Pressure switch location question

[Tubby]

My residential indoor system is unconventional and was put in 40 years ago I presume (I did replace the pressure switch 15 years ago). Please see photo. I'm considering ditching the check valve (A), adding a CSV1A, and installing a new switch and gauge a bit lower down on the PVC, perhaps where the outflow branches off (B).

I notice the following (red text) in the installation instructions:

3. The diaphragm style pressure tank should be installed downstream of the CSV1A. (NOTE: All side and bottom ports on the CSV1A are downstream ports.) There are two options: The tank can be installed/plumbed into the 3/4" port on the bottom of the CSV1A valve with the pressure switch/gauge/presure relief valve installed on the two 1/2" side ports....or the tank can be tee'd off of the main line via a standard tank Cross or tank tee. Pressure switch and other controls can either be installed on the tank tee or tank cross.

Note: Do not install pressure switch directly on main line away from pressure tank. Pre-charge pressure in the tank should be 2-5 psi lower than pressure switch start point.

Does this really matter as long as everything is downstream of the CSV? It seems to me that the entire system would be pressurized equally and a couple of feet of distance wouldn't matter much. For that matter, without that inside (extra) check valve, I suppose the water pressure would tend to equalize back to the valve on the pump, 550 feet away.

So if it doesn't matter, I would install a brass tee at location B for the switch, gauge, and out line (the long part of the tee). Edit: The CSV would go where A is.

There is limited slack in the power line to the pressure switch, so I'll have to replace that wire it if I move the switch much further down.

I might wait on adding a tank tee until it's time to change the current tank.

 

[Reach4]

It matters less, or at least no more, with the CSV than without.

I see "550 feet away" in your text, but I think you should be talking about putting the CSV where the check valve currently is, and the pressure switch closer to the pressure tank than it is now.
Or were you talking about having the CSV 550 feet away, and that is why you mentioned 550 feet away?

 

[Sponsor]

 

[Tubby]

It matters less, or at least no more, with the CSV than without.

I see "550 feet away" in your text, but I think you should be talking about putting the CSV where the check valve currently is, and the pressure switch closer to the pressure tank than it is now.
Or were you talking about having the CSV 550 feet away, and that is why you mentioned 550 feet away?

Right, I would put the CSV where A is.

 

[Reach4]

Right, I would put the CSV where A is.

No problem then.

If you later needed to replace the pressure tank, you could go smaller. But the one you have will work fine.

 

[SuperGreg]

I would just get the CSV kit with pressure tank included and install it all in one go. But I'm spending your money

If you need to extend the electrical, not sure if you've got electrician skills but I would put a four square box right on the bottom of that conduit, run the other romex over to the box as well, and use the box to junction the romex to THHN. Run one piece of flex from the box down to the switch, and run four conductors for the contacts plus ground.

 

[TJanak]

Totally unrelated, but someone must not have had a NPT ball valve because that's like $100 of fittings and valve to go from PVC to pex.

 

[Tubby]

Totally unrelated, but someone must not have had a NPT ball valve because that's like $100 of fittings and valve to go from PVC to pex.

I had an ancient main shutoff valve that was completely frozen, so this is what the plumbers replaced it with.

 

[Valveman]

My residential indoor system is unconventional and was put in 40 years ago I presume (I did replace the pressure switch 15 years ago). Please see photo. I'm considering ditching the check valve (A), adding a CSV1A, and installing a new switch and gauge a bit lower down on the PVC, perhaps where the outflow branches off (B).

View attachment 107625View attachment 107626

I notice the following (red text) in the installation instructions:


Does this really matter as long as everything is downstream of the CSV? It seems to me that the entire system would be pressurized equally and a couple of feet of distance wouldn't matter much. For that matter, without that inside (extra) check valve, I suppose the water pressure would tend to equalize back to the valve on the pump, 550 feet away.

So if it doesn't matter, I would install a brass tee at location B for the switch, gauge, and out line (the long part of the tee). Edit: The CSV would go where A is.

There is limited slack in the power line to the pressure switch, so I'll have to replace that wire it if I move the switch much further down.

I might wait on adding a tank tee until it's time to change the current tank.

The best location for the pressure switch is in the 4" between the last elbow and the tank. Having the switch too far from the tank can cause it to bounce the pump on/off rapidly. However, the CSV does help in that it slows the flow to 1 GPM before the pump shuts off and keeps the switch from bouncing. You can probably get away with removing the check valve, installing a CSV1A in its place, and attaching the pressure switch, gauge, and pressure relief to the extra ports on the CSV1A. If it doesn't bounce, you don't have to move the switch.

