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Review Polaris water heater
AO Smith Polaris 34-50 gallon condensing heater
2023
replace anode rod
Inspect anode each 2-5 years
Anode rod prevents tank from rusting
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Anode rods at Amazon

Resources:
Replace anode rod
How to maintain water heater

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Impact wrench at Amazon

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Replace anode rod
How to remove short water heater nipple
Water pressure gauge

Pressure gauge/ attach to water heater drain valve
Pressure over 80 psi can damage water heater and household plumbing
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Water pressure gauge
Temperature-pressure gauge

Resources:
Identify water heater valves
Troubleshoot water pressure


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Knipex channel locks
Irwin pliers

Polaris cut awayPolaris water heaterLarger image
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Polaris is in a class of heaters called 'condensing water heaters' due to design of the heater ... where heat produced by a large burner is recycled through an helical shaped heat-exchanger located inside tank ... resulting in large output of hot water, and rapid recovery ... which produces a flow of condensed acidic water vapor that must be routed into floor drain.

Polaris is a Power Direct Vent condensing heater.
All brands of condensing heaters are either Power Direct Vent (incoming air supply comes from outdoors, and vent terminates outdoors)., or Power Vent (incoming air supply comes from inside room, and combustion vent pipe terminates outdoors).
Not all power vent and power direct vent heaters are condensing heaters.

Condensing heaters and regulation:
Recent DOE energy standards suggest that any household requiring residential-grade gas water heater larger than 55 gallon must install a high-efficiency condensing heater ... or convert to solar, look to buying two heaters ... or buy high-output, non-condensing water heaters classified as 'commercial grade.' Example spec sheet

Choices are further regulated in states that require Ultra Low NOx heaters to reduce the release of NOx greenhouse gas. This requirement is not universal across all states in 2023.
Polaris, and condensing heaters in general, are Ultra Low Nox by government standard because of the large BTU consumption ... while other commercial grade and commercial grade for residential heaters might NOT be low NOx or ultra low NOx, depending on BTU output and classification of heater.
Resource: Two water heaters
Polaris overview
Polaris has 96% thermal efficiency (percent of heat from burner converted into hot water) and 80.5% overall efficiency (Including operation, standby loss etc).
The Polaris power direct vent heater has long-lasting 'corrosion resistant' 444 stainless steel tank, 'precise temperature control' and is available in 34 and 50 gallon residential and commercial models with choice of 100,000 to 199,000 BTU models that are designed to meet market for high-demand hot water usage. Cannot be exposed to more than 7-12 grains water hardness. Does not require anode rod. 

Polaris will supply large quantities of potable (drinkable) hot water as a stand-alone unit for commercial applications, apartment, or high water usage residential household ... or can be connected to auxiliary storage tank, or used with household air handler for space heating in large or small homes and apartments.

Polaris has residential and commercial models. Both are identical except for model numbers and coloration. Both have been in use many years, and both available for propane or natural gas. Resource: Polaris residential and commercial spec sheets/pdf
Polaris comparedPolaris residential model is rated 'commercial grade residential heater,' with 10-year limited tank, and 1 year parts warranty for residential installations.
The Commercial model is rated 'light-duty commercial,' with 3 year tank and 1 year parts warranty. Commercial heaters usually have shorter warranties, often operating more frequently, and set to higher temperatures that cause more strain on tank. The heater wears out sooner.

Polaris 100,000-300,000 BTU per hour fuel consumption exceeds fuel consumption of typical 30-50,000 BTU residential heaters, yet Polaris is nearly same size.

For example, 50 gallon Polaris is 63-3/4"x22", which is comparable size with residential tank*, but the 50 gallon Polaris can deliver 170+ gallon first hour, with recovery 165-325+ gallons per hour... meaning Polaris can supply 170 gallons hot water in a single steady draw before water temperature becomes unusable (depending on temperature rise, or thermostat setting minus incoming cold water temps) Resource: Recovery chart from pg 9 manual/ .pdf

Contrast with ordinary 50 gallon, 40,000 BTU residential tank used by a family of 3-4 people will  deliver 70-80 gallons of usable hot water in a single steady draw, with recovery about 42-50 gph (gallon per hour depending on BTU rating of heater, thermostat setting, incoming water temperature, condition of heater, etc)

Resources:
Polaris specification sheet
Polaris commercial specification sheet/ pdf
Installation manual applies to commercial and residential
Water heater terminology & formulas/ pdf

Polaris user interface
(image photoshopped for clarity/ resource image/ 34 gallon/)

Polaris has LCD readout with ''electronic controls that give homeowners precise temperature control and advanced water heater diagnostics through a large, easy-to-use touchscreen display.''

