Description
Sunstar SPU Positive Pressure U-Tube CNG Heater | SPU75-30-CNG-N7
The Sunstar SPU75-30-CNG-N7 is a 75,000 BTU/hr natural gas infrared tube heater with 30 feet of radiant emitter folded into a U-tube, so the heater itself is only about 17' 5" long. It is part of Sunstar’s SPU positive pressure U-tube CNG line, built for warehouses, maintenance shops, loading docks, fire stations and other high-ceiling spaces where doors open often and heated air is lost the moment they do.
SPS and SPU heaters use a push-through (positive pressure) burner: a blower sealed inside the burner box drives combustion through the tube, so the heater runs quietly, and Sunstar’s Tube Integrity Safety System (TISS) continuously monitors the space above the reflector for overheating or a compromised tube.
With the firing leg running beside the cooler return leg, a U-tube spreads its heat more evenly than a straight tube of the same length, which makes it the go-to choice for spot heating a bay, work cell or dock door.
This is a two-stage model: it fires at 75,000 BTU/hr on high and drops to a reduced input on low, so it can hold temperature on milder days with less gas and fewer on/off cycles. Control it with a two-stage 24V thermostat or a three-position High/Low/Off switch.
The CNG rating is what sets this model apart. NFPA 30A does not allow heater surfaces above 750°F in garages where CNG or LNG vehicles are repaired, so this heater is built to keep its emitter tube at or below 750°F. That makes it suitable for transit, fleet and municipal shops that maintain natural gas vehicles. It is a natural gas heater and follows Sunstar’s CNG addendum for orifices, mounting heights and clearances.
For planning, mount it at least 13 feet above the floor when level or 12 feet when tilted 45 degrees, and keep 60 inches clear below it and 27 inches to the sides. It can be vented on its own, common vented with other heaters, or run indirect vented with building exhaust, and it can draw outside combustion air through its fresh air collar in dusty or humid buildings. Installation must be done by a licensed contractor to the manufacturer’s instructions and local codes.
Key Features
- 75,000 BTU/hr natural gas input, reduced on low fire
- 30' U-tube emitter, about 17' 5" overall
- 750°F maximum tube temperature for CNG/LNG vehicle repair garages
- Direct spark ignition with 100% gas shut-off
Frequently Asked Questions
How high should the SPU75-30-CNG-N7 be mounted?
Sunstar lists a minimum of 13 feet above the floor with the heater level and 12 feet at a 45-degree tilt. Mount it as high as the space allows for even coverage; going below the minimum can make the area right underneath uncomfortably hot.
What clearance does it need from combustibles?
Keep at least 60 inches below the heater and 27 inches to the sides clear of anything that can burn, including stacked materials and vehicles parked underneath. The full clearance chart, including ceiling and end distances, is in the installation manual.
Can I convert it to propane?
No. CNG-rated heaters are natural gas only.
How do I control the two stages?
Use a two-stage 24V thermostat to switch between low and high fire automatically, or a three-position High/Low/Off switch for manual control. Several heaters can share one control with a two-stage relay kit at each heater.
