United Spa Controls T7-s and C5 Overheat problem

[Jus]

Hello Spa Gurus,

I have an older spa with the Unites Spa Control C5 series spa-pack, it has the B7 board in it.  Recently replaced the topside controller with a new T7-s and both temperature sensors.  

The issue I am having is the spa has never heard a stable temperature like my previously owned spas.  It has been throwing the S-OH (software overheat) code.  I went down the rabbit hole of trying to figure it out.  I had noticed that the original manufacturer had placed both the regular temp sensor and over limit sensor on the heater tube itself under a bolt on cover.  So, I purchased a tub mounted temperature sensor well along with both new sensors.  Installed the sensor well and main temp sensor, no change noted.  Then I installed the High Limit Sensor, also no change.  Water temp set at 95 for testing, still over limits.  I pulled the High Limit sensor out of its heater mount and dangled it outside of the spa pack... no over limit code, but water temp went to over 120f overnight while topside display is reading 89f.

Do any of you have any recommendations to try?  The topside control manual and spa pack manual have no mention of any calibration methods.  

Thanks in advance

 

[CanadianSpaTech]

Not sure if this helps: https://www.unitedspacontrols.com/PDF/T7UsersGuide.pdf

[Jus]

3 hours ago, CanadianSpaTech said:

Not sure if this helps: https://www.unitedspacontrols.com/PDF/T7UsersGuide.pdf

Thanks but I do have the manuals.  I was hoping that someone knows if a calibration process is known.  Might be a bad board but I am hoping to figure it out just throwing parts at it.  

 

[CanadianSpaTech]

On 12/2/2024 at 2:47 PM, Jus said:

 I had noticed that the original manufacturer had placed both the regular temp sensor and over limit sensor on the heater tube itself under a bolt on cover.

@Jus Hi limit goes under the bolt on cover. The temp sensor goes to a fitting on the side wall of the spa and gets pushed all the way into the fitting so the sensor touches the front of the sensor housing. Once pushed all the way into the fitting cover the back with tape where the wire is sticking out so it won't pick up the ambient temp inside the cabinet. See this link below. The fitting is at the bottom of the photo. You should see it on the side wall of the spa in the bather area.

Let us know results

https://pool-spa-supplies.com/a-united-spas-ctt7-control-pack-heater-on-top-back-of-unit-w-heater-topside-panel-cords-ctt7-16118?srsltid=AfmBOopp4qmWbmzEhEL6ofTsg2UqTzxxTDLae0RvJzYJACrEcwgKZXOO

[Spa Board Doctor]

Possibly a sticking or stuck on heater relay. 
Look for 240V across heater terminals right after boot - before the pump turns on. 
Temp sensor is plugged in to J2 and high limit is J3, correct? 
I advise that you insulate around the back of the temp sensor thermowell as it is common for the ambient temperature of the cabinet to throw off the sensor value.

[Jus]

On 12/7/2024 at 1:20 PM, Spa Board Doctor said:

Possibly a sticking or stuck on heater relay. 
Look for 240V across heater terminals right after boot - before the pump turns on. 
Temp sensor is plugged in to J2 and high limit is J3, correct? 
I advise that you insulate around the back of the temp sensor thermowell as it is common for the ambient temperature of the cabinet to throw off the sensor value.

Thanks for the recommendations.  I went ahead and fully insulated the thermowell and that probably didi help.  However, I am still having over temp issues.  I powered down the tub and et it cool down to 80f, then powered things back on.  It is currently set to filter twice daily for one hour, this seems to be the shortest time avaliable in the settings.  

The control head appears to be reading about 10-15 degrees high.  I currently have it set to 85f with my floating temp confirming roughly that.  However, the readout is showing closer to 100f.  It has been running for a few days like this without throwing a code.  If I set it to 104f, it goes to 115-120 on the readout.  

I do have the well mounted temp sensor plugged into J2 and High Limit connected to J3.

I also believe the heater relay is not sticking, instead the control board is sending it incorrect information.  I will confirm this.

 

[CanadianSpaTech]

Do you still have the original temp sensor? If so give it a try and see if you get the same issues

[Jus]

On 12/15/2024 at 5:57 AM, CanadianSpaTech said:

Do you still have the original temp sensor? If so give it a try and see if you get the same issues

I do still have them and swapped them back in.  It appears to be the same results.  Not sure what else to attempt.  

I also tested the heater relays to make sure it was not sticking ON.  It also seems to be functioning properly.  

[Jus]

On 12/15/2024 at 5:57 AM, CanadianSpaTech said:

Do you still have the original temp sensor? If so give it a try and see if you get the same issues

I do still have them and swapped them back in.  It appears to be the same results.  Not sure what else to attempt.  

I also tested the heater relays to make sure it was not sticking ON.  It also seems to be functioning properly.  

[CanadianSpaTech]

Have to ask... Are you sure you have the right sensors of the board?

Temperature Sensor Installation The C5 control box comes with a 1/4” diameter temperature sensor. This is a dry sensor that is not to be exposed to water. Its probe is meant to be installed into a thermowell which itself should be installed mid-water level in the hot tub to provide the most accurate temperature reading. After installing the temperature sensor probe, be sure to plug the connector on the end of the cable into the temperature sensor receptacle on the control box. The included sensor is carefully calibrated to it’s cable’s length, and therefore must in no way be altered or shortened/lengthened.

Have you entered a configuration code using the topside and verified you have the correct code entered?

https://spacare.com/productimages/pdfmanuals/T7Usersguide.pdf?srsltid=AfmBOoqDupuU5stn-w_Tj6QWHRDB9Sk5TLOmrkQL87j_l2GCj6R7gkON

[Jus]

6 hours ago, CanadianSpaTech said:

Have to ask... Are you sure you have the right sensors of the board?

Temperature Sensor Installation The C5 control box comes with a 1/4” diameter temperature sensor. This is a dry sensor that is not to be exposed to water. Its probe is meant to be installed into a thermowell which itself should be installed mid-water level in the hot tub to provide the most accurate temperature reading. After installing the temperature sensor probe, be sure to plug the connector on the end of the cable into the temperature sensor receptacle on the control box. The included sensor is carefully calibrated to it’s cable’s length, and therefore must in no way be altered or shortened/lengthened.

Have you entered a configuration code using the topside and verified you have the correct code entered?

https://spacare.com/productimages/pdfmanuals/T7Usersguide.pdf?srsltid=AfmBOoqDupuU5stn-w_Tj6QWHRDB9Sk5TLOmrkQL87j_l2GCj6R7gkON

Well, those are good questions.  The new sensors and old (original) sensors are of the same shape and size.  Only noticeable difference is the new thermowell sensor is chrome instead of grey.  They both give me the same readings, unfortunately.  The cabling is also not modified on any of the sensors. 

I have read through the manual many times and it seems that the programming codes are correct.  I did not see anywhere a setting that would affect the sensor readout, just when the heater functions and with what mode.  

 

[CanadianSpaTech]

Time to call United Spa Tech Support

[Jus]

Sadly, they do not return calls or emails.  

 

[CanadianSpaTech]

Well to me the issue is centered around the temp sensor. It is what sends the temperature to the pack and on up to the topside. 

16 hours ago, Jus said:

Only noticeable difference is the new thermowell sensor is chrome instead of grey.

Why did you start replacing parts to begin with? 

Where did you get the new sensor and was it specific to United Spa?

[Spa Board Doctor]

Is the display temperature accurate against a known good digital or infrared thermometer?