Temperature probe

[Bobdragon12]

I'm hoping to get some help with a Hottub issue , My hottub had a temperature issue and I replaced the probe , it now reads 10deg lower than it should 25.5deg C on the display 35.5C in the water . I can obviously add resistance but this pushes the temperature the wrong way . Any suggestions as to something I could put in line to correct this ?
Also the sender is not raising correctly it takes more heat than it reads to make the probe work

Any help appreciated Jon

 

[atferrari]

What was the original probé and what is the curren one?

 

[Bobdragon12]

It's a 3 wire resistance probe , I replaced it with the same model that came out although the website part number was different and in the foot note it said all I had to do was move 1 wire to a different pin on the plug as per my original probe . That's all it has on the link as it's an OEM part https://www.hottubpartsuperstore.co.uk/gecko-temperature-sensor-probe-9920-400125.html

The original issue with tub was that the temperature danced all,over the place with all sorts of false readings from 15c to 45c . This has now stabilised but it's just out constantly

 

[Reloadron]

I see where they mention:

Gecko Temperature Sensor Probe 9920-400125
This genuine Gecko Temperature Sensor Probe 9920-400125 is very common and found on Gecko, Spa Builders and Hydroquip Spa control systems.
Manufacturers Part Number
Direct replacement for Gecko part numbers - 9920-400125 & 9920-400342 (Read notes below)
Can also replace Gecko - 9920-400342. To do this you will need to move the black wire from the connector into the position that is empty, as Gecko have changed the order for newer control systems and do not manufacture the older model anymore. The correct order should end up being Red - Green - No Wire - Black. Please note that we can't accept the item back for a refund once the wire has been moved or incorrectly done.

At this point I would give them a call.

Need Help?
If you need any help or advice please do not hesitate in calling us, we have many years of experience with hot tubs and spas, including maintenance, service and repairs. You can contact us by phone on 01342 717982 or through our **broken link removed** page, we will be more than happy to assist you.

I doubt you are alone with this problem. Using a 3 wire RTD sensor the sensor could be faulty or any number of other things including a calibration of the sensor to the display. I just figure rather than venture guesses the guys who sold you the sensor may have a better solution. Especially since the unit was erratic prior to the sensor change and now the new sensor provides incorrect readings.

Ron

 

[Bobdragon12]

Weirdly they are not answering the phone and I had an email bounce back so I suspect they have gone bust , I will obviously keep trying . I have ordered another PT1000 probe off eBay to see what that reads at

 

[alec_t]

Judging by the graph shown here, a ~100Ω resistor in series with a Pt1000 probe should raise the temp reading ~10C.