Rheem pool heater high limit 2 fault

May 7, 2015 · HVAC Technician: Okay, the HL2 is a high limit fault. There are two shown for your unit - #1 and #2. They are positioned on the return and supply outlets, #1 being the return and #2 being the supply. They are both set to open at 135 degrees. There are quite a few things that can cause this to happen.

Rheem pool heater high limit 2 fault. Answered in 13 hours by: A shorted sensor tells the board that the water temp is considerably higher than the highest temp setting, so the system is i.e. telling the heater "it's hot enough" in the form of keeping the heater switch open. This will happen even in service mode. Once you get a new temp sensor to the board, it will let the heater fire.

As with all heat pump pool heaters, compared to other types of heaters such as gas or oil-fired, this heat pump pool heater has lower heating capacity on a BTUH/hr basis. As a result, it will be required to oper-ate longer to accomplish the desired results. It may, at certain times, operate as much as 24 hours per day.

High limit fault, and replacement. High limit fault, 3 flashes on a Rheem gas pack. Replacement of limit. ...more. High limit fault, 3 flashes on a Rheem gas pack. Replacement of limit.Sep 28, 2009 · 3) Heater has power, but no ignition. This can mean several things. The most common cause is flow, a dirty basket, or clogged or dirty filter. A pool heater is an “open boiler” system, meaning the heater is cooled by the water flowing through the heater. All pool heaters have a pressure switch or flow switch that measures the flow rate of ... Heat Pump; Raypak 5450; Rheem Raypak 5450 Manuals Manuals and User Guides for Rheem Raypak 5450. ... And Operation Manual . Rheem Raypak 5450 Installation And Operation Manual (54 pages) Heat Pump Pool & Spa Heater. Brand: Rheem | Category: Heat Pump | Size ... High Water Temperature Limit. 32. High Pressure Switch Lockout. …As for the location I can see where the high limit runs behind the PIB to the outside of the heater, just want to confirm these are the only 2 I need to replace. I ordered a replacement R0023000 150deg high limit switch and a R0457200 130deg high limit switch to replace the 2 in the picture below.You have to replace the high limits. They are the 2 sensors on the bottom of the outlet side of the header. Held in by 2 plastic hex nuts. Its giving the fault code and the heater is coll, right? If so. You need to replace them. There are 2. You can test them with a continuity tester. One is set to open at 135 the 2nd at 150.Raypak residential pool and spa gas heaters include above footing heater models; in-footing heater models from 200K to 400K BTU; and low NOX versions of the in-ground heatrs from 200K to 400K BTU. [1] Raypak as well has a product line of residential pool and spa heat pumps with v models from 48K BTUs to 140K BTUs. [2]Solution: Make sure your thermostat is set to a higher temperature than your pool water. If increasing the temperature makes the heater turn on, then the thermostat is in good condition. Otherwise, you can use a multimeter to check if the thermostat is receiving power. Or, grab the jumper cable again and do a bypass test.

Follow these steps to test the sensor: Step 1: Turn off the power to the heater. Step 2: Locate the thermostat sensor near the heater’s inlet and outlet pipes. Step 3: Disconnect the sensor from the control panel. Once you have completed these steps, use a multimeter to check the resistance of the sensor.The 3LP will show the unit (LP3) after faults and shut down the unit and pool pump for safety. If this happens, you should call for service. HP and HP 6 – Low water flow or faulty high pressure control in the unit. check properly the water flow / backwash. Unit 6 HP will show after the defect (HP 6).common heater problems Heater Faults heater not heating Heater Not Working Heater problem Heater wont ignite POOL HEATER Pool heater fault turns on and off. Charlie Ramirez. ... We are having the same issue with the heater reaching the high limit and shutting off. Heater is one year old. Reply. Matthew Simmons says: June 7, …Googled Rheem Pool Heater Open SW code, found exactly what I needed. Arrived quickly took me all of 5 minutes to replace switch. Heaters works now!!! Saved myself $150 - $200 bucks..too easy Read more. ... RAYPAY 156A HEATER HI LIMIT 2 FAULT - AQUA-TECH. The high limit 2 fault code means the hi limit 2 switch is open. …Faulty water temperature switch, malfunctioning vent pressure switch, and defective temperature limit switch are accountable for displaying the Hayward pool heater LO code. Also, the damaged flow switch diaphragm and clogged filter are responsible for showing this code on your pool heater. However, going through the article, you will learn …Here are a few common Raypak troubleshooting codes and what they mean. Use these to troubleshoot your Raypak pool heater: LP & LP3. Low refrigerant if one “LP”. If “LP3”, likely a low-pressure issue. HP & HP6. Low water flow. Faulty high-pressure switch (shuts down to protect unit) FLo & FL3.

