Pressure Switch for booster pump

**Bob1000** · 03-16-2008, 02:41 AM

I got a SquareD FYG22 pressure switch connected with a booster pump and a pressure tank

I am very familiar with that sort of pressure switches and used them a lot and find that they are all of the same layout .

However this one ( supposed to handel relatively higher pressures then the basic model) I find it difficult to set it up for comfortable usage..

When I tighten the BIG nut to increase the CUT IN pressure setting , it increases the CUT OUT pressure as well even without touching the other small nut of the high pressure setting!!!!!

My target is to have a pressure differential ( Between the High and the Low pressures) of only 15 PSI ( to achiev MINIMUM pressure fluctuation which affests showring etc... ) and it would be ideal for me to have 50/65 or 50/70 settings but that seems to be impossible to achieve with this switch.

I could hardly set the Low to 50PSI but the high now is 80 PSI which is too much for my house . right now the small nut ( the Cut out pressure nut ) is totally LOOSE i.e it is NOT tightened at all YET the high pressure is 80PSI

Any Idea why I have this problem?
Thanks in advance for you all

**Gary Slusser** · 03-16-2008, 11:35 AM

Originally Posted by Bob1000

I got a SquareD FYG22 pressure switch connected with a booster pump and a pressure tank

When I tighten the BIG nut to increase the CUT IN pressure setting , it increases the CUT OUT pressure as well even without touching the other small nut of the high pressure setting!!!!!

That is how all switches work; the tall screw raises/lowers both cut in and out setting. The short screw cntrols the off setting only.

Originally Posted by Bob1000

My target is to have a pressure differential ( Between the High and the Low pressures) of only 15 PSI ( to achiev MINIMUM pressure fluctuation which affests showring etc... ) and it would be ideal for me to have 50/65 or 50/70 settings but that seems to be impossible to achieve with this switch.

The minimum differential is supposed to be 20 psi and usually trying to set it to less than that is difficult to impossible.

The switch is all screwed up, reduce the settings and start over.

hj · 03-16-2008, 04:48 PM

It is not a "cut out pressure" nut, it is a differential nut. Which is why raising the operating pressure also raised the cut in pressure, because the differential stays the same and does not change with that adjustment.

**Bob1000** · 03-17-2008, 11:06 AM

Originally Posted by Gary Slusser

That is how all switches work; the tall screw raises/lowers both cut in and out setting. The short screw cntrols the off setting only.

The minimum differential is supposed to be 20 psi and usually trying to set it to less than that is difficult to impossible.

The switch is all screwed up, reduce the settings and start over.

Thank you for your reply but please explain what you mean by ( short nut controls the off setting ) do you mean differential?
Right now that short nut is totally loose , untightened yet still have differential of about 30 PSI
By the way , this pressure switch is almost brand new !!!

**Gary Slusser** · 03-18-2008, 01:23 PM

The tall screw raises/lowers the cut-in and out settings. The short screw raises/lowers the cut out only. Once you get the cut in close or right, then you use the short screw to prevent the pressure from going too high and eventually set the cut out, which should be 20 psi minimum differential.

**Bob1000** · 03-19-2008, 01:52 AM

Originally Posted by Gary Slusser

The tall screw raises/lowers the cut-in and out settings. The short screw raises/lowers the cut out only. Once you get the cut in close or right, then you use the short screw to prevent the pressure from going too high and eventually set the cut out, which should be 20 psi minimum differential.

Thank you Gary that is clear now..
However , any idea to overcome the problem of pressure fluctuation from 50 to 80 PSI which shows worest during showering ?
I am thinking of fixing a pressure regulator at the pump outlet and set it to 50PSI , what you think? is that a practical thing to do?
I know that CSV is an option but I do not like the idea of the pump struggling through it specially that I bought a new expensive 2HP pump to be able to achieve 80 PSI at any time WITHOUT depending on the city pressure.
Thank you again

**valveman** · 03-19-2008, 05:01 AM

With the nut on the small adjustment spring loosened all the way out, the pressure switch should be at it's lowest differential pressure, which should be about 15 PSI. You must have a bad switch, or that switch was not meant to go as high as 80, and you have completely collapsed the spring under the large adjustment screw.

A pressure regulator before the pressure tank will shut completely at it's set pressure. This will not allow your tank to fill or the pump to shut off. The pump will just be pumping against a closed valve for a few minutes until it burns up.

80 PSI sounds a little high but, if you want 80 PSI then set a Cycle Stop Valve for 80 PSI. There is no "struggling" to get to this point if you set the valve at 80 PSI. The pressure switch will then need to go to 85 or 90 before shutting off the pump. A good setting would be on at 70, off at 85, with a CSV set at 80.

**Gary Slusser** · 03-19-2008, 12:21 PM

Originally Posted by Bob1000

However , any idea to overcome the problem of pressure fluctuation from 50 to 80 PSI which shows worest during showering ?
I am thinking of fixing a pressure regulator at the pump outlet and set it to 50PSI , what you think? is that a practical thing to do?
I know that CSV is an option but I do not like the idea of the pump struggling through it specially that I bought a new expensive 2HP pump to be able to achieve 80 PSI at any time WITHOUT depending on the city pressure.
Thank you again

The higher the pressure, the more apt the velocity increase in the pipes and causes erosion corrosion. It also causes much higher friction losses in the system and you'll have water hammer and the damage it causes. The more noticeable the pressure fluctuation... and ya don't really need to power wash yer butt, do ya?

Listen to Valveman. BTW, he also thinks you're wanting too much pressure as I do. So maybe if the pressure was constant at say 50 psi, you'd be fine? If so go with a CSV. Speedpump knows them very well and sells them.

