Quick Question on backflow properties of Cycle Stop Valve setup

[nvester]

Hello, while looking to design and upgrade my current well setup, I stumbled upon the term "CSV" while looking into various pump options. After a quick Google search, I immediately recognized the value of such an addition and wanted to incorporate it into my alleged setup. I'm currently designing a two house setup using a single well and pump. Given the dynamics of my hypothetical setup, I arrived at my intention to use two cycle stop valves just before entrance to each house. The reason for this was, I noticed there wasn't much literature on the PSI drop beyond the CSV if used on the "main line" close to the pump itself. I noticed that most use cases designed the CSV to be close to the pump without taking to account the additional head pressure loss or total dynamic head loss beyond the CSV. For example, a 50PSI setting CSV at the peak of the well pipe with an additional horizontal pipe run of 200 feet of 3/4" pipe would result in a 45PSI rating at 10GPM at a house 200 feet away. I doubt many would notice, but in larger or longer setups, this could quickly become relevant and might be a good topic to cover if not already. Then again, I perhaps, simply missed it while searching this forum.

Regardless, my  ultimate question is this. At what rate does a CSV allow for backflow, if any at all? Particularly for a CSV125-1 model. My unique setup has a main house and a "guest" or "party house" which is mostly unused, but, in which I intend to tee off from the main line with the sole reservoir tank being located under the main house which is nearly 600ft away. To give a crude drawing, see below:

Well--(Backflow valve+Tee)---------------(330ft TDH)-------------------CSV+(52g pressure tank) (12.8 draw down at 40-60 PSI)---Main house
            |
            |
        (250ft TDH)
            |
            |
          CSV (no tank)
            |
            House

While I understand the pressure drop from the friction of the pipe given this distance, I'm curious if the backflow of the CSV at the main house  pressure tank will allow for unrestricted back pressure flow to the second house at 40/60. I understand this is an unconventional system, and I'm prepared for the additional cost of running it correctly with a central flow point, but under the basis of simple cost savings of running additional pipe near service entry power lines, would this system work and allow the pressure tank to back flow to the second house at 40/60? I apologize if this seems ignorant, but I couldn't find a cut away diagram that showed the internals of a CSV product.

Thanks,
Aaron

[Cary Austin]

Yeah we do this all the time.  You only need one CSV installed prior to the first tee off the line.  The pressure tank can be at either house location, as long as that is where the pressure switch and power come from.  Just don't use any check valve other than the one on the submersible pump, and it will back flow from the tank to anywhere needed.

You may need to make up for some of the friction loss to the far house, but not that much.  The friction loss depends on the flow rate you are using.  If you are using 10 GPM like having three showers and the washing machine all running at the same time, then there will be 45 PSI loss in the long line.  But when only one 3 GPM shower is on, there will be basically no friction loss, so increasing the pressure maybe too much.  If you have a small line and need good pressure at 10 GPM like when using only 3 GPM, you would need to increase the pressure at the pump, then use a pressure reducing valve at the house to keep the pressure from getting too high when only one shower is running.  This is very common for us when supplying multiple houses at different elevations.  We may set the pressure switch at 120/140 with the CSV at 130 to get a constant 60 and see only 50 to 70 min/max at a house that is 160' (70 PSI) higher than the location of the pump.  Then houses that are closer to the pump each have a pressure reducing valve set at 60 PSI.  That way all the houses at all the different elevations have 60 PSI constant.  It would work the same way for needing 10 GPM at a long distance to the second house.

The higher the pressure switch on/off setting the larger the tank needs to be, as they hold less water at higher pressures.  The pressure setting you need will determine the size of tank necessary.   A 10 gallon size pressure tank with 2 gallons of draw is all you need for two houses at 40/60 pressure when using a CSV.  You would only need a tank as large as 52 gallons is the pressure needs to be over 100 PSI.

The real question is.....Will you ever use 10 GPM at one time at the far house?  If not figure the friction loss at 3 GPM for a single shower, as that is all that will be pumped as the CSV only supplies as much as you are using, not how much the pump can supply if needed.

[nvester]

Thanks for the quick response Cary! You've given me more idea's to chew on. I had overlooked increasing the overall main line on/off pressure whilst using a single CSV. However, my thinking still loops me back to using two CSV's just prior to the entrance to each house. Correct me if I'm wrong, but wouldn't the CSV essentially take the place of a pressure reducing valve? I only ask as the cost of two CSV125-1 models is less than one CSV1A + two pressure reducing valves. The only concern was if the CSV would allow for water to flow in reverse at pressure from the single tank or have I misunderstood? Again, this is my first time learning about these products.

