Your guide to Radiant Heating
Radiant Floor Heating / Radiant Heating Radiant heating is widely regarded as the most natural, energy efficient, comfortable, and healthiest heating process available. By warming the floor, you heat the room where it is needed - from the bottom up, warming the feet and body first. Studies have shown that in houses with traditional forced air systems, the hottest part of the room is the top 3 to 5 feet near the ceiling. Instead of circulating heat by moving the air around in the room, a radiant system heats objects including people. Floor drafts, dry air, cold spots, dust, air contaminants, bacteria, and low humidity levels - all problems associated with forced-air heating - are nonexistent in a home with a properly designed radiant heating system. Radiant floor systems allow even heating throughout the whole floor, not just in localized spots as with wood stoves, hot air systems, and other types of radiators. Radiant floor heating also eliminates the draft and dust problems associated with forced-air heating systems, are also quieter, cleaner, and more energy efficient than forced-air heating systems - resulting in a savings up to 40%. There are two types of radiant floor heating: 1. Electric radiant heat: a thin electric mat is installed right under your new flooring material.
1. If you are building a new home: 2. If you remodel your home or plan a major addition: The larger the area you need to heat, the better a hydronic system will be for you. However, even if you plan a whole house, the electric system will be a better choice in climates where you only need to heat a few hours in the morning and a few hours at night. 1. Floor elevation - thin electric systems will elevate the floor by only 1/8". A hydronic floor heating system elevates the floor by a couple of inches, which can be a problem in many remodeling jobs. 2. Time to heat up - hydronic systems are placed 1.5" or 2" into a cement slab. This is so deep into the floor that it usually takes 4 to 7 hours to heat up when they are first turned on. Therefore, they are left on for many months and consume energy during a longer period of time. 3. Energy saving - electric heating mats are placed above the sub-floor, just under the flooring material. They will heat the floor in 30 to 60 minutes under tile. The mats are controlled by a timer and a thermostat and in most cases the homeowners will preset ON-OFF cycles to provide heat only when needed and where needed by selecting rooms and heating from your feet up. 4. Cost of installation - in remodeling jobs or in select rooms of a new construction hydronic systems will cost more to install. In very large jobs (complete home in new constructions), the hydronic radiant floor heating systems will often be less expensive to install. 5. Maintenance and repairs - hydronic systems need to circulate water continuously and they use valves and manifolds, which are prone to sedimentation, mechanical problems, and maintenance issues. Electric heating systems have no moving parts and require no maintenance. If a hydronic installation is faulty, it is difficult to find a leak and the system is difficult to repair. With electric systems an underground fault detector can find the exact location of the break and after breaking just one or two tiles it is easier to splice the electric cable and replace the few tiles removed. 6. Operating costs - the cost of electricity in America varies between 3 cents/kWh up to 18 cents per kWh, therefore, the cost of generating 1,000 BTU with a hydronic system may sometimes be lower than the cost of generating 1,000 BTU with an electric system. However, the real comparison needs to consider the different ways these two systems are used. The hydronic system will be ON for many months, while the electric system will be ON and OFF several times a day according to the ON-OFF settings of each room thermostat. Moreover, during each ON period, the electric system will only use electricity continuously for the initial period of temperature build-up. Thereafter, it will cycle between ON and OFF and will only draw electricity during 25% to 33% of the time remaining during the ON period.
A radiant heater is a portable personal heater, also known as a radiant space heater. These are the most traditional space heaters designed to quickly provide heat to those closest to the heater, rather than providing heat for an entire room. They warm the object or the people in front of them, but not the air directly as there is no other form of energy to circulate the heat. Most of these heaters use a glowing quartz or some type of metal element and reflector to provide heat to a specific area. Space heaters are typically used when the main heating system is inadequate or too costly to install or operate. A radiant heater does not have a fan, because they deliver heat to people and solid objects that are in line-of-sight in the same way the sun heats the Earth. Radiant heaters are generally more comfortable and quieter to operate, and more efficient because they are designed to heat the occupant directly and not heat the room air. The user feels comfortable due to the radiant heat beamed directly to them, despite the fact that the room air temperature is still cold. When using radiant heaters, you are getting a low maintenance, cost effective heater. Not heating the air is an advantage for radiant heaters. There are no drafts from moving air. You're only heating the areas where you want heat. Just point the radiant heater at the area you want heat! Standard features include a thermostat for temperature control, an auto safety shut-off and tip-over protection for added safety. Radiant heaters use a variety of heating elements. Many use quartz tubes. Quartz heaters generally cost less than $70 and are rated between 750 and 1500 watts.
