A pump that clicks on and off every few seconds, or runs when nobody is using water, is wearing itself out. The usual causes are the pressure tank, a leak or a check valve.
A rainwater pump should start when you open a tap, run steadily, and stop shortly after you close it. If it clicks on and off every few seconds while water is running, or kicks on when nobody is using water, it's short cycling. Every start wears the motor and the pressure switch, so it's worth finding the cause quickly. Here's where to look.
This is the most common cause. The pressure tank holds a cushion of air that lets the pump run in longer, steadier cycles. When that charge leaks down, or the bladder fails and the tank fills with water, the pump has nothing to push against and restarts constantly. Our post on low water pressure walks through checking the air charge with a tire gauge. If water comes out of the air valve, the bladder has failed and the tank needs replacing.
If the pump kicks on for a few seconds every so often with every tap closed, water is leaving the system somewhere. Check for a running toilet (a leaking flapper is the classic cause), a dripping outdoor spigot, an irrigation zone or valve that isn't fully closing, or a wet spot along a buried line. Turn off the house supply valve after the pressure tank. If the cycling stops, the leak is in the house or irrigation. If it continues, look at the equipment side.
The check valve keeps pressurized water from draining back toward the tank when the pump stops. If it doesn't seal, pressure bleeds off slowly and the pump restarts to make it up, sometimes with a short hiss or gurgle. A failing check valve can also let the pump lose prime.
When the tank gets very low, the pump can pull air. Many variable-speed pumps protect themselves by shutting down on a dry-run fault and retrying a few minutes later, which can look like cycling. Check the tank level before anything else in a dry spell.
On a pressure-switch system, a clogged sensing port or worn contacts can make the switch chatter. On variable-speed pumps, a wrong setting or failing pressure sensor can cause the same symptom. These are best checked by someone who knows the specific pump.
If the pressure tank checks out and there's no leak in the house, the cause is usually a check valve, the switch or the pump controller. Don't let it run that way for long, because the pump is the most expensive part of the system to replace. We service DAB, Grundfos and other pumps on any installer's system. Call (512) 829-5800 or request service online. Plan customers get a pump and pressure-tank check at every visit; see our maintenance plans.
Questions about your system? Call Dripping Rainwater at (512) 829-5800.
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