The LCD control or UIM user interface module is located on front face of unit.
The UIM interfaces with the CCB (central control board) "at bottom of heater located inside protected enclosure."

Polaris water heaters "are equipped with an enable/disable circuit for use with field supplied external supervisory controls such as time clocks or Building Management Systems." Resource: read section in manual
PolarisControl temperatures
Polaris factory setting is 120°F.
'The “Operating Set Point” for polaris is adjustable from 90°F (32°C) to 160°F (71°C) using the UIM user interface.

Commercial models: 90°F (32°C) to 181°F (83°C).

Both commercial and residential models: the ECO (or energy cut off located inside the thermostat probe) opens (locks out heater) when water temperature inside tank reaches 202°.
The UIM user interface gives error message.
ECO can be reset once tank reaches 140°F by turning off power and re-powering unit to reset UIM user interface.
ECO trip indicates serious malfunction.
Polaris
Enable-disable switch
There is a Enable/Disable switch located at bottom of heater that can be set without removing access panel ... must be set to enable for operation. In emergency, unplug water heater from 120V outlet and set switch to disable.

Polaris factory setting is 120°F.
Typical bath shower is 104°-108°F.
"Maximize efficiency by setting to minimum temperature that supplies acceptable hot water supply."
Higher operating temperatures cause more wear on all water heaters and will decrease life span of water heater by creating more strain on tank walls, more moisture, and more wear-n-tear on parts. Add booster heater if very high temps are required.

Polaris is "equipped with electronic control system to regulate water temperature. The control system senses temperature from two factory installed temperature probes (thermistors), one installed in the top of the tank and one installed near the bottom.

Any temperature setting over 120°F, it is suggested that a mixing valve or tempering valve be installed to temper or cool water to 120 or less before entering household plumbing. High temperatures can kill and permanently injure.
For the mixing valve to work properly and avoid bubbles in water line, the pipe leaving mixing valve must travel vertically. Add air vent if needed.
Resource:
Air vent
Condensing water heaters cycle combustion gas through heat exchanger
Polaris is among a group of high efficiency, high consumption commercial and residential heaters that are classified as condensing.
For example, AO Smith also manufactures the high-efficiency Cyclone series commercial condensing heater with 3 year warranty and two power anode rods, and the lighter-duty, less expensive residential high-efficiency Vertex with 6 year warranty and two heavy duty anode rods among other differences. Resources: Vertex specification sheet .pdf  Example Cyclone spec sheet.pdf  Anode rods protect tank from rusting. The 444 stainless steel Polaris doesn't require anode rod.

As a group, condensing heaters achieve higher efficiencies (80% efficient) than typical residential power vented and atmospheric heaters (60% efficient) The higher efficiency is achieved by recycling hot combustion gasses though the heat exchanger coil before venting gas out of heater. Less heat is wasted up the vent pipe.

How it works:
Improved and 'ultra-quiet' Polaris blower motor draws air into the burner at the bottom of the water heater through air inlet pipe from outdoors. The supply of propane or natural gas fuel is mixed with air inside the burner located at lowest part of the 444 corrosion resistant stainless steel tank.
After burning the fuel, the blower recycles hot combustion by-product through the helical heat exchanger made of 444 corrosion resistant stainless steel, before pushing the by-product out of the tank near bottom and then upward through vent pipes that exhausts outside via side-wall or rooftop vent terminations.
Vent pipe is typical approved 2-3" PVC, CPVC or Polypropylene (solid core only) as per specs shown in installation manual.

According to promotional literature, the thermal efficiency of condensing heaters with the heat exchanger reaches 94-96%. The manual claims that the vent pipe at bottom of heater is not hot to touch. (Thermal efficiency is not same as overall efficiency ... does not include standby losses or enegy consumption of blower).
This means the heat that is produced by the massive 100,000-199,000 BTU burners found in condensing heaters is almost completely recycled into the water, and only 4-6% of heat is wasted up flue pipe. Contrast with ordinary residential heater where '25-30%' of combustion heat is lost up flue pipe.

High efficiency/ high cost
Condensing heaters have high efficiencies, less heat wasted up flue pipe, and produce plentiful hot water, but there is trade off for choosing condensing.

