Sta Rite 400HD has corrosion after 3 months!?

[Kmetz]

Installed a new Sta Rite 400HD towards the end of January. Followed installation instructions exactly, and it has been working wonderfully till 2 weeks ago. The control membrane was freezing up and the heater was turning on all by itself, so I decided to have a pro come out and diagnose it for me. He quickly discovered corrosion on the backside of the control board that is mounted inside the heater housing. I asked if it was an issue with installation, he said the installation was fine and that he has seen this issue with this heater numerous times. Since I installed the heater myself, Pentair will not honor any form of warranty, so I ordered a replacement control board and keypad membrane to repair myself.

I would love to hear some info from anyone who's dealt with this already. My biggest concern is that it is only a matter of time before the next board develops corrosion and shorts. I am attaching some pics below of the back of the board and the corrosion is pretty easy to see. Does anyone know of some sort of electronic water proofing spray that I could coat the board with in order to avoid future corrosion issues? Or is that a terrible idea?

Again, any information would be more than welcome, and thanks in advance!

Kevin

 

[Patrick_B]

Welcome to TFP!

I don't know if there is a way to spray and waterproof a board like that.

 

[JohnT]

Look for "conformal coating". There are several products made to protect circuit boards from environmental damage. Apply it everywhere but connectors. Many of them glow in UV light to let you check how well you did coating the board.

Your board looks like it has had some kind of contamination where the label "AGS" is. Resembles the residue where some kind of liquid dried.

 

[Pool Clown]

You can see that something got on the board. What ever it was, it compromised the coating. My guess (from experience) would be water. I'm not saying that the OP let this happen, or even that it happened after the heater was installed. It is just what it looks like from the pictures. I have seen this before, but have not seen it on a brand new unit.

I'm guessing that this heater was all boxed up and never opened before you took delivery? Maybe it was in a where-house (distribution) for a while and was perhaps subject to high humidity? Very hard to speculate on this. Inspect your new board and make sure that the conformal coating is uniform throughout the board, and that it has no deficits or dull "shine-less" areas, like your board has now.

The plug at the bottom of this picture is pretty much a dead giveaway of water damage. There are more areas that i didn't circle. These are the ones that really stuck out to me.

 

[Kmetz]

Thanks for all the feedback. Yes, this was technically a "new in box" heater that I ordered from Pool Supplies, Spa Supplies and Parts. The box was fairly beat up, but we inspected the heater thoroughly for damage and found none. As you can assume at this point, no, I did not inspect the board itself. I did some digging last night and found the "Conformal Coating" that is mentioned above, so in addition to giving the new board a thorough inspection when it arrives tomorrow, I think I will be giving it an additional coating before I install it.

I am actually surprised at the lack of an enclosed housing for this control board. It is mounted on the underside of the lid of the heater, which is open on the sides, completely exposed to whatever makes its way into that heater housing. Living in Houston, bouts of VERY HEAVY rain are not that uncommon. Does anyone else with this heater have any tricks for making sure it stays nice and dry in there?

 

[ps0303]

When I see this the heater is located in an area where there is moisture more than normal. I see this on heaters that are located close to the bay. This can also happen if for some reason the system is putting off steam. The unit will trap the moisture and cause this to happen. Is it a design issue with the units? Not that I would say. Be careful spraying anything extra on the board especially if it is under warranty. With all the units I repair on a daily basis, I for one have never needed to put anything extra on the board to protect it. But this is just me. BTW< your outside AC unit has just as much access to boards inside as these heaters. I had a snake fry my defrost board some years back so it happens.

Sorry you couldn't get this covered under warranty and hopefully you won't experience this again or some other failure.

 

[JoyfulNoise]

This could also very well be a manufacturing defect that only occurred once the unit was hot and running. I worked with folks that designed and manufactured custom PCBs (it was a in-house fabrication group) and this is quite common IF the board is not properly rinsed after the metal traces are fabricated. Sometimes you can see this after the board comes out of the pick & place tool (where the passive components get laid down) and then after the reflow furnace (nitrogen/hydrogen furnace to flow the solder joints). However, it can happen in latter stages of a boards life especially when conformal anti-environment coatings are applied. This is because the trapped fluids have no where to go and so they will corrode everything they come in contact with.

I'm surprised you could not get this replaced under warranty as it is a pretty common problem with PCB quality control (a few bad apples always sneak through) but I guess they're playing their "professional installation" card on you....hopefully the new part didn't cost too much...