problems coming to full pressure w/ "new" system

I recently moved my pump (goulds 1/2 horse convertible shallow well jet w/ single intake/ single output lines (two total), and added a new bladder tank, placing an intermediate pressure tank between the pump and the bladder tank. The idea of the intermediate tank is to bleed off methane gas entrained in the water in this area . This tank is topped w/ an Amtrol auto-vent valve 700-c. Water comes in high on this tank and is drawn off low to the bladder tank. (Also have another same valve on the output side of the pump) I seem to have eliminated the gas, but I've been having trouble coming to 40 lbs (20/40 system), and I'm drawing air. Re-did my connections on the intake side, tightened, got some improvement today, but after the pump runs I can always let air out of the vent on the intake side. Also, the pump will sometimes come up to its pressure setting, (I've adjusted the cut-out to about 35 so it will shut off) shut off, then the pressure will drop upon shut-off to 20 or so, re-start, zoom back to max, shut off. (all in seconds) Sometimes this takes two or three "trys" to stay shut off, other times it just cuts out at 35 and holds. I'm at a loss to explain what's going on here, though I'm beginning to think that perhaps my draw level has dropped below my intake point a little, fills in but not fast enough, but I'm wide open to any ideas. (New pressure switch; added a water softener to the system when I did all this - not sure how much of this info is germaine to the situation, but I'm trying to be complete!)

What pressure do you have in your pressure tank? It should be set to 1-2 pounds less than the turn-on pressure (measured with the system pump off, a valve open to relieve all water pressure in the system). If the tank is set too low, or the bladder is shot, there is no air in the system to allow a gradual build-up of pressure since water doesn't compress to any extent readily measurable.

Is that aeration tank supposed to be before or after the pressure tank? I say after with a check valve on the pressure tank outlet. Then the aeration tank and the softener.

Gary
Quality Water Associates

reply to both

bladder tank is brand new - 86 gal - mfgr's rep said to drop pressure in bladder tank to 15 from 18 listed to help system come to max - havn't checked in a few weeks, but started at 15, and that's where it was after a subsequent purge.
As to the airation tank, it's placement is consistent with several diagrams I've seen on the web concerning gas in the water, as well as the "expert" at my supply house - if it was after the bladder tank, wouldn't I be putting gassy water into the the underside of the diaphram, causing it to "gas off" there, and, with no relief valve, allowing less and less water to be allowed in on subsequent fills?

This is interesting, I have never had to deal with gas in water before.

I would think the idea is correct with the exception of putting the water in one side of the aeration tank down low and going out the other side low as well. Let the gas settle to the top. If your shoving water in the top through air, I would think that would force more air into the water in that tank like aerating a pond.

As for the pump not getting more than 35 psi, I would think that is a water level problem. If the jet were plugged it wouldn't make that much pressure. If the pump is sometimes turning off/on rapidly, it could be the air in the lines and the switch being not close enough to the pump. Where is the switch???

What kind of tank are you using to eliminate the air? Is the amtrol device getting rid of the air?

bob...

Huronshore replies

Aeration tank is simple galvinized pressure tank - it, along with the Amtrols, does seem to have eliminated my gassy water problem - pressure switch is mounted on pump.

The only idea I have is if the tank pressure is two pounds less than switch on pressure, is the air in the lines. If there is enough to act as a tank and allow enough water to run backwards the pump might do what you say it does. But on the other hand, with that much air, I would think the pump would not be able to pump water.

bob...

I've sold, installed and set up many pressurized aeration (not air injection/venturi type) systems but.... the use of a regular galvanized tank... never. I've also treated methane with spray depressurization and re-pressurization aeration. Mostly I've used air pump systems.

The AVO (air vent off/auto vent) tank is always after the pressure tank. And they all maintain a head of compressed air that the inlet water fills through after a diffuser that breaks the column of water up to expose more surface area for the aeration to work on.

Your bladder won't mind at all if the gas comes out of solution in the pressure tank, but that won't happen anyway, there has been no aeration yet, so don't worry about it. Put the tank after the pressure tank with a check valve on the bladder tank outlet. That prevents the pump's pressure switch from seeing the decrease in pressure when the vent opens to vent the gas off.

Question, where's the air in this type aeration? How does it get into the intermediate tank?

Gary
Quality Water Associates

I think you may have a system design problem.

The pressure on the inlet of your jet pump is below atmospheric pressure. You are trying to get rid of methane after the pump when the pressure is above atmospheric pressure. If there is so much methane coming off in the discharge, it will come out much more easily on the suction side of the pump. So, your "air" is probably methane.

If I had to pump "gassy" water, I would use a submersible set as far below water level as possible to avoid cavitation. I would discharge it to a plastic tank at atmospheric pressure and would control the submersible with a level switch in the tank.

Then I would hook up my jet pump to the outlet of the plastic tank and let it operate independently of the well pump.

I agree with the poor design. The galvanized tank and auto vent is a pump or plumbing supply house design, and they are saying install before the pressure tank. It sounds as if he didn't have the "air" or low pressure problem before moving the pump and adding the vented tank. Or IOWs it sounds as if the methane in the water wasn't a problem for the pump before.

Gary
Quality Water Associates

Has anyone had experience with a down well gas seperator? Any other thoughts on a submersible in gassy water?