Multimeter told me my pressure gauge was lying the whole time

Started by Jason Okafor · · 3 replies
Back to the forum
Reply
#1
Had a weird thing this week, pressure gauge on my sand filter has been reading about 5 psi higher than it should for who knows how long. Only noticed because flow through the returns seemed weaker than the gauge said it should be. Pulled the gauge, they're like $8-10 at the big box, threw a new one on and suddenly my baseline is 15 instead of 20. Kind of unsettling that I've been backwashing off a number that wasn't real.

Makes me want to check it every season instead of just trusting it forever. For what it's worth these things are cheap enough there's no excuse not to swap one if it's been on there since install. Anybody else had a gauge just slowly drift like that or was mine just a dud from the jump.

3 Replies

#2
Had one drift on me too, gauge sat outside in the sun and salt air for a few years and the bourdon tube just gets tired, it's not a dud thing it's a wear thing. Cheap insurance to swap it every couple years, don't wait for it to lie to you.

5psi off is enough to make you backwash later than you should and shorten your sand life. Mine's been a $10 gauge every few seasons since, no reason to overthink it.
#3
Sun cooks everything out here, gauges included. Mine did the same drift after a few summers, figured 20 was just my number until I swapped it and baseline dropped too.

Cheap part, no reason to trust it blind. I just replace mine on a schedule now instead of waiting for the flow to tell on it.
#4
Before jumping on the gauge as the culprit, what's your clean filter start pressure supposed to be at your actual flow rate, not just the number that's always been on the dial. If nobody ever did a startup reading with a known good gauge right after a fresh sand change, the "15 instead of 20" could just as easily be a flow change over the years, impeller wear, something creeping into the plumbing, rather than pure gauge drift. I run mine off a VS pump so I actually watch gpm alongside pressure, and pressure alone without knowing what flow you're at that day doesn't tell you much. Worth figuring out before you just assume the old gauge was the whole story.