Causing a Drop in Water Pressure

[jbehr4x4]

Hi. I have a plumbing question. I have never posted a plumbing question before but this seemingly simple problem has me lost. I have recently noticed very low water pressure in sinks and external hose bibs. I have great pressure for the first 20 seconds, basically until the expansion tank on the water heater empties and then my pressure is very low (~20-30 psi). It is basically like there is another fixture running. I have checked and I can find no other leaks. My water bill is not abnormal so I do not believe there is a leak. I have no easy way of getting to the pressure regulator as it is under the house and behind a ton of HVAC lines. I can get there if that is absolutely required

House is 3,000 sql feet, 2 floors. 3 year old Rheem hot water heater, new expansion tank, replaced all toilets and most sink fixtures over the last 4 years. House is 14 years old and in southeast US region (warm weather region). All plumbing is PEX.

Thanks in advance

 

[Jeff H Young]

Blockage restricting flow . Pressure is the same but takes awhile to build. often valve not fully open or broken at partial opening. Check at street too to verify meter valve fully open

 

[Sponsor]

 

[Reach4]

You have a water bill and a meter. I was wondering.

A thermal expansion tank should normally be empty of water once you have used a bit of water. Your air precharge would normally be set to the highest pressure that the city delivers. Having even 10 seconds of water in the thermal expansion tank is pretty much unheard of.

How big is this expansion tank you are talking about? An 11x15 inch thermal expansion tank is bigger than average.

I am wondering if the precious owner installed a pressure tank to work around a long-standing problem with the city water flow.

 

[Jeff H Young]

So. you checked the pressure and its only 20 to 30 psi ? I gotta pay attention better. That pressure before or after the regulator? if its befor and you are accurate then the problem is your supply from municipality. New water heater and expansion tank dosent sound like a previous owner dealing with wild pressure fluctuation. Your pressure never is above 30 psi? You check at night ? differant times of day?

 

[Reach4]

I missed the part about the regulator. Clean the strainer screen in the regulator (PRV), and maybe re-route the pipes to make the PRV accessible.