Setting pre-charged tank pressure

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Am having trouble getting the cut-in pressure low enough to match the cut-out pressure.
This is all new to me so any advice is appreciated greatly.
New system, Dayton 62 gal. tank and am looking for anything close to 40-60 or a bit less, which would allow for a 16-18 gal. drawdown.
There is 35 psi in the tank.
Just replaced the pressure switch.
Right now, with system down and tank empty, and several adjusting turns CCW, cut in pressure is around 48 and cut out is 58-60!

With system shut off and tank empty, the gauge reads 13psi.
Found this post, [below] (#6) from '09, stating that the gauge should read zero.
It takes the Dankoff Booster pump 1 min. 40 seconds to reach cut-out. Way too quickly and obviously is not holding many gallons of water.

The crazy thing is I had it running perfectly the first couple of days operating. The pump took about 4 minutes to reach cut-out.
Then I decided I should adjust it a little bit better...
WTH am I doing wrong? Is the air pressure at 13 psi when it should be zero part of this?

https://terrylove.com/forums/index.php?threads/replacing-a-pressure-switch.26174/
 

Reach4

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The thing that should be at zero when you adjust the air pre-charge is the water pressure. It is not clear which gauge you were referring to. With a 40-60 switch, the air pressure should be 38 PSI when the water pressure is zero.

If a water pressure switch will not adjust as you need, get a new water pressure switch.

A pump running 1 min. 40 seconds to reach cut-out does not sound like a problem. I think the rule of thumb is that a minute or longer is OK. If it took over 4 minutes with no water being used, that must be a rather small capacity pump. Could it be that you timed 4 minutes when there was a significant use of water going on?
 

Valveman

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With the pump turned off, a faucet open, and the tank empty, the pressure gauge should read Zero. If it is still reading 13 PSI, then your gauge is bad and adding 13 PSI to the correct number.

The air charge should also be checked while the pump is off and the tank is empty, but it will need to be checked with a car tire gauge on the air inlet valve at the top of the tank. It should read 35 PSI at when the tank is empty, but you can use the car tire gauge when the pump is on to verify the pressure on the water pressure gauge. When the pump is on both gauges should read the same.

The pump is not really starting until the bladder in the tank bottoms out at 35 PSI, but at this point your water pressure gauge is showing 48 PSI. Get a new gauge and set the pressure switch to 40/60, or turn up the switch until the old gauge says shut off at 73 PSI, then see what happens.
 

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With the pump turned off, a faucet open, and the tank empty, the pressure gauge should read Zero. If it is still reading 13 PSI, then your gauge is bad and adding 13 PSI to the correct number.
Ahhh..... I had not considered that interpretation. Makes sense.

If you check the air pressure for the tank while there is water in the tank (half full might be best for this), the water pressure should be close to the air pressure. So if you want to compare your air pressure and water pressure gauges, you can check the pressures in that state. Never adjust the precharge pressure while there is water in the tank, however.
 
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"Never adjust the precharge pressure while there is water in the tank"
lol, learned that the hard way, hence the new press. switch. So, I have another air press. gauge, just need to get the correct copper adapter to mount it.
Thanks for the replies, will report back with the new gauge installed..
 
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Reach 4, regarding pump run time....the Dankoff pump shows about 4-4&1/2 gals per min. in specs. So it seems the correct amount if I'm expecting 16+ gallons in the drawdown, no?
 

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Reach 4, regarding pump run time....the Dankoff pump shows about 4-4&1/2 gals per min. in specs. So it seems the correct amount if I'm expecting 16+ gallons in the drawdown, no?

I agree mostly. I would first get the precharge to the right point. It is not good for the pressure tank diaphragm to have too little precharge, plus that could reduce drawdown. But overstretching the diaphragm is the worst part. With a bad gauge, you may have adjusted for a smaller differential than the expected 20 PSI. Plus, a pump will have a spec as to what volume it should produce at a given differential. If that differential is 60 PSI, but you are doing a lot of your pumping with only 30 PSI differential, then the GPM would be higher at those times. What is the pump model? Is the pump pumping more than 5 GPM now or does the tank have a leak in the diaphragm that let water get above the diaphragm? Knocking on the side of the tank while it is empty may tell you.

To measure drawdown, trip the pump on when there is no water being drawn. Wait until the pump cuts off. Then fill 5 gallon buckets to measure what you are getting for drawdown.

When you said "So, I have another air press. gauge, just need to get the correct copper adapter to mount it", I am presuming that you meant that you got a new water pressure gauge. If you will order that and it will take a while, you could buy an additional water pressure gauge that has a garden hose thread. Attach that to the laundry sink or a washing machine hose valve or even the water heater. Use that until you get the new regular water pressure gauge.
 
