Well pressure switch sizing

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Bbqscotty

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ok, just drained tank and there is no pressure at all in the tank. pressure gauge still shows 30 though.
i figure charge tank to 18 and maybe replace gauge ?
 

Bbqscotty

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by the way i am not having pump problems, tank runs for 13 seconds then stays off for 38 seconds when water is on. gauge is stuck at 40.
culligan came to service chlorinator and said tank was bad and wanted to sell me new expansion tank for ike $900 installed. not interested in that option so posted here. if tank bad i will replace myself. another amtrol 20 gallon is like $225 and all other parts are ok.
 

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Yep gauge is bad and need 18 psi air in the tank. But tank probably won't hold air anymore.

Pump maybe still working but running less than a minute and off less than a minute it won't last much longer.
 

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I'm visiting at the hospital with time to kill so I'll explain how air gets out of a perfectly good bladder tank.

When no one is using water and the system is at rest the pressures on the air side and water side of the bladder are equal. But when water is being used the air side has more pressure to push water out of the tank. During this time a little air leaks through the bladder, mixes with the water, and comes out the faucets. Each time the air pushes water out of the tank a little air leaks through the bladder and is lost. The mote times the pump cycles the more air is lost.

The more air that is lost the more the bladder stretches when the tank is refilled. The further the bladder stretches and the more times it is cycled the sooner there will be a split or crack in the bladder. Then the air is quickly lost, which causes the pump to rapid cycle, which in turn causes the death of the pump.

The only time air is not being lost through the bladder is when the air pressure and water pressure are the same. This only happens when the system is not using water or when water is being supplied at a constant pressure as when using a CSV.
 

Bbqscotty

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i just got done draining tank and charged old tank to 18psi. turned pump for well back on to charge wet system again. now pump runs for 19 seconds and stays off for 4 minutes when water is on continually. gauge now say 10psi so that is definitely bad. is there any sense in checking air in tank thru valve when system charged with water ?
maybe i'll stay like this for a couple days and see how it goes?
 

Reach4

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is there any sense in checking air in tank thru valve when system charged with water ?
Yes and no. When there is water in the tank (water pressure is higher than precharge) the air pressure will be just a little less than the water pressure. Why are they not equal? 1. Water pressure falls with altitude and the tank diaphragm is a little higher than the usual place for the water pressure gauge. 2. The diaphragm is not perfectly limp -- it has some tension, particularly at higher water pressures. Those two might add up to maybe a PSI I am guessing.

So that air pressure could double as a water pressure gauge or as a way to roughly compare the calibration of the water pressure gauge and the air pressure gauge.

The "no" parts are 1. that a new pressure gauge is under $20 and is easy to switch (use Teflon tape usually). So it does not make sense to limp along without a good pressure gauge for long, and 2. you lose a little air every time that you check the air. Think of that little psst you hear, at a minimum, when you remove the gauge.

When you shop for a gauge, you would like to find a 100 PSI full scale gauge to get better resolution. http://www.lowes.com/pd_64124-15649-PP100G___?productId=1095371 would be an example. You do not want a 300 PSI gauge.
 
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Valveman

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i just got done draining tank and charged old tank to 18psi. turned pump for well back on to charge wet system again. now pump runs for 19 seconds and stays off for 4 minutes when water is on continually. gauge now say 10psi so that is definitely bad. is there any sense in checking air in tank thru valve when system charged with water ?
maybe i'll stay like this for a couple days and see how it goes?

A 20 gallon tank only holds about 5 gallons of water. So with a 15 gpm pump 19 seconds to fill the tank sounds right. But with 5 gallons in the tank 4 minutes off is only when using a little over 1 gpm. If you turn on 5 gpm the pump will only be off about a minute.

Running or being off for less than 1 minute is not good for any pump. 2 minutes on or off is better and running continuous when using water is the best thing for a pump.
 

Bbqscotty

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i will replace gauge, not sure what it really does as the pressure switch seems to know when to turn on and off and the gauge is more for me to just watch it i guess. kinda trying to figure out if i need the new tank i bought or not. how long you think if my bladder is bad will it lose the air ? like i said this tank is maybe 3 - 5 yrs old. is it possible it just slowly lost it over that time frame and i could be ok ?
once i know for sure i want to adjust to 30/50 and replace the gauge.
attached picture showing gauge i am talking about
 

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Reach4

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i will replace gauge, not sure what it really does as the pressure switch seems to know when to turn on and off and the gauge is more for me to just watch it i guess.
Without the gauge, you don't know what pressure the switch is turning on at. Just because it says 20-40 on the switch label, you can't be sure. Without knowing the turn-on pressure, you don't know how to set the precharge pressure.

