Ask 'Dr. Spa' Q & A Message Board

: I've probably replaced more of these heaters over the years than any
: other tech in New England. They are very laborious and difficult. The
: secret to removal and replacement is to make it a two man job, one
: above and one below. I remove the four conductors, ground and bonding
: wire first. You need a good light and a mirror for that. No need to
: pull the brown control box. Once the wiring is out, remove the screws
: holding the enclosure box to the base of the heater. Take that box
: out of there. Spray penetrating rust buster on the lock nut where it
: threads to the heater body and let stand for a short time. Take a
: long screwdriver or chisel, place it on the top of the lock nut and
: give it a couple of good whacks with a hammer. Do not hit it too hard
: and do not slip and whack the fiberglass body. You just want to give
: the rust buster a chance to somewhat dissolve the corrosion between
: the nut and heater.

: Now for the big secret. Let the guy underneath do the turning with a BIG
: wrench from the left. He may have to remove the shroud over the motor
: or even remove the entire pump/motor on that side. The guy at the top
: uses the largest pair of channel locks that he can fit onto the lock
: nut, but simply HOLDS the nut. It is nearly impossible to turn the
: nut from the top given the physical constraints. Because I only hold
: the nut, I can get my 16 inch channel locks in there.

: When you go back in with the new heater, put silicone sealant on the
: flange of the heater, run the heater up through the hole, have the
: bottom guy hold the heater in its final position with the conduit
: facing the direction you want and put the lock nut on from the top.
: You will be able to hand tighten the nut easily from the top because
: it is new and clean. Get it as tight as possible by hand, then a
: slight additional turn with the wrench while the bottom guy keeps the
: heater from twisting. The nut does not have to be killer tight,
: simply snug. The silicone sealant will make the water seal. Let that
: dry for 24 hours before filling and leak testing. I wire up the
: heater last using lights and mirrors. BE CAREFUL YOU DO NOT BREAK OR
: DAMAGE THE HEATER COLD PINS.

: You are way off base as to the nature of the failure. All heaters fail
: over time. I got 16 years out of my original Jacuzzi heater and I
: thought that was remarkable. Your joints between the heater elements
: and the heater body flange are most in danger of galvanic corrosion
: over time. A functioning GFCI, had you installed one as recommended,
: would have caught this long ago by tripping out long before you had
: this near catastrophe. The heating that occurred with the motor off
: and the thermostats NOT calling for heat was simply one side of the
: 240 volts (120 volts in this case) travelling through the element and
: passing to ground. Essentially, the heater element "saw"
: 120 volts due to the fault to ground from corrosion. The simple
: application of ohms law indicates that a halving of voltage to the
: heater results in getting 1/4 of the normal output of the heater.
: Assuming both elements were faulted without a functioning GFCI to
: prevent problems, your 12 kW heater was probably putting out 3 kW
: when the other hot leg was shut down.

: John

Hi John,

Thank you so much for your tips on getting the old heating element out, I appreciate the time you took to explain the procedure. It's definitely good to know it can be done without removing the entire control box.. that looked like it could be a ton of extra work. Also thanks for the thoughts on how it shorted.. I sortof had that theory of it being 120v shorting if it was both hots were coming over to the hot tub to make the 240v circuit, but wasn't exactly sure how the 240v was coming over. My father is the household electrical wiring expert and he mentioned 240v being made of two 120v hot wires but I didn't know if that was done at the main panel and the 240v carried over with hot/neutral or if it was actually two hots at the hot tub panel. I now see that it's two 120v hot wires that are 180 degrees out of phase with eachother and together create a circuit for the 240v. Anyway between he and I we shouldn't have any issues aside from the tight working space under the tub =)

I'm into electronics repair so mostly have experience with lower voltage stuff running off of 120v sources. I got a huge crash course over the last few years repairing 30+ pinball machines, skee-ball machines, etc -- it's fun taking something dead and getting it working again! I'm pretty good at reading schematics nowadays and troubleshooting the problems on the older technology.. harder with the newer electronics since they're pretty much built to not be repaired with SMT, etc. Anyway, it's without a doubt helped me to repair things outside the arcade/pinball realm since a lot of the knowledge is transferable to other fields. Relays, bridge rectifiers, microswitches, etc all used on the arcade games.. just lower voltage/amp ratings. I'm a younger guy but I like learning the old technology to understand where the new technology came from.. and it helps to know the older technology too since there's still a lot of equipment out there that's older.

Back to the tub -- I plan to replace all the 240v relays in the control panel, 3 or 4 of those have switch contacts that look like they've seen better days. Would you recommend replacing the thermostats and high temp limit safety switch? The thermostats seemed to be working fine...and from what I can tell those parts may be hard (if not impossible) to find exact replacements for, but just wondering if it's something to be concerned about at this point. I also plan to get new pump housing for the filter pump and get that leak solved once and for all.

Thanks again for all your help and friendly advice!