The Pentair 460775 is engineered to withstand being used all day long, 365 days a year. With the ASME designation, it’s built with more durable components (bronze header) to increase its overall durability, making it more reliable as the years go by. Some homeowners decide to spend the extra money on an ASME model for their own peace of mind, but the truth is, you’re probably better off buying the standard version (Pentair 460736) if you’re a homeowner.
For commercial pools, this is great heater. We also compare it to the Hayward H400FDNASME, Hayward’s 400K BTU natural gas pool heater, to give you another option to consider.
Table of Contents...
- 1 Intro | Pentair 460775 Review
Intro | Pentair 460775 Review
When you consider the cost of a pool heater installation and the rising cost of fuel, you may wonder if it makes sense to install one. For commercial installations the answer is mostly yes, it extends the time someone will use the pool and swimming in it is more comfortable. For residential use, one reason for owning a pool is being able to swim when you want to and a pool heater will extend that time. Depending on your location, you may need only a few degrees rise in temperature to make swimming more comfortable. The pool heater will give you this advantage.
The American Red Cross recommends a pool temperature of 78°F for recreational and competitive sports swimming. Many swimming coaches agree and besides that, it is the most fuel efficient temperature to use when heating the pool. Many believe the elderly and young children need higher temperatures too, recommending 80°F and more.
You may have some questions that you need answers for and I aim to do just that in this article. Not only will we suggest two great natural gas pool heaters but we explain some features used that will affect you selection.
Hayward also makes an ASME model | H400FDNASME
This review considers two powerful and capable pool heaters that uses natural gas. Both pool heaters are ASME certified and therefore in the next paragraph I explain what the rating means. Pentair designed the Pentair 460775 pool heater for residential pools with higher usage demands. However, the Hayward heater is fit for use as a commercial pool heater. The Hayward pool heater is also effective with salt water pools because they use the most corrosive resistant materials in constructing the unit.
If you have them installed professionally, these pool heaters conform to all safety standards. The pool heaters will be as safe as any major heating appliance in your home. Both heaters use automatic safety pilots and other ignition safeguards, pressure regulators, blower pressure check switches and other safety features. If you install the heater according to electrical standards and codes you will avoid all electric shock hazards. The pool heaters will shut off automatically whenever the working conditions are not safe.
What does ASME stand for?
ASME is an abbreviation for an American non-profit professional association named the American Society of Mechanical Engineers. ASME is a multidisciplinary engineering society, a standards organization, research and development organization, an advocacy organization and a provider of training and education.
ASME has standards for the application of materials and design for commercial pool heaters. Heaters manufactured according to ASME standards use more durable materials that stand up to everyday, all day use. If you do not use an ASME rated heater in a commercial pool, you risk damaging the heater. You may even compromise the safety of the property and swimmers.
I review two ASME pool heaters the Pentair 460775 ASME and compare it to the Hayward H400FDN ASME. Both designed and built for commercial use and therefore more expensive than a residential pool heater. Nothing prohibits you from using it as a residential pool heater, it does the same job. It’s more robust and manufactured from better materials so it will last longer, it has more advanced controls too.
The target market is the commercial pool. Pools that get used all day by lots of people that jump in and out of the pool, contaminating it and wearing out the chemicals. Commercial pools use more chemicals the swimming activity makes it difficult to control the pH balance of the pool. We clean Commercial pools more often because they are more likely to host bacteria and algae, therefore they maintain higher chlorine levels.
Poor water chemistry is one of the leading causes of equipment failure, especially pool heaters. Sand or diatomaceous earth may get back into the pool from the filter and may contaminate the pool heater. People entering the pool a lot makes it difficult to control contaminants, and filters may clog up, which affects the flow rate of the pump. The pool heater monitors the flow rate because the amount of water flowing through the heaters determines its efficiency.
They design standard residential heaters for residential pool use. Families use the pool occasionally and then it’s mostly used by the family and some friends. Many residential pool owners do not run their pool heaters all day and all week. The manufacturers design the pool heaters accordingly, reducing the cost of ownership. These heaters last a lifetime under normal residential use. There is no justifiable need to install ASME heaters unless your pool is a saltwater pool or you desire the better quality of one. Then an ASME pool heater with a Cupro-nickel Heat Exchanger should be considered.
Pentair 460775 40K MasterTemp ASME
High Performance ECO-friendly residential pool heater. Bronze heater, upgraded thermal regulator with a governing stainless steel sleeve and more ASME-grade components.
Features (ASME heater):
- Bronze header design allows for easy access to the thermal regulator and bypass valve service without use of special tools.
- All internal components of the bronze header are now made of high-resistance, glass-fiber reinforced polymer for long life, lightweight, chemical resistance and wear protection.
- Thick ASME rated fin tube resists erosion in high flow applications
- Cupro nickel fin tubes provide protection for salt treated pools and tough commercial applications.
- Totally enclosed blower motor for harsh environment and salt-air coastal applications.
- High durability military-grade coating control board weathers all coastal elements.
- Upgrades to thermal regulator include a governing stainless steel sleeve for better wear protection and chemical resistance.
