Frequently Asked Questions - Radiant

1. What type of maintenance is required for my radiant heating system?
2. What type of glycol should I use in my snow melt system?
3. How often should I check my glycol system?
4. Can I use any kind of fuel source in my radiant heating system?
5. Can I air condition my home with a radiant floor heating system?
6. I'm planning a large house with high ceilings and lots of windows. Is radiant floor heating practical?
7. Can my radiant system also melt snow and ice?
8. Do older radiant heating systems make the floors too hot?
9. Does a radiant heating system have any impact on air circulation or cleanliness?
10. How much should a typical radiant floor heating system cost?
11. Does a radiant heat system cost less to operate than the alternatives?
12. Are energy saving set-back thermostats desirable on a radiant floor heat system?
13. Does a radiant house take a long time to heat up from a cold start?
14. How is heat transferred?
15. What type of piping should I use?
16. Are baseboard "radiators" really radiant heat?
17. Where do most people install electric floor heating?
18. Does an electric floor mat weaken or strengthen my floor?
19. Is electric floor warming efficient?
20. Do I need floor warming if my bathroom is heated?
21. Is there any advantage to a "low voltage" electric radiant heating system?
22. What voltage do I need for my electric floor heating?
23. Does 120 VAC work better than 240 VAC?
24. What makes your heating elements special?

1. What type of maintenance is required for my radiant heating system?

Most maintenance items center on the pumps and boilers. For the most part, the pumps used today are maintenance free. They use water to lubricate the bearings, which allow for a quieter and efficient life span. In general, these pumps have an estimated life span of 10 years. Most boiler installers will offer a yearly maintenance package, which includes cleaning and general up-keep. Different boiler types will require different maintenance.

2. What type of glycol should I use in my snow melt system?

An inhibited Propylene Glycol solution should be used. Make sure the glycol used is rated for hydronic radiant heating systems and not for automotive engines. Hydronic glycols are formulated differently for the metals seen in boilers, pumps and other system components.

3. How often should I check my glycol system?

Glycol systems should be checked at least once a year to ensure the system pH levels have not dropped below recommended levels. Glycol in general is acidic. The inhibitors that are added to them help neutralize the system pH, and help protect the system components. As the system ages, the inhibitors break down, causing the system pH to drop. At this point more inhibitors should be added to the radiant floor heating and snow melt systems. The system will reach a point where it will require a complete flush and re-fill. This is usually around 5-7 years, but will depend on the glycol used.

4. Can I use any kind of fuel source in my radiant heating system distiller?

Any natural resource can be used to fire the heat source, natural gas, propane, electric, wood, geo-thermal, etc. It does not matter what the heat source is, as long as it can provide the necessary BTU's (energy) at the required design temperatures. There will be a variance between heat sources based on efficiency, response, cost and capacity. Choose the one that bests suites the needs of the heating system.

5. Can I air condition my home with a radiant floor heating system?

It is not advised to try to "air condition" a space with a radiant heating system. In theory a radiant floor can be used to cool a space. In order to lower the internal temperature of a space, the cooling surface has to drop in temperature. This lower temperature "pulls" the heat from the air and is then carried away through the liquid in the tubing below the floor.

Radiant floors can be used to help reduce the overall cooling load in a space. In most cases, an air component will still be required to remove moisture from the air, or to dehumidify the space. If sized correctly, a radiant floor cooling system can help reduce the overall operational cooling costs, while providing a more even internal air temperature.

6. I'm planning a large house with high ceilings and lots of windows. Is radiant floor heating practical?

High ceilings and "lots of windows" are one of the main reasons why radiant heat is chosen as a building heating system. Since hot air rises, in a forced air heating system all of the nice, usable heat is first sent to the ceiling. This may be anywhere from 10 to 20 feet up. By the time this air makes its way to your level, about 6-ft. off the ground, it has lost most of its energy and has started to get pushed down by the other hot air entering the room. If this air is cooler than when it entered, where did all of its heat go? Right out the ceiling.

Radiant heating works in just the opposite way. Since a radiant heat system stores its energy in the floor, all of the room's warmth is kept right where it needs to be, on the floor where you are. The ceiling in a radiant floor system is always much cooler than the floor area, just the way you would want it. This cooler ceiling temperature means less energy is being wasted to the outside. Less waste means higher efficiency.

