Well Tank sizing

[Sumboodie]

Anyone know how to size a well tank?

This new place I bought was originally setup just for a ******* and sink, but now is feeding a kitchen, shower and washing machine. I think the well tank is too small, the pump is on and off a bunch with a load of wash or even using the sink.

The tank is "20 gallon".

Googling says:
Generally, as a rule of thumb, one can follow these guidelines when sizing a pressure tank: 0-10 GPM: 1 gallon of drawdown per 1 GPM of flow. 10-20 GPM: 1.5 gallons of drawdown per 1 GPM of flow. 20 GPM+: 2 gallons of drawdown per 1 GPM of flow.

I don't get what that means though. A shower for example is what, 2.5gpm? So I need a 2.5 gallon tank for the shower? I add everything using water and that's the tank size?

 

[Showkey]

Bladder tank or just tank ? Makes a difference when in size as the equivalence formula.

 

[American Locomotive]

Chances are the tank size is probably okay, and the air bladder is out of air. You'll want to turn the pump off, drain all the water out of the tank, and then check the air pressure. Generally it should be around 25-30 PSI. Usually 2 PSI below whatever your cut-in pressure is.

 

[DennisK59]

I wonder if your pressure switch has failed, a 30-50 for a shallow well.

 

[reader2580]

My understanding is a well pump should run for at least 60 seconds minimum. I had a 20 gallon bladder tank and the pump was running for less than a minute. The tank was very rusty so I replaced it with a 44 gallon bladder tank that I got cheap on a liquidation deal. My well pump now runs for at least 60 seconds when it runs.

 

[Sumboodie]

I wonder if your pressure switch has failed, a 30-50 for a shallow well.

I have it set to come on at about 40 and off at 70. The piping is undersized in the apartment, 30-50 wouldn't be much pressure if 2 things are using water, like the toilet filling and sink going to wash hands.

 

[Sumboodie]

Chances are the tank size is probably okay, and the air bladder is out of air. You'll want to turn the pump off, drain all the water out of the tank, and then check the air pressure. Generally it should be around 25-30 PSI. Usually 2 PSI below whatever your cut-in pressure is.

It was low, but didn't help that much. I have it at a touch under 40. Cut in is just over 40

 

[Sumboodie]

My understanding is a well pump should run for at least 60 seconds minimum. I had a 20 gallon bladder tank and the pump was running for less than a minute. The tank was very rusty so I replaced it with a 44 gallon bladder tank that I got cheap on a liquidation deal. My well pump now runs for at least 60 seconds when it runs.

I was considering buying a 2nd "20 gallon" tank and putting it in series. Not sure if that would be a bigger headache vs replacing the existing one with a larger tank though? Would be a bit cheaper. 20 gallon tank is about $200 and a 50 gallon is almost $400

 

[reader2580]

I was considering buying a 2nd "20 gallon" tank and putting it in series. Not sure if that would be a bigger headache vs replacing the existing one with a larger tank though? Would be a bit cheaper. 20 gallon tank is about $200 and a 50 gallon is almost $400

I don't know why a second tank wouldn't work. I have a 20 gallon tank I was going to add in addition to the 44 gallon tank if need be. I never added the second tank. There is probably someone else here who knows better if this would work.

I only paid somewhere between $50 and $75 for my tank. I just missed out on an 80 gallon tank for less than $100. We had a store locally that sold Home Depot returns cheap. When they first started they had inventory stacked everywhere and it was a treasure hunt. They sold stuff for about 50% of the HD price and then had 50% off sales a few times a year. They tried to go upscale with more organization and higher prices. It caused them to go out of business as they are liquidating the store right now.

 

[Sumboodie]

I ended up ordering in a CSV Cycle Stop Valve. It allows a small tank to be used.

Interesting thing is this well is sort of setup to feed multiple houses. To me it would have made sense to setup a manifold in teh shop and pipe to the house.

But they setup a manifold in teh ground and I guess wired to teh shop and to the house. So it needs a seperate tank and controller at each I guess. No idea how that would work if both call for the pump to be on. Seems like it'd be fed from 2 power sources then?

 

[Sumboodie]

I need to put in an water softener.

Trying to figure out the best approach to this.

From what I can tell, they put in piping to feed the shop as well as feed the house, all from teh well.

