Another pressure tank question

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The pressure tank switch kicks on at 52 psi. Should I inflate my new tank to 50 psi.
Thanks!
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On 08/03/2014 12:32 PM, Michael Wilson wrote:

"ON" at 50???? That's far more typical of cutout pressure. Anything much over that is surely likely to cause premature failures in toilet valves, water hammer, etc., unless you've a PRV before the house distribution.
But, the two-pounds below the cut-in is the rule of thumb but I certainly have never seen a system operating at those pressures.
What's the head pressure of the pump?
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On Sunday, August 3, 2014 1:06:28 PM UTC-5, dpb wrote:

I'm out of my element here. I see a pressure gauge from the line running fr om the tank to the house. And when the pressure switch kicks in at 52. I gu ess I'm looking at the wrong gauge. The pressure tank was delivered with 35 psi. If I just leave it, will I be ok? Thanks.
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On Sunday, August 3, 2014 11:18:44 AM UTC-7, Michael Wilson wrote:

guess I'm looking at the wrong gauge. The pressure tank was delivered with 35psi. If I just leave it, will I be ok? Thanks.
No. The pressure _tank_ does not regulate the kick in/out pressure, the pr essure switch does that.
Normal settings for residence:
20-40 but rather uncommon. Problem with sprinklers, weak showers. 30-50 but some impulse sprinklers don't work well at the low end. 40-60 is the most common - gives good pressure, needle showers, sprinklers work well.
Pressures over 60 are not recommended for residence as it is hard on fixtur es as 'dpb' said.
Note the standard difference is 20lbs between on/off.
If you really have 52 for the cut-in, your cutout then should be 72 - way too high. You need to adjust the pressure switch.
Most have one high screw and one or two shorter ones. the high screw moves the 20lb range up/down to get the cut-in/out where you want it. If you do n't have a 20lb difference between cutin/out then the shorter screw(s) are used to adjust that.
Harry K
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On Sunday, August 3, 2014 2:40:43 PM UTC-4, Harry K wrote:

I guess I'm looking at the wrong gauge. The pressure tank was delivered wit h 35psi. If I just leave it, will I be ok? Thanks.

don't have a 20lb difference between cutin/out then the shorter screw(s) ar e used to adjust that.

I agree that 40 - 60 is typical. Not sure about the adjusting though. I seem to recall that on mine at least one screw adjusted both cut-in and cut-out, the other only adjusted one. But the pressure switches usually have instructions on the inside of the cover. Or you can probably find it online. I would think the tank manufacturers would have online stuff about pressure settings too.
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On Sunday, August 3, 2014 12:05:33 PM UTC-7, trader_4 wrote:

. I guess I'm looking at the wrong gauge. The pressure tank was delivered w ith 35psi. If I just leave it, will I be ok? Thanks.

u don't have a 20lb difference between cutin/out then the shorter screw(s) are used to adjust that.

And if one is leery of screwing with the pressure switch a new, preset one is cheap.
Harry K
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On 08/03/2014 1:18 PM, Michael Wilson wrote: ...

Not if that pressure indicator is at all accurate, no.
If the system is empty/open, does the gauge then read zero or is it way out of whack, maybe? Take it off and be sure it does zero out. Also be sure the feed tubing to it is clean of rust, etc., so it it gets a fair view of actual pressure.
Here's at least a reasonably-arranged installation if not pretty--the well feed would be from the rear, the outlet to the house on this side.
<
http://inspectapedia.com/water/Two_Harbors_2011_0420_DJFs.jpg
It needs to be pretty close proximity to the tank; if it's too far away you're reading pressure wherever it is in the system which depending on pipe sizing, etc., can be quite a bit different.
The bladder/diaphragm in the pressure tank is precisely size to the size of the tank and the pressure differential between on and off and that 2 psi difference between it's dead pressure and the cut-in pressure. It moves from fully up to fully extended where it is just at the top of the outlet when reaching the cut-in pressure--too high and you don't get much of the tank volume, too low and the bladder will actually extend to the point it'll cut off the outlet by stretching too far.
You do need to get this right and if you don't have the skill set to get it set up correctly, spend the bucks and get somebody out to do it correctly--you'll save money in the long run by not screwing up something more expensive to fix.
<http://www.sprinklers4irrigation.com/en-us/pg_75.html At least a minimum description.
Unlike Harry K, I'd say the 30-50 is by _far_ the most prevalent setting I've ever encountered; we run 20-40 here on the farm and have been content for 50+ years; run the house plus all the animal waterers (up to 1500 head worth) plus the lawn/garden (altho use the traveling sprinklers rather than impulse sprinkler heads) and never have pressure issues.
But, I wouldn't quibble with either altho I personally think 60 is too high for household internal use for the aforementioned reasons.
--


