Pressure Tank & Pump Setup with Elevated Cistern - Need Advice!

[Jcwright30]

Unless there was a possibility of cavitation. May not be possible at the flow rates anticipated.

Please do elaborate on this thought. Want to make sure I don't leave anything left out for a successful end product.

 

[Jcwright30]

If 28 psi is your static pressure (no flow) with no pump and no pressure tank, that means the water level in the cistern is 65' higher than where you are taking the measurement.

Your elevations must be off, as it's 65', not 90'. And a larger line won't change the static pressure; what it will do is reduce the frictional pressure loss that occurs during flow. Which is causing the the symptom "if you flush a toilet while a shower is running it's almost a trickle."

But, increasing the pipe size in the house won't do anything about the frictional pressure loss between the cistern and the house. Which is why Reach4 suggested taking 2 measurements at the yard hydrant--static pressure, and pressure while the shower is running. The difference tells you the frictional pressure loss between cistern and yard hydrant (and will increase with increasing flow, so with a helper or a video camera you could also take a pressure measurement at the yard hydrant when the toilet is flushed during a shower). Add to that the frictional pressure loss between yard hydrant and house, and that's all the pressure available to you at the house, without upsizing the outdoor piping.

Cheers, Wayne

Happy Monday All!

I had a chance to grab some measurements this weekend in addition to replacing the faulty check valve with a straight pipe connection, as I will install the new check valve at the inlet of the pump (haven't done this yet as my local plumbing supplier didn't have stock of a 3/4" spring check). Here's my data. Prior to meausuring the static pressure inside house and at yard hydrant, removing the check valve added 2 PSI (28--> 30 PSI) of static pressure in the house. As a summary of my setup: 600+ gallon cistern up the hill on my property, gravity flow into my barn (yard hydrant) then from barn into house. House is about 10' higher in elevation than the barn where the water enters the house. All measurements are after check valve was removed)
Barn (Yard Hydrant) measurements:

1. Static Pressure: 30 PSI
2. Kitchen Sink Turned On: 29 PSI
3. KItchen Sink Turned On + Toilet Flush: 29 PSI (not a typo, no drop in pressure

House Measurements (hose bib on exterior):

1. Static Pressure: 26 PSI
2. Kitchen Sink Turned On: 20 PSI
3. Kitchen Sink Turned On + Toilet Flush: 15 PSI

 

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[Reach4]

Worthwhile test. This says that increasing the path size from the yard hydrant to the the kitchen would help a lot. Now to know if just changes in the house would be sufficient, you would need to put a pressure gauge close to where the water enters the basement.

I suspect that the drop after the water has entered the basement may the bigger factor. What is the distance from the yard hydrant to the basement? What is the OD on that poly pipe in the basement?

 

[wwhitney]

6 psi pressure drop for 2 gpm flow (guess, could simultaneously measure) would be from the equivalent of a 0.5" ID pipe for 130'. So definite obstruction or undersized pipe between yard hydrant and kitchen sink.

Cheers, Wayne

 

[Fitter30]

90' of total height = 39 lbs of pressure at house minus pressure drop through pump and check valve. Pump shut off pressure should be 77 lbs (pressure with discharge with closed) but with 39 lbs of pressure on suction of pump who knows its so far out of design. Never liked checks on suction side of a pump because of the pressure drop. Discharge checks need a minimum 10 pipe diameters entering and 5 leaving. After getting pump running need to see what shut off pressure is then with different valves open. Might have to add a pressure relief valve between pump discharge and suction to limit pressure. When using a pump not design for a particular application it a guess if and how long it will last.

 

[Jcwright30]

Worthwhile test. This says that increasing the path size from the yard hydrant to the the kitchen would help a lot. Now to know if just changes in the house would be sufficient, you would need to put a pressure gauge close to where the water enters the basement.

I suspect that the drop after the water has entered the basement may the bigger factor. What is the distance from the yard hydrant to the basement? What is the OD on that poly pipe in the basement?

