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Watts Radiant | Floor Heating & Snow Melting

Fequently Asked Questions

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.

How is heat transferred?

Heat is transferred from one location, or body, to another by three basic modes. These modes are Convection, Conduction and Radiant Heat.

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. Think of a hot air balloon. It floats because the hot air inside is less dense than the cool air outside. This literally causes the balloon to float in much the same way a boat floats on water.

Another way to think of this is to imagine a metal skillet placed on a stove burner. When the burner is turned on the handle is still cool to the touch, but as the bottom of the pan warms, the heat moves from this now warm source, to the cooler outer edges. Eventually the handle will become too hot to handle and a cooking mitten will be required to handle the skillet.

Explain the types of Heat Transfer

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.

What type of piping should I use?

Watts Radiant offers two different types of radiant tubing options, each has its own unique qualities. Watts Radiant's 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 Radiant 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.

As long as the tubing chosen is installed properly and per the manufacture's recommendations, the radiant heat system will perform beyond expectations.

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.

Please note: This FAQ document is designed to answer common questions. Refer to the product's installation manual or appropriate instructions and warnings regarding installation, use and maintenance.

Please note: This FAQ document is designed to answer common questions. Refer to the product's installation manual or appropriate instructions and warnings regarding installation, use and maintenance.

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