Plumbing a pressure relief valve

[Banjo Bud]

i know the best way plumb one is to run the output into a drain or outside. Neither of those will be easy in any way in my situation. I’m thinking if they blow, (and what are the chances?) there can’t be that much water spewed out before it closes again. So I’m wondering if I can just route the output to a convenient spot in my crawl space. Or into a permanently placed bucket near the pump.

 

[Boycedrilling]

No, it’s going to put out a bunch of water. Say you’re on a 40-60 pressure switch and you have a 75 psi relief valve. What’s going to cause the system to go to 75 psi? A welded pressure switch. It’s not going to shut down.

 

[Sponsor]

 

[Banjo Bud]

Is that common?

 

[ThirdGenPump]

Depends on the size of the pump and potential for damage.

On a regular domestic system it's rare to plumb the relief valve anywhere, it just gets aimed down in front of the pressure tank. logic is it's better it dumps water on the basement floor than blows up a random pipe in a wall somewhere. If the pump stays over pressure it will continue to dump water there.

On larger systems I always hard pipe them outside, preferably to a location someone will notice.

 

[Banjo Bud]

It’s a 1/2 HP shallow well pump.

 

[Boycedrilling]

Plumbing code says to plumb a relief valve to a floor drain or outside. Does that actually get done? Not very often.

 

[Valveman]

99% of the time you will get away with it. But the 1% that has a prv pop off will certainly not like the flood it causes.