A bad gas valve will not allow any gas to go to the burner or pilot light. See the article on 'Hot Water Heater Gas Valves' for the issues surrounding this device. A clogged or partially clogged vent can cause this problem. See Venting a Gas Water Heater for information on keeping your vent clear.
Definition. A hemoglobin test measures the amount of hemoglobin in your blood. Hemoglobin is a protein in your red blood cells that carries oxygen to your body's organs and tissues and transports carbon dioxide from your organs and tissues back to your lungs. If a hemoglobin test reveals that your hemoglobin level is lower than normal, it means you have a low red blood cell count (anemia). Anemia can have many different causes, including vitamin deficiencies, bleeding and chronic diseases.
The hemoglobin test measures the amount of hemoglobin in a person's sample of blood. A hemoglobin level can be performed alone or with a hematocrit, a test that measures the proportion of blood that is made up of RBCs, to quickly evaluate an individual's red blood cells.