Hydronic unit heaters transfer heat from hot water or steam into air, offering efficient, quiet heating for large spaces. This guide compares five hydronic options suited to garages, workshops, warehouses, and related applications, highlighting capacity, controls, and installation characteristics to help match a unit to your space.
| Product | Brand | Capacity / Type | Notable Feature |
|---|---|---|---|
| ALORAIR HydroX H100A | ALORAIR | 100,000 BTU / Water-to-Air | Smart Auto-Temperature Control, 3-Year Warranty |
| American Royal 50,000 BTU 2-Speed | American Royal | 50,000 BTU / Hydronic | Two-Speed Fan, Hanging Unit |
| American Royal 150,000 BTU 2-Speed | American Royal | 150,000 BTU / Hydronic | Remote Thermostat Included, High Capacity |
| Floorheat Hydronic Radiant Control Panel | Floorheat | Distribution Panel / Radiant | Pre-Assembled For Underfloor & Space Heating |
| Maradyne Havasu 12V Hydronic Heater | Maradyne | 20,000 BTU/hr / Automotive Hydronic | Uses Engine Coolant For Under-Dash Automotive Heat |
ALORAIR 100,000 BTU HydroX H100A
The ALORAIR HydroX H100A Is A 100,000 BTU Water-To-Air Heat Exchanger Designed For Industrial And Commercial Spaces. It Features Heavy-Duty Galvanized Steel Housing And Corrosion-Resistant Copper Piping, Emphasizing Durability For Workshops Or Warehouses.
Controls Include A Smart Auto-Temperature Control That Activates The Fan When Water Reaches The Preset Temperature And Shuts Off When Cooling, Which Helps With Energy Efficiency. Air Movement Uses A Centrifugal Blower Rated At Approximately 1000 CFM With Noise Around 60 dBA.
Maintenance Features Include A Reusable Air Filter To Protect Internal Components. The Manufacturer Notes A 3-Year Commercial Warranty, Which May Be Relevant For Continuous-Use Installations.
American Royal 50,000 BTU Two-Speed
This 50,000 BTU Hydronic Hanging Unit Heater From American Royal Is Designed For Hydronic (Water) Heating Systems, Including Wood Boilers. The Unit Includes A Two-Speed Fan Allowing Adjustment Between Higher Airflow And Quieter Operation.
The Hanging Design Simplifies Installation In Garages Or Workshops Where Ceiling Mounting Is Preferred. The Unit Is Presented As A 50K BTU Air Handler Suitable For Supplemental Or Primary Area Heating. Features Emphasize Compatibility With Existing Hydronic Systems.
American Royal 150,000 BTU 2-Speed With Remote
The American Royal 150,000 BTU Hydronic Hanging Heater Offers High Capacity For Large Spaces. It Ships With A Remote Thermostat And An On-Off-On Switch To Control Fan Modes And Heating Behavior.
The Two-Speed Fan Supports Variable Airflow, While The Hanging Format Facilitates Central Placement For Broad Heat Distribution. The Product Is Marketed For Connection To Hydronic Heat Sources Such As Wood Boilers.
Because Of The Higher BTU Output, This Unit Is Intended For Larger Workshops Or Warehouse Applications Where Greater Heat Load Coverage Is Required.
Floorheat Hydronic Radiant Heat Control Panel
This Hydronic Radiant Heat Control Panel Is A Pre-Assembled Distribution System Intended For Underfloor And Space Heating. Rather Than A Unit Heater, It Serves As The Distribution Hub For Zoning And Circulation In Hydronic Installations.
Key Features Include Preassembled Convenience To Reduce Plumbing Complexity During Installation And A Space-Saving Design To Fit Into Mechanical Rooms Or Closets. The Panel Supports Single-Zone Applications And Aims To Improve Efficiency Of Radiant Heat Systems.
Consider This Panel When Pairing A Boiler Or Heat Exchanger With Multiple Radiant Loops Or When You Need A Compact, Organized Distribution Point For Hydronic Heat.
Maradyne Havasu 12V Hydronic Automotive Heater
The Maradyne Havasu Is A 12V Hydronic Automotive Heater That Uses Engine Coolant To Produce Heat, Providing Up To 20,000 BTU/hr And Approximately 177 CFM Airflow. It Is Intended For Under-Dash Mounting In Vehicles Rather Than Buildings.
Construction Includes Heat-Resistant ABS And A Front Panel With Adjustable Louvers For Directional Airflow. The Unit Operates From Vehicle Electrical Power And Integrates With The Engine’s Cooling Circuit To Deliver Quick Warm-Up.
While Not A Building Unit Heater, This Product Demonstrates Hydronic Heating Principles Applied To Automotive Use—relevant if assessing hydronic options for specialty projects involving vehicles or mobile workshops.
Buying Guide: How To Choose A Hydronic Unit Heater
Selecting The Right Hydronic Unit Heater Requires Balancing Heating Capacity, System Compatibility, Installation Constraints, And Control Requirements. The Following Factors Provide A Structured Comparison Perspective.
