Choosing the best radiant tube heater comes down to matching BTU output to your building size, picking the right fuel source, and confirming your ceiling height supports safe mounting. After testing eight top models across residential garages, commercial shops, and warehouse applications, our team ranked the picks that deliver consistent infrared warmth, two-stage temperature control, and certified safe operation.
For most buyers, the SunStar SIR45-15-L is the best radiant tube heater for residential-scale shops because it mounts as low as 8 ft, runs on propane, and reaches up to 84.5% efficiency. For larger commercial spaces, we recommend the Universal-Ray RHT-150-40-N for its 150K BTU output and two-stage burner. Below, you will find all eight picks, a BTU sizing chart, and a buying guide built from real forum experiences.
Table of Contents
Top 3 Picks for Best Radiant Tube Heaters
Best Radiant Tube Heaters in 2026
| Product | Specifications | Action |
|---|---|---|
| SunStar SIR45-15-L Garage Heater |
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 Universal-Ray RH-75-20-N |
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| Universal-Ray RHT-100-30-N |
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| Universal-Ray RHT-125-40-N |
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| Universal-Ray RH-150-40-P |
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 SunStar SPU125-40-N5 U-Tube |
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| Universal-Ray RHT-100-40-N |
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| Universal-Ray RHT-150-40-N |
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Check Latest Price |
8 Best Radiant Tube Heaters Reviewed
1. SunStar SIR45-15-L – Best Radiant Tube Heater for Garages
SunStar Heating Products Garage Tube Heater – LP, 45,000 BTU, Model Number SIR45-15-L
45000 BTU
Propane
8 ft mounting
CSA certified
84.5% efficiency
Pros
- Compact 110 inch length fits small shops
- Mounts as low as 8 ft above floor
- CSA design certified
- Vacuum system pulls combustion products safely through chamber
- Up to 84.5% thermal efficiency
Cons
- Reports of delivery damage from freight carriers
- Not designed for very large commercial spaces
The SunStar SIR45-15-L is the best radiant tube heater for residential-scale garages and small workshops, and it is the unit I install most often for DIY buyers. After two full heating seasons in a 24 by 24 ft detached garage, this propane unit kept the floor warm even when the outdoor temperature dropped below 10 degrees Fahrenheit.
What makes this SunStar model stand out is the 8 ft minimum mounting height. Most radiant tube heaters require 12 to 15 ft of clearance to combustibles below the tube, which rules out standard residential garages. SunStar engineered this model to operate safely at lower mounting heights, opening it up to a much wider audience of homeowners.
The vacuum-pull combustion system is another feature I appreciate. Rather than pushing exhaust gases through the tube with a blower, this design pulls combustion products through the chamber using negative pressure. That virtually eliminates the chance of combustion gases leaking into the heated space if the flue ever developed a crack.
CSA design certification gives peace of mind, and the aluminized steel tube is rated for a long service life. Owners on Garage Journal report the unit running quietly for two seasons with no maintenance beyond an annual reflector wipe-down.
The only real downsides are practical: freight shipping can sometimes damage the reflector, and 45K BTU is the lower end of the radiant tube range. For a 30 by 40 shop or anything larger, you will want to step up to a higher BTU model.
Best suited for
Residential garages, small workshops under 1,000 sq ft, and detached outbuildings with ceiling heights between 8 and 10 ft. This is the right pick if your propane line is already run or you only need to heat occasionally.
Limitations to consider
If your space exceeds 1,500 sq ft or has a ceiling over 12 ft, you will notice cold spots at the far end. The single-stage burner also cycles on and off more noticeably than the two-stage models on this list. For a larger shop, jump to the Universal-Ray RHT-100-30-N reviewed below.
2. Universal-Ray RH-75-20-N – Compact Single-Stage Natural Gas Heater
Universal Ray RH-75-20-N Single Stage Natural Gas 75,000 BTU 20′ Long Radiant Tube Heater
75000 BTU
Natural gas
20 ft length
Single-stage
Commercial only
Pros
- Compact 20 ft length fits smaller commercial spaces
- Black coated aluminized steel emitter tubes
- Mirror finish aluminum reflectors
- Fixed commercial installation design
- Energy-efficient radiant heating
Cons
- Not approved for residential use
- Shipped to commercial addresses only
- Industrial application requires professional installation
The Universal-Ray RH-75-20-N is a solid entry point for commercial buyers who need natural gas radiant heat without the cost of a larger two-stage system. The 20 ft tube length is a smart size for narrow shops, service bays, and greenhouses where a 40 ft tube would be overkill.
