Well pump pressure and drawdown
#1
07-08-16, 04:43 AM
Well pump pressure and drawdown
I have a submersible pump that when it kicks on only draws down about 5 gallon. It only runs about 10 to 15 seconds. the water pressure when in the shower will be good, go low, then kick on and be good again. I only have a small tank in my well pit as there is not a lot of space. I was thinking of putting another tank in my basement and hooking it up, using both tanks to enhance the drawdown. is this possible? I was looking at a water works 86 gallon tank to get an additional 20 gallons of drawdown, would that be the right size? does any one have any experience with water works tanks? I run at 30/50 pressure switch. should I switch to a 40 60? my main concern is that the cycle time for the submersible pump is too short and in time will take out the pump, anything you can think of that I might be missing? thanks.
#2
07-08-16, 05:25 AM
Sounds like the bladder in your tank has ruptured.
Can you shut the pump off, drain the tank and check the air pressure inside the bladder ?
Can you shut the pump off, drain the tank and check the air pressure inside the bladder ?
#3
07-08-16, 06:53 AM
Member
As Vermont suggested, first step would be to drain the tank and measure the precharge to make sure you are getting the best performance from the tank you have. Tank has to be empty and drain valve open to get good reading.
If the pressure in the shower seems like it drops to lower than the 30 psi you would expect, you should clean the nipple between the tank Tee and the pressure switch; it is likely clogged. Easy to do this while you have system drained to check pre-charge. You will have to kill the power to disconnect the switch so you can remove it to clean the nipple.
While a short run time by itself isn't necessarily a pump killer, a tank that is too small will also lead to frequent pump cycles, which does shorten pump life. Adding a second tank in the basement would be a good approach. you would precharge it to the same 28 PSI that the existing tank should have for a 30-50 switch. Adding that tank should give you a runtime close to a minute and should cut way down on cycles.
I suggest you check the precharge and clean the nipple to the pressure switch and see if that by itself helps enough. If not, you can add the tank.
If the pressure in the shower seems like it drops to lower than the 30 psi you would expect, you should clean the nipple between the tank Tee and the pressure switch; it is likely clogged. Easy to do this while you have system drained to check pre-charge. You will have to kill the power to disconnect the switch so you can remove it to clean the nipple.
While a short run time by itself isn't necessarily a pump killer, a tank that is too small will also lead to frequent pump cycles, which does shorten pump life. Adding a second tank in the basement would be a good approach. you would precharge it to the same 28 PSI that the existing tank should have for a 30-50 switch. Adding that tank should give you a runtime close to a minute and should cut way down on cycles.
I suggest you check the precharge and clean the nipple to the pressure switch and see if that by itself helps enough. If not, you can add the tank.
#4
07-23-16, 04:23 AM
I have done all the things that you suggested and from what I can see there is no problem, water shut off 28 pds pressure in tank, pipes all clean and pressure switch working properly. I checked the manufacturers drawdown specs and it is what I am getting, 5 gallons of water from cut out to cut in. questions is how much bigger tank to install in the basement to bring it to a 20 gallon drawdown between cycleswith a 30/50 switch, that means an additiona 15 gallons per cycle. thanks
frank
frank
#5
07-23-16, 04:34 AM
Group Moderator
Just look at pressure tank manufacturers websites. As part of the specs they list the tidal volume of the tanks. Or, you can do math. If your current tank provides 1/4 the drawdown you want you need a tank four times bigger.
#6
07-23-16, 07:14 AM
Member
Here's an example chart: http://www.amtrol.com/media/document...sizingCard.pdf
As you can see, for that brand a nominal 62 gallon tank will give you close to 20 gallon draw down at 30-50 psi.
For a given tank, 30-50 will give you more draw down than 40-60 or higher.
Good luck with your project!
As you can see, for that brand a nominal 62 gallon tank will give you close to 20 gallon draw down at 30-50 psi.
For a given tank, 30-50 will give you more draw down than 40-60 or higher.
Good luck with your project!
