Kybasche

Several years later - but after experiencing a lot of the same symptoms described here (relay board failing over and over, only a few months apart, seemingly no other symptoms), I tried @NotaFanofWatkins's hack on a 220V setup, and by george, the hot tub is back to heating. Thanks to you, and others on here whose patience and knowledge helps the otherwise helpless (like me) 🌡️

Resurrecting this post - as there seem to be some new symptoms that may (or may not?) be related. ~2006 Hot Springs Grandee, inherited from previous property owners middle of last year. I've already replaced the Heater Relay board once (about 9 months ago) as described in the original post on this thread. Here is the current scenario and symptoms: Hot tub was working fine in early December We went on vacation for 10 days and set the hot tub to 80 degrees while we were gone Increased the temp back up to ~101 upon our return (12/27) Hot tub warmed up to set point - but the Green "Ready" indicator never came on (suspicious...) Checked the temp again the next day, and it was dropping (heater not heating) Tried cycling power a few times - tub would heat up and then stop heating again. I put in clean filters - cycled the power again - and set the Set Point to 93 degrees (which is the current water temp as measured with a digital instant-read thermometer). Again - the Green "Ready" indicator is NOT on. Looking at the control board, a few things stand out. Green LIM OK is lit Red HTR ON is lit (despite the water temperature matching the set point...) Circ pump is running On the heater relay board - D10 is green - D9 is blinking red (seeming to indicate a bad relay - despite it being only 9 months old) Any clue what could be going on? My very naive guess was that the temperature sensors could be funky. @RDspaguy you had previously mentioned "I can only imagine that if it is scale in the heater" and to remove the thermistors to check for scale. I have NOT yet done that - I'll need to track down some YouTubes of the process as I'm not familiar. It's currently -12F outside, so I'm not inclined to do much "tinkering" if I can avoid it I'll post a video of the control board if that's of any use. IMG_4073.MOV

@ratchett Good points all around. 1. Testing with a ThermaPen (https://www.thermoworks.com/Thermapen-Mk4?quantity=1&color=16&utm_source=google_shopping&utm_medium=organic&gclid=Cj0KCQjw4ImEBhDFARIsAGOTMj_wpU90sHEmI0yjQxQsSajDhzX9djv1gZwF0k-fuWToC3MaEVSWY04aAl0ZEALw_wcB) - same device used to test previously. I note that the docs say that accuracy is +/- 0.7F, so not SUPER accurate. 2. Testing location varies, always in the top few inches of water - both near the edges and nearer the middle of the spa 3. Temperature probe reads 210-211 in boiling water very consistently (never over 212) TBH - since it's consistently wrong it doesn't present a _problem_ per se - but I'm mildly concerned that this speaks to something that could get worse over time.

@RDspaguy AFAIK the display on our unit only shows the setpoint temperature - not the water temperature. There's a "Ready" light that comes on when the water temp is (supposedly) close to the setpoint.

Hello! We have a c.2007 Grandee by Hot Springs. Recently, I installed a new 77119 Heater Relay Board after the relay board shows a solid red D9 LED (see This Thread for details). The hot tub uses an IQ2020 Logic Board. Prior to the heater going out and replacing the relay board, the hot tub water (as measured with an instant-read digital thermometer) was always right on setpoint. After replacing the board, the temperature is consistently 2 - 3 degree above the setpoint (a setting of 99 has the water at 102). I've measured several times over the course of the day and this seems to be very consistent. Anyone know what to look at in terms of determining why the temperature is "off" in this way? Are there ways to adjust the thermostat to re-calibrate the temperature? What other information would you need to help troubleshoot? Thanks much!

😱 how embarrassing. Could have sworn that the water coming out of the vent was ice cold, but sure enough, several hours later, the tub is 25 degrees warmer. :hides in the forum shadows:

Hello! We inherited a hot tub (c.2006 Hot Springs Grandee) when we moved in September of 2020. Everything worked fine until about 3 weeks ago. Same story as many - came out to use the tub and it was lukewarm. My somewhat uninformed troubleshooting so far has involved the following: Changed the filters out for new ones (ceramic Tri-X) to try and eliminate any issues with old/dirty filters causing water flow issues Removed most of the tubes leading up to and leaving the circ pump to check for blockages - didn't find anything. The circ pump is running, water is flowing from the heater return along with Ozone bubbles at what seems like the "normal" rate. Looking at the IQ2020, I noticed that the D9 LED was blinking red (based on this thread, I took that to mean the heater relay board was bad). Ordered a new 77119 relay board and installed it today. No more blinking red light, but still no heat. Checked the resistance across the heater (measured between H1 and H2 terminals on the heater relay board) - got 15.2 Ohms, which I think is within reason (4 kW Watkins No-Fault). I guess that about 13.2 Ohms is probably expected at 230V (230**2 / 4000) LIIM OK and HTR ON lights on the main board are the right colors (green and red, respectively - no blinking). Measured voltage to the heater (measured between H1 and H2 terminals on the heater relay board) is ~230V. I'm out of ideas at this point. I've seen other threads mention ideas about bypassing some pressure switches on the main motherboard? It seemed like that was mostly a temporary solution or part of the diagnosis process, but perhaps I misread(?) I'm running out of ideas at this point - any other things I can try? How likely is it that the Relay board and Heater both failed at the same time? Are there any other ways to determine definitively that the heating element is no good? Cheers!