SylvanLMP
The 118 pounds COLD water when heated will expand to over 150 PSI in a closed system.
The Velocity of this kind of pressure will erode your piping system.
Any water hammer with this kind of pressure can cause enough hydraulic shock waves to rupture your piping
Having a pressure that can elevate water to almost 273 FEET honestly doesn’t make sense unless your on a mountain top.
Most plumbing screwed fitting fittings are rated to only 125 PSI so any sudden close of a solenoid valve could quite easily cause enough shock waves to rupture a fitting or connection.
About the “flooding condition” the relief valve discharging outside is a LOUSY IDEA as when this valve does discharge it may go undetected and this could someone to get severely hurt.
Listening to ANY HELPER is not a very good idea as most helpers are parroting what they hear and not from actually reading SEVERAL codes.
The very 1st objective is LOWERING the pressure with a bronze pressure reducing valve then of course you can always add an expansion tank to take up the added pressure from heated water.
Most of the better plumbing codes require the in coming pressure to be REDUCED to below 85 PSI.
Personally I think you had better call a LMP or at the very least a Qualified Journeyman, with at least 5 years apprenticeship training.
Think about your washing machine Rubber hoses under this kind of constant pressure? POWWWWWWWWWWWWWWWWWWWWW