BTW, are you sure your new 2 hp pump is getting enough water from the city? It may be trying to move more water than the city is supplying; that would be in gpm. Also, the higher the pressure you run the more frequently the pump has to start, that kills motors and really spins the electric meter.

**Bob1000** · 03-20-2008, 08:13 AM

Originally Posted by Gary Slusser

The higher the pressure, the more apt the velocity increase in the pipes and causes erosion corrosion. It also causes much higher friction losses in the system and you'll have water hammer and the damage it causes. The more noticeable the pressure fluctuation... and ya don't really need to power wash yer butt, do ya?

Listen to Valveman. BTW, he also thinks you're wanting too much pressure as I do. So maybe if the pressure was constant at say 50 psi, you'd be fine? If so go with a CSV. Speedpump knows them very well and sells them.

BTW, are you sure your new 2 hp pump is getting enough water from the city? It may be trying to move more water than the city is supplying; that would be in gpm. Also, the higher the pressure you run the more frequently the pump has to start, that kills motors and really spins the electric meter.

Sorry , I think there is a misunderstanding here ...
I suggested to fix the pressure regulator at the pump SYSTEM outlet ( meaning the pipe that is coming from the pump system enteing the house
My idea is , let the pump cut in at 50 and cut out at 80 but that pressure regulator would keep a steady pressure of 50 psi all the time , is that right?

**valveman** · 03-20-2008, 08:35 AM

Yes a pressure regulator before the pressure tank would keep the pressure at 50 all the time. It would never let it build up to 80 or even 60 and shut off. The pump would just sit there and spin until the water boils and burns up the pump.

A pressure regulator after the pressure tank would work as you stated but, the pump would be cycling on and off continually between 50 and 80 while you are using water. Actually a standard pressure regulator would loose about 5 PSI for every 5 GPM flow. Using 2 GPM you would have 50 PSI. Using 5 GPM you would have 45 PSI, and 10 GPM use would only let you have 40 PSI. Then there is the Valve "creap". When you are no longer using water, the regulator would let water slowly "creap" through until your house had 80 PSI also. Then you would get a quick blast of 80 PSI when you open a faucet and the pressure would quickly drop to 50 again.

A Cycle Stop Valve before the pressure tank would also hold at 50 as long as you are using water but, would let 1 GPM through to fill the pressure tank and safely shut off the pump when you are no longer using any water. And there would be no pump cycling while you are using water.

**Bob1000** · 03-20-2008, 08:37 AM

Originally Posted by valveman

With the nut on the small adjustment spring loosened all the way out, the pressure switch should be at it's lowest differential pressure, which should be about 15 PSI. You must have a bad switch, or that switch was not meant to go as high as 80, and you have completely collapsed the spring under the large adjustment screw.

A pressure regulator before the pressure tank will shut completely at it's set pressure. This will not allow your tank to fill or the pump to shut off. The pump will just be pumping against a closed valve for a few minutes until it burns up.

80 PSI sounds a little high but, if you want 80 PSI then set a Cycle Stop Valve for 80 PSI. There is no "struggling" to get to this point if you set the valve at 80 PSI. The pressure switch will then need to go to 85 or 90 before shutting off the pump. A good setting would be on at 70, off at 85, with a CSV set at 80.

The pressure switch is Square D model FYG22
Technical specifications written on box is EXACTLY as follows :-
Range of rising pressure 2.8-7 Bar ( 40.6 - 101 PSI) ( 1 Bar = 14.5 PSI)
Differential
At min setting 1.2 - 2.3 Bar ( 17.4 - 33.3 PSI)
At Max setting 1.6-2.7 Bar (23.2 - 39.2 PSI)
Factory setting 5.4-7 Bar ( 78.3 - 101 PSI)

What do you think?

**valveman** · 03-20-2008, 08:44 AM

Differential
"At min setting 1.2 - 2.3 Bar ( 17.4 - 33.3 PSI)"

Sounds like they are not too sure about the minimum differential. Could be 17.4 or 33.3. Sounds like yours is 30. Maybe the next one out of the box would let you do 17.4 differential but, how would you know till you tried it?

**Wet_Boots** · 03-20-2008, 08:49 AM

You cannot eliminate the differential built into a pressure switch. It's there to allow for water storage in a pressure tank. If you must absolutely have a constant unvarying pressure downstream of the pump/tank, then you are complicating things. How much money is this 'ideal' worth?

**Bob1000** · 03-20-2008, 08:57 AM

Originally Posted by Wet_Boots

You cannot eliminate the differential built into a pressure switch. It's there to allow for water storage in a pressure tank. If you must absolutely have a constant unvarying pressure downstream of the pump/tank, then you are complicating things. How much money is this 'ideal' worth?

I need to have constant pressure downstream at least during the shower to avoid hot and cold shocks due to changing the hot/cold water mixture
I am thinking of fixing a pressure regulator in the entrance of the house pipe and set it to the cut in pressure of the pump , what do you think?

**valveman** · 03-20-2008, 09:03 AM

Again!!

A pressure regulator after the pressure tank would work as you stated but, the pump would be cycling on and off continually between 50 and 80 while you are using water. Actually a standard pressure regulator would loose about 5 PSI for every 5 GPM flow. Using 2 GPM you would have 50 PSI. Using 5 GPM you would have 45 PSI, and 10 GPM use would only let you have 40 PSI. Then there is the Valve "creap". When you are no longer using water, the regulator would let water slowly "creap" through until your house had 80 PSI also. Then you would get a quick blast of 80 PSI when you open a faucet and the pressure would quickly drop to 50 again.

Also a pressure regulator on the house side of the pressure tank would not allow your pressure tank to be used for thermal expansion. You would need to add another small expansion tank at the water heater or something is gonna blow up.

I forgot you can get regulators with thermal expansion poppets. Then you would not need an expansion tank.