Does it make the most sense to keep with that, or use the shop piping and T off that to feed the house?

Doing that would allow just one well tank, one water softener, etc.

Where the other way, I'd another well tank, another softener.

Only hassle is coming up with a way to pass piping through the floor to the house.

 

[Junkman]

I have 3 air bladder tanks, and on one of them, the air bladder has failed. I never noticed any change in the water pressure or the frequency of the pump coming on. About once a year, I check the air pressure in each tank, and the largest tank had no air pressure. I brought it up to what the others were set and, and checked it a week later, and once again it had no pressure, so I assumed that it has failed. I drained all the water out of it, and then closed the ball valve to it. When I find another good deal on a bladder tank, I will then replace it, but for now, it sits empty. In my previous home, I had only one bladder tank, and when the bladder failed, the pump would come on frequently until I replace the tank. Bladder failures seem to be quite common in water tanks based on my experience.

 

[Sumboodie]

I have 3 air bladder tanks, and on one of them, the air bladder has failed. I never noticed any change in the water pressure or the frequency of the pump coming on. About once a year, I check the air pressure in each tank, and the largest tank had no air pressure. I brought it up to what the others were set and, and checked it a week later, and once again it had no pressure, so I assumed that it has failed. I drained all the water out of it, and then closed the ball valve to it. When I find another good deal on a bladder tank, I will then replace it, but for now, it sits empty. In my previous home, I had only one bladder tank, and when the bladder failed, the pump would come on frequently until I replace the tank. Bladder failures seem to be quite common in water tanks based on my experience.

Look into the CSV. It eliminates the need for a large tank(s).

 

[jblnut]

All I'm going to add about multiple bladder tanks is that it's a good idea to have them plumbed so that the water never goes "the other way" when they are discharging.

For example. If you have a bladder tank in the house and add one in the shop. The house calls for water draining the entire system and water flows from the shop to the house. If the shop calls for water and drains the entire system water flows from the house to the shop. Usually it's not a big deal at all but if you have crappy water and stuff likes to build up and deposit on stuff that same stuff will dislodge and potentially plug stuff up.

My parents place was set up that way and it caused them issues for years until they put a simple check valve on the supply side coming into each building. They eventually re plumbed things with one larger tank for both buildings and haven't looked back.

 

[finn]

I didn’t go through all of the posts, but, yes, you can have too much tank storage capacity, particularly if you have a low flow well.

In that case, your large tank capacity will discharge to the low end pressure switch set point. The switch will turn the pump on to begin filling the tank, but if flow is insufficient, the pump will run dry when it pumps out the head of water above the pump before the tanks fill and the upper pressure limit switch shuts down the pump.

Bottom line is that the tank capacity has to be engineered to match the well flow capacity and pump flow rate, or you’re going to run the pump dry.

 

[dcg9381]

You're talking about a pressure tank, not about having to store water due to a low-flow well.

Yes, the CSV Cycle Stop Valve is what I'd recommend also. It's great.

Softener: Have your water tested and then buy a "commercial" unit (internet) with a Fleck valve. These are currently the best valves on the market that are available to consumers. I prefer to do my water treatment in the "pump house" - but our weather is pretty warm.

I "T" off of our pump house to the shop and then to the house. The shop is fed by a 3/4" PEX line. House line is 2" as it's a pretty long run.

 

[PelicanPines]

I went from a 20 gallon to a 44 gallon... I now have 65 psi water pressure ... up from low 40's.

 

[walta]

I went from a 20 gallon to a 44 gallon... I now have 65 psi water pressure ... up from low 40's.

Come on man the size of the tank does not change the pressure just how often and for how long the pump runs. In the end the pump moves the same number of gallons and runs the same number of minutes the only difference is the the minimum run time is longer with a bigger tank.

If the old tank had a failed bladder, yes, the new tank will work better.

If the old tank bladder were under charged, yes, the new tank will work better.

If they adjusted the pressure switch and charged the new tank to match only then would you see a higher pressure.

Most pressure switches mine included turn on the pump when the pressure falls below 40 PSI and turn it off when it gets above 60 PSI. For the life of me when I am at the kitchen sink, I could not tell you if what I am looking at is 40 or 60 PSI. When I look at the gage when water is flowing the gage is never stationary if the pump is off the pressure is dropping and if the pump is running the pressure is building.

