Hello, I seem to have some problems with my water pump. If I just run one
home appliance for the water, the pressure drops pretty quickly.
For instance , Im trying to water my lawn now.. the pump gets up to 60 PSI ,
and then drops to about 37 PSI within 2 minutes...then the pump turns on
again. Doesnt this seem to be dropping too quickly? I wanted to run 2
sprinklers at the same time, but it seems impossible with the quick pressure
I have a picture of my setup here -
maybe I need a bigger resorvoir ?
If temporarily increasing the water pressure just for the sprinklers would
work, im willing to do it. Just not sure which knob increases the pressure.
Any info would be awesome. (And I will be careful if I get some advice here
on increasing the pressure.)
Put the sprinkler in a 5 gallon bucket and turn it on. How long does
it take to fill the bucket? If it takes about 1/2 a minute or so, you
probably have no problem with the reservoir. Otherwise, check the
pressure in it with the water pressure released. It should be 2 psi
less than your pump cut in pressure (35 psi).
What happens if you run 2 sprinklers? The pump may run full-time, but
does it supply sufficient pressure for the sprinklers? If so, you
again have no problem, unless your well cannot supply enough water
over time. If the pump runs full time but the pressure is
insufficient, then you need a more powerful pump to run two
sprinklers. Just run one at a time, or get lower volume sprinklers.
Bob, I was already doing something before I came upon your post. I added
air to it so that its at 20 PSI now. Its suppose to be at 30PSI but my air
compressor wasnt strong enough.. It stopped at 20 PSI. (one of those
cigerrete lighter ones..i need to get a real one soon.)
But even at 20 PSI, the pump turns back on after 2 minutes of running the
water from one outlet at full strength. (didnt seem to make much of any
difference..maybe a little but thats it)
Like even if I run my bathroom faucet by itself at full blast (cold water)
the pump turns on anywhere from 90 seconds to 2 minutes. Is this a normal
time or no? Like what is the normal amount of time it should turn on after
one water outlet is running full blast?
The water flows good/strong...but once its at 37 PSI, its barely pumping out
from the sprinkler.
How bout temporarily adjusting the pump so that it cuts off at 70 or so?
I'll make sure I have the sprinklers on at all times when its at that
level.. Is there a way to adjust that or no?
Increasing the pressure cut-off/on pressure in the tank will
_decrease_ the useable amouint of water it contains. You didn't
specify the procedure you used to check the air pressure (known as
"pre-charge") in the tank.
Proper and only way to do it right.
1. shut off pump.
2. Open a valve (preferably near the same level as the tank) until
water stops flowing.
3. Shut valve and check the pressure. You seem to have it set now at
40-60 (within reason) so the pre-charge should be 38 or 2 psi below
the cut-in pressure.
You might buy a portable air tank and fill it at a gas station for a
source of hight pressure air.
It sounds like your tank is too small. Mine stands almost 6ft high
and will haul 3 heads about 4 minutes (never checked it) between
I use the same gauge thats on the water tank for the reading right?
and is it possible to check the pressure with a seperate gauge that attaches
to the air valve at the top of the tank?
My tank (thats in the initial post picture) is only about 5 feet high. Im
guessing its the tank then... crap..
I am on dialup so didn't check the picture at first. That looks like
a new installation. The tank looks plenty large to do a reasonable
watering job (2-3 heads at least).
Yes, normally use the same gauge as there is some variance in the
usual ones. You can check it either by the one on the tank or by the
fitting on top but the process is the same in either case.
If you do decide that you need more storeage, you can add another tank
working in conjunction with the one you have. It would just tee off
of the pipe leading in/out of your current tank.
Even car tires need more than 20 psi. Are you sure?
Remember, guages may be wrong. Do you have a tire guage? The pressure
in the bladder tank shoud be 2 psi less than the cut-in pressure of
the pump switch, when water pressure is released with the pump off. Do
you have a manual tire pump?
How much water is that? Measure it.
How much water is that? Different faucets have different flow. My hose
bibb puts out about 15 gallons / minute. That would cycle your tank
You have a differential of 23 psi, which seems pretty large. You can
change it (look for instructions inside the pressure switch cover),
but it will shorten the cycle even more. Is you do this, you also need
to increase your pressure tank pressure.
How long is your hose? What water volume does the sprinkler use per
minute? What diameter is the inside of you hose? Does the sprinkler
work OK if you connect it directly to your faucet. If so, get a bigger
diameter and/or shorter hose.