The trade off is condensing heaters cost more to buy, require more maintenance and repair, repairs are not DIY by homeowner or local handyman, they require very specific installation and larger gas line. For the typical household with 4-6 people, a condensing heater might not save money vrs downsizing usage or installing two ordinary gas heaters.
On the other side, buying a heater that is too small for the job will overwork the small heater, increase maintenance and repairs, and shorten lifespan of unit.
Resource:
Two water heaters
Polaris water heater
Thermal efficiency
Polaris does not have 94-96% energy efficiency.
- 94-96% thermal efficiency refers to the amount of heat that is recycled into the water via the heat exchanger instead of venting out flue pipe. The manual claims the vent pipe leaving bottom of tank is not hot to touch because of the thermal efficiency.

True Efficiency EF or UEF is the combined thermal efficiency, power use, and standby efficiency of water heater.

Polaris has UEF (Uniform energy factor) 88-90 or less, which includes thermal efficiency plus standby loss for total energy consumption including blower motor.

UEF is a formula that must subtract a small percentage of tank volume ... for Polaris that translates to 80-82% efficiency for 34 gallon and less efficiency for larger 50 gallon size Polaris which is very good efficiency when compared to .60 efficiency for ordinary 50 gallon tank heater.
Resource:
How much does it cost to run gas water heater

Acidic water vapor: (reference acid rain from power plants)
When hot gasses are pushed through the helical heat exchanger of a condensing heater, the gas cools, causing acidic water vapor to condense out.
All gas water heaters produce acidic water. With an ordinary gas heater the acidic water vapor is released into atmosphere.

With Polaris, and other condensing heaters, the acidic water is continually drained out of heater at bottom of vent pipe though the exhaust elbow that prevents release of some acidic water vapor into atmosphere.
It does not prevent the release of other toxic gasses, except reduced amounts of NOx.
Resource: Venting instruction suppliment

floor drainIf the condensate drain is blocked on Polaris, water will accumulate inside the exhaust vent causing back pressure. Polaris has two pressure switches. One that monitors incoming air supply (blocked intake switch), and one that monitors flow of air into the vent (blocked outlet switch). If water is obstructing the vent, the blocked outlet switch switch locks out heater until exhaust elbow is cleaned out.
Power requirement
Must be directly plugged into 120 volt 3-prong single phase outlet/ 15 or 20 amp breaker.
Voltage must be steady and cannot fluctuate. Cannot use extension cord. Extension cords, plug-in monitors, surge modules, plug-in wifi controls do not provide 100% reliable connection.
Clean, uninterrupted power is needed.  Three failed start attempts cause lock out. Unplug unit to reset control system.

Blower and heater draw less than 7 amps x 120 volt = 1400 watts.

Outlet must be grounded for the heater to operate without error.
Outlet must have correct polarity.
All water heaters that plug into outlets are polarity sensitive. Use circuit analyzer to check outlet. Polaris will not operate if polarity is reversed ...  'the water heater control system will declare a fault condition and lock out.'
Buy:
Circuit analyzer

Line noise and surge from other motor loads and appliances on same circuit can cause errors and failures.
Recommend dedicated circuit where the circuit supplies power to Polaris and no other load.
"EMI electro magnetic interference or RF I radio frequency interference may cause erratic control system and malfunction."

Surge protection is recommended for all electronic devices including Polaris water heater.
A surge protection outlet is recommended vs a plug-in surge module ... surge outlet is correct choice for reliable electrical connection.
Buy:
Surge outlet

Circuits can have multiple surge protection devices. The closer the surge protection is located to the electronics, the better it protects. No amount of surge protection can protect from direct lightning strike.
Simple power outage and power resumption can destroy electronics. Additional action can include unplugging heater and use disable switch at bottom of heater during power outage or severe lightning storm.
Do not use GFCI, it can cause malfunctions, it is not necessary and not required by code. GFCI can interfere with operation of all power vented, and flue dampered water heaters, both residential and commercial.
Gas pressure
"Cannot exceed 14 WC
Minimum 3.5 WC
Gas pressure must be stable within 1.5 WC

Tankless gas pipeAll models - Maximum Supply Pressure: 14 inches W.C. (3.48kPa)
Over 14 WC requires regulator

Minimum Supply Pressure for Natural Gas: 3.50” (.87kPa)
Minimum Supply Pressure for Propane Gas: 8.00” (1.99kPa)

Minimum pressure must be maintained under both load and no load (dynamic and static) conditions."

Gas line
Use only black pipe. Keep ends of pipe clean, do not let shavings, connection compound, dirt, or teflon tape enter gas valve.
Do not use flexible gas line with high volume gas appliances like Polaris. Bends and uneven pipe can restrict gas flow.
Never use galvanized pipe ... is reactive with gas, and flakes of galvanized will enter gas valve requiring replacement.
Example "Input 199,000 BTUH .... Total pipe length, 80 feet = 1" IPS required.