A roof exposed to the sun for a prolonged period will absorb a great deal of heat, sometimes reaching temperatures in excess of 170° F. Conventional thermal insulation can slow down radiant heat transfer, but will not stop it. Radiant barriers can help prevent overheated attics from warming the interior of a home. Radiant barriers can be incorporated into new or existing homes, although installation is easier in new homes. A radiant barrier is designed to block the effects of radiant heat gain in homes by reflecting radiant heat rather than absorbing it - as much as 97% of radiant heat can be reflected back towards its source, providing substantial energy savings in warm climates. There are a variety of installation options for radiant barriers: rolled foil types, radiant barrier paints, metal shingles, aluminum foil chips, and roof sheathing that has a radiant barrier laminated to it. All of these work in similar ways, but some types work a little better than others depending on the circumstances. The best radiant barrier products are the ones that have the highest amount of reflectivity. Anything that dulls the surface of the radiant barrier film significantly reduces its reflectivity. Many traditional radiant barriers for homes are foil laminates that can be stapled up in an attic or even laid flat on top of insulation. These offer only one layer of protection. They work well until they become covered with dust. As the dust builds up, their effectiveness goes down.
Typical locations for radiant heat barriers include: between the roof sheathing and attic floor insulation, in cavity walls, and around door openings, water heaters, and pipes. Placing a radiant barrier on top of conventional attic insulation effectively blocks the path for radiant heat into a home. Radiant barriers may be installed in attics in several configurations: " The simplest is to lay the radiant barrier directly on top of existing attic insulation, with the reflective side up. 1) One variation is to attach the radiant barrier to the bottom surfaces of attic truss chords or rafter framing. Foil barriers can be applied to rigid insulation, structural sheathing, or as a one or two-sided reflective sheet material. They are installed by stapling and taping to the appropriate surface. Reflective paints are sprayed on to a surface. Thermal insulation is available with a reflective surface pre-applied at the factory. Reflective chips are suitable for use in attics where they are spread between joists. Chips are spread about 1/2-inch thick on top of attic insulation. They can be blown-in using special equipment, and can be installed in a 1500 square foot house in about one hour.
Costs for an attic radiant barrier will depend on several factors: - Whether the radiant barrier is installed by the homeowner or by a contractor. Radiant barrier costs vary widely. As with most purchases, some comparison shopping can save you money. In some cases, radiant barriers are included in a package of energy saving features sold to homeowners. When considering a "package deal", you may want to ask for an itemized list that includes material and installation costs for all measures included. Then shop around to see what each item would cost if purchased individually before you make a decision. Dust or other particles on the exposed surface of a radiant barrier will reduce its effectiveness. Radiant barriers installed in locations that collect dust or other surface contaminants will have a decreasing benefit to the homeowner over time. When radiant barriers are newly installed, some testing shows that the attic floor application will work better than the roof applications. As dust accumulates on the attic floor application, its effectiveness will gradually decrease. The Bottom Line on Radiant Barriers First determine if a radiant barrier is worthwhile for your climate. They are intended for very sunny, hot climates to reduce cooling loads. Radiant barriers tend to offer little if any benefits in Northern heating dominated climates. They are also of minor value if your home's roof is already heavily shaded by trees or has at least the minimum insulation recommended for your climate. Radiant barriers may raise shingle temperatures 1° to 10°F but this has been proven to have no detrimental effects on roofing materials. In addition, check the flammability rating of materials to be used. If you are uncertain ask your local fire department or building inspector's office about suitability of the product you are considering. |