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yeah, you're correct, I meant water pressure gauge, which is mounted on the "T" going in to the precharged tank.
Pump model is Dankoff Flowlight Booster Pump..only specs. are at their website. It's capable of producing high pressure.
did the drawdown test as you describe yesterday, only got 8 -9 gallons..
Have to quit for today, we're getting a lot of rain from the passing hurricane. Thanks
 
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back again, I might be getting closer. Installed a new water pressure gauge at the "T" and it reads zero with pump off, tank empty.
Again, all new pump, tank, etc.
Air pressure in precharged tank reads 34 psi. My tire pressure gauge is accurate, I believe, but am looking for another to double check. Some things are hard to find here..
Pump cuts off at 45 psi, cuts in at 35.
Pump is putting about 12 gallons into tank. At this pressure it should be 19.2 @ 30-50, or 16.6 @ 40-60.
I'm OK with this pressure setting, but how do I increase the tank's holding?
The new pressure switch (Parts 2O, from HD) has a factory set differential, not adjustable.
Do I need to add more air to the tank charge, or less?
Or, tighten the nut on press. switch which raises both cut-in and cut-off pressure?
 

LLigetfa

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Pump cuts off at 45 psi, cuts in at 35.
You need a switch with 20 PSI differential. Those have two springs.

The tire gauge need not be accurate. It is not about accuracy since the water pressure gauge probably is not accurate. It need only to read the same as the water pressure gauge. With the water pressure at 35 PSI, the tire gauge should also read 35 PSI. If it does not, then compensate.
 

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Your pressure switch is only giving a 10 PSI differential (35-45). You will need a replacement pressure switch so that you can get the 20 PSI differential that will give more draw down. Take the bad pressure switch to HD to see if they will swap it out.

You set the pressures so that the air precharge is 2 PSI less than the cut-on pressure.
 
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I'll try anything at this point, however, the pressure switch comes with a factory setting of 30-50...that's what's killing me!
At $30 a pop, another switch is worth a try, won't break the budget, but it's a 2 hour trip to HD.
 

Reach4

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I'll try anything at this point, however, the pressure switch comes with a factory setting of 30-50...that's what's killing me!
At $30 a pop, another switch is worth a try, won't break the budget, but it's a 2 hour trip to HD.
I was thinking that the pressure switch was new and that HD would probably replace it free. If I were buying a new switch from scratch, I would buy a Pumptrol switch such as the FSG2J24CP. If it is a 2 hour trip (maybe costing $30 in gas and depreciation), HD or others would mail it. You still have water, so if it takes a week, that would be OK.
 
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mailing is out, we are in a rural area, so it's a drive to the Post office, which takes about an hour..
that combined with the brand choices available here makes it a challenge. (wouldn't live anywhere else, love having no neighbors). There is a Grainger's here, I could see what they have.
This is not an immediate problem as we're on municipal water at the time...this system is a rainwater collection for backup and will be in use fulltime during the rainy season. Which is ending.
The pump produces about 4.5 gpm (you asked earlier in #7, and also said too little precharge would reduce drawdown)...before I go for a 3rd pressure switch is there any adjustment I should try?
Tighten the nut a few turns tighter?
Thanks, it's much appreciated.
 

Reach4

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The problem with the pre-charge being too high is that the pressure tank does not provide enough water between when the switch turns on and the pump delivers water to raise the pressure. The problem with too low of a precharge is that it stretches out he bladder/diaphragm and reduces the tank life.

Until you get your new pressure switch, if you don't get a pressure dip at pump start, I would leave your settings as they are. If you do get a brief dip, I would turn the pressure switch screw maybe 1/8 or 1/4? of a turn to raise the cut-on pressure to 36PSI, or I would keep it at 35 PSI and change the precharge to 33 PSI.

You have a Grainger? That is good! For the price, I might go for the Dayton Grainger Item # 2T082 (or the Grainger Item # 12T088 if you wanted the automatic turn-off if it runs out of water). In the Pumptrol/Square D line, I would go with maybe Grainger Item # 2FH02 Square D Model # 9013FSG2J21 There are variations, and I don't know the differences offhand.

http://www.grainger.com/category/pr...jzZ1z0r596Z1z0r564?redirect=Pressure+Switches

Somebody might have some insight as to what the variations arE.
 
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Thanks for the good info..this is a 24 volt powered pump, and so far the pressure switch(es) I've used don't seem to notice!
I'll be going to Grainger's..
 

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If you use a 2-pole pressure switch, I would wire both sets of contacts in parallel to reduce resistance.
 

Reach4

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can you clarify that?
Right now I have both wires going to one side of the switch..
. You could cut two jumper wires to maybe 3 inches and strip the ends. Add one end of a jumper to each terminal you are now using. Clamp the other end of each jumper to a terminal that is now empty.

Half of the current (electrons) could pass through the left side of the switch, and half through the right.

In post https://terrylove.com/forums/index.php?threads/burned-out-pressure-switch.57972/ a 120 v pump was overloading a pressure switch. In post 17 discussion starts on wiring the two sides of the switch in parallel.
 
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I'll do as you suggest...it is how the pump diagram shows it. I wired it this way on the advice of a friend with a similar setup, although with house current. He's knowledgeable in electric wiring but not a pro. It's probably not correct.
 
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