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Radiant Floor Heating Frequently Asked Questions

General

Technical


Q. Why is radiant heat (radiant floor heating) superior to other heating methods?

A. With radiant heat, every object in the room becomes warm and contributes to your overall comfort. Because you're heating more than just the room's air, your living space maintains an even, satisfying warmth with no air currents, blowing dust, or cold spots. Unlike other heating methods, radiant heat doesn't dry out the air. The warmth starts at your feet where it is most desired instead of blowing out of ductwork and ending up on the ceiling. With traditional hydronic baseboard heating, the hot air flows up the wall creating a convective current that can actually draw in cold outside air.

Also, with radiant heat, you feel comfortable at a lower thermostat setting, so your fuel bills will be lower...a major plus!

In addition, the system is silent, has only one moving part, needs minimal maintenance, operates more efficiently than any other heating system while offering superior comfort, and if that isn't enough, you can walk around in socks all winter!

Imagine stepping out of your morning shower onto a warm floor. Imagine never again sitting on a cold sofa. Imagine stretching out on a cozy floor and reading the paper, working on a school project with the kids, doing yoga exercises. These are only a few of the reasons why radiant heat has been used in Europe for over sixty years and will soon become the standard in America.

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Q. How much "design assistance" can I get?

A. Our technicians are available to assist you every step of the way in the installation of your radiant floor heating system.. Technical support is the heart of our business. It doesn't matter if you're standing on the jobsite with a cell phone in one hand and a roll of tubing in the other. We'll be there for you. We've designed our systems with the handyman in mind. We don't believe in needless sensors, gauges, or monitors. Our systems are simple and highly effective. All our manifolds are factory assembled and tested and our installation manual is written in clear, concise, non-technical language. We've spent our lives in the heating, air conditioning and construction fields, so we know the value of installation tips and common sense advice.

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Q. Can I use my existing water heater or do I need a boiler?

A. In many cases an existing domestic water heater will do the job. If the BTU rating of the heater is matched with the BTU requirements of the space to be heated, one properly sized unit can provide both space heating and domestic hot water. A boiler is normally not necessary unless the heating requirements exceed 300,000 BTU's. In these cases, a simple mixing valve is designed into the boiler system to provide lower temperature water to the radiant floor.

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Q. Will radiant heat damage my hardwood floors?

A. In years past, some companies used high temperature boilers to send 180 degree water through radiant tubing. This excessive water temperature combined with a poorly insulated structure could cause warping or checking of hardwood floors. Because floor temperatures often exceeded 85 degrees as the floor vainly attempted to match the high heat loss of a poorly insulated structure, the result was high, wasteful energy consumption and damage to the floor.

Radiant Floor Company systems are designed for low water temperatures (125 degrees) and, as a result, floor temperatures will be approximately 5 degrees warmer than room temperature. In fact, many customers have noticed that sunlight striking the floor on a bright winter day will warm the hardwood more than the radiant system.

It could also be argued that, because floor temperatures are kept more uniform during all the seasons of the year, the expansion and contraction of the hardwood is minimized and a more stable and long lasting floor is the result.

The same is true for other floor coverings as well. Whether it's Pergo, vinyl, or any type of laminated floor, the low water temperatures unique to properly designed radiant heating systems keep floor temperatures well within manufacturer's specifications. For more information on hardwood floors and radiant heat, as well as, studies conducted with PEX tubing and its effect on hardwood, see this web site Launstein Floors

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Q. What about carpet over a radiant floor?

A. Carpet will slow the transfer of heat to the living space, but it can't stop it. In most cases, increasing the number of aluminum heat transfer plates in a staple-up system will eliminate the increased "lag time" created by carpet. Installing a rubber carpet pad instead of a urethane one will also help. Using carpet over a heated slab will simply result in warm carpet that effortlessly heats the room.

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Q. Is your tubing potable and approved by building inspectors?

A. Yes. All tubing sold by Radiant Floor Company is rated potable and is suitable for all domestic applications. The Underwriters Laboratories NSF-61 approval numbers and rating information is stamped clearly on the tubing for the benefit of building inspectors and anyone interested in detailed design specifications.

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Q. Why is radiant heat so expensive?

A. It doesn't need to be! In our opinion, too many companies try to present radiant heat as some sort of mysterious, esoteric technology....something beyond the capabilities of a homeowner or handyman with basic construction skills. It's not! Our technicians have designed thousands of radiant systems for homeowners. These same homeowners have successfully installed a simple and highly efficient heating system that is comparable in cost to forced air or baseboard hydronic.

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Q. How much do your systems cost?

A. We sell directly to the homeowner. We have no middlemen or distributors. Our goal is to provide you with all the quality components you'll need to install your own radiant heating system....and save thousands of dollars in the process. Our technicians have years of experience working with homeowners, contractors, and architects. Our specialty is owner- installed radiant systems and we'll help you design an under floor system to suit your needs perfectly.

You'll find that by working with Radiant Floor Company you'll save up to 75% over the cost of a contractor- installed radiant system....and you won't sacrifice a bit of quality.

For more cost information, check out the prices section of this web site.

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Q. How skilled do I have to be?

