I've got a problem with my pressure tank, 1.25 gallons of drawdown on a 20 gallon tank

[Dis360]

I've done some research but can't pin down what wrong with my pressure tank. Ever since I lived in my house my pressure tank has always kicked on/off very often, running a shower or a toilet filling up causes it to kick on more than once every minute. I decided to test it and determined my drawdown is only 1.25 gallons, my pressure tank is 20 gallons and says it's factory charged to 30psi. I've read drawdown for a 20 gallon tank at 30-50psi is about 5.5 gallons. What's wrong with mine?

One odd thing I noticed is the pressure at my whole house filter goes down to about 30psi and almost 60psi on the high side, when the water is running it will drop from 60psi to 50psi within a second or two. Is the pressure switch/valve suppose to spike the pressure above 50psi if it's set to 50psi? One thing I did notice is my pressure tank tee has no check valve, is that required? Is it possible my tanks air pressure is screwed up? Is it possible someone set the pressure switch to 30-60psi, can it be set to any low and high pressure within spec?

Questions?
-- What do I need to look at to try to get back proper drawdown for my 20 gallon tank?
-- Since the water pressure appears to be cycling between 30-60psi, do I just need to adjust it to be 30-50psi or 40-60psi?

 

[Andre Martinez]

This may help if you haven't checked the air pressure in tank.
https://terrylove.com/forums/index.php?threads/pressure-tank-maintenance.20849/

Do you have a bypass at filter that you could test if pressure is changed.

 

[Sponsor]

 

[Reach4]

my pressure tank is 20 gallons and says it's factory charged to 30psi. I've read drawdown for a 20 gallon tank at 30-50psi is about 5.5 gallons. What's wrong with mine?

How old is your tank? People usually say to check air precharge annually. I don't check mine that often.

 

[Dis360]

Do you have a bypass at filter that you could test if pressure is changed.

What do you mean by testing at bypass if pressure changes?

I do have a bypass after my tank at the whole house filter, also have a spin down where I can purge water elsewhere.

 

[Dis360]

How old is your tank? People usually say to check air precharge annually. I don't check mine that often.

The tank was replaced somewhere around 5-8 years ago. I suppose checking the air pressure is my next step. From what I can tell I have to empty the tank to accurately test the air pressure.

 

[Andre Martinez]

What do you mean by testing at bypass if pressure changes?

I mean use the bypass to bypass filter to see if your pressure is better or the same. So you would know the filters are not the problem

 

[Sarg]

Best guess is the air pressure in your tank is not set correctly or your tank has a bladder leak causing same condition.
Turn off the pump and open a faucet so the water pressure goes to zero ...... then check the air pressure in the tank the same as you check a tire. The schrader valve is on top.
Be attentive for any water coming from the valve which would suggest the bladder is leaking. Set the pressure to 2 psi less than the switch start pressure i.e. 28 psi. The pressure tank is critical to your system operation.
The system cycling is probably caused by a slow leak .... dropping the pressure down between the tank and your pump which kicks the pump on.
I would suggest also start studying CSV ( cycle stop valves) . I recently experienced just what you are going through and would guess you will be replacing your pressure tank and finding why your system won't hold pressure ( check valve ).
https://cyclestopvalves.com/

I replaced the whole system.

 

[Dis360]

I mean use the bypass to bypass filter to see if your pressure is better or the same. So you would know the filters are not the problem

Gotcha I see, it threw me off initially because if filtration was causing a problem that would probably be a pressure drop but the drawdown of the tank would be somewhat similar with bypassing it or not. Although I did a test at my pressure tanks water valve and it cycles fast, about 1.2 gallons, which happens in a matter of 10-15 seconds at full blast.

 

[Dis360]

The system cycling is probably caused by a slow leak .... dropping the pressure down between the tank and your pump which kicks the pump on.

You mean the underground line from well to tank? My pressure after the tank does stay completely steady when water is not being used. I'll test the tank pressure today and see how it's looking.

 

[Reach4]

Your 20 gallon tank is small. I think adjusting your precharge may well make it a lot better, but if you do need to replace the tank, go at least 32 gallons. Those still have a 1 inch connection. Above that, it is 1-1/4 -- not that it is not easy to adapt.

