We got our first hot tub at a garage sale for $50. We took it home and filled it up and found that the temperature controller no longer worked. The filter housing and skimmer also leaked because the plastic was cracked and the entire assembly had to be replaced. I found a bait bucket at Kmart that was about the right size, and I built an operational amplifier circuit to replace the temperature controller. Both fixes worked well and we enjoyed that hot tub for many years. I would guess that I spent about 50 bucks beyond the purchase price and about 20 hours of time on our first hot tub.
Recently (two years ago) I saw an advertisement on Craigslist for a larger hot tub with many more features so I gave the guy a call. The hot tub had been drained for the winter, however a small amount of water had been left in the bottom and it had apparently frozen, causing a leak. Everything else about the hot tub worked, and I figured this leak would be easy to locate and repair. I could not have been more wrong!
Unlike our first tub, this much more modern unit had a thin acrylic shell that was completely filled with urethane foam to give it structural strength. All of the plumbing fittings, hoses, and pipes were completely encased in foam.
I felt that the leak was probably in one of the jets, so I began attempting to remove the foam from the lowest ones, the jets that would’ve been most likely to have frozen. The first method I tried was my angle grinder with a wire brush. It did a good job but took a long time and made a hellacious amount of dust. The next method I tried worked far better. I put the 0° nozzle on my pressure washer and used it like a waterjet cutter. It did a great job of slicing the foam away.
After clearing the foam away I could see what I thought was a thin crack in the body of one of the jets. This is exactly what I had expected. The jet however was very difficult to remove from the body of the tub.
The nut that secured the front of the jet had been glued to the jet with silicone seal so I had to make a tool to remove it.
I drew a quick design for the tool in CamBam and then milled it out of a 3 inch diameter steel round.
I cut the round off with an abrasive cutting wheel, then heated it to red heat and quenched it in oil to harden it.
The tool worked perfectly and allowed me to remove the jet.
Unfortunately once I got the jet out I determined that what I saw was merely a scratch and not a crack at all.
So I reassembled the jet and put the tub on five cinderblocks. I filled it up with water and began cutting away the foam looking for leaks. I found a lot of leaks.
In fact, it seemed that every piece of flexible PVC hose had multiple splits.
I found a source online for flexible PVC hose, and I went to Lowe’s and bought a bunch of PVC connectors and elbows. The hose had been pushed on barbed connectors, glued, and secured with a hose clamp. The clamp came off easily enough but the hose was securely glued in place. In order to replace it I needed to come up with a different way of attaching the new material.
What I ended up doing was cutting off the hose at the end of the barbed connector with the Sawz-All.
Then I roughened the old hose with sandpaper and primed it with PVC pipe primer. This got all of the urethane foam off and prepared the hose to accept PVC cement.
I applied the cement and then pressed on a PVC union.
This process worked quite well and left a clean new connection for the new PVC hose. Almost none of the original hose was exposed after the union was glued on.
It took most of the weekend to replace all of the original PVC hose with new hose.
Once all the hose was replaced I rebuilt the frame of the hot tub with pressure-treated lumber and set it down on a couple of sheets of 2 inch thick foil faced insulating foam. Then I filled it with water and gave it a test, not a single leak!
I used Great Stuff urethane foam around all of the jets and underneath the very bottom of the tub to support it and then I filled in all the other openings with 1 inch and 2 inch polyisocyanurate foam left over from building my hexayurt. As you can see by the snow on the ground it has taken some time to get this project nearly finished. All told I’ve spent several hundred dollars on materials and probably well over 100 hours in labor over the course of two years. Like I said, there is no such thing as a free hot tub.