1.   An hour later there was a build-up of pressure when a relief valve failed to open automatically.

2.   Comedy was the relief valve.

3.   Near the top of the hot water heater you should find a pressure relief valve, possibly fitted with a long downspout.

4.   The cure is to replace the pressure relief valve.

5.   The pressure relief valve is a safety feature that is found on most, but not all, hot water heaters.

6.   To avoid both explosions and injuries, the guns have a relief valve that limits how high the pressures can go.

7.   When I turn up the heat and my gas boiler goes on, water comes out from the drainpipe that I think is the safety relief valve.

8.   Embargoes also are likely to include relief valves, such as measures to provide for humanitarian aid.

9.   Authorities said the blast was due to a faulty relief valve.