 

[Sarg]

If your water pressure holds steady ( so your system does not cycle when no water is being used ) that's good news. It indicates the check valve at the pump is holding and it isolates your problem back to the tank.

Study the CSV concepts ... it eliminates small pressure tank issues & cycling of your pump.

Just to mention ...... there is another potential problem area that can generate erratic operation ... and that is the 1/4" nipple that connects your system "T" to the pressure switch. Over time they become plugged with sediment. ( Mine only had a pinhole left when I replaced it )

 

[LLigetfa]

Be attentive for any water coming from the valve which would suggest the bladder is leaking.

On most tanks, the valve is at the top so the tank can be 90% full of water and no water will come out of the air valve. Only when there is 100% water will water come out so it is a dubious test unless you turn the tank upside down.

 

[Dis360]

WOW, what a difference...

I turned the pump off and drained the water, by the way when I turn my pump off it completely trashes my water quality when I turn the pump back on, stirs up all kinds of silt and shale, I believe this is due to the absence of a check valve at my pressure tank tee and dumping water back into the well. I checked the air pressure and it reads 5 psi, so I pressurized it to 28psi, left it alone for about 45 mins, rechecked it and it held the pressure.

Then I turned the pump back on and left a hose spigot open and immediately noticed the pump staying on and off significantly longer. I also noticed the off and on pressure settings were out of wack, it would kick on at 36psi and off at 62psi, I pulled the lid off the pressure switch and it says it's a 30/50.

It took a while but I adjusted it to kick off and on at 30/50psi and the drawdown time lengthened even more, it's completely different now than it was before, the ramp up time takes much longer and the drawdown is magnitudes longer.

My thoughts now is that this pressure tank is original to the house which was built in 1993, I have found paperwork showing the well pump was replaced in 2012 and again in 2019, I think I found out why. I also confirmed the pump currently installed is a Mcdonald 24075k, 3/4HP the specs say at my water level depth it's capable of over 15GPM although I don't think my well can replenish itself that fast, not really sure. I am curious if I can I set my 30/50 switch to 40/60 (it was almost set to that before adjusting)? or buy a 40/60 and use it with my 20 gallon pressure tank? I assume the downside with a 40/60 and a 20 gallon tank is the pump will cycle more often. Are my best options for increasing pressure to go with a 40/60 and either a larger pressure tank or install a CSV and set it to 50psi?

 

[Reach4]

Make checking that air precharge annual for a while. And flush sediment, discussed below. I don't do those that often myself, but annually is a good general timeframe.

I am curious if I can I set my 30/50 switch to 40/60 (it was almost set to that before adjusting)?

Probably. Start with turning the nut on the big screw 3.5 turns CW. Increase the air precharge to 2 psi under the new cut-in.

I turned the pump off and drained the water, by the way when I turn my pump off it completely trashes my water quality when I turn the pump back on, stirs up all kinds of silt and shale, I believe this is due to the absence of a check valve at my pressure tank tee and dumping water back into the well. I checked the air pressure and it reads 5 psi, so I pressurized it to 28psi, left it alone for about 45 mins, rechecked it and it held the pressure.

It may just be sediment that has accumulated. Flush your pressure tank at maybe annually too, via the drain valve. You can run a hose. Cycle until the water runs clean.
https://terrylove.com/forums/index....o-zero-before-pump-cuts-on.77612/#post-645264

 

[Sarg]

"I believe this is due to the absence of a check valve at my pressure tank tee"

You really only want one check valve at the pump ..... none above ground. That creates other problems like the "hammer effect".
You never lost pressure before so you do not have retreating water "stirring things up"..... It stays within the piping. I also have crappy water and I now wet vac my toilet tank about once a month to remove 1/8" of sediment. I imagine next fall I will find lots of crap in my water heater when I do the yearly maintenance.

You're back to your "norm". Good news.

Two ways to reduce cycling ... larger tank or a CSV. If you have a family that likes showers that is where the benefit of the CSV comes in ....... longer duration of usage that keeps the pump running at a specific pressure.