- Ignition Control Module includes a 3-trial for ignition before a hard lockout is initiated.
- Improved gas valve design includes more diaphragm spring force for better gas control and robust operation.
- Fully pre-mixed system with highly efficient air and gas mixture allows for faster heat up times.
- Efficiencies up to 84%.
- 2” x 2.5” CPVC plumbing features.
- Size : 36”L x 29” W x 33” H
Documents for Pentair ASME pool heaters :
- View or download the MANUAL
- View or download the INSTALLATION
- View or download the ASME BROCHURE
- View or download the HEATER CHECKLIST
This Pentair model is part of the MasterTemp range of natural gas pool heaters. This one is a 400,000 BTU ASME model with standard copper heat exchanger.
The Pentair MasterTemp is as easy to use as your home-heating system. It is an ECO Select branded product as one of the “greenest” and most efficient ASME pool heaters from Pentair. This design helps save energy, conserve water, and eliminate or reduce noise.
Control Panel for the MasterTemp Series
The compact Pentair 460775 ASME pool heater fit on smaller, less-intrusive equipment pads. The pool heater has intuitive and easy to use controls. It has user-friendly indicator lights that make system operation and monitoring less of a burden. Pentair designed the 460775 pool heaters to be quieter and less intrusive to help keep the poolside area relaxing. The compact design and quiet operation won’t intrude on your swimming and poolside enjoyment.
Pentair uses premix combustion technology in the 460775 for improved efficiency and faster warm-ups. The pool heats faster and you save on gas consumption which reduces the cost of ownership.
You use a manual gas shutoff when you need to service the pool heater. They certify the Pentair 460775 as a low NOx emission heater. The exterior of the Pentair 460775 ASME looks tough, and it’s rustproof. The heat exchanger is a standard copper heat exchanger with an efficiency of 84%. It is not suitable for use with salt water pools and therefore Pentair rates this pool heater as a residential pool heater.
Read the MANUAL for Proper Installation
The heavy-duty (HD) unit with cupro-nickel exchanger has an efficiency of 82%. For additional protection against low pH, high flow, saltwater or heavy use you need a different model. The Pentair 461021 heavy-duty (HD) ASME model has a cupro-nickel heat exchanger.
Commercial 400,000 BTU ASME pool heater.
Note : A 500,000 BTU ASME model is also available : Hayward H500FDNASME
- Patented Cupro Nickle Finn Plate™ heat exchanger with bronze header as standard
- Independent left or right side electric, water and gas connections
- 2″ x 2 .5″ CPVC flanged connections
- ASME pressure relief valve included as standard
- Electronic lock-out feature prevents unauthorized access to configuration settings
- Easy installation and service via access of single front panel
- Easy gas valve adjustment
- Easy dual voltage conversion with fuse-protected circuit boards
- Texas Heater Kits Available
- BTU’S while using minimal pump room space
- Warranty – 3 Years Parts and Labor
This model is part of the Hayward H-series ASME pool heaters designed and certified for commercial use. This one is the flagship of Hayward’s H-Series line that uses high-end features and construction materials. They offer three models of 250,000, 400,000, and 500,000 BTU. The Hayward H400FDN ASME model is a 400,000 BTU natural gas heater. The whole Hayward H-series universal heaters meet the Low NOx air quality standards in Southern California and Texas. When you receive the unit, you will find the thermal efficiency of the unit marked on one side of the pool heater.
VIDEO | ASME Heater Installation
This Hayward pool heater is a neat unit with a durable finish and easy to reach controls. When Hayward manufactures the H-series universal ASME heaters, they use their patented Cupro Nickle Finn Plate heat exchanger with a bronze header. This ensures the best possible service life of the heat exchanger and allows them to offer a 3 Years Parts and Labor warranty on new equipment.
They designed the pool heater with independent left or right-side connection points for electricity, water and gas. They use 2in x 2 1/2in Chlorinated Polyvinyl Chloride or CPVC, flanged connections to connect to the Cupro Nickle flanges. It withstands higher temperatures better than regular PVC. It makes perfect sense in this environment and they use an ASME pressure relief valve to ensure compliance to safety standards. Hayward marked the inlets and outlet flanges and they locate the water inlet at the back of the heater and the water outlet at the front.
An electronic lock-out feature prevents unauthorized access to configuration settings to ensure that the system performs as intended. The single front panel makes it easy to install and service the pool heater. Hayward uses non-corrosive feet to allow airflow under the heater and ensure that there is no corrosion from the bottom up.
Like the Pentair 460775, the Hayward pool heater incorporates an electrical hot surface igniter that only lights the pilot light when it is heating the pool. The installed a blower vacuum switch as a safety device that stops the ignition sequence if the blower is not developing sufficient airflow for combustion. When the blower airflow is sufficient, it creates a vacuum in the blower housing that closes the contacts of the blower vacuum switch. This is an indication to the ignition control board that it is safe to continue the ignition sequence. They provide the blower vacuum level to the blower vacuum switch via a silicone tube.
Easy gas valve adjustment and lots of error codes make adjustments and troubleshooting the pool heater a breeze.
