I'm getting the dreaded SF code. My research indicates it's the thermistor. My question, admittedly a dumb one, is where is this located when facing the heater from the front? Do I remove the front display panel, other panels? I am doing a DIY but before I start breaking this thing down I would like to know a specific location. The net search hasn't led to a install video or pics that aids me to say where it's located. thanks for any help.
hayward 400 heater thermistor
- Thread starter artd
- Start date
thank you Joe. I assume the control box cover is the display box with the mode and temp up/down arrows correct?
Look at the picture on page 42 where it shows Front Header Parts. https://www.hayward-pool.com/pdf/manuals/h-series-hxxx.pdf
thank you Richard. The other end of that connects to the control board that is behind the control panel correct?
Ok thermistor replaced, worked for 15 min following repair. Just fired up spa for daughter and friend to use and heater is back to not working condition showing the SF code error. Is there another piece to replace that would cause this? thx for any input.
SF only relates to the temp sensor. Your control board could be going and that is why you are getting this error code.
Did you buy a Hayward sensor or a knock off?
Did you buy a Hayward sensor or a knock off?
Hayward one. Funny thing is it worked yesterday for 20 min. Ill try again today for a longer period to see if it works now. Im thinking it might be another issue, possibly c board if it continues.
You could just have a bad sensor, there are actually two thermistors inside the sensor, this is from the maintenance manual
Code SF
Thermistor error
An excessive temperature difference between the two thermistors (5 °F or more)
or an “out of bounds” condition on both sensors (less than 10°F or greater than
180°F) will result in the error code. Automatic restart is 2 minutes after the error
is corrected.
I also found a troubleshooting diagnostic guide for the heaters
https://www.hayward-pool.com/pdf/manuals/UHSDiagnostics.pdf
and on page 35, step 2 it tells you how to measure the sensor for the two thermistors.
I would think using a digital meter would give you more accurate readings for comparison between the two thermistors than an analog meter
Code SF
Thermistor error
An excessive temperature difference between the two thermistors (5 °F or more)
or an “out of bounds” condition on both sensors (less than 10°F or greater than
180°F) will result in the error code. Automatic restart is 2 minutes after the error
is corrected.
I also found a troubleshooting diagnostic guide for the heaters
https://www.hayward-pool.com/pdf/manuals/UHSDiagnostics.pdf
and on page 35, step 2 it tells you how to measure the sensor for the two thermistors.
I would think using a digital meter would give you more accurate readings for comparison between the two thermistors than an analog meter
If after you measure the resistance on the the new thermistor and if you find it to be OK, then I would have to say the ICG board is probably the problem. It does happen to get a bad thermistor but rare. I have seen on these Hayward FD units that the board can go and present you with various error codes.