// Initialize Pentair / Channel Advisor Sales Reporting sTrack.initialise();
Home Pentair MasterTemp 125 Low NOx Pool Heater - Electronic Ignition - Natural Gas without Cord - 125,000 BTU - 461058
NOTICE: The pool & spa industry continues to face industry-wide shortages on many products that most vendors expect to last late into 2022. We're allowing items to be purchased so that customers who choose to wait will have their order shipped when product is available. Most vendors are not providing any ETA on when items will be available. WE WILL EMAIL YOU RIGHT AWAY IF YOUR ITEM IS BACKORDERED. 

Pentair MasterTemp 125 Low NOx Pool Heater - Electronic Ignition - Natural Gas without Cord - 125,000 BTU - 461058

Pentair MasterTemp 125 Low NOx Pool Heater - Electronic Ignition - Natural Gas without Cord - 125,000 BTU - 461058 Pentair MasterTemp 125 Low NOx Pool Heater - Electronic Ignition - Natural Gas without Cord - 125,000 BTU - 461058

Shipping Free Shipping *
Parts AvailableParts Available
Platinum Preferred Manufacturer
  • 82% Energy Efficiency is Highest in its Class
  • 1-1/2" Plumbing-Ideal for Smaller Bodies of Water up to 15,000 Gallons
  • High-Performance, Affordable Heating with Premium Features
  • Pre-Mixed Combustion Technology for Ultra-Fast Heat-Up
  • Easy-to-Use, Digital Display Makes Programming and Monitoring a Cinch.
  • Improved Resistance to Rodent Intrusion
  • Pentair 4" Stainless Steel Appliance Adapter for Horizontal or Vertical Positive Pressure by Heatfab | 77707-0086
    4" Appliance Adapter Horizontal or Vertical Venting, Positive Pressure by Heatfab | 77707-0086

  • Pentair 4" Stainless Steel Appliance Adapter for Horizontal or Vertical Positive Pressure Venting by Z-Flex | 77707-0087
    4" Appliance Adapter for Horizontal or Vertical Positive Pressure Venting by Z-Flex | 77707-0087

  • Pentair Sta-Rite 4x8 Metal Flue Collar for Indoor Vertical Venting - Negative Pressure for Distances Over 8' | 77707-0077
    Indoor Vertical Venting - Negative Pressure 4x8 Metal Flue Collar for Distances Over 8' | 77707-0077

  • Pentair Sta-Rite 4x6 Metal Flue Collar for Indoor Vertical Venting - Negative Pressure for Distance Less Than 8' | 77707-0076
    Indoor Vertical Venting - Negative Pressure 4x6 Metal Flue Collar for Distances Less Than 8' | 77707-0076

MasterTemp® 125 High Performance Heater
Introducing! The High-Efficiency, High Technology Heater for Bodies of Water up to 15,000 gallons
The remarkably affordable new MasterTemp 125 heater gives you the energy savings and advanced operating features that were only available from much larger heaters. With its revolutionary pre-mixed gas combustion technology, the MasterTemp 125 heater offers 82% thermal efficiency - the highest of any heater in its category. Its 1-1/2" plumbing is ideal for smaller applications, including aboveground pools, spas and inground pools up to 15,000 gallons. Featuring the first ever rotating, digital display offered in its class, the MasterTemp 125 heater provides valuable information conveniently and at the touch of a button. Plus, its lightweight, compact design makes the MasterTemp 125 heater easier to install than any other heater in its class - reducing labor costs which saves you money.
New Improved Rodent Resistance for the MasterTemp High Performance Heater
The engineers made improvements to reduce gaps and eliminate access points, including advancements to the heater base, all exterior side panels and louvers, the gas valve and water manifold openings, the exhaust opening and the exhaust cover. These subtle, but important, design changes add up to a better heater, from every angle.
In addition to the new rodent resistant improvements, the features and benefits of a MasterTemp High Performance Heater include:
  • Enhanced LCD display and diagnostics include easy to display and front-facing error messages and icons
  • Best-in-class energy efficiency
  • Eco-friendly certified for low, NOx emission and outperforms industry standard
MasterTemp 125 heater features include:
  • 82% energy efficiency is highest in its class.
  • 1-1/2" plumbing - ideal for smaller bodies of water up to 15,000 gallons.
  • High-performance, affordable heating with premium features.
  • Pre-mixed combustion technology for ultra-fast heat-up.
  • Easy-to-use, digitial display makes programming and monitoring a cinch.
  • 125,000 BTU rating.
  • Available in natural gas or propane gas.
  • 120/240 V electrical.
  • Lightweight - easy to handle and ship.
  • Certified for low NOx emissions.
  • Certified for Direct Air Intake with PVC Pipe.
  • Certified for outdoor and indoor vented installations.
These installations instructions are designed for use by qualified personnel only, trained especially for installation of this type of heating equipment and related components.
Some states require installation and repair by licensed personnel. If this applies in your state, be sure your contractor bears the appropriate license.

