[LazyPup]

John Sprung

Under normal circumstances there should be enough expansion capacity in your water hammer arrestors to compensate for thermal expansion of the water and there should be no increase in line pressure, however100 PSI is definitely tooo high.

The International Residential Code (IRC 2903.3.1) and the Uniform Plumbing Code (UPC608.2) require a pressure reducing valve on the water main whenever the pressure to the building exceeds 80psi.

When the pressure on the main exceeds 80psi you are also required to have an expansion tank on the cold water supply line immediately before the water heater vessel. (IRC2903.4) (UPC 608.3)

In regards to boiler drain cocks,,you can find them in any hardware or big box home supply plumbing dept. They are usually located close to the outside hose bib faucetts. Boiler cocks have the advantage that they are a full bore valve which will effect a better flush.

Also when flushing a tank, first ,,,MAKE SURE THE BURNER IS TURNED OFF or if an electric tank, make sure the electrical breaker is turned off. If a burner comes on while a tank is empty it will do severe damage to the vessel or in the case of electric tanks it will burn out the heating elements.

Attach your hose to the drain cock and run it ourside or to a suitable drain, then open the drain cock and allow it to flush for two to three minutes before turning the water heater supply valve off, that will give it a good forced flush. ( what is known in the boiler trade as a -Blow Down).

Once you turn the cold water supply off, open a hot water faucett in the kitchen or bathroom to allow air to vent in, which will allow the tank to drain quicker.


When the tank is drained, close the tank drain and open the cold water feed line. Keep the kitchen or bath faucett open to vent air as it fills.

Allow the tank to sit idle for 30 min to an hour to allow any sediments to settle, then open the drain valve again to flush that sediment.

Close the valve, remove the hose and relight the burner or switch the electrical breaker on.