Jaccuzi hot tub will not heat?

make sure the heating element isnt touching the casing inside the heating tube. if its an indoor tub, make sure the filtration cycles are not set to constant. constant filter cycles on an indoor tub will generate residual heat from the circ pump running 24/7, causing tub to heat past 104 degrees

Sounds like the heating element has gone out again. Once you reset the circuit breaker and the tub turns on it will start to circulate the water. This usually runs like this for about 2 mins and then the tub will recognize it is cold and send power to the heater. If the element is back at that point it will blow the circuit breaker.
If this circuit breaker pops as soon as you turn it on then you most likely have a bad circuit board.

Rod
www.uspartscenter.com

1) Safety question first
Why hasn't the GFCI tripped.
If your spa is not protected by ground fault., then you are at serious personal risk.
http://waterheatertimer.org/How-to-wire-GFCI.html#arc-fault

2) Replace the element.
http://waterheatertimer.org/How-to-test-water-heater-element.html

3) If element is cracked, it can continue heating to ground wire, causing runaway heating.
This applies to spas, and water heaters of all type.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

hi,

ok so when the pump is on high and the heater is running it doesent trip? you didnt say if it did. undo the heater leads so the pump is isolated completely. run the pump on the control centers gfci and see if it trips. if it does then try wiring directly - with an extension cord to a plug with a gfci in your house and see if it trips the gfci in your bathroom. if no trip inside house then bypass tubs gfci and run it with heater and pump through your bathroom gfci. if no trip then try and replace the tubs gfci, it gets pretty humid in the control center and gfci's have a semiconductor which which do fail after years of rough duty like that. if it trips the gfci in your house with the heater again it has a cracked heater element. craigslist always has old hot tubs and parts. you might have to buy a whole used old hot tub but that may be cheaper than a new heater box.

later

jm

The bath heater you have is not designed to HEAT water - they only Maintain what you start with.
You need to start the bathtub with the hot water you want. It will only heat about 1-2 degrees an hour.

Is the equipment to heat and filter the hot tub separate from the pool equipment or do both bodies of water share a common heater and filter pump? In most cases they share a pump and heater with valves that direct the flow of water depending on how the pool owner wants to use the pools.

The first thing you need to determine then is if the equipment is working properly. Is there flow of water to and from the spa? If so, is the heater burner kicking on? If it is running, is it running properly with sufficient gas pressure, 3-4" tall bright blue flames and stays on continuously during the heating cycle for the spa?

What is 'very quickly' for the time to heat the water? In other words, if everything appears to be operating normally but the water is not warming fast enough or at all how much time is elapsing before deciding the heater is not working?

How old is this equipment and how much experience do you have with this pool tech or the company they are from?

Is it greasy, oily spider web type junk? Coming through the pipes, new construction or new tub? Could be from the pump, not that it is leaking oil but it has oil in it from the manufacture of it. I would call the jacuzzi people and tell them what you have and that your kids play in the tub and drink the stuff, ought to get them to move on that one. Ask them if they know what it is and what to do about it? Hope this helps.

the last time I looked at heaters for jacuzzi tubs they are designed to keep the water at the temperature you filled the tub and not heat up the water from cold to hot.

It sounds like your inline heater has stopped working. The only way to test it is to drain the water back out, remove the inline heater, and hook power to it to see if it heats up.

If it doesn't you can get one at a discount supply house (like Home Depot or Lowes) for less than $150.

Depending on how you heat the hot water, whether gas or electric, is a missing detail in your problem, but if it is electric then your problem is the size, being only 40 gal, and needing probably about that to fill the tub, will always lead to your current position.
If the hot water heater is gas, the chances of it keeping up are slightly better, but again things like the temperature of the water leaving the tank, any mixing valves, etc. will effect the water temp at your tub.  Before raising any temps, make sure you follow local code, as not to scald yourself or others.