very low flow in new home....

[rtstephn]

Hi all,
First time posting. I am building a new home and just finished my plumbing trim out. I have noticed before now (but it's now painfully apparent), that I have issues with water pressure. Pressure is very good when I first turn on the tap, but fades dramatically within 15 seconds or so. I tested the water pressure at an outside spicket and have 80 PSI static pressure, but if I turn on another spicket, then it drops to below 15 PSI. If I turn it all off and wait 30 seconds or so, it builds back up to 80 PSI.

On the advice of local building inspector, I ran 1'' pex from 3/4'' meter to my house, some 525 feet away (with about 275' going up hill). PEX is run throughout the house.

I called in a service plumber, and he told me that I needed a larger meter valve (2''). I called the city water engineer, and he told me I did NOT need a larger meter, but I did need to run 2'' PEX to my home.

At this point, the expense is too great to run new pipe (assuming this would fix it, the plumbing I called in didn't think so....). Do I need a booster pump? Or do I need a booster pump and some kind of tank for on demand water? What do you recommend I do now. The house is now nearly complete and ready to move in (except for water pressure issue).

Any help would be very much appreciated.

[Terry]

The meter can stay the same.
The pipe should have been larger.
Right now you have the equivalent of sucking a milk shake through of coffee stirrer.
525 feet should have been something large like 2"

I just looked this up, 1.5" with a 1" meter should have worked

It's not a booster pump you need, the pressure is already at 80 PSI
You need to store water to be used later.
Choices are,
Run a bigger line
or add storage tanks.

[master plumber mark]

2 inch seems like an extremely large line
to run for a home, even at a distance like that....

one inch or 1 1/4 should have been large enough..

at least in our area....


I probably would have made the same mistake myself...


I suppose your best bet is to put in a large well-x-trol baldder tank in the mechanical room...

try that first before anything else..

[rtstephn]

THanks for the reply. What tank would you all recommend? Do I need a certain size....it's only my wife and I and we are gone during the day...though we hope to grow the family at some point.

Would I just need a tank, or would I need a pump also?

Thanks much,

[leejosepho]

Pressure is very good when I first turn on the tap, but fades dramatically within 15 seconds or so ...
If I turn it all off and wait 30 seconds or so, it builds back up to 80 PSI.

It seems to me that a very large bladder tank could keep the pressure relatively steady for the duration of a normal shower, but then it would take *much* more than 30 seconds for the overall system pressure to again build to 80 ... and who knows how many toilets or washers will be sitting with open valves and waiting for water at the same time.

I would add a small pump-and-CSV combination set to come on around 50 and maintain 60 until the pressure switch again shut it off at 70.

[rtstephn]

-

The pipe should have been larger.
-Right now you have the equivalent of sucking a milk shake through of coffee stirrer.

525 feet should have been something large like 2"
It's not a booster pump you need, the pressure is already at 80 PSI
You need to store water to be used later.
Choices are,
Run a bigger line
or add storage tanks.

So I don't need a pressure booster, even though pressure drops after initial "burst" of water. What kind of storage tank? I am guessing that the pressure is dropping because there is not enough volume to sustain it. Is that right? So If I add volume (by adding some kind of tank), then I would increase available volume and therefore the pressure would remain high? IS that right, or am I reading too much into your post!?
I wish I could go back on the building inspector for recommending a 1''.
THanks much.

[Bob NH]

Like Terry said in the first reply, you need a bladder tank.

You want to store as much water as you can so you want to keep the supply pressure at 80 psi, and you need a tank that has a large acceptance volume.

Let's assume that you want at least 40 psi for your normal flow. Precharge the tank to 40 psi and it will fill to 80 psi when there is no demand (which is most of the time).

If the precharge is 40 psi and the fill pressure from the utility is 80 psi, then the tank will be 42% full of water when the pressure is 80 psi.

You must get at tank that has an acceptance factor of at least 42% or you will damage the bladder. Most will work but some won't.

An 80 gallon tank will give you 33 gallons of storage and a 119 gallon tank will give you 50 gallons of storage. In addition, the supply will provide some makeup while you are using water. Here I am talking about ACTUAL VOLUME of the tank; NOT "equivalent" volume.

An 80 gallon tank (33 gallons drawdown) will be plenty for 2 people.

