systems, as tile is an excellent floor covering type for radiant. The pressure available on the outlet side of a hydronic pump. It is expressed in terms of feet of head. Feet of head represents the height of a column of water that is supported by a hydronic pump under standard atmospheric conditions. hePEX is the brand name for the Oxygen Barrier PEX-a tubing that is made by Uponor Wirsbo. Wirsbo hePEX is designed for use in radiant heat systems. This PEX Tubing comes in several sizes and lengths. A process in which hot water is injected from a primary loop into a secondary loop, using closely spaced tees, a pump, and a mixing control. This is the most preferable way to operate a hydronic heating system. Injection mixing reduces the need for controls in a system that may go bad over time. Injection mixing also increases the level of control over a hydronic heating system. A small pump such as a Taco 007 or Taco 005 Pump will supply more than enough flow. Refers to the portion of PEX Tubing that is needed to get from a manifold, to the space to being heated in a radiant heat system. Leader Length varies depending upon the layout of the building or residence being heated. Describes the amount of PEX Tubing in a Radiant Heat System that is run from the supply manifold to the space being heated and back to the return manifold. The maximum loop length varies depending upon the size of the PEX Tubing being used. For ½" PEX Tubing the maximum loop length is 300'. When loops are run over maximum loop length, head loss becomes too high and flow rate becomes too low for a system to operate correctly. The average temperature of all the surfaces in a room being heated by a Radiant Heat System. These temperatures will be relatively consistent in a Radiant Heat System, however in a forced hot air, or baseboard system the temperatures will vary substantially. This thermal comfort is one of the key benefits of Radiant Heat. A term used for a pattern used to lay-out PEX Tubing in a Radiant Heat system. This method is used when there is one exposed wall, or one main area of heat loss. The PEX tubing is taken to that wall and then "snaked" away in a serpentine fashion. A Radiant Heat or Hydronic Heating system that is open to atmospheric conditions. In an open system components must be resistant to corrosion related to oxygen. The term used for a radiant heat installation in which lightweight concrete (or concrete substitute) is poured over the PEX Tubing. This installation uses a relatively thin layer of concrete as opposed to a slab installation. It refers to the ability of oxygen to pass through certain materials such as PEX. PEX is an acronym for cross-linked polyethylene. PEX Tubing is now being widely used for Plumbing and Radiant Heating applications. PEX is desirable due to its flexibility, durability, and thermal memory. Synonyms for PEX include PEX Tubing, PEX Pipe, and PEX Tube. Refers to PEX Tubing that is made using the Engel Method. This includes Wirsbo PEX Tubing and ThermaPEX Tubing. PB Tubing is manufactured from an oil derived plastic resin. PB Tubing that carries the ASTM D-3309 spec may be suitable for radiant heating. However, PB Tubing is not cross-linked so it can't withstand the high temperatures that PEX Tubing can, and does not have thermal memory. A loop in a Hydronic Heating System that is connected to a boiler or other heat source and is isolated from the secondary loop which feeds the radiant panels or other heat output locations. The idea of using a primary loop is to be able to control the flow and temperature of this loop and offer protection to a boiler. A piping strategy often used in hydronic heating systems in which the flow resistance of the heat source is separated from the distribution circuit. This generally involves the use of a primary pump for the loop containing the heat source. Separation is generally accomplished through the use of closely spaced tees. These tees allow heat to pass through from the heat source to the distribution circuit without allowing the primary and secondary pumps to interfere with one another. proPEX is a PEX Tubing connection system developed by Uponor Wirsbo. This system requires the use of a Wirsbo expansion tool, proPEX Rings, and proPEX Fittings. This system may be used for Radiant Heat or PEX Plumbing applications. A pump is another name for a circulator. Pumps are used in hydronic systems to move water through the system at a desired rate. Two of the largest manufacturers of circulator pumps are Taco and Bell & Gossett. Taco Pumps and Bell & Gossett Pumps come in several models and should be selected based on the needs of the system. Quik Trak is a product made by Uponor(formerly known as Wirsbo). This product consists of ½" plywood with a thin sheet of aluminum underneath. Quik Trak may only be used with 5/16" PEX Tubing. Quik Trak is ideal for Radiant Heat systems where there is an existing slab or sub-floor. A measure of a material's ability to resist the flow of heat. The formula for an R-Value is R=1/U. This value is expressed as BTU/h/square ft. The process in which heat leaves the surface of one object and travels to the surface of another. This takes place in the form of electromagnetic waves. A control used in a Radiant Heat or other hydronic heating system that attempts to equate the heat loss of the building with the heat output of the Radiant Heat Panel. This type of control generally makes use of an outdoor sensor. A description of the relationship between the supply water temperature of a radiant heat system vs. the outdoor temperature. It is the slope of the line formed by the change in supply temperature divided by the change in outdoor temperature. Most low temperature systems will be between .4 and .8, while high temperature systems will have a range of 1 to 2. In a hydronic heating system this is the line that brings the cold water from the space being heated back to the heat source. In a radiant heat system, the return line brings cold water from the manifold back to the heat source. It may be copper, PEX, or some other form of pipe. Sizing of return lines does vary, but is normally ¾" or 1". A loop in a Hydronic Heating System that is separated from the heat source, so that the system is not a direct heat system. This allows a specific flow rate and temperature to be set for the secondary loop. The secondary loop has the heat output sources, such as Radiant panels, running off of them. An entire concrete slab that is greater than 4 feet below the surface. A concrete slab that is less than 4 feet below the surface. This is an abbreviation for Stainless Steel Clamp, a system created by Uponor Wirsbo. This system requires the stainless steel clamping tool and stainless steel clamps to make a PEX Connection. The SSC PEX Fittings are designed with barbs in order to work with the SSC Clamps. In a hydronic heating system this is the line that supplies hot water to the system. The supply line carries hot water from the heat source to the space to be heated. In a radiant heat system, the supply line brings hot water to the manifold. It may be copper, PEX, or some other form of pipe. Sizing of return lines does vary, but is normally ¾" or 1". A floor that is not resting on the earth's surface. Therefore the floor is suspended above the surface. Radiant Heat that can’t be seen, this is what is used in radiant panel heating. A term used for a pattern used to lay-out PEX Tubing in a Radiant Heat system. This method is used when there are three exposed walls, or three main areas of heat loss. The PEX tubing is taken to the three walls and then "snaked" away in a serpentine fashion. A term used for a pattern used to lay-out PEX Tubing in a Radiant Heat system. This method is used when there are two exposed walls, or two main areas of heat loss. The PEX tubing is taken to the two walls and then "snaked" away in a serpentine fashion. A measure of a material's ability to transfer heat. Describes how well an item conducts heat. The formula for U-Value is U = 1/R. This value is expressed as BTU/h/square ft. Uponor, formerly known as Wirsbo, is the world's leading manufacturer of PEX Tubing. Uponor also makes a full line of PEX Fittings, Manifolds, and Controls. Uponor is a Swedish company, their US headquarters are located in Apple Valley, Minnesota. A method of laying out PEX Tubing, in which the tubing is spaced closer together near high heat loss areas. For example for the first 3 to 4 feet along an exposed wall tubing may be spaced 6" apart. Once the tubing moves away from the wall 12" tube spacing may be used. This is a common technique used in Radiant Heat Applications. Zurn is a manufacturer of plumbing products. Zurn makes a full line of PEX Products including Zurn PEX Tubing. Zurn PEX Tubing is designed for use in potable water systems. |
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