Water head, pressure, pipe diameter

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snipped-for-privacy@hotmail.com wrote:

50 PSI is not too high for domestic plumbing. The pump switch at my country cabin keeps the tank pressure between 30 and 50 psi. (The tank level is approximately floor level.) There is a pressure-relief valve rated at 150 psi to ensure that the tank doesn't burst from overpressure, and the pipes can withstand more than that. PVC schedule 40 pipe is rated at 280 PSI cold, derated to 210 at 90F. (Derate to 72% to allow for water hammer.) Where freezing is possible, you may prefer polyethylene, which withstands somewhat lower pressure but tolerates freezing and better withstands water hammer.
In any case, 1-1/4" pipe will generously supply your cabin from any reasonable distance. My cabin is supplied by a 1" pipe through a 100' run from the tank I mentioned. My suburban house is supplied from the main 125' distant through a 1" pipe, and inside plumbing is 1/2" copper, though 3/4 would be better. "Just do it" would seem to be appropriate.
Jerry
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Jerry Avins wrote:

Humm. Thank you for your reply. We plan on burrying the pipe about 24 inches because freezing is a problem. However we will also plumb a fitting to drain the system. The owner of the ranch, bless her heart, wants water in the cabin even in the winter, so we plan on burrying the supply system and then adding drain taps to the shower and sink.
The owner of the ranch suggested 1.5 inch pipe but I said, guessing, that would be "over-kill." However, it also occured to me that bigger is always better. :-) If they can afford the 1.5 inch pipe, I'll install it. I think polyethylene will be used since that is what is used on other parts of the ranch (there is water already going to The Big House and also water going down here in the bunk house where I live).
Your system uses a pump; the cabin where the ranch owners want water does not have any electricity (nearest power line is 22 miles away) so it must all be gravity fed. Elizabeth wants hot water, however, so an on-demand propane heater will probably be used. Since there will be no tanks at the cabin, perhaps we will skip the pressure relief valve.
Thank you for your reply.

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In article < snipped-for-privacy@u72g2000cwu.googlegroups.com

I was going to ask you what you were using for hot water as that will likely be the weak point regarding pressure. Ok, no tanks, fine cylinders for that kind of pressure would be expensive. Just check that your hot water heater can take the pressure you are talking about, preferably +50% as you are likely to get pressure surges when a tap is turned off hard or say when a washer stops filling, derating helps with longevity.
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fred
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fred wrote:

The relief valve on my domestic 40-gallon heater is set for 150 psi or 210F, whichever comes first. 150 psi is about 340' of head. The actual head should be limited to about 200 ft to allow for water hammer.
If I couldn't provide an expansion chamber to cushion the shock when flow is abruptly stopped, I would use no bigger than 1" pipe to minimize the mass of water being stopped. The chamber on the hydraulic ram I sent a link to yesterday has a good model for a chamber. Any tank will do if it has a sight glass for monitoring and valves for adjusting its air level.
Jerry
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fred wrote:

Any standard hot water heater or well storage tank will take pressures way over that 40 to 50 psi he is talking about and they are not expensive. Not needed in his installation though.
Harry K
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In article < snipped-for-privacy@e56g2000cwe.googlegroups.com

I suppose that depends where you come from. If you come from places where mains pressure hot water storage is not the norm then that is not the case. A lower pressure tank can always be made for less than a high pressure one.
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fred wrote:

Your view of pressures is not consistent with reality. Consider that many tires take a static 50-60 psi and all are at least 35psi rating; when you hit a bump psi goes high. Bicycle tires normally run these days from around 50 psi to 125 psi. At my house the city pressure is 70-80 psi and no one has a problem with the pressure. Any metal pipe can easily take a pressure of at least 100 psi and any water heater is designed for an even higher bursting pressure. Really cheap poly pipe is made for 80 psi, better grades are rated at 120 psi and higher. And of course almost all lawn hoses will take a minimum pressure of 70 psi and most are fine with quite a bit more (especially if you don't leave them pressurized in the sun at 105 degrees. Even food grade polyethylene (very soft plastic) will take 40-50 psi as long as you don't let it get hot.
As for tank costs, a 20 gallon air tank rated for 125 psi can be bought for less than $25. And you can buy new empty 5 gallon propane tanks that will take very high pressure for $20.
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In article <5OMMf.473661$ snipped-for-privacy@bgtnsc05-news.ops.worldnet.att.n

Whose particular view of reality is that? Are you familiar with the practices of hot water storage throughout the world? You may notice that at least one of the cross posted groups in this thread is UK specific so you have gained the experience of someone who lives in that area.
Here, hot water, if stored, is generally contained in either copper or stainless steel 'cylinders' to avoid the effects of corrosion. Copper is expensive and so low pressure tanks are made thinner and therefore cheaper. It is not common practice here to store hot water in bicycle tyres or propane tanks.
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fred wrote:

Sounds like bare-faced assertions to me. Care to post any links that show that normal households use such unneccessarily expensive systems? Those are the systems we are discussing, not huge commercial types.
ln any case your concern is unwarranted as the OP is using an ON-DEMAND system. No storage.
Harry K
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snipped-for-privacy@hotmail.com wrote:

You already have your answer -- 100 vertical feet from the cabin will give you 43 PSI static pressure. The pipe size is determined first by your maximum expected draw rate and then by the length. The more gallons per minutes you want, the larger the pipe to avoid too much pressure drop. (sorry, I don't recall the flow rates for different size pipes) Don't forget that there's a 1.25" pipe size.
Bob
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zxcvbob wrote:

Thank you. Unless I can think of any reason other than cost to not suggest the ranch owners buy 1.5 polyethylene hose, that is what I'll suggest: it is the same size and material currently used elsewhere on the ranch.
As for pressure drops, I'll ask the ranch owners what shower head flow rate they plan on installing. Seems to me they could run five gallons a minute and still suffer no pressure drop.

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1.5 DEFINETELY BETTER! Thats what I helped install for my moms main water line. a gazillion years ago, its pretty cheap to.
you might add a solar panel & battery for minimal lighting too.
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snipped-for-privacy@aol.com wrote:

Since I do not have to pay for it, I agree! :-) At the moment it is too dark to go outside, climb the hill (it is heavily wooded forest), and triangulate height and distance--- so I do not know how long the pipe/hose must be. If I recall correctly, the 1.5 poly hose comes on a huge reel. We want to have no breaks in the hose because roots tend to get into pipe fittings when they are buried.

That would be far too good for the ranch's guests. :-) Several so-called "celebrities" have stayed in the cabin using oil lamps to see by since there's no electricity (I could name a few "celebrities" if pressed). Since propane has already been plumbed into the cabin, the idea is to use propane lamps.
As soon as the ground thaws (perhaps in May) we hope to start trenching for the water hose. That in addition to branding the calves, planting the chili peppers, and splitting wood for next winter. Gods! The work involved! :-)
I very much appreciate all who have answered my questions. It makes the job easier when someone else does the thinking for me. :-)
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snipped-for-privacy@hotmail.com wrote:
...

Isn't it wonderful how much traffic a really /practical/ problem generates? :-)
Jerry
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snipped-for-privacy@hotmail.com wrote:

Yeah you are right about almost no pressure drop because it will be very small (about 1psi) for 5 gal/min over 1000' or pipe. You could drop the size to 1 1/4 and not notice the difference. 1 1/2" pipe would give you more capacity (in case someone want to have a shower, run a washing machine and flush the toilet simultaneously).
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before the pipe goes in the house...to help take up the shock when a valve is closed. Or another way is to put a tee in the line then run a vertical pipe up a few feet and cap it...the trapped air will act as a "shock absorber" when valves are closed.
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Keep the drum as near to the borehole as possible.
It may be worth your while making the drum bigger, or multiple drums, for a large water store. Then keep the borehols as small as possible to avoid losing water. If it gushes away you may dry up the water source at certain times of the year. Only you can actually know this being local to it.

Not at 3 bar there isn't.

At about 3 bar (30 foot vertically is approx 1 bar) you don't have great pressure. My house is 4.5 bar from the mains with no pressure reducer. 3 bar will give a nice shower too.

It is called a shock arrestor. It can be the size of a tennis ball. Water hammer tends to be when taps are turned off sharply, like having lever handles. Water hammer may not be a problem as any shocks may work their way back up the supply pipe.

The air pocket will eventually disappear, so best get the proper fitting.
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digitalmaster wrote:
...

That works until all the air eventually dissolves and is replaced by water. Then the riser needs to be isolated and drained. Install the appropriate valves to do than. (I have risers on the water lines to my clothes washer. About once a year, I shut the water, disconnect the hoses, and let the risers drain. If I don't, the noise reminds me why I put the risers in. Bladder-type tanks separate the air and water, making periodic draining (or recharging with air through a Shrader valve) unnecessary. Atmospheric pressure is the equivalent of 34' of head. 100' of head will compress atmospheric air in a riser to a third if its original volume, allowing less room for free motion (and less free volume) than appearance might suggest.
Be sure to put a valve at the top of the feed pipe to make repairs possible, and one before the shock-relief gizmo (tank, riser) so you can drain it. It goes without saying that you need a drain valve for the gizmo and maybe also an air-bleed to let air in so water can come out.
(There is a 40" force main coming into one of the facilities at the sewerage authority I'm associated with. Its downstream end has a valve for emergencies. When flow is at rated, it takes at least two minutes to close the valve without danger of rupturing the ductile-iron pipe.)
Jerry
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snipped-for-privacy@hotmail.com wrote: [diy water storage tank]
Just a thought about how you ought to build this thing. Think about winter. If you get cold enough weather for water to freeze, you will want to allow for a way to drain it all off before that happens. You may also want to be able to arrange that the water is kept out of the collection tank during winter. Otherwise, you could easily have lots of burst piping, maybe a ruptured tank. Could get irritating. Socks
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