Resource: Gas pipe capacity chart
Gas input rate is affected by environmental factors such as:
• Heating value of gas • Air and gas densities (vary due to barometric, pressure, temperature changes) • Venting installations (pipe diameter, length and fittings) • Altitude

Polaris water heater
Sequence of operation:
'-Control system detects water temperature is below programmed set point.
-Heating cycle activated.
-Control system runs diagnostic checks.
-Control system confirms exhaust and intake and ECO contacts are closed (ON)
-Blower turns on for pre-purge
-Spark ignition transformer is energized.
-Hot surface igniter glows red hot.
-24 volt gas control valve opens, and gas flows to main burner.
-Control system monitors flame sensor to determine if gas has been ignited.
-If flame is detected, control system enters heating mode.

-When control system detects tank has heated to thermostat set point.
-24 volt gas control valve is de-energized.
-Gas stops flowing to burner.
-Spark ignition transformer remains on to ignite any remaining gas, then turns off igniter.
-Blower continues to run 60 seconds until end of post-purge cycle, then coasts to a stop.
-Control system goes into standby mode while continuing to monitor water temperature and state of other system devices.'
Resources:
New installation manual resident all
New installation manual commercial model
Specification sheet
Faults , errors, alerts, and problems
When problem is detected, control system issues fault messages on LCD display, and locks out operation of heater.
Lock outs can be reset using the enable-disable switch located at bottom of heater. If fault is still present, then lock out will continue.
Other issues will cause Alert condition, and water heater will continue to operate.

Service manual?
No service manual available for newer version of heater.
Installation manual says ''Only qualified service technician, as defined in Qualifications using appropriate test equipment, should perform any service procedures on the water heater.''

Other highly technical AO Smith water heaters, like Vertex and Cyclone condensing heaters, have service manuals, one wonders why Polaris has no service manual available to the public.
Resource:
Polaris troubleshoot guide
Older service manual
Polaris water heaterPower direct vent overview
Air intake and venting through sidewall or rooftop via approved 2-3" PVC, CPVC or Polypropylene (solid core only).

Operates similar to other power vent water heaters. Has electronic ignition, or spark ignition system ... commonly called hot surface igniter, or flame rod, that glows red hot and stays on throughout heat cycle to continuously ignite fuel.... no pilot flame.

Condensate drain required. Household drain cannot be made of metal or other material that is reactive to acidic water.

Condensate trap might be required on incoming air supply in some circumstances when cold climates create condensation inside intake pipe as cold air inside pipe is warmed by indoor temperatures.

"The vent and intake air piping (direct vent installations) may not be combined with any other appliances under any conditions." In other words, the vent cannot be passively vented up a chimney, or shared with furnace, another water heater or gas appliance as commonly found with some water heater installations.
Vent must be installed according to manual, using correct size and type of materials that do not violate maximum distances, slopes, number and types of elbows etc as instructed in manual.

Power vented water heaters meet LEED standards for home efficiency since power direct venting allows the home to be sealed, or insulated tighter without requiring air penetration to support water heater draft. Maximize the efficiency by keeping mechanical room sealed in winter, and ventilated in summer.
Locate heater close to usage points.
Resource:
Add vent fan to boiler or any power vented water heater
Venting instruction suppliment
Polaris water heater
Installation for
potable (drinkable) hot water
For commercial application, apartment, or high usage household.

Add heat trap to improve overall efficiency. Stops upward heat loss through pipes.

Tempering valve or mixing valve will automatically add cold water to household water supply so Polaris thermostat can be set to 160° to maximize space heating via air handler, and keep household water below dangerous levels. For the mixing valve to work properly and avoid bubbles in water line, the pipe leaving mixing valve must travel vertically
Resource:
Advantages tempering/ mixing valve

Pressure reducing valve required if incoming water pressure exceeds 80psi. 50 psi is ideal.
Resource:
Pressure reducing valve

Expansion tank required if incoming cold water line has pressure reducing valve or check valve. Or if required by local code.
Resources:
Expansion tank
Check valve
Thermal expansion: closed system
TP valve code
Polaris water heaterInstallation for potable hot water and space heating
Can be integrated with air handler for space heating.

''With up to 199,000 BTU, the Polaris unit can easily heat a large or small home by circulating hot water through coil in air handler.'' The air handler blows air across the coil before circulating warmed air through household ducts.

According to manual, Polaris is 'not designed as primary heater for space heating.'
Primary purpose is to produce hot water for household usage.

