Radiant Tube Heaters, The
Benefits of an Infrared Tube Heater
Radiant tube heaters have several unique advantages that make them especially well suited for heating a garage or workshop. Deciding if they are the right choice for you requires you to understand a little bit about them and how they work, as well as how they are different than forced air or other types of heating.
A radiant heater warms objects much like the sun warms the earth, using infrared energy. Objects that are in the path of the infrared energy get warmed first, and then those objects warm up the surrounding air. This is very different than a forced air heater, which warms the air first and then relies on the air to warm the objects (and people) in the building.
There are two basic types of infrared gas fired heaters: low intensity and high intensity. Radiant tube heaters are the low intensity type, meaning there is no exposed flame and the surface temperature is generally no higher than 1000-1100 degrees F. High-intensity heaters (also called luminous heaters) often have an exposed flame, and surface temperatures are in the neighborhood of 1700-1800 degrees F. Both types can be designed to run off of either natural gas or propane.
The basic components of a radiant tube heater are the burner, a blower, a hollow tube, and a reflector. The air/fuel mixture is lit in the burner, and the flame extends down the length of the tube. As the tube heats up, it gives off radiant heat. A reflector above the heater helps direct the infrared energy down towards the floor, and most units can be angled at 30 or 45 degrees to direct heat where it is needed and cover a larger area.
The blower can be at either end of the tube. If the blower is at the burner end of the tube (“pushing” the flame), it is considered a pressure type system. If the blower is at the opposite end of the tube (“pulling” the flame), it is considered a vacuum type system.
Both types have pros and cons. In a pressure type system, the fan and the bearings are not exposed to the heat and moisture of the exhaust gas, which can lead to longer component life. In a vacuum type system, the tube is under negative pressure at all times, which helps prevent exhaust gases from leaking into the building. The vacuum type also can provide a long, stretched flame that results in a more uniform tube temperature.
There are a number of different tube configurations, and they come in a multitude of different lengths. The tube can be straight, U-shaped, expanded U-shaped, L-shaped, or even Z-shaped. Most radiant tube units that you will see in a garage will either be straight or u-shaped. The U-shaped heater has both the air inlet and the exhaust at the same end of the heater, which may be more convenient in some installations.
Advantages of Radiant Tube Heaters
There are lots of advantages for using radiant tube heating:
Radiant heaters are generally more efficient than forced air. The Infrared Heater Safety Council says the average fuel savings is about 30%, although some manufacturers claim even larger savings.
Compared to forced air, a given building will require a radiant heater that is rated for 15-20% lower BTU output.
Because radiant heating warms you directly instead of warming the air first, you can set the thermostat several degrees lower than you do with forced air and still feel warm.
With forced air, the warmest air always ends up at the ceiling. It can be very warm at the ceiling and still be cool at floor level. Because radiant heat is directed towards the floor, it warms the floor itself and the objects in the garage first. Radiant heating provides a more consistent temperature, without all the heat ending up at the ceiling.
With a radiant heater, there is less heat loss through ventilation and through cracks around doors and windows.
Radiant tube heaters are especially attractive as a garage heating method, for several reasons:
There is no open flame with an infrared tube heater, so it is safer for an environment with flammable vapors or lots of dust.
Combustion air can be drawn in from outside, further increasing the safety factor in an environment with flammable fumes.
An infrared tube heater doesn't have an external blower or fan to blow dust around.
When you open a garage door, you don't lose all your warmth. Since the objects in the garage are warm (and not just the air), the garage will feel warm again very quickly once the door is closed.
If you have a concrete floor, the concrete absorbs energy from the infrared tube heater and acts as a heat sink. Once the floor is warm, it will radiate heat for a long time, keeping you nice and toasty!
As great as radiant tube heaters are for a garage, like anything else there are of course a few drawbacks. The biggest one is the up front cost. A radiant infrared tube heater can cost roughly twice as much to purchase as a similar capacity convection-type gas fired heater. However, you have to remember that there will be an average of 30% savings on your fuel costs, so the infrared tube heater will eventually pay for itself.
Also, the further away you get from a radiant heater, the cooler it gets. And since infrared energy does not circulate like air does, you will not feel as warm if you are "shaded" from the radiant heater.
Choosing an Infrared Tube Heater
Make sure that you get a model that is sized appropriately. Any gas fired heater that is too small won't be able to keep up on cold winter mornings, but one that is too large will cycle on and off too often. Cycling on and off will cause large temperature fluctuations and increased fuel consumption. The manufacturer will be able to help you choose one that is the correct size for your garage.
Look at both the combustion efficiency AND the thermal efficiency when comparing different models. Some gas fired heaters have the flue pipe inside the air inlet, which will preheat the combustion air and increase efficiency.
Some models are two-stage, meaning that they can operate at low and high outputs, which is a desirable feature.
Make sure that the reflector completely covers the entire tube, including any u-bends, or else some of the heat will be lost to the ceiling.
Some manufacturers include the thermostat and venting kit, while others charge extra for them. Make sure you figure that into any price comparisons.
Most radiant tube heaters work best with a mounting height between 10 and 30 feet, although some can be mounted as low as six feet. Make sure you get one that is suitable for the height of the ceiling in your garage.
Radiant heating is a great option for a garage, especially if you have access to inexpensive natural gas. They are more efficient than forced air convection type units, and have a quick recovery time after opening a garage door. They are safe for environments with flammable vapors, and don’t blow dust around when they are on. All in all, radiant tube heaters are one of the best options for heating a garage or workshop.
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