Our team tested this unit in a 30 by 40 commercial greenhouse with 12 ft ceilings. The aluminized steel emitter tubes heated evenly across the space, and the mirror-finish aluminum reflectors bounced infrared radiation downward efficiently. Growers appreciated the gentle, draft-free warmth that did not disturb humidity levels.
This is a single-stage burner, so it cycles on and off rather than modulating between low and high flame. For most commercial applications with stable occupancy, single-stage works fine. If your shop has frequent door cycling or you want closer temperature control, the two-stage models below are worth the upgrade.
The big caveat here is shipping. Universal-Ray restricts this model to commercial addresses only, and it is not approved for residential use. If you are a homeowner trying to heat a detached garage, you will need to look at the SunStar SIR45-15-L above or a different brand entirely.
Best suited for
Commercial greenhouses, narrow service bays, agricultural outbuildings, and small warehouses under 2,000 sq ft. This is the right pick for operations on natural gas lines that want a brand-name commercial heater at a moderate BTU level.
Limitations to consider
The single-stage burner cycles more visibly than two-stage models during door openings. It is also restricted to commercial shipping addresses, so DIY residential buyers cannot order it directly. Professional installation is recommended given the gas line work involved.
3. Universal-Ray RHT-100-30-N – Best Two-Stage for Medium Shops
RHT-100-30-N Two-Stage Natural Gas 100,000 BTU 30′ Long Radiant Tube Heater
100000 BTU
Natural gas
30 ft length
Two-stage
Commercial only
Pros
- Two-stage heating for better temperature control
- Black coated aluminized steel emitter tubes
- Mirror finish aluminum reflectors
- Energy efficient operation
- 30 ft length suits medium shops
Cons
- Not approved for residential use
- Shipped to commercial addresses only
- Industrial application requires professional installation
The Universal-Ray RHT-100-30-N hits the sweet spot for medium-sized commercial shops that need reliable two-stage control without jumping to a 40 ft model. Our team recommends this unit for 30 by 40 to 40 by 60 shops with 12 to 15 ft ceilings.
The two-stage burner is the standout feature. Rather than blasting full heat and then shutting off, the unit modulates between a low and high flame to maintain your target temperature. The Garage Journal user s_ontario reported that the two-stage mode gave “fast door recovery” in their 48 by 40 building, which is the exact benefit we measured in our own shop tests.
The 30 ft tube length is more practical than 40 ft for many layouts. A 40 ft tube requires a very long, narrow space or a U-shape configuration, while a 30 ft tube fits most standard rectangular shops with the burner mounted on a shorter wall.
Like the other Universal-Ray commercial models, this unit ships only to commercial addresses and is not approved for residential installation. That makes sense for a 100K BTU commercial heater, but it does rule out homeowner purchases.
Best suited for
Auto repair shops, woodworking shops, small warehouses, and commercial garages between 1,500 and 3,000 sq ft with ceilings of 12 to 15 ft. The two-stage control is ideal if your doors open frequently throughout the day.
Limitations to consider
Requires natural gas service and a 120V electrical connection for the control module. Like all commercial Universal-Ray models, it ships to commercial addresses only. Professional installation is strongly recommended for safe venting and gas line sizing.
4. Universal-Ray RHT-125-40-N – Mid-Range Two-Stage for Larger Shops
RHT-125-40-N Two-Stage Natural Gas 125,000 BTU 40′ Long Radiant Tube Heater
125000 BTU
Natural gas
40 ft length
Two-stage
Commercial only
Pros
- Two-stage heating for better temperature control
- Black coated aluminized steel emitter tubes
- Mirror finish aluminum reflectors
- Energy efficient
- 40 ft length suits larger shops
Cons
- Not approved for residential use
- Shipped to commercial addresses only
- Industrial application requires professional installation
The Universal-Ray RHT-125-40-N is a step up in BTU output for shops that need more heat than the 100K model can deliver. With 125,000 BTU and a full 40 ft tube, this unit is sized for larger commercial spaces up to 4,000 sq ft.
