The Role of Floor Covering in a Radiant Heating system
Floor covering is not considered to be a part of the hydronic radiant heating system. However, it plays a vital role in the performance of the system, as the heat is transferred through it. Depending on the material, resistance to heat flow (referred to as R-value) in floor coverings can range from virtually none to very substantial. Therefore, in most cases, design of the radiant heating system takes into account the type of floor covering that the dwelling will have. Since there is already thermal resistance between the PEX pipe and the floor; installation of floor cover only adds additional resistance to it. The two R-values need to be added to get the total resistance level. The higher the total R-value is, the higher water temperature in the PEX tube needs to be, in order to upkeep set room temperature. Generally dense materials, such as concrete slabs are considered to be less heat resistant than those with a less dense structure (i.e. carpet).
Prior to installing floor covering on top of a radiant heated floor, it should be confirmed that the material can perform under increased temperatures. Also, if adhesives are used in the installation process, they have to be compatible with the maximum operating temperature of the system.
Ceramic tiles, wood, resilient flooring, and carpet are among the most popular floor covering options on the market today.
Ceramic tiles are among the most effective materials used to cover radiant heated floors.
Made out of a very dense material, ceramic tiles serve as a great conduit of heat with a very low R-value. This floor covering is commonly used in areas where people are likely to walk barefoot, such as bathrooms. While very comfortable, tiles are known to develop cracks. A good method of preventing crack would be to install a crack isolation membrane under the tiles.
Floor covering made out of wood is considered to be very effective and popular.
Typical examples include laminate, laminate wood, & hardwood floors. The first two types are also referred to as engineered wood, as it’s made up of a few layers.
When installing wood on top of a heated floor, it’s important to choose the right wood quality and an installer who has experience with installing wooden floors. Such precautions need to be taken because wood may shrink, expand or crack due to changes of temperature or presence of water. Such changes can occur due to the fact that wood can absorb or release moisture, resulting in wood becoming either dry and shrink, causing spaces between the boards, or causing wood to absorb moisture and expand or crack. In order to maintain wooden floor in a set shape and prevent damage, its moisture must remain constant, at the same level as the surrounding environment. ¾” thick wood materials have R-Values ranging from R-0.68 for oak to R-1.19 for OSB.
Providing very low resistance to heat, resilient (sheet or tile vinyl) flooring is considered to be an excellent floor covering to be used with radiant heating. Resilient flooring needs to be properly stretched before installing, as the material can expend and cause wrinkles.
Carpet, area rugs
While generally thin, carpets have a very high level of heat resistance. As a result higher temperatures are required in radiant heated floors that are covered with carpet. Most of the resistance comes from the pad. When selecting a pad for the carpet, higher density pads (such as rubber) would provide the most efficiency.
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