Water pump dying?

Thanks...pulling from both responses:

Old-Biscuit wrote:
Pump cycling ON/OFF (over a short time period) when not using water means there is a leak.
Pump is an ON Demand pump..........meaning pump should only come on when system pressure drops.
So a small leak will cause pressure to drop...pump comes on/pressure comes back up/pump turns off until leak causes pressure to drop again.

There should be NO noise unless pump is actually running otherwise the pump/motor are not doing anything.
Pump running constantly & loud was probably due to low water level in fresh water tank---losing suction (when you were home)

Hum/whine could be due to a faulty check valve in water heater outlet or the one in city water inlet.

I've seen the reference to a small leak before...haven't been able to find anything, although I wonder if the water heater relief valve could be the culprit. It feels rough and corroded/calcified when I open the relief valve when draining the water heater. (Trust me don't unscrew the plug on a pressurized water heater...learned that the hard way, but at least it was cold water :E) I've noticed it sometimes drips, but had not made the connection.

I thought the same about low water level and suction, but at the time the water was still well above the line to the pump.

mlts22 wrote:
I think it is time for a new pump. To keep it from doing late night "burrup" noises, Shurflo sells an accumulator tank, and I'd recommend replacing the pump and adding the tank. That way, when pressure varies, the pump will not need to short cycle, as it will run to pressurize the lines and the accumulator tank.

I've thought about the accumulator tank before...although I was looking at the larger Watts expansion tank that has been posted in several threads. Wasn't sure I'd have room for that tank, so am glad to see that ShurFlo makes a smaller one. Might go that route even if I don't end up replacing the pump.

Thanks...I'll start with the water heater relief valve and go from there.