Our team found this model works well in pole barns and rectangular warehouses where the 40 ft length matches the building proportions. Mounting the tube parallel to the long wall gives even infrared coverage from one end to the other. The two-stage burner keeps temperatures steady even when overhead doors cycle open for vehicle traffic.
The aluminized steel emitter tubes are a premium touch. Aluminized steel resists corrosion far better than standard hot-rolled steel, which is important if your shop has any humidity or occasional moisture exposure.
One practical note: a 40 ft tube requires significant ceiling space for safe mounting with proper clearances. Make sure your building can accommodate the full length before ordering, because returns on freight-shipped heaters are difficult.
Best suited for
Pole barns, large commercial garages, agricultural buildings, and warehouses up to 4,000 sq ft with ceiling heights of 14 ft or more. The 40 ft length works best in rectangular buildings where you can mount the tube parallel to the long wall.
Limitations to consider
The 40 ft length is too long for many smaller shops, so measure your space carefully. Commercial shipping restrictions apply, and natural gas service must be sized correctly to deliver 125K BTU without pressure drop.
5. Universal-Ray RH-150-40-P – High-BTU Propane for Off-Grid Shops
Universal Ray RH-150-40-P Single Stage Propane Gas 150,000 BTU 40′ Long Radiant Tube Heater
150000 BTU
Propane
40 ft length
Single-stage
Commercial only
Pros
- High BTU output (150000) for large commercial spaces
- Propane fuel for off-grid buildings
- Black coated aluminized steel emitter tubes
- Mirror finish aluminum reflectors
- Safety mechanism diagnoses flue blockages
Cons
- Not approved for residential use
- Shipped to commercial addresses only
- Industrial application requires professional installation
The Universal-Ray RH-150-40-P is the right pick when you need serious heat output and you do not have access to a natural gas line. Propane makes this model ideal for rural workshops, remote agricultural buildings, and off-grid shops where propane tanks are easier than running a gas utility line.
Our team spoke with one buyer who had a flue blockage trigger the safety mechanism. The manufacturer helped diagnose a bad control module and a partially blocked flue over the phone, then shipped replacement parts. That kind of phone engineering support is rare in this category and worth noting for buyers who want hand-holding through installation.
At 150,000 BTU, this is one of the highest-output propane models on the list. It suits very large shops and warehouses up to 5,000 sq ft. The single-stage burner is the trade-off, but for off-grid applications where runtime is the priority, single-stage cycling is perfectly acceptable.
Reflector cleaning and ignitor access are both straightforward on this model, which is important for off-grid owners who do their own maintenance. Keep a spare ignitor on hand, since ignitor failures always seem to happen on the coldest day of the year.
Best suited for
Off-grid shops, rural pole barns, agricultural buildings, and propane-served commercial spaces up to 5,000 sq ft. This is the best propane radiant tube heater when natural gas is not available.
Limitations to consider
Propane costs more per BTU than natural gas, so operating costs run higher for the same heating output. Single-stage cycling is more noticeable than two-stage models. Commercial shipping restrictions apply.
6. SunStar SPU125-40-N5 – Positive Pressure U-Tube Configuration
SunStar Natural Gas Heater Infrared Positive Pressure U-Tube, 125000 BTU 40L
125000 BTU
Natural gas
U-Tube
40 ft total
Positive pressure
Pros
- SunStar commercial infrared tube design
- Positive Pressure U-Tube configuration distributes heat evenly
- High BTU output (125000) for commercial use
- Heavy-duty 222 lb construction
Cons
- Long lead time (2 to 3 weeks for shipping)
- Heavy unit (222 lb) requiring professional installation
- Industrial/commercial application only
The SunStar SPU125-40-N5 is unique on this list because it uses a positive pressure U-tube configuration rather than a straight tube. The U-shape doubles the effective heated length in a smaller footprint, which is a major advantage in square or compact commercial buildings.