At times, simply cleaning the element would be enough to fix the issue. Turn off the power to the unit at the breaker box. Remove the water heater’s lower front panel (you would have to access the burners).; Locate the flame sensor and carefully pull it out.Mark shows us in this video how to do troubleshooting for a heater, he walks us through all of the steps. For all the pool knowledge you're looking for, chec...a. Use a pool chemistry test kit to confirm there is no chlorine in the condensation. Or, b. Shut the heat pump OFF and leave the filter pump running to see if the water stops dripping. If the water stops dripping, the heat pump is not leaking. Troubleshooting guide for Rheem Heat Pumps. Get technical support to repair common issues If your ...High limit 2 fault on heater. 15,000 gallon plaster pool with SWG and Raypak natural gas heater installed middle of last season. When I started the pool up the SWG read 0 ppm …Sep 29, 2021 · I just got a new pool and spa. Everything is working fine but when the spa is on I get 2 fault messages on my raypak 266 gas heater. Its pretty annoying because the heater get the spa up to temp and them shuts down and won't keep it warm. When I check the heater it says high temp 2. If I press mode it fixes it. Pressing MODE resets the heater.

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Put everything back into their places. Finally, light up the pilot and turn your water heater, which will fix the heater issue. 4. Bad Thermocouple. A faulty thermocouple is a caveat that causes your water heater to go through the …The major reasons for the Rheem water heater failed ignition lockout include a defective flame sensor, unplugged connectors, broken igniter, lack of airflow in the burner chamber, and corroded spark electrode. Plus, defective ignition control module, bad thermocouple, blocked heater venting, and malfunctioning gas valve are mostly …CircuPool RJ-60 Plus. May 22, 2021. #1. Just installed my new heater. It keeps tripping the high limit 2 switch. I think it’s a 135 degree trip. I put a thermocouple on that switch and noticed that if the side cover is off, it runs 120 - 128 degrees. If I put the cover back on it runs 127 - 137 degrees and trips. Why would it run so hot.Limit Control Switches,Limit Control Switches. Rheem Manufacturing ranks as the global leader in the manufacture of high-quality, sustainable, and innovative water heaters, tankless water heaters, air conditioners, furnaces, pool heaters, and HVAC systems for residential and commercial applications, and is a full member of AHRI, the Air-Conditioning, Heating, & Refrigeration Institute.

I have a Rheem (Raypak) 400,000 BTU pool heater the" Limit 2 Fault" limit switch trips after about 10 min checked gas Ask an Expert Home Improvement Questions HVAC Questions I have a Rheem (Raypak) 400,000 BTU pool heater the" Limit 2 Fault" limit switch trips after about 10 min checked gas... Ask Your Own HVAC Question Related HVAC QuestionsRheem Pool Heater Sensor Failure [5 Easy Solutions] Follow the below troubleshooting steps to get a complete solution for the sensor failure problem of the Rheem Pool heater. Note: You can also …Oct 27, 2010 · 3,192. South Central NJ. Oct 27, 2010. #6. When HL1 is present, it usually indicates insufficient water flow through put. There is a spring loaded bypass diverter in the header may be the culprit. If the heater cycles on to off after a few minutes, it's where I would look. As Ryahn suggests, scale is another possible. Oct 13, 2023 · Less than a hr. E3 reset on rheem pool heater. Less than 2 years I turned…. If you have the model number I can check for the reset procedure.Also, if the rollout sensor tripped it will have to be replaced, but we csn try to reset first and then go from there with the model information. Related Pool and Spa Questions. Raypak hi limit 2 fault er code means the hi limit 2 switches are open, or there is a bad or dirty connection at the switch or faulty wiring to the board from the switch, or a bad switch, or a sooted heat exchanger that may not pass the heat to the pool water. Plus, a faulty PC board could be the reason behind the issue. Solution: 1.ip address scheme for small network; fatal car accident in hartford ct last night; colombian coffee vs classic roast; ashley terkeurst hodges news; why did james brolin leave beyond beliefhoney nut cheerios calories with 2 milk; rheem pool heater sensor failure. Post author: Post published: 18. May 2023; Post category: ryanair outstanding balance;The “Rheem pool heater high limit 2 fault” defines that the high limit sensor is open due to the raising temperature of the system. This typically means the temperature inside the inlet/outlet header has exceeded the 135F temperature. For this, the HL switch opens and shuts off the heater.