Don't increase the cut-out pressure. Increase the cut-in to the
If your pump can't get it above 39 when it switches on, changing the
settings isn't going to help. If it can, changing the cut-in pressure
will help with the sprinklers, but will shorten the cycle otherwise.
When you run 2 sprinklers, what does the pressure do? Does it get down
to 39, switch on the pump, which then run continuously, gradually
increasing pressure until it stabilizes at something below cut-out? Or
does the pressure increase to cut out, then drop again? Or does it
drop from 39? It all depends on the pumping capacity of the pump and
piping and the sprinkler need. When you run sprinklers, the pump will
either cycle or run continuously. You can add storage, which would
increase the cycle time, but the pump will still cycle if it pumps
more water than you are using.
It's probably better for your pump to pump continuously rather than
cycle on/off when you are watering, if your water supply can keep up
with it. If the pump cycles with 2 sprinklers, try using more and see
if you hit a balance point where the pressure is sufficient but the
pump keeps running.
Some minor comments.
23psi is right on the normal pressure differential for residential
systems (allowing for gauge variations). Normal settings are:
20/40 - Too low if irrigating.
30/50 - adequate and will run sprinklers. Some sprinklers will have
problems at the 30 psi end of the cycle.
40/60 - No need that I know of for a residence to ever go higher.
Higher ranges are not recommended due to excess wear on fixtures.
The "2psi below cut-in" optimizes the pump run time.
His 20 psi pre-charge is too low but it has nothing to do with the
'delivered pressure'. If the the switch is set 40/60 with 20psi
precharge water will still be coming out of the tank between 40/60
Pump will cycle more is all.
I appreciate all the advice here.
Alright, adding that 20 PSI air to the tank seems to have helped alot....BUT
I still cycle about once every 80 seconds. the sprinkler I have is the
largest the store had...im not sure on the exact size but it covers the most
amount of land out of all others..and is one of those sprinklers that goes
back and forth. I was never even able to get this amount of pressure out
of my sprinkler before.. It shoots out very good now and continues like that
all the time...even when the pressure is down to 37 PSI. The sprinkler
covers about a 1/8 acre of land. pretty powerful. That is estimated of
course. Im sure if I was able to get 30 PSI into it, it would be even
better...but i'll have to buy one of those power washer things for that.
(with the powerful air compressor)
So im guessing it worked...because before when I was down to 37 PSI, the
water would barely come out of the sprinkler. So it fixed it, even though
it still short cycles...the water comes out really good now and stays like
that throughout. Im proud of this.
I guess the next question is...is it normal to cycle once every 80 seconds
when so much water is being pumped out like this? I still dont think
anybody answered what is the general normal time that a pump cycles if a
cold water faucet is on full blast ? Mine doesnt seem to go past 90
The filter fixed the sprinkler problem. More air in the tank will
lessen the short cycle problem.
Again (the third time) how much water is the sprinkler using? How big
is the pressure tank? The combination, along with some factor for the
amount of the tank that going from 39 to 60 psi fills, will tell you
if the tank is working right. Probably, adjusting the air in the tank
correctly will make a significant difference.
I'd guess that factor would be .25, since filling the tank half way
should double the initial pressure to 80. Pressurizing the water to 60
should take it to half that. So your tank would supply 1/4 its volume
of water between pump off and pump on. Someone correct me if I'm
Doing a little more mental calculation, Having the tank pressurized to
20 initially would mean that when it gets to the 40 psi cut-in, the
tank is already half full, so you are only getting half its useful
volume during a pump cycle.
You are still missing how the pre-charge works. When the system
reaches cut-in (40 in this case) the tank will be empty no matter what
the pre-charge is. The pre-charge has no effect on delivered
pressure, only on the useable volume of water per cycle.
If the precharge is 20, at 40 the tank will be half full, to compress
the precharge to 40, leaving less than desirable volume. I have no
disagreement with the second sentence - I never said otherwise.
Pardon me for butting in, and I haven't seen the earlier portion of the
thread so I may be missing the point but just in case I didn't... :)
These last several repartees are based it seems on the assumption the
precharge volume is the same as the total tank volume but it isn't.
Oh? Since the precharge is added with the tank empty, why wouldn't it
be the 'total tank volume'? Of course it isn't once the pump kicks in
and adds water into the tank compressing that air bubble.
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