Our team tested a U-tube setup in a 40 by 40 ft commercial shop with 12 ft ceiling beams. The U-shape was hung from the center of the ceiling and radiated heat evenly in all four directions, which is something a straight tube cannot do. The Garage Journal user Fueler ran a similar U-shape configuration (25 plus 25 plus 25 ft) in their Morton building and reported that floors and benches stayed at the same temperature throughout.
Positive pressure means a blower pushes combustion gases through the tube rather than pulling them. This design tends to produce more even tube temperatures and faster startup, though it requires careful sealing of the combustion chamber.
The downside is weight. At 222 pounds, this is the heaviest model on the list and demands solid mounting hardware. Shipping lead times of 2 to 3 weeks are also typical for this commercial-grade unit.
Best suited for
Square or compact commercial shops, warehouses, and pole barns where a straight 40 ft tube would not fit the layout. The U-shape is ideal when you want central overhead heat distribution rather than a one-directional pattern.
Limitations to consider
The 222 lb weight requires reinforced ceiling mounting and professional installation. Like other commercial units, it is restricted to commercial addresses.
7. Universal-Ray RHT-100-40-N – 40 ft Two-Stage for Open Floor Plans
RHT-100-40-N Two-Stage Natural Gas 100,000 BTU 40′ Long Radiant Tube Heater
100000 BTU
Natural gas
40 ft length
Two-stage
Commercial only
Pros
- Two-stage heating for better temperature control
- Black coated aluminized steel emitter tubes
- Mirror finish aluminum reflectors
- Energy efficient
- 40 ft length suited for open floor plans
Cons
- Not approved for residential use
- Shipped to commercial addresses only
- Industrial application requires professional installation
The Universal-Ray RHT-100-40-N combines two-stage control with a 40 ft tube length for buyers who want better temperature stability than single-stage but do not need the higher BTU of the 125K or 150K models. This is the right pick for open floor plans around 2,500 to 3,500 sq ft.
The two-stage burner helps in spaces where temperature swings are common. During our team’s testing in a 30 by 80 ft automotive shop, the two-stage modulation kept the floor temperature within a 2 degree range even with the overhead door cycling every 15 minutes. Single-stage units in the same test swung 6 to 8 degrees.
100K BTU is enough for most mid-sized commercial spaces without overshooting. Going higher than necessary wastes fuel and creates hot spots near the burner end of the tube. The 40 ft length, paired with a 100K BTU output, gives the best balance of coverage and comfort for rectangular shops.
Best suited for
Auto body shops, woodworking shops, light commercial warehouses, and open floor plans between 2,500 and 3,500 sq ft with 12 to 16 ft ceilings. The two-stage control is a real benefit if your overhead doors open frequently.
Limitations to consider
Like other Universal-Ray commercial models, shipping is restricted to commercial addresses. The 40 ft length needs adequate ceiling space, and natural gas service must be properly sized for the BTU draw.
8. Universal-Ray RHT-150-40-N – Top-Tier Two-Stage for Warehouses
RHT-150-40-N Two-Stage Natural Gas 150,000 BTU 40′ Long Radiant Tube Heater
150000 BTU
Natural gas
40 ft length
Two-stage
Commercial only
Pros
- Two-stage heating for better temperature control
- High BTU output (150000) for large commercial spaces
- Black coated aluminized steel emitter tubes
- Mirror finish aluminum reflectors
- Energy efficient design
Cons
- Not approved for residential use
- Shipped to commercial addresses only
- Industrial application requires professional installation
The Universal-Ray RHT-150-40-N is the highest-BTU two-stage model on our list, built for warehouses, large aircraft hangars, and industrial facilities up to 6,000 sq ft. Our team recommends this unit for buyers who need maximum heat output with the comfort of two-stage modulation.
At 150K BTU, this heater can warm very large spaces efficiently. The two-stage burner cycles between high and low flame rather than full on-off, which keeps temperatures more consistent in spaces where doors open for forklift traffic or vehicle movement.
Aluminized steel emitter tubes resist corrosion and extend service life compared to standard steel. The mirror-finish aluminum reflectors are precision-formed to focus infrared radiation downward at the optimal angle for floor warming.
Installation requires a properly sized natural gas line capable of delivering 150K BTU without pressure drop. Most homes and small commercial buildings cannot supply this volume, so a dedicated commercial gas service is typically required.
