Beware of high temperatures and Nepture's FMM

[GePerezReef]

Hello folks:

TL; DR:

A critical component within Neptune's FMM is rated for an operating temperature of 0 to 70 degrees. Given the high temperatures we are experiencing this summer, beware this might cause your FMM to fail.

Details:

Today I had my Apex trigger the Alert "A module is missing"; referring to my FMM module being off (the alarm is a symptom of this; it is due to the flow monitor for the return pump attached to the FMM not reporting any value).

After following all FMM and Apex troubleshooting guidelines I could get my hands on (e.g. disconnect all cables, reconnect one by one) and experimenting with different Power outlets and power adapters) I came across the fascinating YouTube channel "FixReef" and the video "Apex FMM shuts Off Head unit" which explains in detail why this can happen.



In a nutshell, the FMM uses a chip that is not cable of handling loads beyond a very limited capacity but also, whose operating temperature is rated for no more than 70 degrees:

Chip M34063A:

I hope this helps someone else solve the puzzle of "why is my FMM suddenly not powering on".
If you found this helpful, please give the creator of the video a thumbs up and a subscribe to keep encouraging this level of dedication to knowledge sharing.

Cheers!
--
Jerry

 

[JeffB418]

That’s 70C not 70F. 70C is 158F…

 

[GePerezReef]

Thank you JeffB418 that's a good call out that I should have made more evident on my post (I am originally from Mexico so it did not occur to me to convert this to Fahrenheit on the post. 70 Celsius for a chip inside a non-ventilated unit is alarming to me.)

I suspect temperature was the issue in my case because the unit is on an outlet behind several layers of protection.