The way I see it setting the pressure above 60PSI is an act of desperation use to mask some other design flaw needlessly wearing out the pump.

Walta

 

[PelicanPines]

Come on man the size of the tank does not change the pressure just how often and for how long the pump runs. In the end the pump moves the same number of gallons and runs the same number of minutes the only difference is the the minimum run time is longer with a bigger tank.

If the old tank had a failed bladder, yes, the new tank will work better.

If the old tank bladder were under charged, yes, the new tank will work better.

If they adjusted the pressure switch and charged the new tank to match only then would you see a higher pressure.

Most pressure switches mine included turn on the pump when the pressure falls below 40 PSI and turn it off when it gets above 60 PSI. For the life of me when I am at the kitchen sink, I could not tell you if what I am looking at is 40 or 60 PSI. When I look at the gage when water is flowing the gage is never stationary if the pump is off the pressure is dropping and if the pump is running the pressure is building.

The way I see it setting the pressure above 60PSI is an act of desperation use to mask some other design flaw needlessly wearing out the pump.

Walta

The benefit of a larger tank is less electrical consumption due to reduced pump cycling, which also reduces premature wear and tear on the pump, switches, and control components. It is not unusual to see pumps lasting 15, 20, and in one case 37 years.

Bigger tank also means bigger charge can be applied.

Bigger is better.

 

[walta]

Bigger tank also means bigger charge can be applied.

Are you saying 80 gallon tanks can be operated at 100 PSI but 20 gallon tanks are limited to 60PSI?

If so will you post links to the tank spec sheets to prove this statement?

The benefit of a larger tank is less electrical consumption due to reduced pump cycling, which also reduces premature wear and tear on the pump, switches, and control components. It is not unusual to see pumps lasting 15, 20, and in one case 37 years.

I agree bigger is better for reduced pump cycling. Electrical consumption will be slightly lower but not noticeable on you monthly bills.

When you are standing at the kitchen sink you will never know the difference until the pump fails years from now.

Walta

 

[finn]

Are you saying 80 gallon tanks can be operated at 100 PSI but 20 gallon tanks are limited to 60PSI?

If so will you post links to the tank spec sheets to prove this statement?



I agree bigger is better for reduced pump cycling. Electrical consumption will be slightly lower but not noticeable on you monthly bills.

When you are standing at the kitchen sink you will never know the difference until the pump fails years from now.

Walta

Highest current draw is the inrush during pump start up.. Typically double the running current for conventional pumps.

Doesn’t last long, but it’s significant.

 

[finn]

You're talking about a pressure tank, not about having to store water due to a low-flow well.

Yes, the CSV Cycle Stop Valve is what I'd recommend also. It's great.

Softener: Have your water tested and then buy a "commercial" unit (internet) with a Fleck valve. These are currently the best valves on the market that are available to consumers. I prefer to do my water treatment in the "pump house" - but our weather is pretty warm.

I "T" off of our pump house to the shop and then to the house. The shop is fed by a 3/4" PEX line. House line is 2" as it's a pretty long run.

You missed the point, obviously. If your well free flows, say 2gpm, and the pump is submerged ten feet below static level in the six inch casing, having a really large tank won’t work. The pump will continue to run until the water level in the casing drops such that the pump runs dry Before the tank is full and the pressure switch cuts the current.

your tank has to be sized to the well free flow, and bigger isn’t, in every case, better.

Probably not a problem if you have a residential well that flows twenty or thirty gpm.

 

[Sumboodie]

Well is around 30gpm if I recall, flow is a non issue.

I got the CSV, just no time to install. Maybe in a few months.

 

[tymbo]

You will love the CSV! I installed mine about a month ago. Now, no matter the demand(dishwasher, sprinkler, washing machine, flush the toilet) the pressure remains the same.

 

[Daveyclimber]

Get the biggest tank you can physically fit in the location. For reference, my tanks are located in my crawlspace. I have 2 86 gallon tanks and don't regret it on bit. Keeps the pump happy, and being off grid it really helps to not have to cycle the pump as frequently.

 

[Sumboodie]

Get the biggest tank you can physically fit in the location. For reference, my tanks are located in my crawlspace. I have 2 86 gallon tanks and don't regret it on bit. Keeps the pump happy, and being off grid it really helps to not have to cycle the pump as frequently.

I got a CSV. No big tank needed.