You could limp along with a bad pressure tank for a while by adding air to make up for what leaks through a hole in the diaphragm. This would require you to add air while there is water pressure. If you overdo it, you could get a blast of air through a faucet. I have not tried it. But if I did, I would want to trickle water out of the faucet closest to the tank. If I heard any air come out of the faucet during the process, I would stop adding air. I am not a pro, and there may be some danger in the process. If you turn off the pump or the electricity goes out, you know there will be a blast of air coming out if somebody opens a faucet or flushes a toilet.
 

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Amtrol putting maintenance free on their pressure tanks back in day wasn't bad because they really did hold it's Precharge with all that cycling. As you can tell now days, there is no pressure tank on the market that says maintenance free, every pump system will lose it's Precharge, even with less cycling, so you might as well start putting the word out, that people need to start maintaining their Precharge in their pressure tanks these days, Quality is just not the same these days, they don't want your pump system to last that long because they are not selling enough products. We tell & show our customers how to maintain the Precharge in their pressure tank, so they can see that long life again, this is why we have so many customers and they will even send us fresh fruit, vegetables, and meat, to tell us thanks for showing them how to get that very long life again.
 
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Bbqscotty

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here here pumpmd
i went to 2 plumbing supply houses trying to get real info and they were just like salesmen also, no different then installers. use to be supply houses gave honest info
glad to have found this forum.
i am going to keep an eye on this for maybe a week and if it holds true with the current cycle times i plan on just replacing gauge and up myself to a 30/50 config and return tank i bought.
 

PumpMd

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This is a DIY forum and more than enough skilled people on here to help you with your install, so install your own pressure tank, we actually tried out RedLion pressure tanks(cheap tank), there has not been one tank failure since 07, even on the pump system I showed on here that was cycling 204 times in a day. I checked it and it still had 39psi Precharge in that RL81 07 dated pressure tank.
 
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PumpMd

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You said your not having pump problems because the pressure tank doesn't stop the pump from producing water, it only stores water, the pressure switch is what tells the pump to kick on. You were about to have pump problems, the pump can only take so much "rapid cycling" because the in-rush amperage to the motor windings. If you can keep your pump for doing that, it can last millions of cycles before it takes out the Biac switch on 2wire pumps or the components in your control box on 3wire pumps. Contactors can save the pressure switch because the low amperage going through your pressure switch's contact points but I have found by using a fine threaded point file on your contact points will do the same thing on light duty pressure switches, just make sure you don't go through the shiny stuff (alloy) on both sides.
 
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Valveman

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Using a 20 gallon tank (5 gallon draw) with a 15 GPM pump is one way to CAUSE rapid cycling. Even if you maintain the correct air charge in the tank the pump will still only have 20 seconds of run time, which IS rapid cycling. A pump needs a MINIMUM of 1 minute or run time. You have just been lucky to get 20 years out of that pump. Luck is the only reason a pump last very long when it is cycling hundreds of times per day. And most people are not that lucky.
 

PumpMd

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Tell that to people who were using standard tanks before amtrol built the first pre-pressurized tank in 1963, which the standard tanks were giving people less than a 1minute runtime. Franklin put that in their book, so you can have a better chance to see longer pump life but doesn't mean you still can't have long pump life with less than minute runtime on residential houses. It's not luck, it's skill! I call that short cycling by the way. You had to buy a 82gal standard tank to see 12.7 drawdown on 20/40, which would give around that one minute runtime on a 10gpm pump, you remember that long pump life back in them days.
 
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PumpMd

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Air volume control on Standard tanks only maintained the atmospheric pressure, this is why amtrol invented their pressure tank because air volume controls liked to plug up and before someone figured out that you could put a Precharge in your standard tanks.
 

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Some background information
 

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Bbqscotty

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still trying to understand the csv option over my set-up. the tank in that holds 1 gallon of water so basically after 1 gallon has been used pump comes on and stays on. my toilets are 1.6 gallon so everytime you flush pump would come on where my setup maybe every third flush would cause pump to come on. my appliances and their usage : washer 15 gallons, dishwasher 6 gallons, shower maybe 15 gallons per person ( 2 people).
Assuming my 20 gallon tank holds 5 gallons of water and to fill my tank takes 30 seconds. :
washer = 3 cycles 1.5 minutes vs ? run entire cycle after first gallon
dishwasher = 1 cycle 30 seconds vs maybe same time
shower same as washer......
is the point to just have less cycles by using csv system? if so toilets seem to causes excessive pump cycles where by the others seem similar
 
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