7. Can my radiant system also melt snow and ice?

Snow melt systems are becoming more and more popular, especially in areas where nature conservation is important. Snow melt systems eliminate all of the other necessary chemicals and pollutants used today to keep areas free of ice and snow. No more salt to track indoors. No more uneven melting. Streams and rivers no longer get polluted with unnecessary additives.

Snow melt systems also protect your investment. Slabs last longer. Salt and other chemical additives will begin to break down the surface of a concrete slab over the years. For brick paver applications, snowmelt systems provide a certain amount of physical protection. Keep dangerous snow plows away and retain the beauty of your investment.

8. Do older radiant heating systems make the floors too hot?

In the past, radiant heating systems were designed and installed in much the same way as a conventional baseboard system. High temperatures and simple controls were used to control the radiant heating system. These high temperatures were in fact too high from a comfort standpoint. The higher the water temperature in the floor, the higher the floor surface temperature will become. For all systems a maximum floor temperature of 85°F is maintained to ensure comfort. In these older systems, the floor temperature could actually exceed this limit, causing the floor to feel uncomfortable.

Today there are endless arrays of controls and piping methods to ensure this does not happen. Lower water temperatures are maintained to prevent overheating. Indoor/outdoor reset systems are used to help predict heating needs and to increase response times. Radiant heating technology is becoming more and more advanced every day.

9. Does a radiant heating system have any impact on air circulation or cleanliness?

Yes. Since the air is not carrying the heating, and is not being forced to move through the house, less dust and mold is being distributed. This helps to keep allergies and other ailments to a minimum.

10. How much should a typical radiant floor heating system cost?

System costs will vary greatly depending on the installation requirements, control choices, and project size. Simple radiant heat systems in large slabs in temperate zones cost only slightly more than the alternatives. However, if you select the many options and features that radiant can offer your home, the first cost will be higher.

Remember that the principal advantages of radiant are comfort and lower operating costs. You should review your plans and requirements with your installing contractor to get a firm price on a turn-key system.

11. Does a radiant heat system cost less to operate than the alternatives?

Yes they do. The amount of savings will vary depending on the heat loss, how well the structure is built, how well the building is insulated and the natural fuel source being used. For the most part radiant floors will operate anywhere from 25% to 40% more efficiently that other forms of forced air heating.

12. Are energy saving set-back thermostats desirable on a radiant floor heat system?

It is not recommended to use a set-back thermostat on a radiant heat system. Radiant heat systems do not respond as rapidly as a convection type heating system, mainly because a radiant floor heat system uses the mass of the building to store energy and to provide a more even heat.

13. Does a radiant house take a long time to heat up from a cold start?

Most radiant floor heat systems take about a day to come up to full temperature. The reason for this is due to how the radiant heating system stores energy. Before a radiant floor can emit energy (heat) into a space, it first has to raise the floor temperature. Depending on the floor construction and the initial floor temperature, this start up time may be anywhere from a few hours to a few days. Slab on grade floors will see the largest start up time, mainly because they will have the highest mass value.

14. How is heat transferred?

Heat is transferred from one location to another by Convection, Conduction and Radiant Heat.
Convective heat transfer is what most of us are familiar with. This is how our forced air heating system or our baseboard system transfers energy (heat) to a space. Air moves over a heating element, becomes warmer and expands into the space. In a forced air environment, most of the hot air is at the ceiling, much the same way the hot air balloon rises, so will the warm air in a room heated with forced air. Convective heat transfer is the least efficient means to transfer energy.
Conductive heat transfer refers to two surfaces touching each other. Imagine a metal pan on the stove. If your hand is positioned an inch above the hot handle, you really won't feel much from the handle, and you can keep your hand there as long as you wish. But, when the handle is touched, your hand instantly begins to feel hot. This is conductive heat transfer. The pot is giving off the energy (heat) in the handle to your hand in a very fast, efficient manner. Conduction is one of the more efficient modes of heat transfer.
Radiant heat transfer is the best because it isn't slowed down by air. Radiant energy is only felt when the energy wave strikes another surface. This means the surrounding surfaces all reach set temperature. By enclosing your body by warm surfaces, we can better control how our bodies lose heat. Radiant floor heat means better comfort with higher efficiency. One basic rule to all three modes is this: heat does not rise, hot air rises. Heat moves from a hot source to a cold source.

