Weird Heating Issue

[Bobman58]

So when I manually turn the tub on it heats up and circulates the way you would expect. The issue is when the pump shuts off the heating element comes on and boils the water in the pipe( I can hear it and feel it seeping out of the jets even though the pump is not on) until it goes into overheat and shuts the heater down. Mine is not digital so it has no trouble codes but it does go into a stand-by mode and won't reset by itself. I've already replaced the pressure switch. Not it. Same as it was.
Anybody? Ideas?

Robert

[Dr. Spa™ Ret.]

Brand, model and year?

[Bobman58]

It's a Jacuzzi. Small, like a 4 seater. Pretty old, maybe 15 years. Bought from Costco. I can go out and get the model number if it's important.

[Tman122]

Flow sensor.

[Bobman58]

That's normally where I go first too. Replaced it. No difference. Today I circulated till it was up to temp and the pump shut off, there's a few seconds and then I hear the heating element boiling the water in the pipe till it kicks out the overheat switch. I waited a few minutes and pushed the "on" button again. The stand-by blinking light went off and it didn't circulate because it was already up to temp but I heard the water in the pipe start to boil again so I unplugged the flow sensor wires and it continued to boil till it kick out again. The flow switch has no effect on the over heat

Robertissue.

[Tman122]

That's normally where I go first too. Replaced it. No difference. Today I circulated till it was up to temp and the pump shut off, there's a few seconds and then I hear the heating element boiling the water in the pipe till it kicks out the overheat switch. I waited a few minutes and pushed the "on" button again. The stand-by blinking light went off and it didn't circulate because it was already up to temp but I heard the water in the pipe start to boil again so I unplugged the flow sensor wires and it continued to boil till it kick out again. The flow switch has no effect on the over heat

Robertissue.

Rather than unplug it you would have to jump it. The contact is what controls it. The flow creates the contact.

[Hottubprosne]

Stuck contactor. If you turn down the temp and the thermostat quits sending voltage its a stuck contactor.

[Bobman58]

Where would I find the contactor? Is it something that can be tested and or replaced?

[AngelaOlmstead]

One can search online for contractor.

[Dr. Spa™ Ret.]

I don't think you need a contRactor to replace a contactor.

[Bobman58]

They say contactors are noisy but mine makes no noise. Not sure mine even has one. It does have some sort of transformer in the corner of the box.
The real issue seems to be that the heating element is still powered up after the pump shuts down. Then the water boils in he pipe and the overheat sensor shuts very thing down.

[Dr. Spa™ Ret.]

Yours has one...probably more than just one. But the one that controls power to the heater,  there's a GOOD possibility it's stuck closed.

[Bobman58]

You guys are freakishly smart! I did find the heater contact that was stuck closed. Popped it open and no more overheat BUT...now I have a different problem. The tub won't stop circulating( meaning the pump won't shut off) unless I turn off the power or unplug the thermo control knob. It seems to be holding the temp( although I haven't watched it long enough to make sure the heat indicator goes off) but it's only supposed to run for a certain time period after its up to temp and then the heater kicks off and shortly after the pump shuts down. Now I did find the solenoid that operates the pump and opened it manually and the pump shut off but when I release it it closes again and turns back on.
Ideas?

[Bobman58]

Ok so it doesn't seem like it's heating up to operating temp like it should. I suspect this is why it won't shut off. The heat indicator light is lit but it doesn't seem to be getting any warmer. My volt meter says 18.90 volts on each leg going to the heater.

[Bobman58]

Just checked with a different multimeter and I am getting 121 volts on both poles of the heating element but it doesn't seem to be warming the water. Seems weird but I think maybe the element has gone bad.
How would one test the element?