Using a pressure tank for storage on a low yield well.

Using a pressure tank for storage on a low yield well.


Today I wanted to go over how to use a
pressure tank for storage in a low yield well situation. this can be done
down gallon, two gallon per minute wells and still have enough supply for a house
even though it’s not optimal it’s cheaper than the alternative of having a
non pressurized storage tank and then pumping it back out with a booster pump.
You got a lot less moving parts but a lot less maintenance and initial upfront
investment is cheaper too. It varies a little bit depending on the type of tank
you have the best most capable tanks for doing this or a full bladder tank
there’s two different types of captive air tanks there’s well actually three
different types of captive air tanks you’ll either have a bladder tank or a
diaphragm tank or I’m going to separate that one further into a diaphragm with
top containment there bladder tanks are the easiest to adjust and get the most
storage out of the volume of the tank the simplest way to do them is to pick
out what your minimum requirement is for the amount of water or pressure that you
need if the tank is in the basement of the house it’s going to be someplace
around 15 pounds maybe 20 that’s going to be the minimum amount of pressure
that you need to get it to come out of the faucets you might even get down as
low as 10 pounds if the customer will let it get that low the lower you can
get the air pressure the more storage you’re going to have in the tank
the after you get your air pressure set on the bottom you want to turn your
pressure switch up and limit the differential on the decrease it from
let’s say 40 60 take that down to 50 to 60 pounds or whatever your switch will
let you get away with by doing this you’re going to have the pump kicking on
sooner and higher in the pressure tank and leave you a lot more storage than
what you would normally have if you started
out with the 25 gallon tank 25 gallon drawdown tank holds roughly 60 gallons
to start with or something like that that tank you could you can use well
above the 25 gallons you can probably get 35 to 40 gallons of storage out of
the tank after the pump kicks on now that does decrease the amount of cycle
time on the pump but when you’re dealing with two gallon and it will say you
don’t need a twelve minute cycle time plus longer if you’re using in water
what you do need is storage on a diaphragm tank with a top containment
dome it’s going to be a similar setting but you can’t go quite as far you’ll
notice once the diaphragm gets up to the limit of the dome the pressure is going
to ramp up real quick that’s because you’re physically
restricting the top side of that bladder
you can only use about half the tank well so you won’t be able to get from
let’s say a 10 pound air pressure up to a 70 pound switch someplace around 50
pounds that’s just going to start ramping up so on that one you can adjust
it a little bit higher on the air pressure side maybe 20 pounds on the air
pressure and then run your switch up and you still want to keep the differential
low on it let’s say 60 to 70 pounds just watch your gauge on that when your
pressuring it up and make sure that when it does hit that containment that’s
where the top side of your switch is on a diaphragm tank without a captive dome
on it I wouldn’t really recommend doing it but if you’re careful you can still
get by with it you got a pay attention mostly with the gallons that you get out
of it if you look at the volume storage for the 20 to 40 switch setting that
most tanks that have listed at least in the literature if not all
the tank itself then that’s the amount that you’d want to have the maximum
amount of water that you can store in there to set that one you’d have to
measure the amount of water either going in or coming out and set your tank at
twenty pounds and then adjust your switch to where it’s running instead of
twenty to forty take it as small as you can maybe thirty to forty or even thirty
five to forty five and check your go ahead and cycle it from the top of the
switch all the way to the bottom of the tank and see how many gallons you’ve got
and that should give you a pretty good idea of where you’re at in that bladder
if you get beyond the amount of water that you can store in there it’s going
to start stretching the top diaphragm and eventually will cause it to fail so
so it’s not really recommended mostly because you don’t have the visual
indicator of hitting that top containment dome though if you do go past there’s a real
good chance of damaging your tank if you’re dealing with a non captive air
tank like an air charged tank with air release that’s built into the side of it
there’s not a lot you can do you can’t change the adjustment level there for
how much air is in the tank even if you could shorten it up some of them screw
in on a pipe from the top it doesn’t gain you a lot because after it gets
down past that air release it’s going to start letting the air out of the system
anyway now you can gain just a little bit not much
turning the differential down on them doesn’t help you much either because
that differential is always set from the bottom going up into the tank well from
the air release going up into the tank so you’re you’re cut in pressure is
always going to be at the bottom of that air release give or take an inch or two
so anyhow I didn’t have any visual aids for this
but I hope I made it kind of clear enough to understand it’s a pretty
simple concept once you start thinking about using it for storage instead of
trying to use it for cycle time have a have a good day

4 thoughts on “Using a pressure tank for storage on a low yield well.

  1. Correction on the tank volumes, the 25 gallon (95 liter) draw down tank is about a 85 gallon (325 liter) total size tank. These tanks will give you 60+ gallons (225+ liters) of storage when adjusted as described in the video. We have some put in that are a 120 gallon (450 liter) tank with 35 gallon (130 liter) draw down that will store someplace in the 90 gallon (340 liter) range.

    If someone wants to do the math on compression ratios you could come up with precise numbers, but the tank air pressure setting and pressure switch settings would need to be known.

  2. Yea that definitely works I have never had to do it that way, luckily our wells get at least 10gpm. But on some occasions when I had a customer with to small of a tank and not ready to replace it. I would adjust the pressure differential to 30-40 just to get extra storage/cycle time. So say a submersible pump at 10 GPM on a 40 gallon standard tank I would put pressure setting at 30/70 and get a minute cycle out of it. They notice the low pressure sometimes but if taking a shower the pump would not cycle it would hold close to 70 also saving the pump.
    Take it easy man,
    Casey

  3. Nice video Kenny. We run into this situation alot with some wells around here barely producing 1 gpm. You explained it better than any vendor ever could

  4. I posted this response to Kenny's last comment, however, he is a busy well drilling man, and may not get back to me.. so I decided to post it at the top of the video in hope of some feedback……it goes like this……

    Kenny, thank you for this video, it is helping in my circumstance..

    Hopefully yourself or someone can weigh in on my particular circumstance.

    I have a low yield well, that is fine for us, however, when a lot of family come home for holidays, it gets drained.

    We have a 6 inch casing, 235 foot well with a 3/4 hp two wire submergible pump. I will have to check for static water line…. but I do know there is reasonable well pipe storage, as it takes 5 showers, and a couple loads of laundry and dishwashing before it taps out for awhile…..

    I have a an existing fairly new 20 gallon pressure tank and was considering adding a new 120 gallon Flexlite Flexpro2 fiberglass diaphragm pressure tank…

    Or could you recommend a better tank for this? This Flex-Lite tank specs out with a drawdown of 47.9 gallons at 20/40 and 41 gallons at 30/50….I think that gives me enough storage? Would I be risking the diaphragm to lower the 38 preset psi to 20?…..

    I would like to have the pump come on for shorter rather than longer runs, which is, as you mentioned, best for low yield well. I was thinking per your video 30/40?

    I will have the Franklin pumptec control, that senses the amperage of the pump so that it does shuts the pump down if there is not enough water load with a timer….

    Appreciate any advice here….Thank you again for posting this video.

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