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Fish4Fun2 · Mar 13, 2013, 08:49 AM

As stated in the title I have a private well system that supplies my home with water; however, it may well be the most complex private well system ever, lol, so I will spend a bit of time describing it, and explaining why it is so complicated.

First the "why", we live in a coastal area with notoriously bad well water and just as notoriously bad municipal water. We built the house on an acre of land adjacent to our previous home. A couple of decades ago I drove an 1 1/4" shallow well on the property to supply my garden with water. (At the time wire was a lot cheaper than pipe, lol) Amazingly the water from my garden well was spectacular in complete contrast to all the surrounding wells. (There are 16 wells within a half mile radius, including our previous house, and none of them have water that is even remotely palatable without treatment.)

The problem with this 1 1/4" shallow well is that 3.5 GPM @ 0 PSI is about the best it will do, and this simply isn't enough supply for intermittent demands. My solution was to build a "water shed" with a 550 gallon cistern in it. The well pump is connected to a float switch that maintains the cistern level while the cistern feeds a 25 GPM industrial "booster pump", which, in turn, supplies the house via 2 large pressure tanks.

Now, on to the problem. One of the pressure tanks is located in the water shed very close to the booster pump, the second is located about 100 feet away inside the house. The pressure tank in the shed is connected to the pump with 1 1/4" PVC. The feed from the water shed to the bladder tank in the house is 3/4" PEX with a check valve located at the pressure tank inlet. Both pressure tanks are "80 gallon equivalent" bladder tanks. The pressure switch on the booster pump is set to "cut in" @ 50PSI and "cut out" @ 65 PSI (with 0 GPM demand, this is 1min 45 seconds run time). MFG instructions for the bladder tanks suggest pressurizing them to 2 PSI below "cut in" (ie 48 PSI in this case); however, with this setting on both tanks, when the booster pump turns off, the system pressure "normalizes" to ~55 PSI. I assume this 10 PSI drop represents the resistance in the 100ft 3/4" PEX line, and the subsequent pressure drop is the second tank continuing to accept water after the pump has stopped running. In the house, when there are multiple water demands, there are noticeable pressure fluctuations as the pump cycles.

And, finally, the question, LOL: Obviously the pressure tank pressures (and perhaps the pump pressure switch) need to be adjusted to minimize the pressure fluctuations. Intuitively I think the pressure tank in the house should be pressurized to less than the one in the water shed; however, I am not sure how much less. Ideally I would like the pressure in the house to always be above 40 PSI, and preferably not fluctuate; how much does this imply dropping the pressure tank pressure in the house? From the "normalization pressure", I am assuming the pressure in the house tank should be at least 10 PSI below the pressure in the shed tank, but this is just a SWAG. Would increasing the system pressure in the shed 10PSI have the same effect as lowering the pressure in the house pressure tank? (75 PSI cut off seems awfully high, however, if the system "normalized" to 65 PSI the "high pressure" would only be intermittent... )

I would appreciate any thoughts; that may help to minimize the number of trial and error cycles.

Thanks in Advance!

Fish

jlisenbe · Mar 13, 2013, 11:17 AM

Are the two tanks about the same as far as elevation goes? If the second one is lower than that first, then I could see that causing problems.

Ideally I would like the pressure in the house to always be above 40 PSI

, Are you saying the tank in the house drops below 40# of pressure? How are you measuring that? That doesn't sound right.

Probably the easiest solution is to simply get rid of one of the tanks. I can think of no reason to have both. With two tanks separately by 100' of pipe, I think you will just have these problems. You would be better off to keep the one outside since it is close to the pressure switch, and that is the recommended practice. You might even, if you just insist on having two, put them both together at the shed.

I don't know if "playing with" the tank pressures will help or not, but I rather doubt it. But with two tanks, and all the problems it is causing, I'd ask myself why I would want two tanks to begin with. With your pump above ground, pump cycles are not as critical. You have what sounds like a 35 gallon or so bladder tank. That should be plenty of tank.