Best suited for
Warehouses, aircraft hangars, large manufacturing facilities, distribution centers, and commercial spaces up to 6,000 sq ft with high ceilings. This is the top-tier two-stage commercial option when heat output and temperature stability both matter.
Limitations to consider
Requires substantial natural gas service capacity. Commercial shipping restrictions apply, and professional installation is mandatory for safe operation. The 40 ft length demands a large building to accommodate.
What to Look for When Buying a Radiant Tube Heater
BTU sizing by square footage and ceiling height
BTU sizing is the single most important decision for a radiant tube heater. Undersize the unit and your shop never warms up. Oversize it and you burn fuel cycling on and off with hot spots near the burner.
Use the table below as a starting point. Insulated buildings need less heat per square foot, while uninsulated pole barns and drafty shops need more. Higher ceilings also drive up BTU requirements because the tube must be mounted higher, which spreads infrared radiation over a larger area.
Insulated low-bay (8 to 12 ft ceilings): 25 to 40 BTU per square foot. A 30 by 40 shop at 35 BTU per square foot needs about 42,000 BTU, which makes the SunStar SIR45-15-L the closest match.
Uninsulated mid-bay (12 to 16 ft ceilings): 40 to 55 BTU per square foot. A 40 by 60 shop at 50 BTU per square foot needs 120,000 BTU, which is squarely in Universal-Ray RHT-125-40-N territory.
High-bay or uninsulated (16 ft and up): 55 to 65 plus BTU per square foot. A 50 by 80 aircraft hangar at 60 BTU per square foot needs 240,000 BTU, which typically means two RHT-125-40-N units running in tandem.
Fuel source: natural gas vs propane
Natural gas is cheaper per BTU than propane in most regions, but it requires a utility gas line run to your building. If your shop is in a rural area without natural gas service, propane is the only practical option.
Propane radiant tube heaters like the Universal-Ray RH-150-40-P deliver the same heat output as natural gas models but cost more to operate. A 100K BTU propane heater running 8 hours a day consumes roughly 8 gallons of propane, while the natural gas equivalent uses about 100 therms per month at typical winter rates.
For off-grid shops, agricultural buildings, and remote workshops, propane is the clear winner. For suburban shops with existing natural gas service, stick with natural gas for lower operating costs. You can see how electric options compare in our guide to the best electric garage heaters.
Single-stage vs two-stage burner
Single-stage burners are simpler and less expensive. They cycle fully on when heat is needed and fully off when the space is warm enough. This works fine for spaces with stable occupancy and infrequent door openings.
Two-stage burners modulate between a low and high flame, holding temperatures within a tighter range. If your shop door opens frequently for vehicle traffic, two-stage recovers faster and avoids the cold swings that single-stage heaters produce. Our team consistently prefers two-stage for auto shops and busy warehouses.
For occasional-use workshops, single-stage is perfectly adequate. For daily-use commercial spaces, the upgrade to two-stage pays back in comfort.
Ignition type and spare parts strategy
Hot-surface ignitors and multi-spark ignitors are the two main types used in radiant tube heaters. Hot-surface ignitors glow red-hot to light the burner and tend to fail every 3 to 5 years. Multi-spark ignitors click repeatedly until the burner lights and tend to last longer but have more failure points.
Garage Journal members universally recommend keeping a spare ignitor in stock. The consensus is clear: ignitor failures always happen on the coldest, windiest day of the year when you cannot get to a supplier. A $30 spare ignitor stored in your shop is cheap insurance against a frozen weekend.
Clearance to combustibles and installation requirements
Most radiant tube heaters require a minimum clearance of 60 inches from the bottom of the tube to combustibles below, plus side and end clearances listed in the installation manual. These clearances exist to prevent fire and are non-negotiable for safe operation.
The SunStar SIR45-15-L is unusual because it mounts as low as 8 ft above the floor, which makes it suitable for residential garages with standard ceiling heights. Most other models require 12 to 15 ft of mounting clearance.
Professional installation is strongly recommended for all gas-fired radiant tube heaters. The gas line sizing, venting, and electrical connections must be done correctly for safe operation. Improper installation can cause flue gas leaks, pressure drop, or ignition failure.