Ok - I grabbed some measurements and for the fun of it I just reconfigured my plumbing to add a by-pass to the pump and tank which should have been there anyway. I gained only about a PSI when by-passing but again that needed to be done anyway.

Regarding the measurements - the distance between the yard hydrant and the house is about 90'. The OD on that poly is 1.4" which tells me I have 1 1/4" coming in. I'm still in pursuit of finding a 3/4 check valve I'm happy with before I install that at the inlet of the pump.

 

[Reach4]

What are the ODs on the threads at A and B?

I am thinking that instead of E you could put a full size brass/bronze tee. Then the side port would go toward the pump, and the straight port would feed bigger pipe to your un-boosted house use.

Also note that a place to have a pressure gauge nearby this area would be good too.

 

[Jcwright30]

I think what I would do here is to replace that entire section of pipe from the poly to my tee that exists at pump/pump by-pass (which I installed yesterday). First think I'll do it do get the check valve (pikcing up this evening) and I'll make sure pump/tank do the job as expected. Once this works itself out, I'll then see if i can't adapt 1 1/4" poly to 1" Pex. Then 1" PEX runs to the WH Tee (for the pump by-pass section). The pump segment would remain 3/4" with the 3/4" Check Valve. So overhead the pump I'd have one tee (1" straight with 3/4" sideport to pump) then the second tee would be 1" to 3/4" straight where 3/4" feeds to WH) and 3/4" side port coming from pressure tank. How's that sound? I can always draw a sketch

 

[Reach4]

I don't understand all of what you propose, but I would not try to change out the barbed adapter. I don't know that you have 1 1/4" poly.

 

[Jcwright30]

I don't understand all of what you propose, but I would not try to change out the barbed adapter. I don't know that you have 1 1/4" poly.

OK - let's put the reconfiguration of the 3/4" pipe to 1" to the side for a bit. I installed the check valve last night and I'm a bit puzzled on the result...
I've attached three pics of my updated setup. This shows the bypass I've constructed plus the check valve I installed last night.

When i got the check valve installed and turned the pump back on it pumped for a very short time and only to about 35 PSI. The check valve is working as that pressure finally held. There is no water filling in the pressure tank. To ensure I didn't have a tank issue I drained and did as necessary to check the air pressure in tank (right around 38 PSI). I was hoping it was a minor blockage due to sediment but that wasn't the case. So now I'm left with the pump short cycling and the tank not filling up. Any ideas?

 

[Reach4]

When i got the check valve installed and turned the pump back on it pumped for a very short time and only to about 35 PSI. The check valve is working as that pressure finally held. There is no water filling in the pressure tank. To ensure I didn't have a tank issue I drained and did as necessary to check the air pressure in tank (right around 38 PSI). I was hoping it was a minor blockage due to sediment but that wasn't the case. So now I'm left with the pump short cycling and the tank not filling up. Any ideas?

The reason the pump turned off is that the pressure switch told it to turn off.

Much of the reason that the pressure switch turned off before the tank was filled to even its reduced capacity is that the pressure at the pressure switch was higher than the pressure at the pressure tank. You have a fairly long run of smallish pipe carrying water to the pressure tank. There is pressure drop during the flow of filling the pressure tank.

Ideally the pressure switch, or the far end of the sense line to the pressure switch, would be down by the tank tee. The sense line is that small tubing hooked to the pressure switch.

I was not trying to talk, you out of using bigger piping, but rather I was suggesting that you might consider larger stuff. A valve in the bypass line ideally should be a full port valve to add less restriction. I also thought it would be wise not try to replace the existing barbed ("insert") adapter at the poly pipe. You don't have room to cut that poly pipe back.

I suspect your barb is 1 inch MIP output.

1 inch pex is about 0.862 ID. 1 inch PVC is about 1.029 ID. 1 inch CTS CPVC is about 0.901 ID

If my suspicion about a 1 inch MIP output on the barb fitting, you could use a 1" x 1" x 3/4" FIP Brass Tee or 1" x 1" x 1" FIP Brass Tee with the side port going to the pump. Then make the bypass piping as big as practical, with 1 inch pex being a good minimum to strive for, and maybe 1-1/4 to minimize drops.

