Cusser

Maybe the poster's issue is that it would be more expensive to run a 230 VAC circuit to the indoor tub than a dedicated 110 VAC line.

I've had nice success on my '88 CalSpa with liquid leak sealer. I'm also unable to pinpoint the leak, and one side is 100% inaccessible.

I was also thinking pressure switch-related issue as stated above. Sorry, could not make the video NOT show.

Post the price for a brand new 14x7 maxx spa. I figure like buying a pre-owned vehicle: I buy vehicles like 6 years old for 40% of the original price. Obviously, pay much lower if that used spa is not 100% operational before you purchase it. And be sure to get quotes in advance for moving it to your location, new electrical hook-up, etc. In Arizona, seems like every week someone is trying to give a spa away on Craigslist.

I have a couple of cracks on my 1988 CalSpa, smaller than what you show in your photo. I tried epoxy a decade ago, didn't hold up over time due to 100% soaking in water, so I have purchased some "marine epoxy" to try next time I have it drained and dry. I do have a small leak "somewhere" (not in the equipment side), but have been unable to pinpoint where, and one side is 8" from my home block. So I use leak seal liquid like once or twice a year, and the stuff DOES work !!!

What's the tub voltage? Do you have a cover? Is this tub new or new to you, and did it ever heat up OK and something just went wrong?

I've used a floater and 1" bromine tablets in my spa since 1988. When your spa reaches that age, drop me a note.

Had my spa installed on my patio back in 1988. So one side sits about 10" from the block wall. Yes, not accessible, but the other non-equipment sides are not designed to be opened up either. And with sprayed-in foam insulation, good luck pinpointing any internal leak anyway if not in the equipment area.

I should add that my 1988 CalSpa required and uses a 40-amp 240 VAC circuit, for a 7-foot, approximately 350 gallon unit. I believe that many newer spas use 50-amp or 60-amp circuits for similar sizes/water volumes. To me, that somewhat indicates that newer spas might require more heat to reach and maintain 104F temperatures, maybe in the past 3 decades there's been less insulation added as cost-savings, out of sight strategy.... A good quality cover will also retain more heat.

Yes, amount and type of insulation is very important. When Mrs. Cusser and I had a bathtub installed into our home, we asked for additional insulation to be added around it before the "pony" walls were built, and it does help keep the heat in. Because we have the exact same bathtub in our place up north (was installed before we bought the place).

Might be easier and cheaper to drain and refill the spa.

I'm in Arizona, and at this time of year our high temperatures are 65-70F, and gets down to 40F at night. I have a 1988 CalSpa, set to operate only when water temperature drops, and needs to pump/heat to get back to 104F. My spa actually runs less than 1/2 hour per day for that, so my costs are low, figure under $15 a month for electricity and chemicals.

What about fiber washers, unless you spa temperature sender needs stainless steel washers to make a grounding connection??? On my 1988 CalSpa, I don't have such issue, as my heat control is simply a rotating dial, no readout of degrees either, I use a floating thermometer. On mine, the heat sensor slips into a stainless steel tube, and I image that moving that farther away from the heater housing would make it "think"that the temperature is low and would signal to heat.

The test strips will work. The readings will be a little different though. I can't remember the conversion, some here will know, or see Google.