The water heater heats the water but non on demand. I turn on the faucet/shower and I get hot/warm water but then it starts cooling down and I check the water heater to see if the burner is going on and I see that it is not. I turn up the thermostat and the burner kicks in but soon after it stops and when that heated water is consumed the burner does not turn on again. Where is the problem? Thanks for the help. agal2@yahoo.com