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Thread: Spa heater needs replacement. What caused the failure?

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    bbrock's Avatar
    Join Date
    Apr 2014
    Livermore, CA

    Spa heater needs replacement. What caused the failure?

    Our home is still under home warranty. The spa is included in that. I had someone come by through the warranty company to inspect the spa as to why it continues to shut off/trip breaker. What led up to this is that the spot intermittently works. Of course when I use it or want to, the breaker will trip. I had originally diagnosed it as a pump versus heater, but low and behold today when we accessed the control panel I noticed that the heater terminals had corrosion. This was not evident about a month and a half ago when I disconnected the heater terminals and then the pump to determine if the heater was causing the short. Anyhow, please take a look at the pictures:

    The heater is a Balboa 4 kilowatt 15 inch 2x2. Spa guy then said that what causes heaters to fail is water chemistry, more so having my pH out of whack. After meeting with him today, I YouTubed some info about heaters, and in one video, it stated that the most common cause of failures is water seepage getting onto the terminals and oxidizing them. I generally have been keeping my pH from 7.2 to 7.6 in the spa. Some more questions:

    Can a low pH because this corrosion on the heater terminals?
    Or, is the Spa guy just misinformed, like so many people I have come across in the Pool/Spa industry (not saying that I know everything at all)?

    I take what this guy says with caution because he also said I shouldn't be using chlorine and bromine together because they could cause a rash.

    Is the process of replacing the heater as simple as just disconnecting it, removing the heater and put a new one back in? Or, do I need to seal all the joints with silicone and do other stuff when I put it in?
    19k gal IG plaster, built '70s, probably resurfaced in '80s-'90s; Blue Haven Hayward filter C4520BHMB (Filbur FC-1275 cartridges); Hayward MaxFlo sp2302 VSP 1.5hp; 6 solar panels 288. sq. ft. total (142"x47.5" ea.) on 1 story hm; Pentair Compool LX220 Solar Controller; FlowVis flow meter; Maytronics Dolphin S200; AG 300 gal AquaTerra spa; TF-100 & Speedstir; gone: Pentair Challenger 3/4 HP 1 speed; Polaris 280

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    Mod Squad JVTrain's Avatar
    Join Date
    Feb 2014
    Central Minnesota

    Re: Spa heater needs replacement. What caused the failure?

    It's not necessarily low pH causing the corrosion. From the looks of it, it appears to be galvanic corrosion. In the presence of an electrolyte (pool/spa water is definitely and electrolyte), there is accelerated corrosion where 2 dissimilar metals join. The best preventative to help this from happening quickly again is to obviously try to keep the area around the heater dry. Not so easy though in the hot tub area. I would recommend coating the new terminals with a dielectric grease. This should help keep corrosion at bay. DO THIS WITH BREAKER OFF FOR SAFETY. When you replace the cell, I'd want to rip into the inside of the old one and see if corrosion was throughout the heater or started and spread from the terminal area.

    Usually it is fairly straight forward replacing a heater but YMMV. Just take pictures before so you know how things were connected. A new heater should come with instructions. If not, scour the internet for help on your particular model.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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