A routine annual inspection and cleaning by a qualified, licensed heating contractor keeps your hot water heating system running for many years without trouble. But you can also keep an eye on the pressure and bleed the system to make sure that all is well between inspections.
Don't be pennywise and pound foolish. A dirty, inefficient boiler costs you far more than a service call. The service-person will catch little problems before they become big trouble, and a neglected system fails years sooner than a well-maintained one will.
Most hot water systems have a single gauge that measures three things: pressure, temperature, and altitude (the height of the water in the system).
Monitoring the pressure is important. Most boilers run with only 12 to 15 pounds of pressure. The boiler can become seriously damaged and even dangerous if the pressure exceeds 30 pounds.
Regularly monitoring the pressure is probably all you ever need to do to maintain your system. The majority of the maintenance tasks should be left to a heating professional. However, if the pressure is abnormally high, you may have a waterlogged expansion tank that can be drained. Before calling in a repairperson, attempt to resolve the problem yourself by draining the expansion tank.
Located overhead near the boiler, a conventional expansion tank is cylindrical and has a drain valve at one end. To drain the excess water, turn off the power, turn off the water supply to the boiler, and let the tank cool. Attach a garden hose to the valve, open it, and let water out until the levels of the pressure gauges on the boiler and the expansion tank match. Don't forget to close the valve, turn the power back on, and reopen the water supply.
If you have a diaphragm expansion tank, the pressure problem is not too much water — it's too little air. You need to recharge the expansion tank. Use an ordinary tire pressure gauge to check the air pressure. If it's lower than the recommended psi, or pounds per square inch (look on the tank for the correct reading), use a bicycle pump to juice it back up.
Check with a representative from your local building department or public utility to determine which type of expansion tank you have.
After the expansion tank has been drained or the diaphragm tank has been refilled, restart the system and monitor it carefully. If the pressure goes back up, turn the system off and call a professional. You've done all you can do!
Boilers must have a proper pressure-relief valve, located at the top, which opens when the pressure reaches 30 pounds to prevent the boiler from exploding. If you ever see water draining out of the relief valve, chances are that the system is operating under excessively high pressure and should be checked by a professional.