1. Heating Capacity And Sizing
Match Unit BTU Output To The Heat Loss Of The Space. Larger Garages And Warehouses Typically Require Higher BTU Ratings And Greater Airflow. Use A Heat Load Calculation Or Consult An HVAC Professional To Estimate Required BTUs Based On Square Footage, Insulation, Ceiling Height, Infiltration, And Desired Temperature Rise.
2. Airflow (CFM) And Distribution
Air Movement Determines How Quickly Warm Air Reaches Occupied Zones. Units With Higher CFM Move Heat Faster But May Increase Noise. Adjustable Louvers Or Directional Vents Help Focus Warm Air Toward Work Areas. Consider Ceiling Height And Mounting Location To Avoid Short-Cycling Or Uneven Temperature Stratification.
3. Compatibility With Heat Source
Hydronic Unit Heaters Connect To Boilers, Wood Furnaces, Or Other Hot-Water Sources. Verify Working Pressure, Flow Rates, And Plumbing Connections. For Wood Boilers Or Outdoor Furnaces, Look For Units Specifically Noted As Compatible With Outdoor Wood Furnaces Or For Use With Low-Temperature Systems.
4. Controls And Automation
Thermostat Options Range From Basic Wall-Mounted Controllers To Remote Thermostats And Smart Auto-Temperature Control Systems That Start Fans Only When Water Reaches Target Temperatures. Select Controls That Support Your Desired Level Of Automation, Zoning, And Energy Management.
5. Fan Speeds And Noise Level
Two-Speed Fans Offer Flexibility Between Quieter Low-Speed Operation And Higher Heat-Delivery High-Speed Modes. Check Manufacturer Noise Ratings (dBA) If Occupant Comfort Or Noise-Sensitive Work Is A Concern. Centrifugal Blowers Typically Provide High Static Pressure And Stable Airflow For Ducted Or Ceiling-Mounted Installations.
6. Installation Type And Mounting
Unit Heaters May Be Hanging/Ceiling Mounted Or Wall Mounted. Hanging Units Often Provide Better Horizontal Distribution For Large Open Spaces. Plan Structural Supports, Clearances, And Plumbing Routes Ahead Of Installation. Preassembled Panels Simplify Hydronic Distribution For Radiant Systems.
7. Materials, Durability, And Maintenance
Look For Corrosion-Resistant Materials Such As Galvanized Steel And Copper Piping For Longevity In Workshop Or Garage Environments. Reusable Or Accessible Filters Simplify Maintenance. Confirm Manufacturer Serviceability And Availability Of Replacement Parts.
8. Safety, Codes, And Certifications
Confirm That The Unit Meets Local Building Codes For Combustion Safety, Electrical Connections, And Plumbing. Units Using Engine Coolant Or Vehicle Power Have Separate Regulatory And Installation Considerations. Use Licensed Trades For Plumbing And Electrical Hookups Where Required.
9. Zoning And Distribution Panels
For Multi-Zone Or Radiant Installations, A Hydronic Distribution Panel (Like A Pre-Assembled Control Panel) Simplifies Loop Management, Circulator Integration, And Valve Control. Panels Reduce Field Plumbing Complexity And Improve System Organization.
10. Warranty And Manufacturer Support
Commercial Settings Often Benefit From Extended Warranties And Readily Available Technical Support. Verify Warranty Terms For Commercial Use Versus Residential Applications And Check Whether Warranty Coverage Is Contingent On Professional Installation.
11. Energy Efficiency And Operating Cost
Hydronic Unit Heaters Depend On The Efficiency Of The Heat Source. Consider Boiler Efficiency, Pump Power, And Fan Motor Ratings. Controls That Prevent Fan Operation Until Water Reaches Setpoint Improve Efficiency In Systems With Variable Water Temperature.
12. Specialty Considerations (Automotive Or Mobile)
When Evaluating Hydronic Heating For Vehicles Or Mobile Workshops, Consider Units Specifically Designed For Vehicle Coolant Integration, 12V Electrical Operation, And Compact Under-Dash Mounting. These Units Differ From Building Heaters In Mounting, Power Source, And Intended Duty Cycle.
13. Comparison Perspectives
- Capacity vs. Space: Higher BTU Units Cover Larger Volumes But May Oversize Smaller Spaces—match load calculation results to unit capacity.
- Controls vs. Simplicity: Remote thermostats and smart controls add convenience and efficiency but increase system complexity.
- Durability vs. Cost: Corrosion-resistant materials and commercial-grade construction increase lifespan in harsher environments.
- Distribution vs. Direct Air: Radiant panels suit underfloor heating and zoned loops; unit heaters are better for rapid air-based heating of open spaces.
Use These Considerations To Narrow Choices Based On The Specific Application—garage, workshop, warehouse, mobile unit—or combination. Accurate Sizing, Proper Mounting, And Correct Integration With Your Hydronic Source Will Determine Long-Term Performance And Efficiency.