Heater Kicking off breaker

the two biggest amp drawing parts are the pump and the heater which can cause your problem first test and check that pump is turning and not frozen or jammed --then test the heater which usually short out

Check the Thermal Reg in the header and also make sure you have adequate water flow thru the heater, make sure your filters are clean and there are no external by-pass valves open.
If you remove the Thermal Reg in the header and the heaters seems to run fine the replace with a new one.

that is usually an indicator of water flow not the air flow.
What does the hot tub do when you turn the breaker from off to on?
does it run through the purge cycle?
is it kicking out the GFCI?
if it is not tripping the GFCI then you most likely have either too little water flow for the heater to kick in or not enough water flow to activate the heater.
Try taking out your filter and see if that solves the issue.
you may also have a bad temp sensor if the tub just runs and runs but never heats up.


Rod
US Parts Center
888-521-6183

Breaker trips when heat on wire exceeds amp rating, or when breaker is bad.
Most breaker are slow acting, and do not trip immediately.
Shorted elect could cause problem.
http://waterheatertimer.org/Water-heater-is-tripping-breaker.html

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

Additional information would be helpful!
Are you receiving any error codes, flashing on the screen or anything when you reset the breaker to the heating unit?
Start by turning the breaker off, then on for the heater. Turn the unit on see if it runs through its start-up sequence, or if you get any type of reading on the display.
It is possible that you have a bad circuit board on the heater.

If the smoke got out of it it's bad. ;-)
Most transformers are 110v and 220v be sure how you are wiring it. I this is a Hayward heater you can find a book for it at
http://www.haywardnet.com/inground/products/manuals.cfm
Their are a couple of different heaters but they should all take the same transformer. I would go ahead and find the correct heater and print the book so you have it.
Once your sure of the wiring make sure you have the proper power going to the unit. To say if it is kicking the breaker you may just be getting half the power to come back on. Then unhook the transformer from the heater and see how much power you have. If your not getting a full 24v you may have burnt half the transformer. This means a new transformer. If it is still kicking the fuse you need to check all the wiring to the box and make sure that your problem is not there. If it's not kicking the fuse and you have good power, It will be in your heater and you will have to go through that to check for shorts. Your book will have a trouble shooting flow chart to help with this. Good luck.

When you drain and refill most spas you will get an air lock in the plumbing. You will need to find the drain valve and open it to flood the pipes. It's possible you may have burnt the element and may have to replace it. Hopefully the breaker kicking spared you this expense. Myself I burnt two of them before I learned. Good luck.

This usually indicates an ignition lockout...The heater tried to fire but either didn't fire or a flame was not detected. Check and ,ake sure ignition is good, gas valve is opening and make sure all grounding is intact..