The heat wont turn on and pilot does not stay lit

Turn off the gas supply and unplug the heater.
Remove the control knob and check for any debris or damage.
Clean the control knob and the area around it with a soft cloth.
Reattach the control knob and turn on the gas supply.
Turn on the heater and check if it works properly.
If these steps don't work, then it's best to contact a professional technician

Are you holding down the pilot light button long enough for the heat sensor probe to get hot and turn on the gas valve? It takes up to 3 minutes

if its a pilot lightr that stays lit all the time,then its the thermocouple next to the pilot light thats bad and cant keep the pilot on

If the fan comes on and blows out the pilot light then you need a new furnace because that's the sign of a crack in the heat exchanger. Need a little better description. Do the burners light then the fan come`s on and then it goes out completely?

I would check to make sure control on gas valve is in on position and pilot is lit if you have a standing pilot. If you have a spark or hot surface ignitor make sure they are trying to lit pilot. If you have standing pilot model and pilot lit is not on. Turn control on gas valve to off,wait five mins. then turn to pilot. Depress botton and try to light pilot. If it lights hold down for a couple of mins. then release.. If pilot stays lit turn control to on. If thermostat is calling for heat this should bring main burner on. If pilot does not stay lit then replace thermocouple. Hope this helps. Thanks

You need a new thermocouple - or maybe the Pilot flame is not lined up properly to the thermocouple? The thermocouple is a "sensor" that is heated by the flame - which in turn keeps the gas supply to the pilot light on. It the pilot light goes out, then the thermocouple no longer "senses" the heat of the flame, so it turns the gas supply off to the pilot to prevent buildup and explosion.

there is a small adjustment screw on the gas valve,turn it clockwise to increase pilot,if that does not work the vent cap on the gas regulator on the back of the unit could be stopped up,remove that cap ,clean out or replace unit can operate without it just fine.If you increase the pilot and it still wont stay lit replace the thermocouple

Do you have the serial number or the manufacture date? There are some design changes and I would need to know the year of manufacture to assist accurately. Usually it is a relay or the thermocouple connection that will affect the unit staying lit.

Check the pilot light.Older standing pilot systems use thermocouples to verify the pilot is burning before the gas valve opens.If the pilot wont stay lit replace the thermocouple.
Newer systems light the pilot.On a call for heat the igniter lights the pilot. When the heat is verified the gas valve opens . Some systems use an circuit board with flashing led lights to help troubleshooting.