The flow of hot water is not adequate to keep the water heater operating. This can be caused by flow restrictors and water saving low flow taps. You’ll need to have a plumber increase your hot water flow rate to a minimum of two to three litres per minute. To find your local Rheem Approved Plumber, contact us or call Rheem Service on 1300 556 ...

Jun 24, 2021 · From https://www.justanswer.com/ythiJustAnswer Customer: I have a rheem pool heater model 266, getting a error code HL2 after the heater runs for about 20 mi... Aug 8, 2018 · Hi all. I have a Hayward pool heater (model #H250FDN). Over the past week, the heater fired up and heated just fine. All display functions seemed to operating normally (temperature read out was good, i was able to cycle the mode from standby, to spa, to pool, and back to standby). Pool Heater P-M156A-EN-C High Limit 2 Failure Where is this switch located I replaced the one right behind the gas valve, ... -EN-C pool heater. When i turn it. Hi. I have a Rheem P-M336A-EN-C pool heater. When i turn it on, I get the following fault code: R V l LON, followed by GVO. ... Model No. P-M406A-EN-C for. I have had a Rheem …Gas-Fired Pool and Spa Heater Bronze ASME and Polymer Low NOx Heat Exchanger Models 207A, 266L, 267A, 337A, 399L, and 407A A S M E HW ... Added "Is Open" to High Limit cells. Added new section "High Limit Events" and supporting Figure 45 to "Status and Diagnostics" section. Added additional service kit information support for …The HL2 fault occurs when there is a failure at measuring the temperature of the water leaving the heater. Thus, it exceeded the recommended temp. The result of this is that water moving too slowly through the heater picks up too much heat. If your heater is making loud popping noises then it is without question the internal bypass assembly.Googled Rheem Pool Heater Open SW code, found exactly what I needed. Arrived quickly took me all of 5 minutes to replace switch. Heaters works now!!! Saved myself $150 - $200 bucks..too easy Read more. ... RAYPAY 156A HEATER HI LIMIT 2 FAULT - AQUA-TECH. The high limit 2 fault code means the hi limit 2 switch is open. …STEP 1: TRANSFORMER CHECK. If your heater has no power at all, check the circuit breaker or look for a popped GFCI outlet. Next, verify that you have 24 volts coming in and out of the transformer. Place your test meter on VAC (AC Volts), on a low scale 100 or 200 volts.Rheem SP12015 High limit thermostat, to get the best results, use only Rheem spare parts to repair your Rheem water heater, manufacturer: White-Rodgers, series producer: 11B79, high limit adjustment (F): 195, high limit differential (F): Manual reset, thermostat adjustment range (F): 100 to 180, differential thermostat (F): 4,Metro length (in. Provinsi = Jawa Barat Range Realita Kodepos = 45150 ‒ 45652 Jum Kec./Distrik = 40 Luas Wilayah = 1.076,76 km² (BPS 2022) Kode Wilayah Administrasi = 32.09 Range Alokasi Kodepos = 451 xx - 456 xx Jum Kelurahan & Desa = 424 Jum Penduduk = 2.380.074 (DKCS 2022)Notice: Trying to get property 'display_name' of non-object in /home4/santoni78/dexorate.com/wp-content/plugins/-seo/src/generators/schema/article.php on line 52

