Hola all. I've spent the last few days tracking down a leak that I still haven't found. I'm going to simplify all the "pipe in concrete" syndrome and
go around the ##@&&**##!! mess. I have a pila on the roof and have never hooked up the water pump I have. Hey, it's only been five years! I
want hook up the pump but keep the gravity flow capability when the pump goes down, or I shut off the electric for a hurricane. I've figured out all
the twists and turns of running the piping but I don't know if the genius that put this mess together did things because they were convenient with
what he had laying around, or, if they actually had a beneficial impact on gravity flow. To simplify, he came from 1 1/2" from the pila, reduced to 1
1/4" through the concrete, then down to 1" into the house. Does anyone know if I can go from 1 1/2 straight to 1", skipping the 1 1/4" without
affecting the flow?jerry - 8-25-2007 at 02:18 PM
it shouldnt make any difference on gravity flow and unless your using a big pump it shouldnt bother there eitherwoody with a view - 8-25-2007 at 02:27 PM
it's all about pressure, er gravity. shouldn't matter. although i've seen a pila with a 1" feed get FULL of dead bees to the point that the water
won't flow.....Al G - 8-25-2007 at 03:15 PM
Maybe there are some fluid dynamics people here...I am not one.
that is said so here goes nothing...gravity is the effect of weight in a vertical column. Horizontal weight has no energy...requires energy to
overcome said weight. Increasing vertical pipe size will produce energy...decreasing horizontal pipe size will reduce weight...lowering needed energy
and producing more head pressure at shower.
When using pump energy...gradual pipe downsizing works best, because abundant energy make friction more important.
Well it sounds good to me anyway...aliibike - 8-25-2007 at 03:20 PM
That's what I was thinking, but it sure looks like it was designed to taper down. I guess I needed to bounce it off someone else. No way for bees to
get in though unless I left the lid off!bajamigo - 8-25-2007 at 04:56 PM
Ask Dennis. He knows more than Galileo.DENNIS - 8-25-2007 at 05:04 PM
Fluid dynamics? Yep. That's my field. It all boils down to one thing. When the Pacifico bottles are empty, go immediatly to the store and trade
them in for full ones.aliibike - 8-25-2007 at 05:08 PM
I'm off to town tomorrow, but this time of year it's to maintain emergency supplies.DENNIS - 8-25-2007 at 05:12 PM
Actually, giving your dilema a bit of thought, the taper down theory doesn't mean anything with a gravity feed. The water will exit the system at
the speed the smallest pipe allows. Only added pressure will accelerate the flow. If you want more gravity pressure, use a bigger pipe.
The full Pacifico bottles are no less important.aliibike - 8-25-2007 at 05:39 PM
So the end pipe diameter is the max flow. Going to a bigger pipe would mean tearing up lots of concrete, which I might have to do once I put a pump on
it anyway! The Pacifico's have never been a problem, unless you ask my wife.Russ - 8-25-2007 at 05:58 PM
KISS theory is important here. I'm sure that there are a lot of flow dynamics but unless you have a very long run I don't believe it matters much. I
have used 3/4" PVC throughout Except for copper on the hot water runs. If you need more pressure either raise the tank or get a pump. I wish you good
plumbing but simple is best.Bedman - 8-26-2007 at 01:03 AM
Hehehe..here's my 2 cents.
The larger the vertical pipe (from the overhead pila) the greater the weight, mass and volumne at the outlet.
Hydraulic mining used a step down pipe in the vertical to enable those Great plumes of water to be shot to distances as far as 800 feet. The
originating pipes were as large as 3 feet and the exit end as small as 1 inch.
BedmanAl G - 8-26-2007 at 10:37 AM
Quote:
Originally posted by DENNIS
Fluid dynamics? Yep. That's my field. It all boils down to one thing. When the Pacifico bottles are empty, go immediatly to the store and trade
them in for full ones.
Dennis...that is what I said...just could not find the right words
The pacifico bottle is the example I should have used for the taper down on the vertical...That is how I got my degree in vertical fluid dynamicsPescador - 8-26-2007 at 03:41 PM
In a straight up vertical pipe, a 1/14 inch pipe holds .0638 gallons of water per foot, while a 1 1/2 inch pipe holds .0918. Hardly significant. The
friction is also insignificant at anything under 100 Gallons Per Minute which is way under what you could pump if you do decide to hook up the pump.
I would use a fairly sensitive pressure guage, or if you don't have that I would use a tire guage. Pump the pipe up with pressure (about 50 lbs)
and see how fast it leaks down. If it comes down within 10 minutes or so, you have a pretty good leak and need to further investigate. If it holds
the pressure, then I would not worry too much about itDENNIS - 8-26-2007 at 04:44 PM
Quote:
Originally posted by Pescador
In a straight up vertical pipe, a 1/14 inch pipe holds .0638 gallons of water per foot, while a 1 1/2 inch pipe holds .0918. Hardly significant.
So what, if this is a gravity system. Wasn't that the question?
I'm unable to establish a flow rate without a source size. It would be variable anyway, depending on the water level of the tank.
Who cares? Have an adequate tank and a proper outlet and you will have a wet shower.
Want more wet? Get bigger pipes in the system, keep the water level high and avoid the urge to save water with the one you love. These eforts are
usually water intensive.Bruce R Leech - 8-27-2007 at 09:22 PM
wrong wrong wrong.
the size of the pipe has nothing to do with the pressure at the bottom of the column. theoretically you will have the same static PSI at the bottom of
a drop with 1/2 inch pipe as you will have with a 12 inch pipe with the same drop. you get about 1/2 lbs of static PSI per foot of fall regardless of
pipe diameter. the only benefit of a larger diameter pipe will come when the watter starts to flow. as velocity increases friction will callus it to
lose some PSI. so increase diameter to lower velocity especially on long runs.Diver - 8-27-2007 at 09:47 PM
One thing that has been missed is the concept of "required flow".
For example, a low-flow shower head may use 2gpm.
With a given pipe system, you would like to supply at least this amount of flow to the shower head. (same principle with toilets, etc.).
Bruce is correct in that pressure does not increase with larger pipe size.
As Dennis implied, flow can be increased with a larger outlet and pipe size or less pipe friction.
A stepped system is one way to ramp up pressure with a high head pump.
Stepping down pipe size is also commonly used in houses where branched systems supply less and less fixtures, down the line.
As for your leak repair, sounds like you can step down from 1 1/2 to 1 1/4 then 1" within the length of the reducers but I would keep the pipe size as
large as the connection into the house (but 1/4" larger never hurts especially if the connection is at a 90 degree elbow).
.aliibike - 8-28-2007 at 04:36 PM
Thanks everyone! I have decided to go with the "if it ain't broke....." theory. I got stuff to bypass where my problem is. I don't need to pressure
test to see how bad it is, it leaks enough to leach into the bedroom wall. I'm going to use the tapering down that was there before and plumb an
adjustment before it goes back into the concrete foundation to pressurize later. That's where I will pressure test before hooking up a pump. Make
sense?Bruce R Leech - 8-28-2007 at 08:32 PM
