Jacuzzi J-235 Overheating - need help

[Sonnyw72]

Hi everyone,

New here, but troubleshooting a problem that's been going on a few months.  Never had a single issue with my (2017 model year) Jacuzzi J-235 until this year when the main pump started to squeal, then eventually seized up and died.  The GFCI would trip within 1 second of the pump sequence starting after resetting the breaker.  

So, I replaced the #1 pump.

It seemed to work well for about 2 weeks then the heater went out.  Within a second of the heat cycle turning on (red light indicator for "heat" on panel) the breaker would trip.

So, I replaced the heater.

Ever since then...about 3 months ago, it's been an unusually hot summer here so I wasn't sure if that was part of the problem, but the water temps would be anywhere from 105 to 108 and I kept it on the Economy Cycle with temp set to 95 degrees.  As far as I can tell, the heater never had to even come on, but the heat would run up.  One day, I went out to check it and the temp was 115, so I turned off the breaker and propped the cover open a few inches to let it cool.  It took a few days, then I turned the breaker on again (left the cover propped open a bit) but it still kept creeping up to the 108 range.

The pH levels and everything are checked weekly and are fine.  It had water replaced at least three times (maybe 4) during the parts replacement.

I've read elsewhere there's a "hard reset" procedure...and I may try that next...but otherwise, I'm not sure what to do.

Any advice on troubleshooting this would be very much appreciated.

 

[CanadianSpaTech]

See page 28,29. Check to see where your filter cycle duration is set. F2 will cycle the pump for 2 hours out of 12 if set to F8 it will run the pump for 8 hours out of 12 or 16/24. Heat shedding off the pump running for extended periods of time can heat the spa water from the inside. 

http://online.fliphtml5.com/iiho/qgqv/index.html#p=32

[Sonnyw72]

Thanks, it's F1 that does the 2 hours per 12...which is the factory default.  I was running F4, which is the same, but only allowed the heater to turn on during a filter cycle.  

Either way, I've owned this spa for 6 years and it never had an issue until this year.  It's never overheated in the past with these filter cycles.  It would have to get a LOT of heat from the pump to get it up to 115 (F) without ever turning the heater on.  

Could it be something else like a faulty temp sensor?  The display is reading out the correct temp of the water (I've checked it with a digital cooking thermometer).  How do you test these?  

[CanadianSpaTech]

47 minutes ago, Sonnyw72 said:

It would have to get a LOT of heat from the pump to get it up to 115 (F) without ever turning the heater on.  

pump running for 15+ mins will generate 150-160 degrees so had to ask. Most common cause for overheat is filter cycle set to high/long. Is the spa in a deck?

[Sonnyw72]

No worries...any ideas on what else it could be?

[CanadianSpaTech]

Well if the temp sensor is matching your thermometer then I would say it's likely good. I might try and open the front panel for a day and see if the temp still climbs to see if it is a venting issue.... again I ask... Is the spa sunk in a deck?  

[Sonnyw72]

The spa is above ground.  Nothing has changed with the setup of the spa since I bought it new 6 years ago.  The only thing that changed was the main pump in the spring when the original died...then 2 months later when the heater died.  Both were replaced within a week of failing.

Here's an interesting detail, though...the replacement pump seems to have more suction than the old one.  It was strong enough to create a small whirlpool effect over the filter and suck in air for a second, which caused it to "pulse"...it'd do this pretty regularly while the pump would run.  I fixed the surging by placing a plastic object near where the whirlpool would start that interrupted the whirlpool...so no more pulsing.  Either way, still strange that the new pump seems to have more suction...not sure if that could cause the temp to run up.

Also, a new development this week.  I found the troubleshooting manual for the Jacuzzi J-235 online and decided to test the temp sensor and hi-limit sensor.  The hot tub had been unpowered for the past week while I was testing things...but when I plugged it back in, I got a SN2 fault...which is the regular temp sensor.  The multimeter readings were OK, but very well could be out of tolerance at the upper end of the range...so who knows.  

I decided to swap the pins of the high limit sensor and the temp sensor on the board to aid in troubleshooting...and when powered back up, the SN2 fault was gone.  So the main temp sensor is definitely bad.  Replacement on the way.

However, while I still have the hi-limit sensor acting as the regular temp sensor, I decided to let it run a few days to see if the temps would creep up.  The first couple of days they were great...but this morning, when I checked the temps were 3 degrees higher than the set temp on the panel.  Verified with an external thermometer.  The heater was "off", as it should be since the temps were already above the set temp.

So, my new question is this...would it be possible to have a bad replacement pump that's somehow increasing the water temp?  I know a lot about electronics, but not much about fluid thermal dynamics.  How can the heat from a pump transfer into the water?

 

[CanadianSpaTech]

On 9/19/2022 at 7:41 AM, CanadianSpaTech said:

pump running for 15+ mins will generate 150-160 degrees so had to ask. Most common cause for overheat is filter cycle set to high/long.

 

[Sonnyw72]

I feel like we're going in circles.  Haha.

To be clear, nothing is different prior to the pump being changed out. So I'm trying to troubleshoot a problem. I understand that the pump can generate a lot of external heat. I don't necessarily believe that a pump running for 15 minutes is going to heat someone's hot tub 150°.

I truly appreciate your help, though. 

[ratchett]

16 hours ago, Sonnyw72 said:

I feel like we're going in circles.  Haha.

To be clear, nothing is different prior to the pump being changed out. So I'm trying to troubleshoot a problem. I understand that the pump can generate a lot of external heat. I don't necessarily believe that a pump running for 15 minutes is going to heat someone's hot tub 150°.

I truly appreciate your help, though. 

How old are you filters?  Have you replaced them recently?  Have you flushed them with filter cleaner?  I'm far from an expert, but maybe old filters are reducing flow through the heater, allowing it to get hotter than it should before entering back into the tub?

[Sonnyw72]

Howdy! I replaced the filter about 6 months ago when I replaced the pump.  Oddly enough, it seems to be holding steady with the Hi-Limit sensor acting as the temp sensor.  Although it's reading temps from the heater tube, and not the water, so when the water filtration cycle isn't going, the water in the tube cools down to the mid-80's, while the water temp stays in the high 90's.  Once the pump starts back up, the tube water is replaced and the sensor reading is correct again.

I'm hoping it was just a regular temp sensor issue.  I'll report back in a couple days when i replace the sensor. 

 

[Sonnyw72]

Just out of curiosity, because I did replace the filter, would a clogged filter that flows less water cause it to overheat?  Or am I thinking about that backwards? Having a very free-flowing filter, or no filter at all, would flow a lot of water. Would that cause it to run cooler or hotter?