Pressure switch 'rubber banding' on & off

[TinHead]

I have an open geothermal loop in a 400' well with 120' of return line.
I also use this system for domestic water.
I have 2 pressure switches, one for the bladder tank, one for the geo loop. They are wired in parallel so either or both can call for pump.
There is a check valve on the bladder tank.

The problem I am having is with the geo loop pressure switch, on initial start the switch starts a 'rubber band' type of on then off.
When it's running the pressures run about 44 in and 32 out. It does not 'rubber band' most of the time... it normally starts smooth.
I have tried to remedy the issue by setting the press switch to a large differential of 10/60, but it still happens.

All piping is for 9gpm, the pump is 7gpm, with a very high static level.

It seems to me (I'm not a well/pump professional) that the initial surge is overwhelming the resistance of the geo valve on the return line and sending the pressure switch above high limit.
Was wondering if there are any 'slower acting' pressure switches available that might ignore an initial momentary surge?
Or maybe a way to absorb some of the surge, like a small expansion tank?

Every now and again (couple times a year) the system struggles to push the air out of the return line. My geo heat pump is several feet below my pitless. Not sure this has anything to do with my problem.. just figured I'd throw it out there in case it's a clue

The system was done piecemeal at my direction, so I'm the only one to blame.
I figured I should put that out there so it's not a distraction.

Your constructive feedback is welcome

Thanks in Advance
Andy

PS I'm going abroad in 2 days, so there might be a void in my response

 

[Valveman]

You only need one pressure switch. It doesn't matter if the water for the geo comes on or if you use water in the house, the pressure should drop from 60 to 40 and the pressure switch will start the pump. The bouncing is usually because the pressure switch is too far away from the pressure tank. Make sure the one pressure switch you need is installed right next to the pressure tank.

 

[Sponsor]

 

[TinHead]

Thank you for your reply.

After your suggestion I realized I should have used a diagram to be clearer and to facilitate any questions, so I created a 3d model and I'm attaching an illustration.

With my current arrangement neither pressure switches will operate the system properly from their current location without modification.

How should I arrange a single pressure switch and check valve with the current piping layout?

Thank you for your time!
Andy

 

[Valveman]

I can't really tell where the lines or going or coming from. But the pressure switch close to the tank should be ok. The PS in the back is of no use and too far from the tank, I would remove it. And you really do not need a check valve at all. But if the check is on the line coming in from the well and not keeping water from going out of the tank to the heat pump or house, it will be ok until you start noticing water hammer on pump start, then the check will need to be removed.

Nice drawing. What did you use to draw it?

 

[TinHead]

Thanx, it's Google Sketchup, it's free.

Sorry about no labels on the lines, I added some text in paint.

I'm guessing your recommendation will still be to remove check valve and back pressure switch (which sounds like a great idea) I just want to be sure cause I'm leaving in a couple of days and don't want to leave the wife with a problem.

Thanks again for your time.
Andy

 

[Valveman]

Yes if you remove that check valve then water can go backwards from the tank to the heat pump until the pump comes on, then it will go directly from the well pump to the heat pump. That way you can just remove the pressure switch on the heat pump line, as I am sure that one is bouncing and giving lots of problems.

 

[TinHead]

Yes if you remove that check valve then water can go backwards from the tank to the heat pump until the pump comes on, then it will go directly from the well pump to the heat pump. That way you can just remove the pressure switch on the heat pump line, as I am sure that one is bouncing and giving lots of problems.

Thank You!

I will do exactly that.

Regards
Andy

 

[Valveman]

Also remember that you can remove the guts of the check valve and use the housing as a piece of pipe to to re-plumb the line.

 

[TinHead]

Also remember that you can remove the guts of the check valve and use the housing as a piece of pipe to to re-plumb the line.

I really appreciate you coming back and telling me that, it will be very very helpful in the future.

I've already made the changes and the result is obvious... it works 100% better!
There is no jump in the pressure gauge needles anymore, smooth as silk both on and off.

Now I have a spare press switch, check valve, 40 va transformer, and relay.
It's like Christmas. 8)

Thanks again for your help!
Andy

 

[Valveman]

You are fast! Just glad you got it working like you want.