Fish4Fun2 · Mar 13, 2013, 06:08 PM

Jlisenbe,

Thanks for the suggestions! I spent the afternoon working on it and made two discoveries. Most notably the pressure tank in the house has a ruptured bladder. It is ~ five years old, but I installed it under the house prior to building the house, and it is too large to physically remove, however, I will in fact disconnect it from the system. The second discovery was that the bladder tank in the shed was pressurized considerably less than it should have been (should have been 48 PSI, was actually ~25 PSI) . I pressurized the shed tank to 48 PSI, adjusted the pressure switch to cut in @ 50 PSI and cut out at 70 PSI. Finally, to ensure the water was working when my wife came home, I pressurized the bladder tank under the house to 40 PSI with only a small amount of water in it, the idea being that with a ruptured bladder it might act as a "conventional pressure tank" until I can disconnect it from the system. (I won't be able to disconnect the tank until I have more time.)

The reason for the pressure tank @ the house in addition to the pressure tank in the shed involves a previously unmentioned iron removal system (Calcite and Filox) between the two pressure tanks. This system back flushes for ~40 minutes every night beginning ~ 04:00. The thought was to ensure there was enough water during the cycle to flush toilets, wash hands etc. For this same reason I will need to install a second pressure tank (but this time in the shed) after the water treatment system.

Are you saying the tank in the house drops below 40# of pressure? How are you measuring that? That doesn't sound right.

Yes, I know the pressure in the house was dropping well below 40 PSI because of the recent addition of a "Brew Room" (for home brewing beer). In my "sink set up" I have a rather elegant configuration of SS ball valves, Quick Couplers, Nipples, Tees and Elbows that allow me to direct H/C water, heated Sanitizer, Heated Cleaner, Air, Vacuum or CO2 to any combination of several outputs, and I installed a pressure gauge as a visual safety feature (primarily because of the Air input). The house pressure frequently dropped to <30 PSI, then would jump to ~60 PSI which I could not explain. Combined with the perceived pressure changes while showering, I decided I had problem. The post above was from my notes on the system when I set it up; when I actually checked the tanks (after my post) I quickly realized there were multiple problems. When first installed (~five years ago) the system performed exactly as it was suppose to. Since I hadn't really noticed any problems except the pressure changes in the shower, I wasn't worried about anything until I installed the pressure gauge in the brew room a few months back. Checking everything out was today's project, sadly I will need to schedule another day or two to complete repairs. Checking the pressure tank pressures annually is now on my "upkeep list". (I am a bit concerned that the pressure tank in the shed was so far below where it had been originally. I will check it again in a month and then again in the Fall to make certain there isn't an air leak.)

**I know most people wouldn't worry about "not having water" from 04:00 - 04:40; however, we have a large house and frequent company; and I myself keep rather odd hours... (OK, my OCD cannot handle knowing something isn't working 2.8% of any given day, lol).

Thanks for taking the time to respond!

Fish

jlisenbe · Mar 14, 2013, 06:56 AM

Good detective work, Fish!

I pressurized the bladder tank under the house to 40 PSI with only a small amount of water in it, the idea being that with a ruptured bladder it might act as a "conventional pressure tank" until I can disconnect it from the system.

You are correct It will work as you described for several weeks, perhaps even a little longer.

**I know most people wouldn't worry about "not having water" from 04:00 - 04:40; however, we have a large house and frequent company; and I myself keep rather odd hours... (OK, my OCD cannot handle knowing something isn't working 2.8% of any given day, lol).

Trust me... I understand all too well!

jlisenbe · Mar 14, 2013, 07:06 AM

One thing to consider. Each pressure tank has a reserve, simply meaning how much water it can deliver before pressure drops off to, in your case, 50# and the pump cuts on. I am going to guess that reserve for your tanks is about fifteen gallons each. So, once you burn through 30 or gallons of water, the pump cuts in. For whatever the need is at that point, including backwashing, you are now dependent on what the pump can deliver. See my point? Once you use more than 30 gallons (or whatever it is), you are down to what the pump can deliver. The second tank provides no benefit after then. So the second tank only provides an additional reserve, but once that reserve is used, it adds nothing.