 

[Sarg]

I'd convert to conventional.

 

[Tubby]

The best location for the pressure switch is in the 4" between the last elbow and the tank. Having the switch too far from the tank can cause it to bounce the pump on/off rapidly. However, the CSV does help in that it slows the flow to 1 GPM before the pump shuts off and keeps the switch from bouncing. You can probably get away with removing the check valve, installing a CSV1A in its place, and attaching the pressure switch, gauge, and pressure relief to the extra ports on the CSV1A. If it doesn't bounce, you don't have to move the switch.

That would already be happening with my current system, right? But I'm not sure how I would know. My hand-held current detector doesn't show any obvious off/on/off when the switch shuts off.

I am hoping to avoid putting a conventional tee on the tank until the tank has to be replaced anyway.

 

[Reach4]

To the extent that there would be a little pressure drop between the pressure switch and the pressure tank due to flow, the pressure switch would turn off a little early, but only a little. Bounce would show as pre-mature shut-off. With 1 inch PVC between the pressure switch and the pressure tank, bounce would be less significant than with smaller pipe.

However it is normal for some settling of pressure to occur after shut-off, and you could confuse that effect with bounce.

https://terrylove.com/forums/index....lbs-of-pressure-at-cut-off.67940/#post-504741 is a study I made of my pressure vs time after shutoff. Mine is a 44 gallon pressure tank. I attribute the drop to a relaxation of the diaphragm with time.

I had a 40/60 pressures switch. Then I got a good deal on a digital 0-60psi pressure gauge, and I dropped my pressure.

Previous to the 40/60 pressure switch I had a 30/50 pressure switch. Both were good pressure from my point of view, so turning the pressure down to put my pressure in the range for my gauge was not a problem for me.

 

[FredG]

However it is normal for some settling of pressure to occur after shut-off, and you could confuse that effect with bounce.

https://terrylove.com/forums/index....lbs-of-pressure-at-cut-off.67940/#post-504741 is a study I made of my pressure vs time after shutoff. Mine is a 44 gallon pressure tank. I attribute the drop to a relaxation of the diaphragm with time.

This is due to water rushing into the pressure tank at a fast pace at shutoff. If you have a csv filling the last little bit at 1 gpm, it won’t do that.

Without a csv, you can run water close to what the pump puts out at shutoff, (out of a garden hose etc.), then when it shuts off the gauge will read exact shutoff pressure and stay there.

 

[Reach4]

This is due to water rushing into the pressure tank at a fast pace at shutoff. If you have a csv filling the last little bit at 1 gpm, it won’t do that.

Without a csv, you can run water close to what the pump puts out at shutoff, (out of a garden hose etc.), then when it shuts off the gauge will read exact shutoff pressure and stay there.

I don't think so. The CSV can strongly reduce the tendency to turn off early, but note the left side of my graph is when the pressure switch cut off. I could see the pressure rise continuing for a second or two being the water having momentum, but that is not IMO going to account for the slow pressure drop.

A slow-to-close check valve could explain that, but I don't think that is what is going on.

 

[Valveman]

When the pressure switch is that much ahead of the pressure tank, the switch usually bounces on pump start. When the pump starts and pops open that check valve, the surge of pressure can quickly reach 60 PSI and bounce the pump off. Then because there is really only 40 PSI in the system when the pump started, it quickly drops back to 40 and re-starts the pump. Sometimes it will bounce 2-3 times before the pump stays on. It doesn't always bounce, and it is not always noticeable. If a large tap is open when the pump starts, it may not bounce. But a small use of water turning on the pump can cause the bounce. If it happens occasionally it can break a pump shaft or cause other problems.

You don't need a tank cross. Just glue in a regular tee before the pressure tank and reduce the stub up to 1/4" for the switch.

 

[Tubby]

You don't need a tank cross. Just glue in a regular tee before the pressure tank and reduce the stub up to 1/4" for the switch.

So I would get a tee like this? And connect a 1/4" adapter/nipple on the top?

 

[Reach4]

You have PVC pipe according to your first picture. The tee you pictured does not glue to PVC.

 

[Valveman]

You need a sch 40 PVC tee. Then glue in a female adapter to the top and bush the 1" threads down to 1/4" for the nipple to the pressure switch.