Polaris cannot take the place of a boiler. A boiler produces 200° water (Polaris heats to 160°). Boiler requires chemicals in the boiler water to inhibit reaction with metal pipes etc.

Polaris cannot be exposed to boiler chemicals. Same chemicals can never be allowed into potable (drinkable) water used inside home or business.

"Polaris comes with 1” NPT recirculation loop return connections located on side of tank.
When air handler calls for heat, the circulating pump draws hot water out of Polaris and circulates through heat exchanger coil located inside air handler.
Use separate 120 VAC power for circulating pump.
Do not draw power from Polaris circuit ... can cause electrical line noise and erratic control of heater."

"• Do not use Polaris with piping that has been treated with chromates, boiler seal or other chemicals and do not add any chemicals to the water heater piping.
• If the space heating system requires water temperatures in excess of 120°F, a mixing valve must be installed per the manufacturer’s instructions in the potable hot water supply to limit risk of scald injury.
• Pumps, valves, piping and fittings must be compatible with potable water.
• A flow control valve (check valve) is required on pipe carrying hot water to air handler to prevent thermosiphoning." Typical swing check valve allows water to flow one direction inside the pipe, but not the other direction, and must be installed in horizontal position to function correctly. "Thermosiphoning is the result of a continuous flow of water through the air handler circuit during the water heater off cycle. Weeping (blow off) of the temperature-pressure relief valve (T & P relief valve) or higher than normal water temperatures are the first signs of thermosiphoning."
Polaris
Resources for current models:
AO Smith, American, State, Lochinvar, etc
Polaris-parts-sheet-2019
Polaris parts sheet 2 -2019

Residential Polaris-installation-manual.pdf
Commercial installation-manual-2.pdf

Polaris-commercial-spec-sheet.pdf
Polaris-residential specification-sheet-6.pdf
Residential-and-commercial-spec-sheets.pdf
AO_Smith-polaris-33.pdf

Polaris-troubleshoot-manual.pdf

Design change over time
The older version, and newer version are same in many ways and differ in others. AO Smith, American, Lochivnar, State all sell same updated version today.

Same design features
Both old and new are identical size according to specification sheets.
This means identical height, diameter, weight, BTU rating, insulation etc.

Exception: the older version offered 100 gallon 199,000 BTU unit, while newer version only has 34 and 50 gallon sizes, but no 100 gallon.

Overall purpose is same: to efficiently supply high volume of potable hot water, with secondary purpose of supplying hot to auxiliary tank ... and/or space heating home/ apartment.

Internal heat exchanger, tank, water heating capacity, etc are same/ similar.
Both have corrosion-resistant stainless steel heat exchanger and tank, and do not require anode rod.

Plumbing connections might have different orientation, but remain same.

Both have hot surface ignition (no pilot light).
Both require same standard pipe size for BTU:
Locating heater is same:
.... within few feet of 120 volt dedicated outlet, next to floor drain.
Both must be plugged directly (no extension cord) into 120 volt single-phase outlet. Dedicated circuit recommended.
Power consumption 7 amp max, or 7 amps x 120 volts = 1400 watts.

Locate where blower noise will not be objectionable.
Locate so water heater can be vented properly.
Install vent terminations where noise will not be objectionable and exhaust cannot be sucked back into home.

Differences between old and new
Newer model has redesigned blower motor for less noise ... or 'whisper quiet' as claimed in promotional literature.
Venting and air supply requirements can be different.
AO Smith manual says: ''When replacing existing (older) Polaris unit, it is recommended that the venting system be reviewed for compliance with the requirements contained in the new instruction manual.'' Installation manual

Thermostat: older unit had hand adjustable thermostat knob, with single temperature sensor ... a 10K ohm at 77°F (25°C) thermistor located in mid upper part of tank.
Newer units have LCD temperature control and 2 temperature probes, located at bottom and mid upper parts of tank.

The control system on new AO Smith version has been modernized with more electronics, and completely different wiring and control interface.
Older style heater had "self-diagnostic control automatically monitoring all critical functions which indicated status of all functions using flash code sequence."
Newer Polaris has LCD readout with ''electronic controls that give homeowners precise temperature control and advanced water heater diagnostics through a large, easy-to-use touchscreen display.''

Resources for Older models
Lennox-Polaris-installation-manual.pdf
Older version/ replacement parts/ pdf
Polaris®-Troubleshooting-guide.pdf
Polaris-service-manual.pdf
Lennox polaris heating system sell sheet

Parts are not interchangeable between older and new models.
Older parts sheet
Newer parts sheet

Resource: Polaris old and new specification chart

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