Also, just to provide some backstory, the 52 gallon pressure tank is in there just to recycle existing parts and not particularly a mainstay design element, but is just assumed to be able to be made to work. The main house is/was being run by a 12gpm submersible with a small 15 gallon pressure tank. The 52 gallon pressure tank was added last year while upgrading to 1" pipes. Unfortunately, the bored well supplying this house has developed a hole in the concrete well tile just below the water level and is now weeping mud into the system. The second house is on a different well along with a small 1/2hp jet pump that is now at the end of it's life. After nearly 15 years of very light sediment, I believe the plastic impellers have worn away and this pump is now only able to supply approximately 2gpm at 30-40ish psi. A simple toilet flush reduces any other faucet to a mere trickle for 2+ minutes... In an attempt to kill two birds with one stone while keeping cost down, my intention was to install an overachieving 2HP submersible in the clean well to fuel both houses. The 10gpm estimate is coming from the fact that the intended pump is capable of supplying that much to the furthest house at 60 psi with a TDH of 397.1 feet, but also the perceived "worst case scenario" would be a shower and washer running at both houses simultaneously with a random toilet flush thrown in. With the possibility of the secondary house one day being rented, I wanted to go ahead and future proof any potential water demand problems even if it is slightly over-engineered for the current use.

Thanks again!

[Cary Austin]

No the CSV does not work like a pressure reducing valve.  You just need one CSV to control the pump, then tee off as many times as you want.  I still do not see anything close to 397' of head?  From a shallow well and needing 50 PSI (115'), even if you add 45 PSI friction loss, that is only another 104' of head.  Then if you set the pressure switch at 85/105 with a CSV setting of 95 PSI (115 + 104 = 218' or 95 PSI), you will have 95 PSI when only using one 3 GPM shower.  That is enough pressure to blast your eyeballs out of their sockets or peal your shin off.  I would split the difference and shoot for about 70 PSI (161') on the CSV and use a 60/80 pressure switch.  At 161' of head, a 10 GPM, 3/4HP will deliver about 15 GPM.  A 1HP is overkill and a 2HP is completely out of the question unless there is more head than I can see?  Not having enough head or back pressure on a pump causes upthrust and can be very bad for the pump.

[nvester]

I believe we mismatched on total length somewhere. For the sake of simplicity, we'll forget the second house for the moment since any setup delivering 10gpm to the main house further away would do just fine for the second. Here is how I arrived at a total of 397.1 feet of total head.

Well: 60' deep
Total Horizontal Pipe Run: 330' of 1.25" PVC
Friction Resistance of 390' of 1.25" PVC + fittings @ 10gpm equated to the equivalence of 7.1' of additional pipe
60+330+7.1 = 397.1

And for reference, the pump I was looking at shows a flow rate of 13gpm @ 57 psi assuming 394 feet of total dynamic head:

[Cary Austin]

You don't add the horizontal run, just the vertical run, friction loss, and pressure needed at the house.  And even though the pump maybe set at 60', the pump is only lifting from the actual water level.  I would guess the pumping water level would be like 30'.

So 30' of lift plus the 7.1 friction loss and the 115' needed to make 50 PSI at the house only adds up to 152' of head for the pump.  Even if you give 20 PSI cushion for added friction loss to the house at a distance, that is only a total head of 198'.  A pump designed for 525' would be destroyed fairly quickly from upthrust.  10 GPM at 200' of head only requires a 3/4HP at most.

Oh and how did you post that picture?  I can't make pics look big like that?

[nvester]

Thanks Cary! I'm glad I asked! I believe you've saved me from a very costly error.

As for the picture, I just used the "Insert Image" button and inserted the web address to the image between the IMG tags. I was surprised as well that it displayed in full size but I suppose that is default?

Lastly, do you have an equation or a chart that displays how 115' equates to 50 PSI? I'm not questioning your math, but simply how it was derived. Does pipe diameter come into play?

[Cary Austin]

Every 2.31' in elevation is the same as 1 PSI.  2.31' = 1 PSI.  50 PSI = 115.5'.

Never knew that "insert image" button was there.  Thanks