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On Sunday, August 3, 2014 2:05:25 PM UTC-5, dpb wrote:

Thanks for the help! The tank is off and the pressure gauge that is visible still reads 52. The switch is set for on at 40 and off at 60. Should I inflate the new tank to 40? Should I change out the gauge?
Much appreciated help on a Sunday afternoon!
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On Sunday, August 3, 2014 2:18:02 PM UTC-5, Michael Wilson wrote:

Also, is there a standard size for the fitting of the PVC into the tank itself? It's a Flotec FP7120. I can't find anything in the owner's manual or on the mfg web page. Thanks.
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On Sunday, August 3, 2014 2:35:10 PM UTC-5, Michael Wilson wrote:

Here are the specs. It says the pipe tap size is 1 inch, but it seems to measure a little more than that on the measuring tape.
Specifications:
* Body Construction: Heavy Guage Steel * Body Finish: Electrostatically Applied Baked On Polyester * Tank Precharge: 40 psi Nitrogen Rich Charge * Tank Capacity: 35 Gallons * Equivalency Rating: 82 Gallons * Drawdown with 20/40 Switch: 12.7 Gallons * Drawdown with 30/50 Switch: 10.7 Gallons * Drawdown with 40/60 Switch: 9.3 Gallons * Bladder/Water Cell: One Piece Seamless PVC * Tank Diameter: 20" * Tank Height: 36-1/4" * Flange: Glass-Filled Polypropylene * Pipe Tap Size: 1" NPT * Distance Floor To Tap Center: 2" * Maximum Pressure Rating: 100 PSI
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On 08/03/2014 2:56 PM, Michael Wilson wrote: ...

Yes, nominal 1" pipe is >1" OD; it's based on a nominal ID for (iirc Sch 40) iron pipe is pretty close.
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On 8/3/2014 3:35 PM, Michael Wilson wrote:

Probably half or three quarter NPT.
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On 08/03/2014 2:18 PM, Michael Wilson wrote: ...

What does "tank is off" really mean? And where is this gauge?
How do you know the pressure switch is set to 40/60? Is it new from factory marked that way or what?
Again, as the instructions I linked to say, the tank should be at 2 psi _LESS_ than the cut in pressure when if is completely empty before installation.
Again, I can't tell you from here, but if the system is open and the gauge is at atmospheric and reading 52 pounds, then it's broke and needs to be replaced, yes.
If it's on some other portion of the system that has 50 lb pressure, then, as you say, you may be looking at the wrong thing.
We really, really, really, can't tell what your installation looks like from here to do more than outline the basics. You've got to have sufficient understanding of your system as you look at it to know what it is that you've got.
--



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On Sunday, August 3, 2014 2:47:56 PM UTC-5, dpb wrote:

In the picture you posted, it's the round gauge that's visible. It reads 52. And the tank is completely removed from the system now. Everything is turned off and there's no tank connected to the T. It's a 40 on, 60 off switch.
Thanks again!
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On 08/03/2014 2:50 PM, Michael Wilson wrote: ...

Well, if there's no input, how could it possibly be reading 50 psig and be anything _but_ broke?
It and possibly its connecting nipple if full of corrosion needs replacing, yes.
The (empty) tank should then be pressurized to 38 psi for a 40-60 switch.
BTW, the specs posted show one advantage of the lower pressures in the larger drawdown capacity.
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On Sunday, August 3, 2014 3:24:37 PM UTC-5, dpb wrote:

I think I just need to put in a new T and be done with it. But for now the tank is installed, pressured at 38psi, and apparently functioning well. Can't tell you how much I appreciate all the help from you and the other group folks.
Mike
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On 8/3/2014 8:18 PM, Michael Wilson wrote:

pressured at 38psi, and apparently functioning well. Can't tell you how much I appreciate all the help from you and the other group folks.

Nice to hear a good word, you're welcome.
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On 08/03/2014 7:18 PM, Michael Wilson wrote: ...

Be my recommendation -- the gauge doesn't make any difference to the operation, obviously, but it is nice to have the visible evidence. It's not at all unusual for them to fail with time so not at all unexpected need another. The small diameter nipple tends to clog as well...
Glad to hear you're in business again...
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On 8/3/2014 3:18 PM, Michael Wilson wrote:

Might still BE 52 PSI. Please open a faucet and see if the gauge drops.
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Not if the switch is set to kick on at 52, no.
Tank pre-charge pressure should be 1 to 2 psi below the switch cut-in pressure. But as others have already noted, 52 psi is a very unusually high cut-in pressure -- in fact, that's much more characteristic of a cut-*out* pressure.
A fairly common arrangement is to set the switch to turn on at 40, off at 60, and set the tank precharge pressure to 38 or 39.
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