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3) Heater has power, but no ignition. This can mean several things. The most common cause is flow, a dirty basket, or clogged or dirty filter. A pool heater is an “open boiler” system, meaning the heater is cooled by the water flowing through the heater. All pool heaters have a pressure switch or flow switch that measures the flow rate of ...Pool Heaters. ajax pool heater repair; ajax pool heater service; bowmanville pool heater repair; brooklin pool heater repair; courtice pool heater repair; durham pool heater repair; durham pool heater service; markham pool heater repair; oshawa pool heater repair; scarborough pool heater repair; stouffville pool heater repair; whitby pool ...Mar 28, 2015 · 7. Low power to transformer can cause a GVO fault. CODE: HL1 PROBLEM: The high-limit has exceeded 135F. FIX: 1. Possible excessive water temperature in the tube bundle. Once heater cools, high limits resets automatically. 2. Check for blockage in tubes. 3. Check for low water flow. 4. Check Unitherm governor - replace if necessary. globalimageserver.com Mark shows us in this video how to do troubleshooting for a heater, he walks us through all of the steps. For all the pool knowledge you're looking for, chec...globalimageserver.com I have a Rheem Pool Heater, model RHM-15-0165 010165 P-M407A-EN-X - installed about three years ago. Over the last twelve months, the heater will stop running after about an hour or so of operation, d …Common rectangular in-ground pool sizes include 10 x 20, 15 x 30 and 20 x 40 feet; however they can be built to any shape or size. Homeowners should consider the intended use of the pool, who will be using it and the limitations of the spac...Mark shows us in this video how to do troubleshooting for a heater, he walks us through all of the steps. For all the pool knowledge you're looking for, chec...Raypak Pool & Spa, Residential and Commercial Hydronic Products - Sustainability; Careers; Training; Pool & Spa. Residential Pool & Spa Gas Heaters; Residential Pool & Spa Heat Pumps; Residential Electric Spa Heaters ... Get Pool Heater Sizing Help; Heat Pump Charging Charts; Boilers & Water Heaters Toolbox. SureSpec Heater Sizing; BIM …My journey returning to Zim after 20 years living in the UK. Menu. effect of bat entering the house in islam; places to take pictures in hutchinson, ksThis is a plumbing manifold that diverts a percentage of water “around” the heater, bypassing it back to the pool. The next stop for the power is to the high limit switches. Most heaters have two high limits, usually located side-by-side on the outlet manifold, a ‘low’ high limit usually set to 135° and a high-high limit set to 150°. ….