A. Our systems are designed for the reasonably skilled handyperson. No special tools are required and only basic plumbing and construction experience is needed.

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Q. How many people does it take to install your system?

A. Running the radiant tubing is a two person job. Depending on the size of the installation, even having a third worker for a day or two can really make the job easier. The mechanical aspects (plumbing the system, running the thermostats wires, etc.) can often be handled by one person. That's because most of the soldering is done at the factory. Our manifolds are pre-assembled and tested for leaks. Our goal is to sell a complete installation package, complete with mounting hardware, plumbing and electrical schematics, and everything you'll need to make the job as easy as possible. We want you to spend your valuable time installing your radiant system , not running back and forth to the hardware store.

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Q. How much tubing can go in one zone?

A. A zone basically means "thermostat and pump". One thermostat monitoring the temperature in a given area, and one properly sized pump can, in theory, supply thousands of feet of tubing. In most cases, however, zones are much smaller. The important thing to remember is that most zones consist of multiple parallel "circuits" or "loops", and a loop should be no longer than 400 ft. (300 ft. for ½ PEX tubing). This is because after the hot water travels through 400 ft. of tubing, it has lost too much heat. An efficient radiant system should have only a 5 to 15 degree differential between the water going to the floor and the water returning to the heat source.

So, you can see that if your basement zone, for example, requires 1200 ft. of tubing, you'll want to use either (4) 300 ft. loops of tubing, or (3) 400 ft. loops of tubing.

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Q. How many zones will I need?

A. Our experience has shown that minimum zoning is usually the best way to go. One zone shouldn't heat two separate elevations, but in many cases, one zone per floor is the most cost effective and efficient design. However, if there are architectural or lifestyle reasons why one area of a given floor should be noticeably warmer or cooler than the rest of the floor, then multiple zoning is desirable.

One example would be a great room with lots of windows, or a sunroom. You wouldn't want a thermostat thirty feet away in the living room calling for heat in a zone that included the sunroom because the sunroom may already be twenty degrees warmer than the rest of the floor due to thermal gain from south facing windows. And by the same token, those same windows will cause a greater heat loss in the sunroom at night. That means that trying to keep the sunroom at living room temperatures overnight will most likely overheat the rest of the living space. So logically, the sunroom should be on its own zone.

It's also undesirable, and a waste of money, to over-zone. Because radiant heat is so even throughout the entire heated space, the temperature tends to equilibrate regardless of zoning. It's usually best to zone large sections of a given floor. Two or more rarely used guest bedrooms, an entire master suite, or a garage, would be examples of appropriate zones. The above mentioned sunroom, or great room with lots of windows are also good examples because, by nature, they have a different heat profile than the rest of the living space.

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Q. Do all the "loops" need to be the same length?

A. As nearly as possible, yes. The reason is simple. Uneven loop lengths create unequal pressure resistance. If you need three loops total, two are 400 ft. long, and the third is 300 ft., the short length will tend to steal the water because it offers the pump less resistance. Uneven heat is the result.

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Q. Do I need an "oxygen barrier" tubing?

A. Studies indicate that if water temperatures remain below 140 degrees, no significant amount of "oxygen diffusion" will occur. An OPEN system using a stainless steel water heater (i.e. Polaris) as a heat source will suffer no negative effects from oxygen diffusion in any case. However, radiant systems using higher water temperatures would probably benefit from oxygen barrier tubing. So would a steel boiler in a CLOSED configuration because that type of boiler is more vulnerable to oxidation than a cast iron boiler. As a result, oxygen barrier tubing could prolong the life of the boiler.

In addition, some municipal codes simply require oxygen barrier tubing in any radiant system. This despite the fact that none of the experts seem to agree on how much, if any, damage is being done to the radiant system. As mentioned above, at normal, low radiant temperatures, oxygen diffusion is minimal. Is it worth spending more on tubing in order to, maybe, prolong the life of the system? Especially since non-barrier tubing has been used for years in low temperature systems without any reports of accelerated damage.

Nevertheless, for customers meeting local code requirements, or for anyone desiring the added peace of mind, Radiant Floor Company offers oxygen barrier tubing in both 1/2" and 7/8" PEX.

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Q. How far apart are the heat diffusion plates spaced?

A. Normally, the diffusion plates are spaced 8-12" apart. However, under carpeted areas or rooms requiring maximum heat diffusion like bathrooms, run the plates continuously.

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Q. What water temperature do you recommend?

A. A water temperature range of 120 to 135 degrees is ideal.

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Q. Should radiant tubing be installed under cabinets and bathtubs?

A. Yes. Install the tubing wherever you can fit it. Avoiding cabinets and bathtubs will only make those areas colder than the warm floor. And since radiant heat tends to equilibrate over the entire heated space, the thermal energy will flow to those unheated areas anyway. It's better to warm all the objects in the room and allow them to contribute to the overall warming of the living space. Besides, from an installation standpoint, it's often more trouble to avoid cabinets, bathtubs, and showers than it is to simply run the tubing up and down each joist bay. The one exception to this rule would probably be under the refrigerator. But even there, rather than diverting the tubing, simply insulate the few feet of tubing that passes under the refrigerator.

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