Spa pump runs continuously (and it shouldn't)

[JT8Diesel]

I've had a spa since new in Fall 2020.

Recently I noted that the spa displayed "Oh" and the pump was running continuously. I shut it off. The water was over 108º.

I've since been doing some troubleshooting. I first thought (hoped) that the kids and changed the filter cycle. They had not.

1) I've double checked and it is in "Standard Mode"
2) I've checked the filter cycle and it's set to F2 (2 hour filtration in 12 hour period). It is NOT set to FC.
3) I've opened the control pack hoping to find a stuck relay. Tapping them didn't change anything, and no obvious signs of damage / failure.


My first thought was that the kids accidentally changed to continuous filter mode. They did not.
Second, I thought a relay might be stuck, however the button behaviour doesn't bear that out.

Intended "Jets 1" button behaviour is to toggle between off, low, and high. However with my pump already running on low, pressing Jets 1 turns the pump to high. Pressing Jets 1 again turns the pump back to low. Pressing Jets 1 again turns it to high.

My Balboa Circuit board is a VS501Z.

Other thoughts / musings...

With the heat temp set below the current temp, the pump continues to run and I cannot turn it off. There should be a 2 hour time out (per the manual) but it runs continuously after that.
With the heat temp set above the current temp, the pump runs (as designed) and the heat light illuminates. Turning the set temp below the current temp results in the heat light extinguishing, but the pump continues to run.
It's acting almost as though the pump thinks the heater is running continuously (even though it's not based on the heat indication light and electrical consumption).

	Start condition	First Press	Second Press	Third Press
Normal Behaviour	Off	Low	High	Off
Stuck relay expected behaviour	Low (instead of off)	Low	High	Low (instead of off)
Current behaviour	Low	High	Low	High

 

[RDspaguy]

Second, I thought a relay might be stuck, however the button behaviour doesn't bear that out.

Buttons have nothing to do with this, and it's most likely a stuck heater relay. Once it reaches temp to trigger an oh error it will continue to run the pump in low until it cools (at the sensor in the heater)as a safety precaution while simultaneously opening both high-limit relays for the heater (different from the heater relay, which is the on/off switch for it). Since it lacks the ability to cool itself, the pump ends up running a long time.

It's acting almost as though the pump thinks the heater is running continuously (even though it's not based on the heat indication light and electrical consumption).

Since the heater does turn off via the high-limit relays your power usage is not an indication of heater function. Test voltage to the heater, terminal to terminal, testing to ground is pointless, when the water is above set temp but no errors are triggered. It should be 0 volts. If it's not, it's a stuck relay.
Remember, the sensors are in the heater, and the controls have no idea if the high temp is just in the heater or in the whole spa. It might get the same reading from a dirty filter or bad pump.

 

[JT8Diesel]

Buttons have nothing to do with this, and it's most likely a stuck heater relay. Once it reaches temp to trigger an oh error it will continue to run the pump in low until it cools (at the sensor in the heater)as a safety precaution while simultaneously opening both high-limit relays for the heater (different from the heater relay, which is the on/off switch for it). Since it lacks the ability to cool itself, the pump ends up running a long time.


Since the heater does turn off via the high-limit relays your power usage is not an indication of heater function. Test voltage to the heater, terminal to terminal, testing to ground is pointless, when the water is above set temp but no errors are triggered. It should be 0 volts. If it's not, it's a stuck relay.
Remember, the sensors are in the heater, and the controls have no idea if the high temp is just in the heater or in the whole spa. It might get the same reading from a dirty filter or bad pump.

Thank you for the reply.

The heater relay seems fine. I can hear the relay click, as well as see 240V at the terminals, when heat is called for. Also, once the set temp has been reached, 0V is seen at the terminals. I can understand the pump running continuously in a stuck heater / high temp situation. However this behaviour continues at all temperatures. Currently set to 86º. I observed the heater turn on (heard relay click, saw 240V). It then turned off when the tub reached 87º, observed 0V). However the pump continues to run on low speed, even an hour later.

I will continue to test and observe for now. Frustrating.

Thanks again

 

[RDspaguy]

Has there been any work done on the circuit board lately? Post pics of circuit board, wiring diagram, and equipment area.

 

[JT8Diesel]

Has there been any work done on the circuit board lately? Post pics of circuit board, wiring diagram, and equipment area.

No work done in the last 18 months. Replaced the heater tube and element last year as it had rotted through.

Been working great since. Not home now, pictures to follow.

 

[cliffs]

Sounds like a stuck/failed relay on the board. Ours failed in ~April this year, it had been in service for nearly 4 years at that point, OH made an appearance on the topside from time to time. Same control pack as you've posted. The pump would run on low speed at startup, a jets=on button push it would lock up the pump and cause it to stop as one of the relays wasn't releasing when it should have. (The pump's capacitor had also failed, and was replaced just prior to the board being repaired.)

There is a shop out in Guelph that rebuilds the board - in talking to him relay failure is not uncommon with the unit. The repair was a little less than half the cost of a new board.