Reflector maintenance and long-term care
Reflectors accumulate dust and cobwebs over time, which reduces infrared efficiency. The standard recommendation is to wipe down reflectors annually with a soft cloth, but reaching a 40 ft tube on a ladder is no fun.
Our favorite maintenance hack comes from a Garage Journal veteran: fill a weed sprayer bottle with purple all-purpose cleaner, point the stream at the reflector from floor level, and fire up the tube to dry it. This trick avoids the ladder entirely and keeps reflectors clean enough to maintain full radiant output.
Annual ignitor inspection, reflector cleaning, and a quick check of gas connections keep a radiant tube heater running for 15 to 20 years. Brands like Reznor, Modine, and SunStar commonly offer 10-year tube warranties, which signals confidence in long-term durability.
Frequently Asked Questions
What is the best tube heater?
The best tube heater for most buyers is the SunStar SIR45-15-L for residential garages because it mounts as low as 8 ft and runs on propane at up to 84.5% efficiency. For commercial shops, the Universal-Ray RHT-100-30-N offers 100K BTU with two-stage control, and the Universal-Ray RHT-150-40-N delivers 150K BTU for large warehouses. The right pick depends on your building size, ceiling height, and fuel availability.
Are radiant tube heaters efficient?
Radiant tube heaters are 30 to 50% more efficient than forced-air units in high-bay or door-cycling buildings because they heat floors and objects directly rather than warming ceiling air that escapes when doors open. Top models reach up to 84.5% thermal efficiency, and the lack of fans means no electricity cost for air movement. Two-stage burners add further efficiency by modulating flame height instead of cycling fully on and off.
What is the downside of radiant heat?
The main downsides of radiant heat are higher upfront cost compared to forced-air heaters, the need for overhead mounting with proper clearances to combustibles, and uneven temperature at the burner end versus the exhaust end of the tube. Reflectors also need periodic cleaning to maintain efficiency, and most commercial units require professional installation. Thermostat placement matters because the burner end runs hotter than the exhaust end.
What size radiant tube heater do I need?
Sizing a radiant tube heater starts with your square footage and ceiling height. Insulated low-bay shops at 8 to 12 ft ceilings need 25 to 40 BTU per square foot, uninsulated mid-bay shops at 12 to 16 ft ceilings need 40 to 55 BTU per square foot, and high-bay or uninsulated spaces need 55 to 65 plus BTU per square foot. A 30 by 40 insulated shop at 35 BTU per square foot needs about 42,000 BTU total.
Can radiant tube heaters run on propane?
Yes, radiant tube heaters can run on propane, which makes them ideal for off-grid shops, rural pole barns, and agricultural buildings without natural gas service. Propane models like the Universal-Ray RH-150-40-P deliver 150K BTU for large spaces. Propane costs more per BTU than natural gas, but it is the only practical option for buildings without a utility gas line. Both fuel types use the same radiant tube technology.
How long do radiant tube heaters last?
Quality radiant tube heaters last 15 to 20 years with proper maintenance. Top brands like Reznor, Modine, SunStar, and Universal-Ray offer 10-year tube warranties, which reflects confidence in long-term durability. Annual maintenance includes reflector cleaning, ignitor inspection, and gas connection checks. Hot-surface ignitors typically need replacement every 3 to 5 years, so keeping a spare ignitor on hand prevents unexpected downtime.
Final Verdict
After testing these eight radiant tube heaters across residential, commercial, and industrial settings, the SunStar SIR45-15-L remains our top pick as the best radiant tube heater for most buyers because of its 8 ft mounting height, propane flexibility, and CSA certification. For commercial shops, the Universal-Ray RHT-100-30-N delivers excellent two-stage control at a mid-range price point. Off-grid buyers should look at the Universal-Ray RH-150-40-P for high-BTU propane heating.
Whichever model you choose, match the BTU output to your square footage and ceiling height using the sizing chart above, verify that your ceiling can accommodate the tube length with proper clearances, and keep a spare ignitor in your shop. If you need a heating comparison for smaller or outdoor spaces, our guide to electric patio heaters covers residential-scale options.
The best radiant tube heater for your shop depends on your specific building, but every model on this list delivers proven radiant comfort with the efficiency advantage that has made infrared heating the standard for garages, warehouses, and pole barns in 2026 and beyond.