Brand: Pentair
BTU Rating
Gas Type
Natural Gas
Q & A
Start typing your question and we'll check if it was already asked and answered. Learn More
Browse 42 questions Browse 42 questions and 38 answers
I have a 15,000 gal inground pool would a higher BTU heat faster than 125K?
A shopper on May 30, 2017
Will this size work on a 15,000 gallon in-ground pool?
A shopper on May 18, 2017
BEST ANSWER: Yes, in my opinion it should work just fine for that size pool. It is a very well designed and a very efficient natural gas heater. It is easy to install, control, and it runs fairly quietly. It is a quality piece of equipment!
need the right heater for 24' intec above ground pool 52" deep?
Joshua P on Mar 2, 2019
will this heater be efficient for my spa and 14000 gallon pool ?
James F on Nov 24, 2015
BEST ANSWER: i have a similar sized pool with a small spa (fits about 4 people). The heater is used for the jacuzzi 99% of the time, and heats it up fast, about 1 degree/minute. The pool we only heat for special occasions -- probably takes about a degree/hour.
Do you need a seperate pump to pump water into the heater?
Paul P on May 22, 2019
BEST ANSWER: Yes, the heater is attached to your circulating filter pump. Water runs through the heater at all times but only heats when the auto thermostat turns it on.
What does cord and no cord mean?
A shopper on Jun 25, 2018
BEST ANSWER: I just noticed this email. No cord means you have to run electrical wires to the inside and make a connection. If it comes with a cord, it may have a plug to go directly into an outlet or just wires so that a connection can be made at the outside power source. Mine came with no plug.
Should I cover this heater in the winter months?
L M on Oct 23, 2016
BEST ANSWER: Depends on your climate conditions. I would say yes if it will be subjected to a lot of rain and/or snow in winter and also if subjected harsh sun in summer. The outside is plastic and I think could be harmed or weakened by adverse exposure. A simple lean-to cover would probably suffice.
i have 2" plumbing, can i just put a reducer on it?
A shopper on Jun 6, 2016
BEST ANSWER: I reduced mine with no problems.
Is this too big of a heater for a 12 by 20 oval above ground pool? It holds about 6500 gallons.
KATHERINE O on Aug 29, 2021

I used it on a 18 foot round pool and the rule of thumb for me was 2 degrees and hour. I did not run it 24/7 but if I knew the kids were coming over I would turn it on early that day. It heated the pool just find, I think it would handle a 12/20 just fine.
power on the filter pump when heater comes on. Does this have the ability to trip an external relay so that when the heater comes on, it will also turn the pool pump on? Because I read in the manual that the pump must be running when the heater is on!
A shopper on May 19, 2021
BEST ANSWER: There is no relay, just temp setting but the pump must be on so water is going thru the heater to heat the water. If no water is going thru the heater and the set point is high ( ex:84) and it’s only75 in the pool and the pump is not pumping water thru the heater, the heater will trip on high limit and eventually lock out. Hope this helps
what does NOx pool heater mea?
Doug B on Sep 1, 2020
BEST ANSWER: NOx is short for Nitrogen Oxygen compounds. They are greenhouse gases and the x stands for a number, so NO, NO2, NO3, etc.
A shopper on Aug 22, 2020
BEST ANSWER: It would be too small.
what material is the heat exchanger?
Adam L on Mar 30, 2020
BEST ANSWER: {COPPER}..Its the best for heat transfer.......

