Skip to main content
All CollectionsProduct Infoi12-LP/NG Whole Home Tankless Water Heater
Eccotemp i12-Liquid Propane Indoor Tankless Water Heater E3 error code
Eccotemp i12-Liquid Propane Indoor Tankless Water Heater E3 error code
Updated over a week ago

Eccotemp received an email from a customer with an i12-LP tankless water heater shutting off after igniting and heating up water and going beyond the set temperature and having an E3 error code. The customer has provided pictures of their water heater below.


The image above illustrates an improper installation of the i12 Liquid Propane tankless water heater. Specifically, the Red Arrow (1) points to the vents, while it does have the backflow preventer, it lacks the required stainless-steel material, and it is neither horizontally or vertically installed and the destination of the vents is unclear. Regarding the water connections, the Yellow Arrows (2) indicate the use of appropriately sized ½” water pipes. For the gas connection, as shown by the Green Arrow (3), a ½” flex line connection is correctly employed. Additionally, we have advised the customer to ensure that gas pressure falls within the acceptable range, specifically between the minimum and maximum inches of water column.

The E3 error code on an i12 Liquid Propane Tankless water heater signals overheating. This can result from either reduced or blocked water flow, or heat from the vents affecting the overall temperature of the water heater.

  • First, we advised that the customer use a manometer to assess their gas pressure. They should ensure that the gas pressure falls within the acceptable range, as indicated in the right-side panel of the water heater for reference, between the required minimum and maximum inches of water column.

  • Second, we advised the customer to inspect the water inlet filter, clean it, and verify that there are no obstructions present.

  • Third, we recommend descaling the water heater, particularly if the water supply has high mineral content or is considered hard water. Performing this maintenance task every six months is crucial to minimize the effects of corrosive elements and mineral deposits that restricts water flow. This routine ensures unimpeded water flow and prolongs the lifespan of the water heater. To assist with descaling, we suggest using our Eccotemp EZ flush kit, a comprehensive solution that simplifies the process. Connect the kit to the water heater to maintain proper water flow within the pipes.

  • Fourth, we advised to change their vents to the proper vents that is required by the i12 Liquid Propane Tankless water heater. They can either get the 3” horizontal vent kits or the 3” vertical vent kits if they want it to be up to the roof. We do not recommend the vents going down as indicated in the first picture.

How we fixed the E3 error code for the i12 Liquid Propane tankless water heater. After confirming that the water filter is clean and unobstructed, and ensuring that the gas pressure falls within the acceptable range (minimum to maximum inches of water column), the next step is to inspect the water gauge. Ensure that it is set to the "+" instead of the "–" as this regulates the overall water flow, with the "+" indicating the maximum opening for water flow. For additional assistance in resolving this issue, please consult the image provided below.


Following the customer's completion of the troubleshooting steps outlined above, the i12 Liquid Propane tankless water heater operated seamlessly, and the E3 error code was successfully resolved. The issue stemmed from a restricted water flow due to that the water inlet filter is not clean and they have not descaled the water heater in a long time. We have further reiterated the importance of changing the vents to the required vent kits for the water heater.

We always recommend taking advantage of our Free Pre/Post Purchase Consultation call with one of our experts to better understand the uses, installation, and common mistakes made when installing one of our products. We also always recommend hiring a professional licensed installer to ensure your installation is correct and intended for the product you purchased.

To take advantage of our consultation services or to schedule a call with one of our experts, please visit our booking page. Investing in professional installation and seeking expert advice ensures that you get the most out of your tankless water heater and enjoy reliable, energy-efficient hot water for years to come. Click here to schedule your call with our team today!

Did this answer your question?