I installed mine and I'm now satisfied with my system.

Just be aware you may still have issues with your current tank ... I never realized the bladder in my old tank had a rupture until I lifted it out and shook it ......... there was water trapped above the bladder. And just looking at your first picture the tank doesn't look like it has been in service 27 years .......... but my last tank was 14 years old when replaced.

One last suggestion ..... the piping in your first picture ... the house feed looks like the gray stuff I am familiar with ..... If it is the polybutylene pipe ..... I would stick with the 30/50 setting.

 

[LLigetfa]

I also confirmed the pump currently installed is a Mcdonald 24075k, 3/4HP the specs say at my water level depth it's capable of over 15GPM although I don't think my well can replenish itself that fast, not really sure.

When you turned the pump off and drained the system in order to adjust the precharge, the pump then started against less head. Pumps run on a curve, meaning at higher head they produce fewer GPM. Starting it at less head produced more GPM than when it starts at 36 PSI so the additional GPM may have motivated some sediment.

If when the pump shuts off at 50 PSI and there is no water used, does the pressure hold? If so, there is no problem with the check valve in the pump. As mentioned, there should not be a check valve at the tank.

 

[Dis360]

It may just be sediment that has accumulated. Flush your pressure tank at maybe annually too, via the drain valve. You can run a hose. Cycle until the water runs clean.

I think you nailed it. I didn't realize sediment could be building up in the pressure tank itself I thought it just shot through. I am noticing today that I am getting huge amounts sediment clogging up my 50 micron spin down filter, to the point where water almost stops at the faucets, and then I have to go and purge the spin down filter to get them running again, its never been this bad before. I think I have woken up the sediment beast after inflating the bladder probably after 10's of years of no maintenance. Yesterday when I was running a hose from the house spigot while setting the 30/50 pressure switch every time the pump would kick on the water would turn brown and have visible sediment in it. I will attach a host to the pressure tank and purge is multiple time from there, hopefully I can clear it out.

 

[Dis360]

If when the pump shuts off at 50 PSI and there is no water used, does the pressure hold? If so, there is no problem with the check valve in the pump. As mentioned, there should not be a check valve at the tank.

Ok that makes sense and I assume same goes for the pressure tank itself, stirred up more sediment. The pressure does hold when the pump stops.

 

[LLigetfa]

by the way when I turn my pump off it completely trashes my water quality when I turn the pump back on

Was there any sediment when you drained the tank or did it just start after the pump was turned back on? If only after, the sediment is probably coming directly from the well and is not an accumulation in the tank. If it does not clear up with hard pumping, you might need to add a dole valve to limit the pump GPM.

Also, if the bottom of the well filled with sediment up to the pump's intake, then the pump motor is buried in sediment. That could shorten the life of the pump. That depends on the well formation and whether the water is coming from above or below the pump.

My well is such that I have to limit the GPM to keep from motivating sediment.

 

[Dis360]

Just be aware you may still have issues with your current tank ... I never realized the bladder in my old tank had a rupture until I lifted it out and shook it ......... there was water trapped above the bladder. And just looking at your first picture the tank doesn't look like it has been in service 27 years .......... but my last tank was 14 years old when replaced.

One last suggestion ..... the piping in your first picture ... the house feed looks like the gray stuff I am familiar with ..... If it is the polybutylene pipe ..... I would stick with the 30/50 setting.

I may have the same problem with my tank, there seems to be a very large amount of sediment trapped inside of it, maybe it's getting above the bladder. From quick research I see my 20 gallon pressure tank with a drawdown of 6.8 gallons @ 30/50 psi is substantially undersized for my 12.5 GPM @ 50psi pump, I understand you want 1.5 x 12.5GPM = 18.75 gallons of drawdown and I've only got 6.8, the pump will never run for a minimum or 1 minute like that.

I think at minimum I need either a much larger tank ~60 gallon or a CSV or something to reduce the GPM, this pump isn't matched to the tank size, this house originally came with a 6GPM pump.

And yes that is polybutylene but is in good shape, it uses the copper fittings instead or the older plastic ones.