15. What type of piping should I use?

Watts offers three different types of radiant tubing options, each has its own unique qualities. Onix tubing is the most diversified product in the market today. It is the only product that can be installed under a frame floor with no additional accessories required (no heat transfer plates, no special clips). Since the Onix does not expand or contract with temperature changes, it is the quietest system around.
Watts also offers a PEX line (cross-linked Polyethylene). This product is typically used in slab or thin-slab applications, but can also be installed under a frame floor with the use of heat transfer plates or clips.
In addition, we offer polyethylene raised temperature (PE-RT) tubing constructed with five layers of material, thus giving it significant strength. Flexible and easier to install than other piping materials, PE-RT tubing can be used in hydronic radiant heating, cooling, snow melting, and distribution piping applications. As long as the tubing chosen is installed properly and per the manufacture's recommendations, the radiant heat system will perform beyond expectations.

16. Are baseboard "radiators" really radiant heat?

Baseboards are actually convectors. They heat the air by creating a temperature differential across the fins. This temperature difference "pulls" the cooler air across the heated fins. The warmed air then rises, adding to the pull.
Radiators operate in a similar fashion as a baseboard unit, but with one difference. Because radiators have a much higher mass and tend to have more exposed heated surface, they do provide a certain amount of radiant heat to a space.

17. Where do most people install electric floor heating?

Bathrooms are the most common place, followed by kitchens and entryways. Mudrooms are also a great place for a warm floor.

18. Does an electric floor mat weaken or strengthen my floor?

Watts mats have been tested by the Tile Council of North America (TCNA) to ASTM C 627, officially known as "A Standard Test Method for Evaluating Ceramic Floor Tile Installation Systems Using the Robinson-Type Floor Tester." It tests for deflection under increasing weight loads on a wooden framed floor or with a concrete slab floor. Our mats passed these tests for HEAVY classifications, such as shopping malls and commercial areas. Mats apparently add tensile strength to the tile and mortar sandwich. When in doubt, follow TCNA and ANSI (American National Standards Institute) specifications.

19. Is electric floor warming efficient?

Radiant floors warm people and objects directly without overheating the air. Electric radiant converts nearly all its energy into a usable form. You can set the home thermostat lower and still be comfortable. Use a programmable thermostat and the system automatically sets to a lower temperature when the rooms are not in use. Insulate below the floor or below the heating system and on top of the concrete slab to allow the system to respond faster and use less energy.

20. Do I need floor warming if my bathroom is heated?

Even when bathrooms are heated with forced air or baseboard, tile floors can feel cold. Imagine starting the day by stepping out of the shower onto a warm, comfortable tile floor!

21. Is there any advantage to a "low voltage" electric radiant heating system?

No. Watts and competitors deliver about the same amount of energy to the floor. They may use less voltage, but require higher amperage to be able to generate the same wattage (heat delivery). Watts, however, uses line voltage, and lower amperage to deliver the necessary wattage. This allows a larger system to be installed with a smaller breaker. Low-voltage systems use transformers that are noisy, hot and hard to hide, both visually and acoustically. All North American bathrooms have access to 120 Volt (VAC) power and by code, must install electric floor heating systems with GFCI protection. A GFCI detects ground faults and will disconnect the energy to the heating system within milliseconds if necessary.

22. What voltage do I need for my electric floor heating?

Watts electric heating systems are built for 120 VAC or 240 VAC (for warming larger areas).

23. Does 120 VAC work better than 240 VAC?

Both systems have the same efficiency. The best option is to see what power is available for your installation. 240 VAC is more common outside the United States and in commercial applications. A Watts thermostat can control up to 150 square feet of heated floor on 120 VAC or 300 square feet on 240 VAC.

24. What makes your heating elements special?

Heating elements must resist job-site abuse and long-term aging. Watts uses an expensive wire insulation called ETFE (ethylene tetrafluoroethylene). The physical properties of this polymer are unmatched for the application, notably its water resistance, dielectric properties and long-term temperature aging. We also use oxygen-free alloys in our heating elements to give them greater longevity. The dual heating elements are protected with a copper ground shield and jacketed cables are coated with either a highly visible water resistant PEX polymer jacket or a very resilient TPU jacket that provide outstanding properties that avoid damage from minor job-site abuses. No one builds a better heating element wire.