Hayward uses three printed circuit boards for the ignition control system in this pool heater in this heater. The ignition control board, display board, and the fuse board and a keypad. The ignition control system functions as the heater’s thermostat, safety control system, and controller for the gas combustion system.
Hayward rates this heater for 50 PSI and suitable for indoor installations. It measures 36-1/2-inch long by 29-1/2-inch wide by 24-inches high.
Considerations when choosing a pool heater
The engineers design so-called Lo-NOx heaters using improved combustion control to minimize levels of nitrogen-oxide (Lo-NOx). These pool heaters are more environmentally safe so they offer a responsible way to heat the pool. When you consider purchasing a heater, determine if the health and safety codes in your neighborhood requires Lo-NOx pool heaters. ASME pool heaters use Lo-NOx controls and therefore complies with air quality emissions standards and qualify for state rebates in California. Both the Pentair 460775 and the Hayward pool heaters conform to this standard.
Pool heaters, including natural gas heaters, need fresh air containing oxygen for combustion of the gas. When the manufacturer designs the burner, they balance the fuel flow rate with naturally available oxygen at sea level. The higher you go above sea level; the less oxygen is in the air which reduces the efficiency of the heater. High altitude kits are available from the suppliers that will adjust the mixture to improve combustion. It is worth the effort to confirm with the supplier that the unit is suitable for the planned installation.
Cupro-nickel Heat Exchanger
Cupro-nickel is an alloy of copper that contains nickel and other strengthening elements. Because of this, it is highly resistant to corrosion caused by the extended and higher intensity use of commercial pools. More dirt and chemicals circulate through the pool heater, and higher chlorine levels affect the service life of the heater. Chlorine is a harsh chemical that attacks the heated walls of the heat exchanger. Another application is when the pool contains salt water. Using a pool heater with a cupro-nickel heat exchanger will extend the life of the heater. The Pentair 460775 does not have a Cupro-nickel heat exchanger but rather uses a copper unit.
Pool heaters can use two different types of gas, the two pool heaters we review use natural gas but models are available that use liquid propane. You should verify which gas is freely available in the area where you will install the pool heater. That will dictate which type of pool heater you will purchase. In areas where it is available, natural gas is more cost efficient than propane. We consider natural gas a greenhouse gas, occurring in nature as a mix of methane and other gases. It is therefore important that all connections are secure and the equipment working properly.
Propane is not a greenhouse gas, it is a Liquefied Petroleum Gas. It is colorless and odorless and therefore the refineries odorize it so we can detect its presence when released accidentally. It is more expensive than natural gas.
Ignition Type : Electronic and Millivolt
Residential pool heaters are available in two different ignition styles, electronic or millivolt. You should note the differences between the two and take it into consideration before making a purchase.
1. Electronic Ignition
They design pool heaters with an electronic ignition so it only generates a pilot when there is a call for heat. Keeping the sensors active requires power, therefore, the installer must install power to the unit.
- Only use fuel when necessary
- If wind extinguishes the pilot light during startup, it will automatically restart.
- 24 V power permits the use of digital circuitry, providing more sophisticated control capabilities.
- Temperature control is easy and accurate.
- There is always a small power consumption to monitor the sensors.
The Pentair 460775 and the Hayward H400 range both use electronic ignition.
2. Millivolt Ignition
They design millivolt ignition pool heaters with a constant pilot light that generates a small current that keeps the gas supply valve open. If something extinguish the pilot light, the valve loses power and blocks off the gas supply.
- The gas control circuit of the pool heater is independent of utility power.
- You are always using a small amount of fuel to keep the pilot alive.
- Wind buffeting can cause the pilot to be extinguished and must be re-lit.
Maximum size pool for a 400,000 BTU pool heater
We normally size pool heaters based on the pool surface area and the difference between the pool and air temperatures. For the calculation, we use the average air temperature for the coldest month we use the pool.
The desired temperature minus the average temperature = Heat rise. Next, we must determine how much the heater must raise the temperature in one hour. We divide the heat rise by the number of hours a day we will use the heater.
For example, 82°F – 70°F = 12, if the pool heater will run 8 hours a day, 12/8 = 1.5. Therefore, the heater must raise the temperature by 1.5°F per hour.
Things such as excessive wind exposure or much cooler night temperatures than daytime air temperatures could also affect the heater capacity. The intended use of the pool and also the surface area of the pool also affect the heater size.
These heaters are 400,000 BTU heaters. 400,000 BTU can heat a pool of 40,000 gallons to 80,000 gallons with a surface area of up to 1200 square feet. That’s a pool of roughly 40 by 30 feet.
You will need a larger gas-fired heater to heat a pool quickly after intermittent shutdowns. We also recommend a larger than standard size heater in colder climates when heating the pool for extended periods.
You will use the same amount of fuel to maintain the temperature of a pool regardless of the size of the heater, it will take longer. If you plan to shut down the heater when you do not use the pool. you will need a larger heater to bring it up to a temperature more quickly. Depending on how you use it, you may even save fuel because of the faster heat times.