 

[Jcwright30]

The reason the pump turned off is that the pressure switch told it to turn off.

Much of the reason that the pressure switch turned off before the tank was filled to even its reduced capacity is that the pressure at the pressure switch was higher than the pressure at the pressure tank. You have a fairly long run of smallish pipe carrying water to the pressure tank. There is pressure drop during the flow of filling the pressure tank.

Ideally the pressure switch, or the far end of the sense line to the pressure switch, would be down by the tank tee. The sense line is that small tubing hooked to the pressure switch.

I was not trying to talk, you out of using bigger piping, but rather I was suggesting that you might consider larger stuff. A valve in the bypass line ideally should be a full port valve to add less restriction. I also thought it would be wise not try to replace the existing barbed ("insert") adapter at the poly pipe. You don't have room to cut that poly pipe back.

This makes sense in principle - what doesn't add up to me in my unique situation of having 28PSI of head pressure is why the tank doesn't fill up on its own (even with pump turned off). I'm expecting the tank would fill to hold 28PSI without the pump. But there is no water in the tank. The gauge reads 28 PSI because of the head pressure. If i shut off the supply water and open a faucet that 28 PSI almost pretty quickly falls to zero.

 

[Reach4]

This makes sense in principle - what doesn't add up to me in my unique situation of having 28PSI of head pressure is why the tank doesn't fill up on its own (even with pump turned off). I'm expecting the tank would fill to hold 28PSI without the pump. But there is no water in the tank. The gauge reads 28 PSI because of the head pressure. If i shut off the supply water and open a faucet that 28 PSI almost pretty quickly falls to zero.

You have ~28 psi of air precharge in the pressure tank. At 28 psi, or less, of water pressure, no water enters the pressure tank. If the air precharge was 25 psi, just a little water would enter at 28 psi of water pressure.

 

[Fitter30]

The line feeding the pressure switch can't be hook to the side of the pump its not looking at system pressure. When the pump runs it not looking at suction or discharge pressure but something else not full discharge. There should be a tap at expansion tank fitting.

 

[Jcwright30]

The line feeding the pressure switch can't be hook to the side of the pump its not looking at system pressure. When the pump runs it not looking at suction or discharge pressure but something else not full discharge. There should be a tap at expansion tank fitting.

This tank/pump was with the house when i bought it but it was a package deal that was preassembled and installed by a reputable company. This is what has always eluded me also. So i should plug the sense line at the pump, relocate the pressure switch to the T fitting at the tank (there is room for it) and then run new wiring from pressure switch to pump.

Why would anyone have setup it up the way the did?

 

[Reach4]

Why would anyone have setup it up the way the did?

Less informed or more lazy.

You don't need to remove the existing pressure switch. You could just wire around it or through it.

Your current setup would work better if you routed the pump output to the pressure tank with 1-1/4 pipe, but that is still not as good as having the pressure switch at the tank tee.

Regarding your system, suppose you had a low-pressure drop check valve in series with the bypass path. https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/20393-source/es-lf600-pdf looks interesting. The pressure drop seems to be as low as 1 psi at low flows.

Then have a pressure switch set to maybe 25/45 on the pump. If the pressure stayed above 25 psi, gravity supplies the water. If the flow rate pulled the pressure down to 25, the pump kicks on automatically. No manual switchover needed.

 

[Fitter30]

This tank/pump was with the house when i bought it but it was a package deal that was preassembled and installed by a reputable company. This is what has always eluded me also. So i should plug the sense line at the pump, relocate the pressure switch to the T fitting at the tank (there is room for it) and then run new wiring from pressure switch to pump.

Why would anyone have setup it up the way the did?

Have no idea unless your at the entering or discharge should being off the side of the impeller isn't a correct pressure reading.