Submersible pump, 20 gallon bladder tank, 30/50 switch. Since about a week ago the pump kicks on and off roughly every 20 seconds during a shower and the pressure noticeably surges. Tapping the tank sounds solid most of the way up rather than hollow at the top. Nothing else has changed and the water is clear. Is this the tank or the switch, and is running it like this doing damage?
That's a waterlogged tank, and yes, it's hard on the pump, so I wouldn't leave it for weeks. The bladder has either failed or the air charge has leaked out, and a tank that sounds solid most of the way up is the classic sign. Test it properly: turn off the pump breaker, open a tap to drain the pressure to zero, then check the air valve on top of the tank with a tyre gauge. It should read 2 psi below your cut-in, so 28 for a 30/50. If air comes out fine but reads low, recharge it and see if it holds. If water squirts out of that valve, the bladder is torn and the tank needs replacing.
Bigger is generally better, longer run times and fewer starts. The only limits are space and the fittings. Going to a 40 or 44 gallon is a common upgrade and your pump will thank you.
Water out of the valve. So that's that. Any reason not to go bigger than 20 gallons on the replacement?
When you do replace it, set the air charge with the tank empty and the pump off, and check it again once a year. It's a two minute job with a bike pump and a tyre gauge, and it more or less doubles the life of the tank.
Before you buy a tank, also make sure the small tube to the pressure switch isn't clogged with iron or sediment, which produces very similar surging. It's a five minute check and I've seen it be the whole problem twice.
@uptime_hoarder · 3mo ago · 2 replies
Short cycling is the single most common way people kill a well pump, because it's the startup current that wears the motor, not the running. A pump that starts three times a minute in the shower is doing many times the wear of one that runs continuously for two minutes. Fix it soon rather than at your convenience.
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@skillet_sig · 3mo ago
Can confirm the expensive way. Ignored a waterlogged tank for two months and replaced a pump instead of a tank.
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