Description
Reznor UDX 400,000 BTU Natural Gas Unit Heater – NUDX400
Reznor model UDX gas-fired unit heaters are great for space heating applications. These units are power vented to eliminate heat losses up the flue pipe. Each heater features a two-tone black and white powder coated, scratch-resistant paint scheme and has clean rounded corners and edges with no visible screws or fasteners. For air circulation, the UDX series utilize an axial propellor fan.
Features
- 83% AFUE Efficiency
- TCORE2 titanium stabilized aluminized steel heat exchanger
- Multi-try, direct spark ignition with time lockout
- Vibration/noise isolated fan and venter motors designed for low noise operation
- External status indicating LED that blinks if there is a problem that needs service
- 7-segment display board that shows fault code for quick and easy troubleshooting
- Optional integrated downturn nozzle and integrated vertical louvers
What our Experts Think
- Efficient small‑space propane heating
The Reznor UDX 45,000 BTU Propane Unit Heater (NUDX45, N1036536R) delivers efficient 45 k BTU heating for workshops, garages, utility rooms, or smaller commercial spaces, offering strong warmth without oversizing. - Solid efficiency for daily use
With about 83 % AFUE thermal efficiency, it strikes a good balance of fuel economy and heat output, helping manage propane costs over time. - Durable commercial‑grade build
Features a TCORE2 titanium‑stabilized aluminized steel heat exchanger for long service life under frequent use, ideal for commercial or workshop environments. - Quiet, reliable airflow
The axial propeller fan and power‑vent design promote effective circulation with low noise operation, making it comfortable in busy workspaces. - Service‑friendly design
Power‑venting and external gas connection improve installation flexibility, while diagnostic LEDs aid in quick troubleshooting and maintenance. - Flexible installation options
Can be ceiling‑mounted or suspended to suit layout needs, and includes options for different venting configurations.
Q&A
Q1: What space size is the Reznor UDX45 heater best for?
A: With 45,000 BTU input and up to ~37,300 BTU output, it’s suited for small to medium garages, workshops, and commercial spaces needing efficient propane heating.
Q2: What fuel type does this model use?
A: It operates on liquid propane (LP) using the factory‑specified propane configuration (SKU N1036536R).
Q3: How efficient is the UDX45?
A: It delivers around ~82–83 % AFUE efficiency, maximizing heat output with reduced energy waste.
Q4: What durability features does this heater include?
A: It features a TCORE2 titanium‑stabilized aluminized steel heat exchanger for long‑term durability and corrosion resistance.
Q5: What are airflow and noise specs?
A: The unit circulates air with an axial propeller fan (~629 CFM) and runs at a low noise level (~40 dBA) — comfortable for workspace environments.
Q6: Is installation and maintenance easy?
A: Yes — the heater includes status LED, 7‑segment diagnostic display, multi‑try direct spark ignition, and external gas connection for straightforward service and troubleshooting.
Q7: What are the electrical and venting requirements?
A: It runs on 115 V single‑phase power (~2.4 A) and uses a 4″ power vent for safe venting of exhaust gases.
Maintenance Tips
- Clean air pathways: Regularly remove dust from the fan, louvers, and intake screen to maintain strong airflow and efficient heat distribution.
- Inspect heat exchanger: Annually check for cracks, corrosion, or soot buildup to ensure safe combustion and long service life.
- Test ignition & propane supply: Verify the direct spark ignition and propane pressure/connections to prevent misfires and uneven heating.
- Keep venting clear: Make sure the power vent and flue are unobstructed to avoid exhaust buildup and heat loss.
- Check electrical components: Inspect wiring, controls, and diagnostic LEDs; tighten loose connections to prevent faults and downtime.
- Verify conversion kit (N1036536R): Ensure proper installation and calibration for safe propane operation.
- Annual professional service: Scheduled servicing helps maintain efficiency, reliable performance, and warranty compliance.






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