Reliance 505 Water Heater T&P Relief Valve Home › Forums › Public Forums › General Plumbing › Reliance 505 Water Heater T&P Relief Valve This topic has 1 reply, 2 voices, and was last updated 23 years, 9 months ago by SylvanLMP. Viewing 1 reply thread Author Posts 14 Apr 2001 at 7:56 pm #274870 MasterPlumbersKeymaster Valve stays open. Other than defective valve, could there be any other cause? i.e., sediment causing heater to overheat somehow? 15 Apr 2001 at 7:14 pm #290634 SylvanLMPParticipant A normal T&P watts 3/4 valve cost me about $3.50 IS IT REALLY WORTH guessing rather then having the existing one changed? Remember the T&P is your ONLY safety on these tanks the rest are just operating controls READ THE ASME section 2 and IV Author Posts Viewing 1 reply thread You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In