Does it have to vented if installed in a pool room?
A shopper on Oct 30, 2019
BEST ANSWER: Yes but I've had nothing but problems with mine. When it works it does a great job heating the water. But I would not buy another one.
How Many amps does this heater need?
A shopper on Jul 29, 2019
BEST ANSWER: 15 amps
Can this be converted to lp gas?
Brian H on Jul 20, 2019
I am at a high elevation. Will it work well at 6,100 ft elevation?
A shopper on May 26, 2019
BEST ANSWER: I am at almost Sea level, but I don't see why it wouldn't work at a higher elevation, as long as the Gas pressure in your area is if sufficient as per the specs. Of course because of the higher elevation, it might take a bit longer to heat as the temperatures would be lower.
Can this heater be used with a saltwater pool?
Phyllis C on May 22, 2019
BEST ANSWER: yes if installed correctly.
I am considering installing solar to run my pool equipment. How many watts does this heater draw?
Dan G on Jul 19, 2018
BEST ANSWER: Do not buy a Pentair. The warranty only lasts 90 days if you install it yourself. Find a better manufacturer that backs their heater against defects for at least a year.
What does with or without cord mean? What's the cord???
A shopper on Jan 21, 2018
BEST ANSWER: power cord to plug it in or without for direct power hookup.
I have a 20000 gallon in ground pool. Will it just take longer to heat? Is waiting longer the only issue?
A shopper on Dec 5, 2017
BEST ANSWER: Yes, the Mastertemp will take 2.5 times longer to heat the pool compared to a Mastertemp 400.
can I buy this Pentair gas pool heater through Home Depot?
A shopper on Aug 25, 2017
BEST ANSWER: Hello, we are not affiliated with Home Depot so we are not aware of the products that they sell. They may purchase Pentair products through us or you can order direct from the website or call our office and a sales rep will happily assist you. Thank you.
will this heat an above ground pool 5000 gallon?
sarah w on Aug 17, 2017
BEST ANSWER: for sure, we have a 10,000 gallon pool and heats just fine
I have an indoor therapy pool 8ft x 17ft does this brand operate in a confined space and come with a remote control or separate wire to control the unit?
A shopper on May 1, 2017
BEST ANSWER: Yes will operate in confined space as long as you VENT IT TO THE OUTSIDE.No remote control, on unit control only.Very happy with heater and this price is the best i found.
We just opened our pool and the heater would not work. So we opened the heater and found all the wires had been chewed to nothing. How can we keep this from happening again? Help
A shopper on Apr 16, 2016
BEST ANSWER: put the moth balls in the bottom of it
I have an intex above ground Pool. Is it compatible? 16 by 8? Also does the grill gas work for it And how long would gas last?
Ecuatorianos22 on Feb 6, 2022
what will I need to hook this heat up????
William O on Jun 3, 2021
Do you have any propane pool heaters in stock 100-150k btu?
A shopper on May 31, 2020
I have a 7000 gallon pool, what is the best size and make propane heater to get?
Chris O on Apr 26, 2020
4.4 / 5.0
11 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Rated 5 out of 5
Excellent.. Very happy with this purchase..Saved thousands$$$ !!!
I would recommend this product I saved atleast $2,000 with this purchase just by waiting a little longer for the heat which gets really hot .when friends are coming over at 6pm I just turn it on at 5pm that's the only difference with the more expensive heaters .Excellent Quality!!! just more wait time..very happy with my purchase!!!
September 9, 2016
over 6 years ago
Rated 4 out of 5
Very good small heater
While talking with my pool guy, he recommended this small heater for my 10,000 gallon pool and its working like a champ, always happy with Pentair products and this was perfect for my needs.
October 1, 2016
Rated 5 out of 5
Great purchase!
Good communication. Fast shipping. Most importantly, I am very pleased with my Mastertemp 125 so far.
August 22, 2016
over 6 years ago
Rated 4 out of 5
Works as advertised
It's so nice to have a heater that just works. A must have for people in cold areas that want to still enjoy their pool.<br>
April 4, 2017
Rated 5 out of 5
Works very well with my Endless Pool.
It heats the water (2500 gallons) by 3-4 degrees an hour which is quite quick for its size I would think. It is controlled poolside through the EP Gecko. Very satisfied.
October 23, 2016
over 6 years ago
Rated 5 out of 5
Purchased this heater on line, arrived in great condition, installed and have used it once to date. So far so good.
July 9, 2017
over 4 years ago
Rated 5 out of 5
Great place to purchase pool equipment
Great price for the heater. Pick up in Onterio was fast and easy.
September 29, 2020
1 year ago
Rated 5 out of 5
Great cheap heater for a good price.
This little heater heats the water up much faster than expected, i would buy it again and would recommend it for a nice cheap spa heater.
December 14, 2018
over 3 years ago
Rated 5 out of 5
Just installed a week ago but seems like a quality unit. Digital display is nice
September 7, 2021
9 months ago
Rated 4 out of 5
It warmed my 13000 gallon pool 15 degrees in 12 hours.
May 26, 2019
over 3 years ago
Adobe Acrobat PDF Brochure
Adobe Acrobat PDF Owners Manual

