Pentair MasterTemp® Natural Gas High Performance Heater 125K BTU
The Pentair MasterTemp® Natural Gas High Performance Heater 125K BTU brings the energy savings and advanced operating features of larger heaters to a remarkably affordable, compact package. With revolutionary pre-mixed gas combustion technology, the MasterTemp 125 delivers 82% thermal efficiency — the highest of any heater in its category.
Its 1-1/2 inch plumbing is ideal for smaller applications including above-ground pools, spas, and in-ground pools up to 15,000 gallons. The first-ever rotating digital display offered in its class, lightweight compact design, and tool-free installation make it easier to install than any other heater in its class — reducing labor costs. No cord included; hardwire electrical connection. 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
125,000 BTU — Highest Efficiency in Its Class
82% thermal efficiency via pre-mixed gas combustion — the best in the 125K BTU category.
Above-Ground and Small In-Ground Pools
1-1/2 inch plumbing ideal for above-ground pools, spas, and in-ground pools up to 15,000 gallons.
Pre-Mixed Gas Combustion Technology
Revolutionary combustion system delivers best-in-class efficiency.
Rotating Digital Display
First-ever rotating digital display in its class — valuable information at the touch of a button.
Lightweight, Compact Design
Easier to install than any other heater in its class — reduces labor costs.
Hardwire Electrical Connection
No cord included — connects via hardwire electrical. See the with-cord model (461059) if a plug-in connection is preferred.
Energy Efficient
Green certified — energy savings previously only available from much larger heaters.
2-Year Warranty
Pentair residential warranty coverage.
Who It's For
- Above-ground pool owners wanting a compact, efficient natural gas heater with hardwire electrical
- Spa owners needing purpose-sized heating connected via hardwire
- In-ground pool owners with pools up to 15,000 gallons
- Installations where the electrician will hardwire the connection rather than using a cord
Specifications
Heating Performance
| BTU Input | 125,000 BTU |
| Thermal Efficiency | 82% |
| Fuel Type | Natural Gas |
| Combustion Technology | Pre-Mixed Gas |
| Max Flow Rate | 70 GPM |
| Pool Size | Up to 15,000 gallons (in-ground); above-ground pools and spas |
Construction
| Control Type | Digital (Rotating Display) |
| Plumbing Size | 1-1/2 in |
Installation
| Gas Connection | 0.75 in |
| Voltage | 120V / 240V |
| Amperage | 15A |
| Frequency | 60 Hz |
| Phase | Single |
| Electrical Connection | Hardwire (no cord included) |
| Application | Indoor / Outdoor / Pool / Spa |
Physical
| Product Weight | 100 lb |
| Cabinet Dimensions | 21 W × 23 D × 21 H in |
| Shipping Dimensions | 23 × 36 × 25 in |
Approvals & Warranty
| Energy Efficient | Yes (Green Certified) |
| Warranty | 2 Years |
What's in the Box
- Pentair MasterTemp 125K BTU Natural Gas Heater
- Union Fittings
- User Manual
Warranty
The MasterTemp 125K 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
Frequently Asked Questions
What is the difference between this (461058) and the with-cord model (461059)?
Both are identical 125K BTU natural gas MasterTemp heaters. The 461058 (this model) uses hardwire electrical connection — no power cord is included. The 461059 includes a 120V power cord for plug-in connection. Choose this model when your electrician will hardwire the connection as part of the installation.
Is it suitable for above-ground pools?
Yes. The MasterTemp 125 is specifically designed for above-ground pools, spas, and in-ground pools up to 15,000 gallons. Its 1-1/2 inch plumbing matches the smaller diameter plumbing common in above-ground pool systems.
Does it require professional installation?
Yes. A licensed contractor should handle the natural gas line connection, hardwire electrical connection, and proper venting to ensure safety and code compliance.
What is pre-mixed gas combustion technology?
Pre-mixed combustion blends gas and air before ignition for a more complete, efficient burn — which is why the MasterTemp 125 achieves 82% thermal efficiency, the highest in the 125K BTU class.