Trouble with Booster Pump Switch

[RichT]

Below is the diagram of my RO/DI system. What am I doing wrong? Currently the Bar Faucet, and Ice Maker are not hooked up. The product water tube from the DI has a JG ball valve and is filling a 32g brute. When there is no demand for water the pressure solenoid (came with the Kent float valve kit) closes when the bladder tank gauge reads around 55 psi. The pump continues to run because the pump switch was preset to 80 lbs. In an effort to reduce the shut off pressure, I backed out the allen screw on the top of valve. The pump continued to run. I actually back the screw all the way out (and promptly lost it) and still, the pump continued to run. These switches come preset at 40, 60 or 80 psi. Are they different switches or are they the same switch at different presets? If there is something different with the switches than that would explain why I wasn't able to adjust the switch down enough. If they are the same switch than I either have a bad switch or there is something wrong with my hook up. Please advise.
Also, I have a call into Aquatec, and a email into Freshwatersystems.com. I figured I would be able to get a faster answer on RC. Thanks!
Design drawing:

Switch: (I installed the stove bolt to make it easier to adjust)

DIY Mixing Chamber: (works great!!!)

 

[Fast Fred]

I would say to try tightening the screw to see what happens. Other than that, maybe try moving the pressure switch to the other side (before) the solenoid.

Any RO system experts have any ideas?

HTH,
Fred

 

[RichT]

Fred,
Tightening the screw seemed to increase the required pressure to shut off the pump. I tested this theory with an air compressor. The gauge on the RO chamber runs around 92 psi on average. If I was to place the switch on the input side of the solenoid than, unless I turned the pump pressure down below 80, the pump would cycle on and off. The directions for the pump said the switch is to be placed as close to the bladder tank as possible. I guess what I'm looking for is for someone to confirm that a 60 psi preset switch can be lowered to say 54 or 53 psi. Or, is there anyway to increase the closing pressure for the solenoid valve. I feel I could get it to run reliably with either adjustment.
Thanks,

 

[andro]

I have a similar setup to what you have. I have found, that putting the booster pump pressure switch about 1 foot away fro mthe booster pump itself works best. I tried it by the pressure tank, but never got it to shut off.

I have mine set to 90 psi, and because my tap water is 40 psi, when the pressure switch would turn the pump off, I backfed my house fro mthe ro and it turned the pump back on, so now I have a check valve right before the booster pump also.

You will get the best production from your ro at around 80 psi if you can get it to work for you.

-Ian

 

[RichT]

Here's what I've learned today

Here's what I've learned today

First I want to say the people at Freshwatersystems.com are great. That is were I got the pump, switch and tank. Steve went way out to help me. There prices are good and the delivery was prompt. Everyone should at least give them a look when making a purchase. Anyway, enough of the commercial. This is what I learned:

The switch I bought (80 psi preset) was way to high. The pressure shut off solenoid (actually a hydro-pneumatic solenoid valve) closes when pressure on the output side of the membrane reaches 66%+/- of the membrane input pressure . Therefore.... if my pump is pumping around 90 lbs, the solenoid will close when the output pressure reaches 60 lbs. Mine actually closes when the tank gauge reads 56 - 57 psi so the pressure switch would never see the 80 psi needed to shutoff the pump. My first instinct was to get a 60 lb switch but then Steve told me about TDS creep and back pressure. That much back pressure from the tank will cause more water to be unnecessarily rejected and even cause some of the removed TDS to find its way to the membrane output. If I wanted that much pressure/water in the tank I would need a permeate pump to counteract the back pressure from the bladder tank. If I wanted to have 80 psi in the bladder tank I would need a combination of a permeate pump, and a electronic shutoff valve to replace the hydro-pneumatic valve and, because the RO membranes are not designed to operate at that much back pressure, I will be risking water quality and unit efficiency. So, in the end, Steve is sending me a 40 psi switch for the cost of shipping. I can of course crank it up a few notches (hopefully to at least 50 psi). There will be plenty of pressure and water in the bladder tank and the pump will shut off as expected. Hopefully alls well that ends well and maybe a few people will read that the results successfully and they save a few nights tinkering with valves and tubes . I'll post the results as soon as I have hooked it up and tested the switch.

 

[sjdyer]

have you tested it yet?