IMPORTANT: ALWAYS SCREENSHOT OR DOCUMENT CURRENT FIRMWARE VERSIONS BEFORE ATTEMPTING FIRMWARE CHANGES OR UPDATES.
When it comes to firmware, we try to follow the motto "If it ain't broke, don't fix it!"
Firmware is not like software, where you want to be running the latest version for security or features. Rather, it is very specific to the components and ECU version in the heater itself.
If your heater is otherwise working correctly, there is typically no need to update the firmware. All heaters are tested at the factory with the firmware they are shipped with as working.
There are also different firmwares for diesel vs. gasoline heaters.
Below we will cover the different ECU versions we have out there and the corresponding firmware versions for each ECU version.
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How to find ECU Firmware Versions: The source of truth for current firmware version is on the thermostat controller SET SYSTEM TIME page. It also listed on the Firmware Update page in the phone app.
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4.0 ECU Boards (Purple)
These boards run firmware in the 4.x versions.
Latest 4.0 Versions: 4.01 (for gasoline), 4.02 (for diesel)
If using 4.0 ECU on unit made prior to 05/2025 then 4.5 gas or diesel is the latest.
All available 3.5 versions:
(do not change to these unless already on it or advised by Velit support to use):
4.00, 4.70, 4.71, 4.90, 4.5
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3.5 ECU Boards (Blue with special marking)
These boards run firmware versions 3.50 - 3.80 but keep in mind the latest version number may not be the correct version for your heater running a 3.5 board. For example, 3.80 is a specialty firmware as 3.62 is the current latest version.
Be very careful to distinguish 3.0 board from 3.5 boards with the special marking!
Latest 3.5 Version: 3.62 (for gasoline or diesel)
All available 3.5 versions:
(do not change to these unless already on it or advised by Velit support to use):
3.50, 3.51, 3.53, 3.57, 3.59. 3.54, 3.80
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3.0 ECU Boards (Blue without special marking)
These 3.0 boards run firmware versions 3.08 - 3.69, but do not include versions for the 3.5 boards listed above. There is complexity because of version number overlap, but it's important to know that 3.5 ECUboard firmware CANNOT be used on 3.0 ECU boards and visa-versa.
Latest 3.0 Versions:
Depends on Fan Motor Manufacture Date.
Pre-05/2025 is 3.26 Gas or Diesel.
After-05/2025 3.13 Gas or Diesel.
Always check with Velit support if unsure as wrong firmware can degrade performance.
All available 3.0 versions:
(do not change to these unless already on it or advised by Velit support to use):
Pre-05/2025: 3.02, 3.05, 3.07, 3.17, 3.18, 3.2.0, 3.21, 3.22, 3.23, 3.24, 3.25
After-05/2025: 3.08, 3.09, 3.10(7.69), 3.11, 3.12, 3.14, 3.15, 3.16, 3.61, 3.40, 3.41, 3.63, 3.64, 3.65, 3.66, 3.68, 3.69, 3.70,
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1.0/2.0 ECU Boards (Green)
These slightly older 1.0 / 2.0 boards are typically used on heaters made prior to 2025. These boards are not compatible with newer bluetooth style thermostat controllers. These boards are also not OTA update compatible and require manual firmware flashing if needed. Typically there is no need to update firmware on these boards. If you are having issues it's more likely fuel delivery/fuel line related.