Gas Boiler Has No Pressure

Function

• Gas boilers create heat for your home through combustion of natural gas that heats water provided through your main supply. Pipes draw water from your main line through a heat exchange unit that transmits heat from a lower combustion chamber. The hot water or steam is then distributed throughout the home. The heated water services both plumbing systems like tap and shower valves as well as radiant heat systems like baseboards and radiators. Pressure valves maintain an adequate and safe level of both water and natural gas in your boiler.

Types of Pressure Valves

• Gas boilers often contain several pressure valves. The main pressure valve monitors the water temperature and pressure in the supply pipes. The water pressure should be maintained between 12 and 15 psi to ensure a properly functioning and safe boiler. Gas boilers also monitor the pressure in the natural gas pipelines. When there is an inadequate supply of natural gas, the drop in pressure triggers a shut off mechanism that prevents the boiler from firing until the natural gas availability is restored.

Problems

• Low or no pressure prevents the boiler from functioning. If water pressure is too low, water is not drawn through the heat exchanger. If natural gas pressure is too low, the boiler is automatically shut down. Either situation results in a lack of available hot water or heat for your home, which can create potentially dangerous situations during cold winter months.

Troubleshooting

• A sudden drop in pressure may indicate a disruption in the water or natural gas level. If the water pressure gauge reading is less than 12 psi, you can open the boiler's water feed valve to manually increase the amount of water in system. Once the gauge reads 12 psi, close the valve and allow the boiler's automatic filling system to maintain the pressure. If the filling system does not maintain at least 12 psi, you may have a water leak that must be serviced by a technician. Failure to maintain 12 psi may also indicate an inadequate supply of natural gas. Check the natural gas control valve; if the valve is closed, open it to restore fuel to the boiler. A gradual decrease in pressure is more indicative of deposit buildup in the water pipelines of the boiler system. A technician can flush the system to clear the deposits and restore pressure.