FGX831FS gets hot water even when set to cold

I would check the water tempeture knob with a multimeter, u did check the water outlet hoses to see u are getting hot and cold water from them? Also if ur water inlet valve is bad it may only allow cold water or only hot water?

my last two washing machines, totally different brands and types, did the exact same thing. It must be a new way of setting them up, I don't understand either. I can't get straight hot water. My new one does seem hotter than the old one I had which was very distinctly hot then cold then hot then cold even on hot hot water.

Is the Hot water hose connected to a Hot Water source? Is that source turned on? It almost sounds like you aren't getting hot water to the spigot.

Good luck,
Mark

The problem with all that type of water heater is that once the hot tap is turned on sufficient flow must be maintained through the water heater to keep the main gas burner alight. If the heat adjuster is turned up to high, then the person using the hot water will turn it down to a low rate which means the main burner will turn off and result in cold water. Try setting the heat control to the lowest setting that still gives hot enough water. If you have a thermometer adjust control for a temperature of around 50 to 55 degrees Celcius. You may have to fiddle with fine adjustments to get the temperature and flow rates to maintain a constant output of hot water. You may still have intermittent problems. If the heater only supplies baths or showers you could set the temperatuer even lower (45 to 50) to ensure that the hot tap is used more than the cold which will maintain flow and therefore heat.

Newer machines know the water temperature. It will mix hot water even on a cold setting if the incoming water is too cold. Detergents need a temperature of at least 60 to activate.This will only happen in the winter usually.

F-20 error code in Whirlpool Duet Sport washing machine is indication of inadequate water supply. Check both hot and cold water supply lines to make sure machine gets enough water intake. If you do not have a hot water supply to the machine you can only run it with the cold temperature setting. This machine does not have an internal water heater and relies on the hot water supply from the house water heater.

If the washer fills very slowly when you have it on a cold setting the cold water may be shut off behind you washer or possibly the hot and cold are switched. if that is not the problem then you have a relay problem with the machines electrical system.

It sounds like you have the hot and cold water lines to the washer reversed.  Try turning off the tap for the hot water then setting the washer to just cold wash and then  hot washif you get nothing on the cold and cold water when set to hot they are probably reversed.  Typically if the auto-temp control is broken you will only get hot or cold coming out on any setting. 

Make sure the cold water is turned on ,otherwise a plugged screen in the water valve or in the fill hoses will cause the problem .

Another reason would be a defective cold water valve solenoid if so you need to replace entire water valve

Is the tap to te cold water turned on
I would check that