Water Tank/Piping Size - Flow/Pressure Problem

[Jeff Givens]

Here is my situation in a 4 y.o. home:

140' well with a Jacuzzi submersible pump, spec officially unknown at the moment (model t7s41011p-s2, order #9253-3702), well cap stamped as 40 GPM.

Incoming line appears to be 1 inch to the tank and from the tank is 1/2 inch in entire house. Tank is a Well-Rite 85 gal. running at 42 on/65 off, pump cycle time less than 1 minute.

The problem is that at every point in the house pressure (or flow depending on pov I guess) is anemic. Not pitiful but annoying, functional though.

The other day I had on three outside spigots for watering, 'moderately' open, and at almost every point in the house there was no water to be had.

I just recreated the above scenario and checked the tank operation. The well pump was running and tank pressure was at 44 psi and climbing, albeit at a much slower rate as a 'no load' situation. After about a minute it had gotten to almost 50 psi.

Using the kitchen faucet as a test point, I get the usual weakish but usable flow with no other load and then the outside spigots on moderately and it just dribbles out in the kitchen. Pressure at tank is (essentially) no different than in the light load condition, which leads me to conclude there is a flow problem somewhere, my guess being the pipe diameter.

Is 1/2 inch an acceptable pipe size? Would upsizing it fix my problem or only expose the weakness to be somewhere else?

I can't imagine the tank/well pump being a problem as it maintains at least

45 psi regardless and if that pressure threshold is always maintained then the fault would seem to be downstream of there.

One other point, we have a geothermal heating system which has an 'always on' water recirc loop that drains back into the aquifer. I don't know the flow rate of this loop but I suspect it is small - I can hear the water trickling in the return pipe. However, the need to keep this loop intact is important and I am afraid of just living with the current situation and not trying to shower when watering will lead me to starving the system of its exchange water, thus the need to fix this issue. _________________________________________________________________ JG... Jeff Givens mailto: [e-mail]

"My hovercraft is full of eels."

[Charles Spitzer]

are the screens on the taps clean?

[Jeff Givens]

Yup, everything looks nice and scale free. I did have to replace a water heater element a little while ago due to an electrical problem and it (upper) when removed had a moderate amount of salts on it, about 3+ years in service at the time.

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"My hovercraft is full of eels."

[Chris Lewis]

According to Charles Spitzer :

1/2" is anemic. I'd advise anyone to use 3/4" for any line that supplies more than one fixture, and 1" for more than 4 or 5.

That said, with 45-50PSI on the tank, and two or three taps open to hoses causes it to come close to sucking air on the fourth means something is wrong. 45-50PSI should push more water than that, even on 1/2" (the backpressure on the garden hoses should assure that).

If it's maintaining pressure that high with poor flow, you have an obstruction of some sort.

Your description seems to indicate that the poor flow isn't restricted to just one faucet, thus more or less ruling out screen obstruction.

I'd be suspicious of valves on the outlet of the pressure tank. Washer may have come loose and obstructing, hunks of grit, or something like that. Or washer type valve.

You might want to consider shutting off the water, draining the pressure off, and pulling the valve stem out of any stop valves checking for blockages.

If you have washer-type valves in the feed, I STRONGLY recommend pulling it out and replacing it either with a gate valve or full aperture ball valve. Washer-type valves restrict flow something awful. Particularly in 1/2" feeds.

If it _is_ the pipe size (after ruling out obstructions and washer valves), plot out where the "highways" (feeding more than 1-2 fixtures) are, and replace those with 3/4". Leave the driveways (single fixtures) alone ;-)

[Yeah, replumbing is a PITA. I had to do it once. Managed to keep the amount of work relatively minimal. Major improvements.]

For comparison purposes, we're on a well too with a 1/2" HP pump. Hits about the same pressure as yours when nothing being drawn. When the irrigation system fires up (around 10GPM), we still have enough pressure to run the dish washer, laundry machine, shower, AND run another hose...

Must be around 18GPM or more.

