I am rejuvenating a hot tub that has been sitting drained for over a year. I got everything set-up and running, but the water was heating very slowly. The hot tub is running on a 220V wiring, and the temp went from 45 to 80 degrees in 24 hours. I then drained the tub, swapped out the heating element (I had an extra one that I knew was good) and restarted it again. It appears the slow heating is happening again.
A few things about the tub, I pulled off all of the siding to fix a few leaks so right now, it is sitting out there with the sides exposed (The cover is on). The temps have been in the 30 and 40's when I've been trying to heat it up. I know this could lend itself to slow heating, but things still seem slow even when I factor that in. What else could be the problem if the heating element isn't the cuplrit? The heater seems to be staying on the entire time so I don't think it's a trip switch either.