No incidents or injuries have been reported. Sold At: Pool equipment distributors nationwide between December 2020 and January 2021 for between $2,200 to $3,100, depending on the model. Manufacturer (s): Pentair Water Pool and Spa Inc., of Sanford, N.C. Manufactured In: United States. Recall number: 21-119.Sub Menu #2; Sub Menu #3; Sub Menu #4; Sub Menu #5; other words for baddie slang; oven liners sainsbury's Random Article; Home/university of scranton athletics staff directory/ rheem pool heater sensor failure. how old was naomi when she returned to bethlehem rheem pool heater sensor failure.Hi Limit 2 Fault. High limit 2 open. Rollout Sw Open. Rollout switch open ... pressure switch cannot be further adjusted or if the heater makes banging noises or ...Hayward Pool Products Inc is a leading manufacturer of high-quality pool equipment, including pumps, filters, heaters, and cleaners. If you’re lucky enough to own one of their products, it’s important to keep it in good condition to ensure ...Check for your high limit switch on your pool heater. You can take jumper cables and jump the cables that hold the high limit switch and if the heater turns ...SWG Type. Hayward Aqua Rite (T-15) Sep 26, 2023. #1. We have a Rheem 337A Low NOX Model pool heater. When it tries to start it shows a CFH (Call for heat) then shows a "SPR" (Spare Fault code indicator). I can't find what that means. I just wanted to check here before I order a replacement board. I had already fixed some cold solder joints in ...What does E5 mean on my Rheem tankless water heater? E5 on a Rheem Tankless Water Heater means there is a high flow rate. It means the desired water volume is too high that exceeds your desired preset temperature. To fix this issue, you need to slow down the flow rate.I have a Rheem Natural gas heater part of the 206a, 266a, 336a, 406a family which was put in last April. The unit worked perfect all of last year. Today I powered it up to heat up the pool and it thro … read more Rheem pool heater high limit 2 fault, Sep 29, 2021 · I just got a new pool and spa. Everything is working fine but when the spa is on I get 2 fault messages on my raypak 266 gas heater. Its pretty annoying because the heater get the spa up to temp and them shuts down and won't keep it warm. When I check the heater it says high temp 2. If I press mode it fixes it. Pressing MODE resets the heater. , New Product: ICI 200 Gas Heater, ICI 400 Gas Heater RAYPAK / RHEEM Gas Pool & Spa Heater Spare Parts: ... Hurlcon Astralpool Heater Hi-Limit Switch - 42-45°C - Inlet - F2 Errors Sale. Hurlcon Astralpool Heater Hi-Limit Switch - 42-45°C - Inlet - F2 Errors Regular price From $33.00. Regular price $66.99 Sale price From $33.00. Unit price / per . Sale ..., 7. Low power to transformer can cause a GVO fault. CODE: HL1 PROBLEM: The high-limit has exceeded 135F. FIX: 1. Possible excessive water temperature in the tube bundle. Once heater cools, high limits resets automatically. 2. Check for blockage in tubes. 3. Check for low water flow. 4. Check Unitherm governor - replace if necessary., CircuPool RJ-60 Plus. May 22, 2021. #1. Just installed my new heater. It keeps tripping the high limit 2 switch. I think it’s a 135 degree trip. I put a thermocouple on that switch and noticed that if the side cover is off, it runs 120 - 128 degrees. If I put the cover back on it runs 127 - 137 degrees and trips. Why would it run so hot., 636 satisfied customers. Jandy pool heater. My handy lrz heater is on, acknowledges. jandy pool heater. My handy lrz heater is on, acknowledges it needs to heat my pool and I hear it light the pilot and kick on. It runs for a couple … read more., Check The Power. When you are working on troubleshooting a pool heater, one of the most common culprits is the power source. Sometimes the fix can be as simple as ensuring the pool heater is plugged in properly. Check to ensure that your pool heater is properly connected to the power source and that there are no electrical connection issues., Clean the Filter. Your pool heater needs enough water pressure to run properly, usually at least 40 GPM. If your heater isn’t getting a steady stream of water, it could be due to a clogged filter or dirty pump basket. Clean your filter, skimmer, and pump baskets. Turn off your heater and pump before cleaning., Jun 12, 2018 · No high limit errors today but we will see if this is a final fix. The old bypass had rusted and the spring looked stuck (see photo). I have now: 1) replaced both high limit sensors and added thermal paste. 2) replaced unitherm governor. 3) replaced internal bypass. 4) added a heat shield. , Pool Heater P-M156A-EN-CHigh Limit 2 FailureWhere is Pool Heater P-M156A-EN-C High Limit 2 Failure Where is this switch located I replaced the one right behind the gas valve, still failing … read more, boidcrowdah • 2 days ago. This generally happens when the pool is shut down without allowing the heater to cool down. Sometimes a simple on/off and the toggle switch will reset it. ramblinbobandy • 1 min. ago. High limit switch 2., 2151 Eastman Ave. Oxnard 93030. 31 total complaints in the last 3 years. 11 complaints closed in the last 12 months. View customer complaints of Raypak Inc., BBB helps resolve disputes with the ... , If your Rheem pool heater is not turning on, the first thing you should check is the circuit breaker. Look for the circuit breaker that controls the power to the pool heater and make sure it is in the “on” position. If the circuit breaker has tripped, reset it and try turning on the pool heater again. Power Supply is another factor to check., May 17, 2010 · Posted May 17, 2010. My kids were using the hot tub and I went to my pool equipment and saw that my Raypak P-R406A heater was throwing the HL2 code. I turned it off and it started working again. About 15 minutes later the code appeared. Turned off the equipment for 10 seconds then turned back on and it worked fine. , The 3LP will show the unit (LP3) after faults and shut down the unit and pool pump for safety. If this happens, you should call for service. HP and HP 6 – Low water flow or faulty high pressure control in the unit. check properly the water