Pentair Mastertemp 400 Heater - The Mouse Edition

Jun 19, 2017
2
chester, NY
Good afternoon, all.

I've been a long time member, but first time poster. I've learned a lot and solved many problems from this forum, so thank you for that. Now that pool season is behind me, I'm posting this in preparation for Spring 2025...

This weekend I was winter prepping various items around my house and came to find a critter beat me to the pool heater. You'll find in the photo below that something found it's way into the control area. Besides the mess and lightly chewed wires (far left red and nearby black), everything else seems to check out. However, when I took it apart to clean properly, I noticed a piece on the circuit board has come off (L10 - photo attached). It doesn't look like it was caused by an animal and I have no clue when it could have happened. I closed the pool mid September and everything ran fine at that time.

My questions... I tried turning the heater on to see if it was still getting power, but nothing came on the display screen. This is the only time I've ever tried to do so without water flow (pool closed), so not sure if anything would show on the display or it remains completely off for safety.

Also, does anyone know what the L10 on the circuit board is? Does it do anything? Is it repairable? Do I need a new board? Etc.

Any information/advice is appreciated. Again, this is for Spring knowledge as we're in winter mode (New York) over here. Thanks in advance.


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Welcome to TFP.

You need to rat proof your heater...


What is the white lettering on the top side of the component?

@ogdento any idea what L10 could be?

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Ugh, I thought I was on top of my rat proofing, but these little buggers proved me wrong. Since my second season, I put metal mesh around most outside openings (they stay year round), then plug up the larger holes in the winter with brillo and other products. This guy had a month to build (mid-September to now) and he took advantage of his time.

The heater is a Pentair Mastertemp 400, if that's your question in regards to the white lettering...
 
L10 is an inductor (a coil) that's part of the power supply... which is likely the reason the board won't power up, but I'll have to verify where it is in the circuit. I have some scrap mastertemp boards kicking around somewhere so I'll see if I can verify what I just said ;)
 
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