Strange issue with Birm Iron Filter

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Dave23

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Here is the issue: (See attached diagram as well)

Most nights my filter tank backwashes without any issues, however some nights (always the nights there has been a lot higher then normal water usage since the last backwash) as soon as the first rinse cycle starts on the fleck 5600 valve within 10 seconds the pressure on the pressure gauge/switch, drops immeditally to below 10 psi and then pressure switch shuts pump off. If you manually prime the pressure switch after this happen, pressure comes right back up and backwash continues all the way through normal. However If I don't notice it has happened then fleck valve still cycles all the way through with pump off and hence no backwash actually happens.

I have changed the following in the last 2 years but issue still happens.
New Pressure tank 2 years ago
New 1.25 Inch well line 2 years ago
New Birm/Calcite media in tank 1 year ago w new distrubutor tube.
New Fleck 5600 control value 1 month ago

My well pump is a 1/2 HP pump at a depth of approx 120-140 feet. It's a gould pump with 1/2HP franklin motor 240V pump with control box. Pump is

approx 6-7 Years old.

Fleck Air Injector shown in the diagram is at least 15 years old.

Pressure tank sits on a shelf higher then the birm filter, as the birm filter sits on the floor below it. Someone had mentioned to me that I should have the pressure tank on the floor and lines coming in at a higher height then the two tanks, due to having the air injector valve, however I'm not convince this will solve my issue.


I'm at a loss, does anyone have any ideas?

PlumbingDiagram.jpg
 

Bannerman

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My first thought is either a defective pressure switch, or a blockage in the small diameter pipe feeding the switch. You did not specify those were checked or replaced so iron or other debris may be blocking flow, causing the switch to not fully sense system pressure. First remove the pipe and fittings feeding the switch to ensure there is no blockage.

What type of pressure tank are you using? If a bladder or membrane type, air injected before the tank will eventually fully displace any water holding capacity. The same will occur in a non-bladder tank unless an air volume control valve is in-place to vent off excess air in the tank.
 
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Reach4

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Your backwash rate is probably about 5 gpm. It sounds to me as if one of these is true:

  1. Your well ran short of water
  2. The water level ran down enough that your pump cannot maintain enough pressure. to keep your pressure switch from cutting you off, while pumping 5 gpm.
  3. Your precharge air in the pressure tank is too high. Measure the air precharge now. What did you read? While 2 psi below the cut-in is the norm, you could go to 3 psi below the cut-in, or even 4, if necessary. Your pressure switch may be set higher than you think, or your air and water pressure gauges are calibrated differently. To compare calibration, measure the air pressure when the air pressure is near the middle of its normal range. The air and water pressures are very close to each other a that point. That is only for comparing calibration. Precharge air is only measured and adjusted while the water pressure is near zero.
Expansion of discussion... Suppose your pump were 10 gpm 1/2 HP. Lets presume the low-pressure cutoff is at 20 psi on your 30/50 pressure switch. For the pump I checked against (Franklin J-class), it should still be able to deliver significantly more than 6 gpm and lift 140 ft... allowing for some additional lift. A 7 gpm pump would able to deliver from deeper still. So not-enough pump is probably not it. So if the pump is OK, the we are left with the well running dry, or the precharge set to high. Start with the precharge.

If the air precharge reduction does not do it, I suggest moving your backwash time later to give the well more time to recover after your showers.
 

Dave23

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Thanks for the replies.

Pressure switch /small diameter pipe is about 5 years old, but easy item to replace might be worth me just replacing that.

Well is not running dry or even close to dry, (I've checked level many times and always about 20-30 feet from surface. It happens as soon as initial rinse cycle starts). I've run hose for 4 hours before and still have lots of water in well.

I will try changing the precharged pressure in tank down to 36psi (as my switch is set to 40/60), then replace with new pressure switch. What device should I be using to calibrate pressure switch reading?

Yes it is a bladder tank, so should I be putting some type of air release valve somewhere ? If so any suggestions on what I'm looking for?

Strange it only happens if i've used a lot of water since last rinse/backwash.
 

Dave23

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He's another example. Lets say I let my water my filter backwash nightly, no issues at all (using average amount of water). If I set it to backwash every 3rd day for example, then the problem occurs (3x amount of gallons has gone through filter tank this way - and this seem to drive it happening). Still using average amount of water each day.
 

