I have a question for my personal home - I was getting a light water hammer at the washing machine so I tested the cold water outlet and it read 82 PSI (same as exterior faucets). The home is a new build and under warranty so I reached out to see if I could get a PRV installed as preventative maintenance to save them the later cost of potentially shortened appliance lifespans and leaking in the walls. They wouldn’t go for it.
I am happy to install one myself, just figured I would try to save the ~$100 for parts and some time - but my question is, do I really need to install one? With 80PSI being the max recommendation, surely they is some safety margin before you really start to have issues, so would y’all opt to fix this in your own homes or just look past it?
85 is excessive, 65 is what I recommend. Higher pressure is not a way to overcome poor plumbing design. By the way, hammering is caused by excessive water velocity and instant shutting off of water. Fix either one and hammering will stop. Too many of today’s crappy plumbing components are not designed for pressures of the past.
I had 100psi in my home for years and the only fixture that gave me a problem was the toilet. I have since installed a PRV and the minimum pressure of 70psi for the setting and that took care of any knocking. Years ago I installed one of these at the toilet before I installed the PRV. Left over from a school I was building. I still have it behind the toilet. LOL Works great.
Generally they are required on all quick closing valves appliances like washing machines, dishwashers and toilet valves. We don’t usually see water hammer arrestors on coffee machines and refrigerator ice makers because the flow rate is small, the velocity is low, and historically they are never a problem.
Homes with pex piping or cpvc don’t have a problem with knocking.
So did I until I started switching from metal risers to crappy braided. Had a flood in the kitchen, the riser decoupled at the crimp. Max rated at 125psi, throw in hot water and poor workmanship and bam! The new stuff just does not last when you’re pushing 80+ PSI
I never had a problem with those stop valves and neither with the braided connector hoses. Matter of fact the washing machines require those in lieu of rubber hoses.
Must be the quality that you bought or something.
I always install metal supply lines. I don’t trust the braided plastic hose garbage. There’s something satisfying when using a tube bender to make a brass supply line perfect. When I moved to NM I had to train my entire crew of trim plumbers on a hotel how to bend tube…ugh!
One Standard and what I believe is in the InterNACHI coarse/reference material will state that 40-80 psi is considered normal range. However there are a few things to consider. The extra 2psi per say may not be that big of a deal however seeing that most Pressure Reducing Valves or “Water Pressure Regulators” (that is what we call them in these here parts). Have a range that they can be set, usually something like 25-75 psi. (Factory set is usually 50 psi and is stamped on a tag)
The thing to Remember is 75 psi is the high side for those regulators. If you are reading over 75 psi, most likely the regulator is bad or the system does not have one installed. and that 82 reading may be Much higher at other times.
Now if I’m reading the OP correctly, The System does not have a regulator installed and you are reading 82 psi. At least where I am, city pressure fluctuates and normally always over 80 psi. 120-140 psi is very common here.
There are two reasons you need a “Pressure Regulator”
To keep water supply pressure at a “Safe Level”
To keep the pressure Consistent and Stable.*
Fluctuating pressure is not good. The weak link in most systems is the water heater, and fluctuating pressures (even if always in the normal range of less than 80 psi), will cause metal fatigue and that will eventually cause the WH tank to fail. (main reason for a thermal expansion tank and why your water heater warranty is void if a Thermal Expansion Tank not also installed )
*This is why I prefer the term “Pressure Regulator” and not simply Pressure Reducer.
Thanks Larry for the very detailed information, that will definitely help me explain things down the road to clients as I will surely encounter this on an inspection.
And correct - there is no regulator currently installed.
jdeoliveira2
(John Paul de Oliveira, GB-2 #86934 / AB #44580)
17
Same here Larry, have yet to see water utility pressures under 80 psi, over 110 psi is rare. Well pumps are typically in the recommended range.
Have rarely seen any problems with braided steel supply lines. There might be the occasional manufacturer defect.
jdeoliveira2
(John Paul de Oliveira, GB-2 #86934 / AB #44580)
18
Never thought about the fluctuating pressure inducing metal fatigue, definitely in the realm of the possible!
I still have it behind the toilet. LOL Works great.
maybe this shall help:
