First, let me thank everyone answering posts with troubleshooting tips. You all got me this far. Now I hope someone can see me to the finish line " title="Wink" /> It's a Jacuzzi Echo Z120, with a Balboa controller box & heating unit (see attachments). What I've come up with so far is: 1. the heater relay does not click closed when ramping the thermostat 2. I have 11 ohms across the heater terminals 3. Voltage across the heater terminals is in millivolts 4. Bypassing or shorting the pressure switch makes no difference 5. All fuses are good 6. I can find no reset switch of any kind 7. aside from the heat, everything else works as expected Hope someone can suggest something I haven't tried. Thanks, - Doug

Few more tips you may have already tried....

You must keep the press switch shorted for at least 10 seconds bofore the heater relay will close. Additionally, the spa will only heat on "low" speed. The spa will not heat while the pump is on "high" speed.

SOunds like the heater is likely ok (11 ohms is fine), and the temp sensors are fine as well.

I'd be curous if you ohm'ed out the press/switch, both on the terminals of the press/sw, and at the end of the harness where it plugs into the circuit board (PCB)

It likely the P/S harness or P/S may be bad, or there might be a little corrsion that needs to be scraped from the male posts on the PCB(where the harness plugs into the PCB). Try taking a small screwdriver and holding it inbetween the posts (thereby shorting them) where the press/sw plugs in. Be carefull not to let the screwdriver tough anything else on the PCB while doing this. Although there is very little current used through the press/sw, there's plenty of voltage in other places inside that control box! Hold the screwdriver against the two posts while the tub is running on low speed for at least 30 seconds. If the heater relay doesn't energize, you're looking at a new PCB....If it does energize, either a new P/S, or new P/S harness...
Good luck

Thank you Swine! Even the most benign tip can be huge... this spa came with the house but no manual, and it's my first self-contained spa. I never knew it had to be on low to heat, and had never tried it. I thought low was just a setting to keep it from freezing.

The good news it that the heater relay now clicks and the the temperature LED lights when set higher than the current temp. The bad news is there's still no heat, but I must be getting closer to the truth.

Any other tips, ideas?

Thanks,

- Doug

It heats s l o w l y. And only with a cover. 2 degrees/hr WITH a spa cover... just give it time... plenty of time. You're probably ok " title="Very Happy" />

Holy smokes, really? So much for spontaneity. My tub at my last house had a 200k BTU gas heater attached to it... went from ambient to 105 in 10 minutes or less. I thought that was typical. I'm going to go fire it up now, and wait & see. It may be working just fine. Thanks again - Doug

I just inherited the SAME EXACT model jacuzzi. It aslo has a heat issue exactly like this one. I'm curios as to how this was resolved or if anyone else has ideas on how to get it going???

Thank you,

Dar...

Yup, that spa is wired for 120V, will be a sloooow heater!

Great news for me too! I got a used tub from some "lieing no good skumbag" who told me everything worked great! Well the high speed pump and the heat didn't work when I finally got it all hooked up, and ready to go.

I replaced the high speed pump, great, works fine.

I still had no heat. If I triggered the relay to the heater, and let it sit for 6 hours, I got heat. So the heater was working, but not automatically.

My problem was I did not wait 10 seconds while manually triggering the pressure sensor. After I tripped it for 10 seconds, BAM the relay turns on!

So, why isn't the pressure sensor working? Because the KNOB was messing with it. I adjusted it so that it trips on low pressure. Everything works great now!!

One question though, is it supposed to do something different on high pressure (When the high speed pump is on?) It should heat then too, correct?

...Tim

MOST spas won't heat on high speed due to the huge amperage draw of the motor and heater. Low speed uses just a fraction of the power high does.