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U-Tube vs. Straight Tube Radiant Heaters


One of the key design features of a gas-fired low-intensity infrared tube heater is its design flexibility. This is especially true with Detroit Radiant Products’ Re-Verber-Ray line of tube heaters. As you may know, there is rarely a one size fits all option for heating any given space. Because of this, the flexibility in designing a tube heater layout is very important. But, how do you choose between a straight tube layout and a u-tube layout? Let’s examine the differences.

Straight Tube

Gas-fired infrared tube heaters can stretch from 20 to as much as 80 feet in a straight formation. The longer the run, the more BTU’s you can pack into a space. More than one heater is usually appropriate for a vast coverage area. Straight tube layouts are often common vented to reduce penetrations.

Straight tube layouts also have the ability to include a 90-degree elbow for extra modification in the coverage area. This is the last stop before a full U-Tube configuration. Including an elbow in your heater layout is useful if you are attempting to extend the coverage area further into the middle of a space. An elbow is also a solution when a heater is mounted in the middle of a space but needs to turn towards a sidewall exhaust penetration.


For areas with high heat loss, consider a U-Tube configuration. High heat loss areas could include an outdoor patio, buildings with large overhead doors frequently opening or staying open for long periods, or older, loosely insulated builds that are tough to keep warm. U-Tubes are used for spot heating as well.


Using a U-Tube system allows a concentration of more heat in a smaller area. If the size of a room does not easily accomodate a straight tube heater, a U-Tube configuration may be appropriate. For example, with a straight tube system you would need more than a 40 foot space to pack in up to 175,000 BTU’s. However, with a U-Tube, a 175,000 BTU system would have 40 linear feet of tubing but the system itself measures only about 22 feet. This produces a concentrated heat effect in a smaller physical area while also doubling the coverage size of the heater.

Typical coverage size for a straight tube is two times the mounting height. If you mount a heater a 15 feet the coverage area from left to right on the floor beneath is 30 feet. Mounting heights for a U-Tube will be greater due ot the higher concentration of BTU’s. However, this also means you have a greater coverage area with more heat in a smaller space. Placing a U-Tube near a large overhead door would mean greater heat recovery and a more comfortable workspace if the door remains open.

Concentric Venting

One additional benefit with a U-Tube is it makes using a concentric vent kit easier. A concentric vent kit is used when only a single wall or roof penetration is desired for both exhaust venting and combustion air intake. These kits come in 3, 4, or 6-inch penetrations depending on the amount of BTU’s present in the installed tube heater. With proper clearances observed, the concentric vent kit may be an ideal choice for your space.


Straight tube layouts are appropriate for covering a large commercial or industrial space where even heat distribution is the goal; U-Tube layouts are more ideal for spot heating applications with a focus on combating high heat loss. Tube heaters are efficient in fuel consumption and heat recovery when the right design is installed in the correct application.

Our experts at Great Lakes Radiant are able to provide design assistance, heat loss calculations, and guide product slection for your next project. Contact one of our four offices today to speak with an expert. We are available by phone (888-501-0252) or email ( when you’re ready to start the process!