Register your Pentair product online at www.pentair.com.

You've always been able to count on the quality and long service life of Pentair products. Pentair uses state of the art workmanship, materials and manufacturing processes to create the most innovative pool and spa equipment anywhere. And now Pentair products can deliver even more value and peace of mind, because Pentair offers extended warranty coverage on select products that are installed by a qualified installer*.
While the majority of Pentair products are covered by a sixty- (60) day warranty, a select number of products qualify for extended warranty coverage.
Select Bundled Products: applies to purchases and qualified installation of a minimum of a pump and filter, and one or more of the following: heaters, heat pumps, control systems, automatic cleaners, lighting, salt chlorine generators or UV sterilizer**
*Note: Qualified Installer - Defined as a licensed professional who charges a fee for his services, and possesses a business license, contractor's license and/or resale permit. Common examples of a "qualified installer" include: Swimming Pool, Home Repair or Landscape Professional; Plumber or Electrician; General Contractor; Heating and Air Conditioning Specialist.
**Note: Bundled products - must be purchased on the same invoice and installed at the same time. If any product within a bundle is ineligible for the bundled warranty coverage then all products within the same bundle will be disqualified from receiving the three (3) year extended warranty coverage for bundled products.
TradeGrade products must be purchased from a retail store (brick & mortar), pool builder or pool service company to receive a one-year, two-year or three-year warranty. If purchased online will only receive a sixty-day limited warranty. View the list of TradeGrade Products.
Ecommerce (EC) products: Products purchased from an Authorized Pentair Online Reseller (products beginning with EC-) receive a one (1) year (parts only) warranty from the date of purchase. The exceptions are: IntelliChlor cells and IntelliFlo SVRS pumps which receive a two (2) year warranty. EC products are not eligible for the bundled three (3) year extended warranty.
Visit www.pentair.com to submit your product warranty registration.
This information was updated on 11/19/2021. For the most current information and full warranty policy please visit www.pentair.com/warranty.

 Adobe Acrobat PDF Warranty Information
Hay muchas maneras diferentes de contactarnos, y nos gustaría hablar con usted sobre las preguntas de su compra, ayudarle a diagnosticar los problemas de su equipo y escuchar acerca de cómo podemos mejorar y todo lo que está en su mente.
Click Here
6am - 6pm Monday thru Saturday
Pacific Standard Time
Will-Call Hours Click Here
Be the first to know the latest news, deals & special events!


By signing up you indicate that you agree to the terms of our privacy policy.

Pool Supply Unlimited is an e-commerce company that loves water. We love to pump it, filter it, heat it, chlorinate it, light it up and stare at it while we're barbequing a fat, juicy steak. There are real pool professionals working here. Our guys have seen thousands of pools in their careers, no exaggeration. We are based in Southern California and can land most products to your door (within the 48 contiguous states) in less than a week.
Visa Mastercard Discover American Express PayPal