Pressure tank size

[garymace]

Hello,

We have a home built about 3 years ago. It has a 800' deep well and a system I think they call constant pressure. It uses a subdrive but a much smaller pressure tank that our last home with a standard system and large pressure tank.

That darn sub drive just seems to run and run and run. Seems to rarely shut off. And when it does, even getting a glass of water starts it up running again. And it is just annoyingly loud, but I'm told thats normal.

The pressure tank installed is very small. About the smallest you can get I think. Smaller than a gas grill propane tank. I did check the PSI in tank and it is to spec.

My question is would installing a larger pressure tank allow this stupid subdrive to run less?

I hate this system but stuck with it unless I want to dump a lot of money on a standard system. Which is what I am likely to do when this pump goes south!

Thanks.

 

[Valveman]

That little pressure switch that comes with a Subdrive only has 2 PSI between on and off. So adding a larger tank won't help anything. You need more than 2 PSI pressure switch to make any size tank hold water. With only 2 PSI between on and off you don't put any water in a tank or get any out like you would with a standard 40/60 pressure switch. Now having said that, you can switch out that little dinky pressure switch for a regular 40/60 pressure switch, and then a larger tank would help.

But since the pump is running all the time I doubt that it can reach the shut off pressure, and the larger tank and switch may not help anything. My guess is that the Subdrive running the pump at 4700 RPM instead of the normal 3450 RPM has worn out the pump and it can no longer build enough pressure to reach the shut off point. I think you are going to need a new pump.

When you switch it back to a regular single phase motor and standard 3450 RPM pump, you can use a CSV to get your constant pressure, make the pump last longer, and still be able to use a small pressure tank. CSV's are sized to match the pump. So we would need to know the size of the pump and the depth to water in the well.

 

[Sponsor]

 

[Craigpump]

How do know it's not shutting off? Is your electric bill high? Poor pressure? Are you sure you're not hearing the fan running?

Not defending Sub Drives, just asking questions

 

[Reach4]

And it is just annoyingly loud, but I'm told thats normal.

I am curious about what makes noise. I don't know such systems. I would not have guessed that there would be a noise problem with a submersible pump. Is that the controller whining, or what? Is it a hum, a ticking, or what?

Can you feel the pieces to see where the noise comes from, and does grasping any part change the noise significantly?

 

[Craigpump]

The controllers are basically a computer and they require a fan to keep them cool. He's probably hearing the fan running.