Pentair MasterTemp® Digital IID ASME Liquid Propane Low NOx Pool & Spa Heater 400K BTU
The Pentair MasterTemp® Digital IID ASME Liquid Propane Low NOx Pool & Spa Heater 400K BTU delivers all the efficiency, convenience, and reliability of the MasterTemp platform — with ASME-certified construction and LP fuel for commercial pool installations without natural gas access. User-friendly indicator lights make operation and monitoring a snap, and the compact, super-quiet design won't intrude on poolside leisure.
Built by Pentair with ASME certification, Digital IID ignition, Low NOx emissions, 400,000 BTU LP output, and the compact 23-inch MasterTemp cabinet. Backed by a 2-year warranty.
⚠️ Professional Installation Required. Pool heater installation involves propane gas line connections and electrical wiring. Always use a licensed contractor to ensure safety, code compliance, and warranty validity.
Key Features
ASME Certified — LP Commercial Grade
Built to the most rigorous pressure vessel standards — required for many commercial pool installations. LP version for sites without natural gas.
400,000 BTU Liquid Propane
Maximum-capacity LP heating in the ASME-rated MasterTemp platform.
Digital IID Ignition
Intermittent Ignition Device — reliable electronic ignition without a standing pilot light.
Low NOx Certified
Meets low emissions standards — green certified.
Digital Indicator Lights
User-friendly indicator lights for simple operation and monitoring.
Compact, Quiet Design
Same 23-inch wide MasterTemp cabinet — super-quiet operation.
Indoor and Outdoor Rated
Suitable for both indoor and outdoor pool and spa installations.
2-Year Warranty
Pentair warranty coverage.
Who It's For
- Commercial pool installations requiring ASME-certified heater construction at 400K BTU without natural gas
- Hotels, aquatic facilities, and commercial spas on propane where ASME is required by code
- Indoor and outdoor commercial pool and spa heating at maximum LP capacity
- Anyone who needs the MasterTemp 400K ASME platform in liquid propane
Specifications
Heating Performance
| BTU Input / Output | 400,000 BTU |
| Fuel Type | Liquid Propane |
| Ignition | Digital IID (Intermittent Ignition Device) |
| Emissions | Low NOx |
| Max Flow Rate | 120 GPM |
Construction
| Control Type | Digital (Indicator Lights) |
Installation
| Gas Connection | 0.75 in |
| Voltage | 120V / 240V |
| Frequency | 60 Hz |
| Phase | Single |
| Application | Indoor / Outdoor / Pool / Spa |
Physical
| Product Weight | 149 lb |
| Cabinet Dimensions | 23 W × 28.2 D × 21 H in |
| Shipping Dimensions | 36 × 25 × 30 in |
Approvals & Warranty
| Certifications | ASME Certified |
| Energy Efficient | Yes (Green Certified) |
| Warranty | 2 Years |
What's in the Box
- Pentair MasterTemp Digital IID ASME LP 400K Pool & Spa Heater
- Union Fittings
- User Manual
Warranty
The MasterTemp Digital IID ASME LP 400K comes with a 2-year manufacturer warranty from Pentair. Clearflow Pool Supply is an authorized Pentair dealer and will assist with any warranty service needed.
Downloads
Frequently Asked Questions
What is the difference between this (460776) and the NG ASME model (460775)?
The 460776 runs on liquid propane and the 460775 runs on natural gas. Both are ASME-certified 400K BTU MasterTemp heaters with Digital IID ignition and Low NOx emissions. Choose the LP model if natural gas isn't available at your installation site.
What does ASME certified mean for this heater?
ASME certification means the heat exchanger was built to the most rigorous pressure vessel standards. Many commercial pool installations require ASME-certified heaters per local code — hotels, fitness centers, aquatic facilities. The standard residential MasterTemp 400K models are not ASME certified.
Does this heater require professional installation?
Yes. Propane heater installation involves connecting to a propane supply line, electrical wiring, and proper venting. A licensed contractor must perform the installation to ensure safety, local code compliance, and warranty validity.
Can it be used indoors?
Yes. The MasterTemp is rated for both indoor and outdoor installation. Indoor propane installations require proper venting per local code. Consult the install guide and a licensed contractor for indoor venting requirements specific to propane appliances.