flow / backwash. Unit 6 HP will show after the defect (HP 6)., common heater problems Heater Faults heater not heating Heater Not Working Heater problem Heater wont ignite POOL HEATER Pool heater fault turns on and off. Charlie Ramirez. ... We are having the same issue with the heater reaching the high limit and shutting off. Heater is one year old. Reply. Matthew Simmons says: June 7, …, Get technical support to repair common issues If your heater does not operate or does not heat your pool water. Call Us Nationwide: 1-800-741-9956. West: ... Troubleshooting Guide for Rheem Heat Pumps. For technical support, call 1-877-720-2076. ... such as high wind, spillage, rainfall, flow through solar panels at nights, or a high water ..., The heater is equipped with two automatic high limits. Both are located in the inlet/outlet header. Both are set to open at 135°F. To troubleshoot this, 1. Shut off main electrical power switch to heater. 2. Remove inlet/outlet inspection panel. 3.Locate the high limit and test it for continuity with your multi-meter., Aug 8, 2018 · Hi all. I have a Hayward pool heater (model #H250FDN). Over the past week, the heater fired up and heated just fine. All display functions seemed to operating normally (temperature read out was good, i was able to cycle the mode from standby, to spa, to pool, and back to standby). , Check The Power. When you are working on troubleshooting a pool heater, one of the most common culprits is the power source. Sometimes the fix can be as simple as ensuring the pool heater is plugged in properly. Check to ensure that your pool heater is properly connected to the power source and that there are no electrical connection issues. , 2.9 If the pool or spa heater is not sized in accordance with the guidelines in Raypak’s pool & spa heater literature, any resultant fault will not be covered by Rheem's warranty. 2.10 The Rheem warranty is not applicable if the installation of the pool or spa heater is carried out by an installer not approved by Rheem or a person, Jun 24, 2021 · From https://www.justanswer.com/ythiJustAnswer Customer: I have a rheem pool heater model 266, getting a error code HL2 after the heater runs for about 20 mi... , Once again the spa heater stopped heating at 99 (its internal reading, actually 97) and said to press "mode" to reset limit. Pressing went to off, and then pressing again restored the heater and to got to 107. What might I do to resolve high limit 2 errors. Seems to happen once most days as heater goes from 86 to 107, usually at 99 or 100., Nov 25, 2022 · Heaters have high-limit switches for temperature, pressure, and refrigerant (if a heat pump) that will open and shut off the heater in a low-flow scenario. In a heat pump, when the flow is low, the system will run high head pressure. However, in a gas heater, the exchanger can begin to cavitate and make a loud banging noise. In my experience ... , If your Rheem pool heater is not turning on, the first thing you should check is the circuit breaker. Look for the circuit breaker that controls the power to the pool heater and make sure it is in the “on” position. If the circuit breaker has tripped, reset it and try turning on the pool heater again. Power Supply is another factor to check., Sub Menu #2; Sub Menu #3; Sub Menu #4; Sub Menu #5; other words for baddie slang; oven liners sainsbury's Random Article; Home/university of scranton athletics staff directory/ rheem pool heater sensor failure. how old was naomi when she returned to bethlehem rheem pool heater sensor failure., How to fix it: Check that pool pump is receiving enough water. Ensure that your pool pump is sending water to the heat pump. For variable speed pool pumps, try putting the pump speed up a notch Check for any clogs or backups causing poor water circulation. The same is true if what you use is in your pool is the Raypak pool heater., Summary of Contents for Rheem Raypak 2450. Page 1 INSTALLATION AND OPERATION MANUAL Heat Pump Pool & Spa Heater Models 2450, 3450, 4450, 5450, 6450, 6450PD, 6450HC, 8450 & 8450HC FOR YOUR SAFETY: Do not store or use gasoline or other flammable vapors and liquids or other combustible materials in the vicinity of this or any …, 3,192. South Central NJ. Oct 27, 2010. #6. When HL1 is present, it usually indicates insufficient water flow through put. There is a spring loaded bypass diverter in the header may be the culprit. If the heater cycles on to off after a few minutes, it's where I would look. As Ryahn suggests, scale is another possible., By displaying a code on your tankless heater, you, or a professional, can read the code to understand what went wrong and how to fix it. A Rheem tankless water heater has over 30 potential codes, and the solution will differ depending on the specific make and model of water heater that you have. The most common codes include Codes 5, 11, 13 ..., 2. Check that the pool or spa heater you have been supplied is suitable for the gas type that is available. 3. Ensure that your gas fitter checks that the gas supply pressure is between the minimum and maximum specified on the heater ... High Wind Areas Raypak pool & spa heaters are atmospherically vented and so may not function correctly in areas of sudden …, Solution: Inspect the heater’s gas valve, and check that it’s set to the “OPEN” position. Possible Cause: Gas supply valve. Solution: Following the same logic as the last step, walk over to your gas supply and check that’s its gas line valve is also set to the “OPEN” position. Possible Cause: Pilot light isn’t lit., 8. Low power to transformer can cause a GVO fault. HL1: The high-limit has exceeded 135F: 1. Possible excessive water temperature in the tube bundle. Once heater cools, high limits resets automatically. 2. Check for blockage in tubes. 3. Check for low water flow. 4. Check Unitherm governor- replace if necessary, Possible Causes: Water temperature in heater exceeds the internal limit. Limit switch fault. Remedy: Inspect vent for obstructions or blockages. Indoor installations, check vent pipe for bird, insect or rodent activity that could cause a blockage. Replace switches. Refer to qualified service personnel. Report.