Product Overview

The Pentair MasterTemp 125 Heater 461058 is a compact, high-performance natural gas pool and spa heater designed for smaller residential pools, spas, and above-ground pool applications. With a 125,000 BTU heating capacity, 1-1/2 inch plumbing connections, and 120/240 VAC electrical capability, this heater delivers dependable heating performance in a compact, easy-to-place design.

The MasterTemp 125 is built with pre-mixed gas combustion technology, digital controls, low NOx performance, and a lightweight cabinet, making it a strong choice for pool owners who want efficient heating without needing a large full-size heater.

Ideal For

Smaller residential swimming pools

Spas and hot tubs

Above-ground pool systems

Small in-ground pools

Pools up to approximately 15,000 gallons

Compact equipment pads

Natural gas pool heating applications

Replacing or upgrading an older small-capacity gas heater

Key Features

125,000 BTU natural gas heating performance

1-1/2 inch plumbing connections for smaller pool and spa systems

120/240 VAC electrical capability

Compact MasterTemp 125 cabinet design

Digital control panel for simple operation and temperature control

Pre-mixed gas combustion technology for fast heat-up

Low NOx certified heater design

82% thermal efficiency

Hot-surface ignition with no standing pilot

Designed for outdoor or properly vented indoor installations

Lightweight cabinet for easier handling and installation

Benefits

The Pentair MasterTemp 125 461058 gives pool owners dependable gas heating in a smaller, more compact heater body. It is ideal when a full-size 200K, 300K, or 400K BTU heater is not necessary, but fast and reliable heating is still needed.

Its 1-1/2 inch plumbing connections make it well suited for smaller pool systems, while the 120/240 VAC electrical design gives installers flexibility during setup. The digital control panel makes operation straightforward, and the low NOx design helps meet modern emissions requirements in many areas.

Specifications

Compatibility & Ordering Notes

Confirm this is the correct natural gas model before ordering.

Verify that 125,000 BTUs is properly sized for your pool or spa.

Confirm 1-1/2 inch plumbing compatibility with the existing equipment pad.

Verify gas line size, gas supply, electrical requirements, venting requirements, and local code requirements before installation.

Professional installation is strongly recommended.

Installed or used heaters may not be eligible for return.

Customer-Facing Q&A

Q: Is Pentair 461058 natural gas or propane?
A: Pentair 461058 is the natural gas version of the MasterTemp 125 heater.

Q: How many BTUs is this heater?
A: This heater is rated at 125,000 BTUs.

Q: What size plumbing connection does this heater use?
A: This model uses 1-1/2 inch plumbing connections.

Q: Can this heater run on 120V or 240V?
A: Yes. This heater is designed for 120/240 VAC electrical operation.

Q: Is this heater good for large pools?
A: This model is best for smaller pools, spas, above-ground pools, and in-ground pools up to approximately 15,000 gallons. Larger pools may require a higher BTU heater.

Q: Does this heater use a standing pilot light?
A: No. The MasterTemp 125 uses hot-surface ignition and does not require a standing pilot.

Q: Should this heater be professionally installed?
A: Yes. Gas pool heaters should be installed by a qualified professional to ensure proper gas, electrical, plumbing, venting, and safety setup.