Pentair MasterTemp® Natural Gas High Performance Heater 400K BTU
The Pentair MasterTemp® Natural Gas High Performance Heater 400K BTU offers all the efficiency, convenience, and reliability features you want in a pool heater — plus a lot more. As easy to use as your home heating system, with user-friendly indicator lights that make system operation and monitoring a snap. The compact design and super-quiet operation won't intrude on your poolside leisure time.
Built by Pentair with a heavy-duty cupro-nickel heat exchanger that stands up to the harshest applications — low pH, high flow, or heavy use — the MasterTemp 400K BTU NG is the maximum-capacity option in the standard MasterTemp lineup. CSA certified. Backed by a 2-year warranty.
⚠️ Professional Installation Required. Pool heater installation involves gas line connections and electrical wiring. Always use a licensed contractor to ensure safety, code compliance, and warranty validity.
Key Features
400,000 BTU Output
Maximum-capacity natural gas heating for larger pools and spas.
Cupro-Nickel Heat Exchanger (HD)
Heavy-duty exchanger withstands low pH, high flow, and heavy use applications.
Best-in-Class Energy Efficiency
Green certified — outperforms industry standards for efficiency.
Digital Indicator Lights
User-friendly indicator lights make system operation and monitoring a snap.
Compact, Quiet Design
Same 23-inch wide cabinet as all MasterTemp models — super-quiet operation.
CSA Certified
Meets North American safety standards for gas-fired pool heaters.
Indoor and Outdoor Rated
Suitable for both indoor and outdoor pool and spa installations.
2-Year Warranty
Pentair residential warranty coverage.
Who It's For
- Larger pool owners wanting maximum natural gas heating capacity in the standard MasterTemp platform
- Salt water and chemically demanding pools that benefit from a cupro-nickel heat exchanger
- Indoor and outdoor pool installations requiring top-end BTU output
- Anyone stepping up from 300K BTU for faster heating of a larger body of water
Specifications
Heating Performance
| BTU Input | 400,000 BTU |
| Fuel Type | Natural Gas |
| Max Flow Rate | 120 GPM |
Construction
| Heat Exchanger | Cupro-Nickel (HD) |
| 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 | 136 lb |
| Cabinet Dimensions | 23 W × 28.2 D × 21 H in |
| Shipping Dimensions | 36 × 25 × 30 in |
Approvals & Warranty
| Certifications | CSA Certified |
| Energy Efficient | Yes (Green Certified) |
| Warranty | 2 Years |
What's in the Box
- Pentair MasterTemp 400K BTU Natural Gas Heater
- Union Fittings
- User Manual
Warranty
The MasterTemp 400K BTU NG 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
- Product Brochure (PDF)
- Product Brochure Alt (PDF)
- Install Guide (PDF)
- Install Guide Alt (PDF)
- Technical Manual (PDF)
Frequently Asked Questions
What is the difference between this (460736) and the 400HD model (460805)?
Both are 400K BTU natural gas MasterTemp heaters sharing the same 23-inch cabinet and cupro-nickel heat exchanger. The 460805 HD is specifically rated for the most demanding applications — low pH, high flow, heavy use — and includes a rotating digital display. The 460736 is the standard residential 400K model with digital indicator lights. For typical residential use, either is suitable; the HD is recommended for chemically demanding or high-flow installations.
Does this heater require professional installation?
Yes. Gas heater installation involves connecting to a natural gas supply line, electrical wiring, and proper venting. A licensed pool contractor or plumber must perform the installation to ensure safety, local code compliance, and warranty validity.
Is it compatible with salt water pools?
Yes. The heavy-duty cupro-nickel heat exchanger provides superior resistance to salt water corrosion, making the MasterTemp 400K a strong choice for salt water pool installations.
What size pool is the 400K BTU suitable for?
As a general guideline, 400,000 BTU is typically suited for pools in the 30,000–50,000 gallon range depending on climate, desired temperature rise, and heat loss factors. A licensed pool professional can calculate the correct BTU requirement for your specific pool and location.
Can it be used indoors?
Yes. The MasterTemp is rated for both indoor and outdoor installation. Indoor installations require proper venting per local code. Consult the install guide and a licensed contractor for indoor venting requirements.