Multiple tanks with total capacity work the same as one tank but take more room and a bit more plumbing. Consider the cost per installed gallon when comparing tanks of the same quality. Here are a couple of sources of tanks.
http://www.wwpp.us/wellmate/wm-tank.shtml

You need a tank with a bladder that will not be affected by chlorine. I know that the Wellmate tank with a polyethylene liner will survive the chlorine levels in municipal water.

You don't need a tank-tee kit because you aren't using a pump with pressure switch and relief valve. It will be installed with just a plumbing tee.

If you don't like the pressure swings you can install a regulator set at maybe 50 psi AFTER the tank. The pressure loss in the regulator will affect the available pressure a little but not much. I would hold that until you see if there is a problem with pressure variation.

[rtstephn]

So what would you think of the of WellMate WM-25WB
87 Gallon Tank from http://www.wwpp.us/wellmate/wm-tank.shtml
This would give me 26 gallons drawdown at 30/50.

Is this enough? Just from browsing the web abit, I'm pretty impressed with Wellmate. Their prices are super competitive.

[Bob NH]

The 30/50 drawdown of 26 gallons has no meaning with your system. That is the drawdown for a pump with a pressure switch setting of 30 and 50 psi start/stop.

The 87 gallon tank will have about 36 gallons "drawdown" from 80 to 40 psi operating range as I described.

I would precharge it to the lowest pressure at which you want good flow unaffected by the pressure loss in the long pipe from the meter. I suggest 40 psi. If you use enough water to empty the tank then you will still get water but at low flow rate until the tank can recover at the flow rate available from the meter.

[rtstephn]

Oh, that makes sense, I was thinking those numbers were dynamic vs static pressure. Thanks for the clarification. Would I be shortening the life of this product the tank would have 80 PSI on it most of the time (when no water demand). Also, what kind of pressure swings will I have. Will it be noticible in a typical shower? Or will the pressure swing only start to happen as the tank is depleted of water.

Thanks so much for the guidance here. I feel much better about the prospects.

[hj]

Your supply line can only supply a finite amount of water so if you were to put a pump at the house it could suck the pipe dry and not give any additonal water. A diaphragm tank will supply the volume you need and the city line will keep it pressurized. You would have diminished pressure once the tank was empty and then had to rely on the original volume of water for your usage, but with a large enough tank that should not occur very often.

[jadnashua]

The pressure would drop from the supply pressure of 80 until the tank's stored energy and water can no longer produce anything, which would be if the overall system pressure dropped to 40 or less. At 40# (assuming that's th evalue you set the precharge in the tank, it can't help push stored water out any longer, and you'd be limited by what's in the supply line. So, you'd never get less than what you have now without a tank, but would get a minimum of 40 (starting at 80) water pressure and volume until the stored water is basically gone. If you reach that point, you can either add more stored water or add a pump to force more into the system, or, produce fairly constant pressure (the end result depends on where you put the pump). I think you'd prefer to avoid the expense in materials and power to avoid a pump unless you can't live with what you have. You're lucky you stilll have 80# at the top of your hill, otherwise, you'd need to add a pump regardless.

[master plumber mark]

it would seem to me that a one inch line should have
done you ok

A one inch line can put out literally
a whole shitload of water...at 80psi

at least in the mid-west it does....


I have installed a one inch line for commerical buildings
before.....

so....it makes me wonder if you have not kinked or crushed the
pex line somehow in the process of re-filling the ditch.>>>


or are you sure that you dont have a bad gate valve at your main stop????

[Redwood]

I find myself wondering the same thing!

[Bob NH]

Here is a link to a chart for head loss in ft of water.

http://www.cozyheat.net/MTR/tubing/pdf/headloss.pdf

The chart gives the head loss for each 10 ft of pipe (an unusual scale).

At 5 GPM for 1" PEX the head loss from the chart is 0.35 ft per 10 ft; which is 8 psi loss for 525 ft. That is not too bad and you shouldn't notice it.

At 10 GPM for 1" PEX the head loss is 1.25 ft per 10 ft and the pressure loss for 525 ft is 28 psi.

If the line is kinked you will have a hard time finding it until it fails and causes a leak.

Try to do a bucket flow test to determine the flow rate and pressure at the house. If you get a pressure gauge that goes on a faucet where there is a hose fitting, and then measure the flow at another faucet while reading the pressure, we may be able to suggest something about the pipe.