The pressure on the tank drops down to about 20-25PSI and the pump goes on continuously and can just barely keep it there.

Yeah, we have a pressure balance shower valve ;-)

[And 3/4" plumbing virtually everywhere except for the stubs directly on the fixtures. The irrigation feed is mostly 1"]

[Jeff Givens]

Good point. It would be nice to have a pressure gauge on the other side to measure any drop. I failed to mention that there also is a water purification system online due to TCE around here, but I was treating it as a fixed volume and wasn't considering its impact. It is a sed filter, uv and 2 carbon filter beds and, of course, there is no bypass installed. All water except for a/c water runs through here.

But I will check out the valves and even install a bypass around this thing (there should be anyways) and check again. Thanks for the pointers and info.

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[Brikp]

I'm no expert but I seem to recall a handy gauge thingy that you could attach at various points throughout your system, like at the hose bib. Could something like this be useful in locating the problem area?

A minute on Google found this

If you putting in a bypass for your filter system maybe you can add an outlet with a hose connection there. While you are at it right? Then you can read the pressure there. Work your way back to the pump and see where the blockage may be.

Good luck, keep us posted as to the results.

[Jack Alexander]

Hi Jeff,

Seems to me that the problem is the 1/2" pipe. At any given pressure

1/2" pipe will only allow a certain amount of water to flow through it. In your case, you have a run of 1/2" pipe from the pressure tank trying to provide enough water at 3 or 4 additional outlets that are also fed by 1/2" runs. What I'm trying to say is that the flow through one 1/2" pipe will not supply 3 or 4 more 1/2" pipes down stream with adequate flow pressure at the same time. It's basic hydraulics. The only way to increase the flow is to either maintain the existing pressure from the tank but have 3/4" or 1" pipe from the tank to the take-offs, or increase the pressure which is probably not recommended since you're already running at 65 psi on the high end.

Of course, the easy option is to only open one or two discharges at the same time. This reduces the flow demand and allows the residual pressure (that's the pressure left on the system when water is flowing) to stay higher.

Jack

[Greg]

I just did a bit of studying pipe sizes, flow rates and friction loss while I was designing my pool. Pipe size is the biggest factor and going up one size makes a huge difference. I also have a well set 30--50 and I will never put another stick of 1/2" pipe in my house unless it is just the stub out to a single faucet. The next biggest bottleneck is the water softener.

[Chris Lewis]

According to Greg :

I did quite a bit of studying when I did my irrigation system. And I agree.

[I just wish I had heard the irrigation expert say "NEVER EVER PLUMB ANY IRRIGATION WITH 1/2" before I ran the line to the garage. All of the rest of the irrigation system _does_ respect that. The garage line is used for other things.]

However, in this particular case, it seems a little extreme even for that.

Standard washer valves are quite flow-restrictive - two direction reversals and a venturi at most 3/8"... This is one thing to look for before deciding to replumb and relatively easy to fix. A smooth-bore full aperture ball valve is best.

[Greg]

1" sch200 is the standard for irrigation around here. That has a larger ID than sch40. Since irrigation uses all you feed it you end up with some pretty low pressures and you need big pipe to keep the flow rate decent.

[Jeff Givens]

Jack et al,

Thanks for pointers and advice. My first step is to install the bypass about the filters and at the same time hard pipe in a gauge. I suspect that I will see no pressure drop across the input side of the tank and the house side of filter. If that is indeed the case then it appears a pipe upsizing job is in the future. This is assuming that there is no restriction downstream from this measuring point - like a calcium blockage somewhere.

If there is a substantial drop I guess I will work backwards either to the filters or the valving on the tank - replacing with a ball valve.

However, my experience with this problem makes me certain that I won't see any pressure drop and it is a pure volume issue - 1/2 inch can't supply the volume at these pressures to more than several devices at a time.

I'll post updates to this but it may on the order of weeks now due to other stuff going on.

Thanks. _________________________________________________________________ JG... Jeff Givens mailto: [e-mail]

"My hovercraft is full of eels."