iHeat Tankless Water Heater Troubleshooting

iHeat Tankless Water Heater Troubleshooting

This is a complete guide on iHeat Tankless Water Heater Troubleshooting. In this article, I will break down 5 common problems of your iHeat tankless unit. They are: 

  • Unit won’t start
  • The water heater starts and then goes off
  • The water doesn’t get hot enough
  • Water is flowing but getting no hot water
  • Unit does nothing

Apart from these, I will give a chart of diagnostic codes that will pop up on the controller display and how you can solve them. 

So, let’s get started. 

Table of Contents

iHeat Tankless Water Heater Troubleshooting [5 Common Problems]

This chapter will describe five common problems your iHeat Tankless Water Heater may go through. Plus, you can learn what troubleshooting steps you need to follow to resolve the issue. 

1. Unit Won’t Start (No Audible Clicks At Startup)

Not enough water pressure is the number one reason responsible for not igniting your Iheat Tankless Unit.  

Apart from this, the following culprits I blame most if the tankless water heater won’t come on: 

  • Incoming and outgoing water lines get reversed
  • Dead batteries or you install them in the wrong direction
  • One of wirings inside the unit may come loose or get detached during shipping
  • Filter screen gets clogged by dirt or debris

How To Fix: 

The first step of troubleshooting your Iheat tankless water heater is to check the water pressure. To activate the unit, you should have a minimum of 20 PSI of sustained water pressure. 

In the second step, I recommend you move forward to inspect the incoming and the outgoing water lines. If they get reversed, the unit won’t work. Ensure the incoming water line is on the right and the outgoing is on the middle of the unit. 

Thirdly, make sure you install the batteries in the right direction. If you position the battery correctly but the unit doesn’t work, replace the batteries with new ones. 

Fourthly, verify no wire is coming loose from its connector. To do that, ensure the gas is off. Then, remove the four screws (two on the top and the other two on the bottom) that hold the front cover in place. 

Afterward, pull out the front cover and take a look at the wiring. All wiring is down with push together plastic connectors. If any of them gets detached, just reattach the wiring into the connector. 

Finally, ensure the filter screen is free of blockage. If it’s dirty, just take a tiny brush and scrub away the blockage. After that, rinse the filter and reinsert into its place. 

Also, don’t forget to check the water regulator. If epoxy or debris makes the way into the water regulator, the iHeat water heater will not work. In this case, attach the water source to the water outlet side and back flush the system to remove blockage from the water regulator.  

2. Unit Starts And Then Goes off

Iheat Tankless Water Heater will come on and off due to the following reasons: 

  • Inadequate water pressure
  • High wind
  • Air in the gas cylinders
  • Ignition sensors get bent or too close to the burner
  • Thermocouple goes too high or low

How To Fix: 

For proper water heater operation, the iHeat Unit requires a minimum of about 2 liters per minute and a minimum of about 20PSI. 

Keep in mind; the water pressure (20 PSI) is at the lower end of the operating parameters. You will need a sustained water pressure between 40-60 PSI for adequate use if you have a 12/15/120 volt pump. 

Secondly, if you install the water heater in a high-wind area, it will cause the unit to cycle on and off. To fix the issue, install the unit in an area where there is absence of high wind. 

Thirdly, if the propane gas cylinders get contaminated with air, purge the air out of the cylinder. Regarding this, cycle your water heater on and off by using the shower head switch for 5 times. It will help purge the air from the gas. 

Next, take a look at the ignition pins and heat sensors. They should be in a vertical position or 90 degrees to the back of the box.  If they are not straight, use pliers to make them straighten. 

And lastly, make sure the thermocouple is not going too high or too low to complete the circuit. It should flush with the hole in the heat exchanger. 

3. Not Enough Hot Water

You will never get the comfort of hot water out of your iHeat Tankless Unit if you’re operating it above 6,000 feet. Turns out, a cracked gas regulator can cause the unit to not heat the water sufficiently. 

How To Fix: 

If you want the unit to deliver enough hot water, ensure you use it below elevations of 6000 feet. 

Next, look through the viewer panel on the front cover to see the flame. If the flame turns yellow, I bet the gas regulator is at fault. 

In this case, turn the unit off right off the bat and call a professional to replace the gas regulator for you. 

4. Water Is Flowing But Getting No Hot Water

The water is flowing through the unit but you get no hot water! This is a result from cross plumbing, inadequate water pressure, insufficient gas in the propane bottle, and dead batteries. 

How To Fix: 

Start with inspecting the unit for cross plumbing. 

Ensure you hook up the incoming water supply and the outgoing water supply properly. The water supply should be connected to the incoming connection, which you can find on the far right. 

On the other hand, you should attach the shower head to the outgoing water, which is located as the center connection.  

Once you verify the incoming and the outgoing water supply are correct, check the water pressure. To operate the unit trouble-freely, you should have sustained water pressure of at least 20 PSI. 

Next, ensure there is enough gas in the propane tank. Also, make sure you thread the LP regulator all the way onto the unit. 

Finally, examine the condition of the batteries. You need fresh batteries for ignition spark. Turns out, ensure you align the batteries in the proper polarity. 

5. Unit Does Nothing

iHeat tankless water heater does nothing at all! If this is the problem you are going through, check the following things: 

  • Verify the water source is connected with the water inlet side and the shower handle is attached to the water outlet side. 
  • Make sure you get sufficient amount of propane supply to the unit 
  • Ensure the batteries are fresh and you install them in the proper polarity. 

iHeat Tankless Water Heater Error Codes

If you own the iHeat Tankless Water Heater of AGL series, error codes may appear on the controller display. 

And the following chart will reveal the meaning and why those error codes pop up. Plus, the table below will guide you what corrective actions you need to take to resolve the issue. 

Error CodeProblem & Possible CauseCorrective Action
E11Inconsistent resistance of inlet temperature sensorReplace the inlet temperature sensor
E12Inlet temperature sensor comes looseReconnect the inlet temperature sensor firmly
E21Inconsistent resistance of outlet temperature sensorReplace the outlet temperature sensor
E22Outlet temperature sensor gets detachedReconnect the outlet temperature sensor
E31Interrupted water flowWater flow sensor gets defectiveEnsure you get continuous flow of water or at least get the minimum water flow activation rate (1.5L/MinReplace the water flow sensor
E32No water flow signalFix the water flow issueReplace the water flow sensor if needed
E41First heating element is at faultCheck the wiring and replace the first heating element if needed
E42Second heating element gets defectiveReplace the second heating element
E43Third heating element goes badReplace the third heating element
E51Power is on but the PCB doesn’t workReplace the computer board with a new one
E52PC board failureReplace the PC board
E60Overheat ProtectionEnlarge water flowSetting the correct power levelReplace the outlet temperature sensor


Now, you don’t need to worry if you encounter any of the issues (I mentioned) with your iHeat Tankless Water Heater. 

Just follow the troubleshooting tips I offer and fix the problem to enjoy the comfort of hot water out of your iHeat Water Heater. Best of Luck!

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