How much psi do you think I'll get ??

[maarass]

Going to find this out soon from the city but thought I'd give you gurus a shot. My house is situated some 700 feet from the street. Were outside the city limits but we can hook up, but the meter pits are at the street though. We'll have 90 psi coming under the street through a 2 inch solid copper pipe. It then splits off at a Y to two 1 1/4 inch pipes. (my neighbor and I only) Each 1 1/4 goes about 4 feet to the meter pits. Get reduced to 3/4" standard in the meter box, then goes out ALL the way to my house in a 1 1/2 pipe on FLAT ground. I know that now I'll have the volume of a 3/4" line, but what would you estimate the psi entering the house would be ?

[Sparks]

I would say 90 psi static. Volume would be affected. Let us know what you find. 700 ft. from the street, I envy you, I thought I was alright at 250'.

[maarass]

Thanks for the reply. I thought I would loose psi because of that length of run. Wouldn't 90 psi be too much pressure and cause problems with corrosion and the like ?

[bkrahmer]

You should have a pressure reducing valve at your house that takes it down to normal pressure, around 50 psi.

According to a chart that I'm looking at, at 10 gpm in a 1.5" schedule 40 pipe, you'd have a loss of 1.8 feet of head from friction, which is less than 1 psi. 3/4" has about 28x more friction, which is kind of interesting.

[Sparks]

I don't think corrosion would be an issue, just damage to pipes and valves, etc from high pressure (bad water hammer causes damage). But like mentioned, you'll need a reducing valve. Some towns have specs. written out on exactly what brand and type reducing valve they require. Friction loss of head I believe would only be an issue when there was flow, as we know, psi is not a measure of flow. Standing pressure should be constant throughout the pipe run. (with no flow) I believe your comparision on your chart regarding friction loss with 1.5" and 3/4" would be due to velocity differences, if you run a gallon of water through a 4" main, there isn't much friction to slow it down, if you run a gallon of water through a 3/8" tube, there's alot of friction. This of course, is assuming that there is flow, standing pressure is a whole lot different.

[bkrahmer]

Knowing how much pressure there is when there is zero flow is about as useless as... (insert favorite saying here.) I gave an upper example of 10 gpm so he could see that he doesn't have much to worry about.

[Sparks]

Oh I agree competely. I wasn't criticizing your response, I was just clarifying mine that psi was not a measurement of flow or volume, just pressure. Obvioulsly there are more factors to consider and you explained them well.

[maarass]

Thanks for all the replies. City water inspector came out and did a pressure test. We have 55 psi comming in the house. At the street (90psi) the 2" pipe reduces to 1" then to 3/4 at the meter and back to 1.5" (700'). This, as explained above dose not effect psi, but does it have any effect on normal house usage, like showering and running dishwasher etc.. ? thanks again

[Sparks]

So it goes from 3/4" to 1 1/2", that's interesting. 55 would still be fine for showering, etc, I wouldn't consider that low. Can I ask how you knew it was 90 psi at street, was this measured by inspector today? Sounds like 55 was measured at a time of high usage on main or 90 was an estimated figure or maybe a difference in elevation between house and street. According to the UPC and IRC (plumbing codes) a pressure regulator is required when pressure exceeds 80 psi, I don't know if your town has any other requirements.

[maarass]

thanks for the reply. Boy now i'm confused. LOL.
There is no reducing valve at all and no faucets were open. Inspector just had his guage thing and attached it to the faucet (at 12 pm.) as in this photo: http://home.comcast.net/~thomas9780/water1.jpg
Right above the faucet is another valve which was off to the rest of house. Look at these pics :
http://home.comcast.net/~thomas9780/water2.jpg
http://home.comcast.net/~thomas9780/water3.jpg

Two inch comes in, splits to two 1 " to each meter pit, then goes out in a 1 1/4 plastic to house (700' away). 2nd pit is not on yet. Actually there is no meter in pit yet. (free water !!). There is only one coupling in middle of field where they added another roll of pipe. Then it comes through wall. The grade is level if not slightly downhill. So I only suspect psi loss from friction.
p.s. if you noticed the connection at house, There're going to replaces those radiator clamps with a compression coupling and add a vert, pipe for water hammer.

[Sparks]

Ok, I understand what you have there, sorry my responses are confusing. All I'm really getting at is static psi is not dependent on length, how could friction be an issue if there is no movement? The pressure will equalize throughout pipe run statically speaking. If you have 55 psi at house, I wouldn't be concerned. Given your pipe sizes, you should have ample flow and pressure at your fixtures. Like I said, I'm 250' feet from the street and I have 90 psi at the street and 90 psi at my meter,(I personally measured this at the town shut-off, I fabricated a tool, don't tell the town) all with 3/4" poly pipe. I have no issues at all with flow or pressure and of course I needed a pressure reducing valve being that I was over 80 psi. I run my pressure at about 45 psi and have no problems even on second floor (kitchen and one bath is on 2nd floor). If I were you, I wouldn't worry, your install sounds like it will perform fine. Upsizing pipe after meter is common, this allows you to add more ficture units if desired ( see UPC ) Hydraulic principles are confusing, they are not always as simple as they sound.

[maarass]

thanks for the quick responce. I get it now. Static pressure is constant reguardless of length. There might be a reducing valve in the black meter pit itself, what else could explain the drop in psi on level ground.

[Sparks]

The only thing I could ask is did you personally measure the 90 psi at the street? Maybe there is a reducing valve somewhere, I've never seen this, but who know's. As I mentioned before, maybe there was high demand on the towns main for some reason. In some areas around here, water pressure drops significantly during high usage because the city or town mains were installed many years ago and are undersized for the present population and usage. This is very common in my area, they are constantly updating water mains to accomadate new development, they just installed a new water tower in a neighboring town to compensate for pressure drop during high usage, water tower being a resovoir to boost pressure and volume when needed. Water pressure can vary a great deal depending on time of day, weekend or weekday, etc, etc.

[maarass]

I'll check the meter pit tomarrow. There's no meter in it yet but I'll see what else is there and take a pic or two.