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Balboa M7 Not Heating unless High Jet Setting On


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Hopefully my final question:

I noticed with this new system when the spa is idle for a while and I open the cover, the temperature is not displayed, there are instead 4 dashes. I click the pump on and the temp is then displayed and in range of the set temp. I checked the manual and all it says for the dashes is: “water temp unknown- after pump runs for 1 minute, temp will be displayed.”

Is this normal to show up every time the hot tub is idle for a while? I’m just not used to seeing this as the prior system always displayed the temp, no matter how long it was idle. Not sure if it means I may have an airlock or some other issue... I did empty and refill the tub yesterday.

Thank you!

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  • 2 months later...
On 5/19/2021 at 2:01 PM, RDspaguy said:

Those are 2 of the three relays controlling the heater. The single thermostat relay is the one that fails, as it is the one that switches on/off during normal use. 

They are soldered to the board, hence the need for an electronics guy. If your repair guy doesn't know this, he is not an electronics repair guy. Perhaps you should just buy a new board. It sounds like the guy you are talking to doesn't know what the **** he is doing.

Which one is the thermostat relay in the board? (K1, K3 or K5)? 
I'm guessing it's one of the three that are close to the heater terminal



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1 hour ago, RDspaguy said:

Not sure, I don't do circuit board repairs. I'd get all the relays replaced, even the pump relays, if I were getting it done.


if you were to guess: are the pump ones the small ones or still the big ones?, I'm guessing K2, K6?

I'm having a similar problem as stated in this forum. Instead of no heat - I get very little heat only 2-3 degrees every eight hours. Reading 0V between heater terminals and the resistance when connected seemed ok. I got a hot tub tech checking it for me and he recommended a replacement for the board.
So I was going to swap the relays myself before swapping the entire board. 

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  • 3 weeks later...
On 9/30/2021 at 10:20 PM, RDspaguy said:

That is no heat. And if there are no error codes and you are not in sleep mode, it is a bad relay or connection. Unplug it and test at the board pins, they are notorious for failing.

Otherwise, start your own thread and include pics of your circuit board and equipment.

Just posting an update.
I ended up replacing all the 5 relays in the main board (HF2150-1A-12DEF) as suggested ($1.12/relay fix).
It got fixed, I can read voltage on the 2 terminals of the heating element and the hot tub has warmed up tot he correct settings. My guess is that it was the two Hongfa relays near the heating element port. But replaced all 5 just in case.
Thanks for the help!

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