Dave23

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Another thing I just thought of. When this issue happens it will take about 10 seconds or so for the pressure gauge reading to go from say 50 for example down to about 20-30 PSI before pressure switch cuts out. When this is happening I can hear water running into the filter tank but no water is coming out of the drain from the filter tank. If I hold the lever down for the pressure switch to keep it engaged after about 20-30 seconds, water starts to flow out of the drain side of the filter tank, and pressure on my pressure switch/gauge goes back to normal and everything functions properly for the rest of the 2 hour cycles. It's almost like there is an air bubble or something happening inside of the filter tank causing it. However this a complete un-educated guess.

Again this happens immedially when the cycle starts on the filter tank (right on the very first rinse cycle).
 

Reach4

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I will try changing the precharged pressure in tank down to 36psi (as my switch is set to 40/60), then replace with new pressure switch. What device should I be using to calibrate pressure switch reading?
While using water, watch the pressure gauge. Note when the pressure switch clicks, which should be pretty much the minimum pressure seen on the gauge.

With your confidence that the well cannot be drained down, you could put in a pressure switch without the low-pressure cutoff. Then if the precharge was a little too high, there would just be a momentary pressure drop that might not even be noticed. I think swapping the pressure switch and nipple is probably not needed, however. I think your current pressure switch will probably be fine.

As an alternative to dropping the air precharge pressure a bit, you could raise the pressure switch setting. 3.5 turns clockwise, on the 3/8 nut on the big spring, is about 10 psi. So instead of dropping the air pressure, you could maybe turn that nut 1/3 to 1/2 turn CW.

I think the drop in air precharge will do it for you
 

Bannerman

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You are attempting to make the pressure tank do 2 things although it is not designed for 1 of those. A bladder tank is designed to prevent air (captive charge) to not mix with water as the air and water are on opposite sides of the bladder. There is no provision in a bladder tank for an air control device on the water side.

As you are injecting air, ferrous iron will start to oxidize to ferric iron from the air injection port forward. Ferric iron will settle out as solids (rust) which will accumulate within the tank and associated piping. Neither the pressure tank nor its fittings normally incorporate a method to flush out solids that accumulate and so this configuration will continue to be problematic even after any blockage is cleared out.

If the air injection is performing well to supplement the iron reduction performed by the BIRM media, then it would be more suitable to inject air after the pressure tank, with the airated water then flowing to a contact tank to allow the solids to settle to the bottom of the tank and lower iron water to exit the tank from a location above the tank bottom. The tank should incorporate a large, full port blow down ball valve to allow settled solids to be discharged.
 
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Dave23

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I'm not sure why the clack air injector was ever installed. It was there when I bought the house 15 years ago. I wonder if I should just remove it?
 

Reach4

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Air injection can turn ferrous iron into ferric iron so that it can be filtered out mechanically. So it might have been a supplement to make the small amount BIRM have less to do or to oxygenate the water to help the BIRM.
 

Bannerman

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Is there a method to bypass the air injector without removing it? If there is, you could then temporarily use only the BIRM media tank for iron reduction, to establish how effective it will perform by itself.

Perhaps BIRM was not utilized initially and air injection was the only method employed to address the iron problem.

Removal and cleaning the existing pressure tank and fittings is usually a relatively straightforward and simple procedure. With today being a statutory holiday in Canada, you may wish to postpone disassembly to a day when suppliers will be open for business, in case something becomes broken and replacement parts are needed.
 
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Bannerman

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doesn't say which way to adjust to cut down on air injection

Perhaps installing a removable sealant or even tape could be utilized to block the air inlet port.

Interesting the PDF shows using the pressure tank as a contact tank. Although not stated and no air control or allowance for flushing is indicated, I expect this configuration would be more suited to a non-bladder pressure tank utilizing an air control valve.

Even with changing the tank pre-charge, with the air injector in its present location, air will continue to enter the water side of the bladder tank, thereby displacing its ability to store any amount of water.
 
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ditttohead

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In general Birm needs to be replaced regularly. It is not a very strong media but it is fairly easy to backwash and does a decent job of iron reduction as long as there is a decent amount of dissolved oxygen (DO). Do is introduced with the air injector. Only the micronizer is still typically used, the blue injector in the previous post. These should be rebuilt with a new check valve every year or so. Replacing the check takes about 1 minute. I would remove the pressure switch and clean out the tee that it is installed into. These commonly get plugged up with iron. A new switch is readily available at any hardware store for less than $40 so replacing it should be an obvious choice.
 
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