House water pressure via expansion tank

[Rocky345]

I currently do not have a pressure gauge that fits an outdoor bib but I do have a tire pressure gauge. If I check the pressure at the schrader valve assuming the system is pressurized, will that give me the water pressure for the house?

 

[Reach4]

Maybe. However those garden hose thread pressure gauges are pretty inexpensive.

If the air precharge is lower than the house water pressure then yes. BUT the air precharge should usually be set to the highest incoming pressure, so if the current water pressure is less than the air precharge pressure, then NO.

 

[Sponsor]

 

[Rocky345]

Maybe. However those garden hose thread pressure gauges are pretty inexpensive.

If the air precharge is lower than the house water pressure then yes. BUT the air precharge should usually be set to the highest incoming pressure, so if the current water pressure is less than the air precharge pressure, then NO.

I had checked the pressure via the schrader valve pressurized by the system and it was 49psi. I then turned off the inlet water supply and turned on a faucet to let off the pressure and the schrader measured ~47.

 

[Reach4]

If the 49 was due to thermal expansion, and opening a valve gave 47, then you would expect to see 47 after you close that valve. If the reading went back up to 49, things would be less clear.