Pilot light is on, but no hot water. thermostat is turned all the way up to HOT.

<p>If you are having<b> trouble with the temperatures</b> of your <b>gas hot water heater</b> fluctuating too much, or after <b>changing the thermocouple</b> of your gas <b>hot water heater</b> then you may need to change the complete <b>gas valve and thermostat assembly</b>. Also if you have changed the <b>thermocouple</b> and the pilot still will not stay lit, then the gas valve could be bad or the <b>ECO (Emergency Cutout)</b> may have activated and is open. This is a onetime device and cannot be replaced.<br /> <p><br /> <p>These instructions are for the older style <b>gas valve and thermostat combination</b>. These commonly have a large red knob that adjusts the temperature of the water. Also note that the burner tube nut for <b>natural gas</b> is right hand thread, but if you have <b>LP or propane gas</b> the burner tube nut is left hand thread.<br /> <p><br /> <p>The newer <b>gas valve thermostat combinations</b> that have come out recently are similar, but they have a well in the tank that the sensor slides into. The assembly is held fast with a set screw. With this type of <b>gas valve and thermostat unit </b>the tank does not need to be drained, but most of the rest of the change out is similar.<br /><br />To change a <b>gas hot water heater thermostat</b> you will need to first buy a new gas valve for your <b>hot water heater</b>. The <b>gas valve</b> and the <b>thermostat</b> are integrated into one unit.<br /><br />To <b>replace the thermostat on a gas hot water heater</b> you must follow these procedures....<br /><br />1. Turn off the incoming water and<b> drain the hot water heater</b>.<br /><br />2. Remove the <b>pilot tube</b>, the <b>burner gas tube</b> and the thermocouple from the gas valve. Turn off the <b>gas line</b> and remove from the gas valve.<br /><br />3. Get a <b>pump pliers</b> or a<b> wrench</b> in behind the gas valve and turn the whole assembly CCW to remove it from the tank.<br /><br />4. After applying pipe dope or tape to the new gas valve threads, turn the new gas valve into the tank by turning in a CW direction. Be careful not to damage the small wires to the <b>ECO</b>. They are the little red wires on the back. If you break them the assembly is irreparably damaged.<br /><br />5. Reinstall the gas line, thermocouple, burner tube, and the pilot tube to the gas valve.<br /><br />6. Fill tank with water. Make sure to open a <b>hot water faucet</b> and <b>purge all air from the tank.<br /><br /></b>7. <b>Check for leaks</b> where the gas line hooks up with soapy water.<br /><br />8. Relight pilot light and check operation.<br /><br />9. Set the new temperature setting to a medium setting and then adjust the temperature to your liking from there and adequate time for heating completely<br /> <p>