[TheForge] OT - Water pressure problem. OT:ish

Mon May 16 08:29:59 EDT 2011

How would the pump activate on demand?  I'd have to go to the pump,
turn it on, then go back to the hose nozzle and water.  When watering
gets interrupted, I'd have to either let the pump keep running with
zero flow, or waste water, or go back and turn off the pump.  Or, I
could run an electrical lead along the hose and put a switch at the
nozzle (which would require me always to use the same hose).  Or I
could come up with some non-wire remote control to turn on and off the
pump.  These strike me as burdensome AND assume that I want to water
at the full pump flow.

If I could equip the downstream side of the pump with a pressure
sensor, then the pump could turn on when that pressure dropped below
some minimum.  But that still assumes I want to water at the full pump
flow.  And with that level of complexity, I might as well add an
accumulator tank of some sort (air-pressurized or water tower) so that
the pump can run at its maximum efficiency and then turn off, but
water would be available even when the pump is not running.

My objectives here are (1) to pressurize the accumulated rain water
sufficiently for use in the garden, and (2) to do this cheaper than it
would cost me to just use city water.

So far, I've spent $125 on tanks (~600 gallons total), and maybe about
$25 on plumbing parts (I haven't checked my receipts, just guessing
from memory).  I have a very nice pump I plan to use.  I have no
pressure or flow sensors suitable for use with it, but I can design
and build electronic circuits needed to control it.  I'll probably
cannibalize an existing pump controller that takes a contact closure
input and closes a 12V relay to control the 115V pump. I may have to
use a transistor to close the contact, and drive that from sensor
inputs of some sort.

On Mon, May 16, 2011 at 1:32 AM, peter fels <artgawk at thegrid.net> wrote:
> That's much too straight-forward!
>
> On May 15, 2011, at 8:09 PM, Lynn and Susan Lang wrote:
>
>> Bruce
>> Why not just collect the water in a stock tank and when water is needed
>> have a small pump to charge your garden hose.....Not knowing your task
>> makes suggestions a shot in the dark...
>>
>> lynn
>>
>> -----Original Message-----
>> From: theforge-bounces at mailman.qth.net
>> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Bruce Freeman
>> Sent: Sunday, May 15, 2011 8:45 PM
>> To: Blacksmithing List Sponsored by ABANA
>> Subject: Re: [TheForge] OT - Water pressure problem.
>>
>> I've had two ideas since first asking.  One is to mount a plastic
>> barrel horizontally on four or six legs as a water tower, but lean
>> this structure against the back of the garage, which (1) hides it from
>> casual view, (2) provides the extra rigidity from the existing
>> structure, and (3) allows me to use the space beneath as a "shed", if
>> I enclose it.
>>
>> But on reading Peter's contribution, it struck me that I could
>> pressurize a tank using air from an air compressor.  When the water
>> level got too low, the air pressure would be released until low enough
>> for the water pump to handle.  The water pump would refill the tank,
>> then the water pump would shut off and the air pump would come on and
>> pump the tank back up to operating pressure.  Clearly, one would want
>> a tank large enough for the watering job at hand.  And a manual switch
>> to initialize the refill cycle would be handy. Main advantage -- no
>> tower structure to build and worry about.  Main disadvantage --
>> obtaining a suitable tank.  Anyone know a source of such tanks --
>> cheap?
>>
>>
>>
>> On Sun, May 15, 2011 at 4:18 PM, peter fels <artgawk at thegrid.net> wrote:
>>> Storing water under the house in sealed tanks has thermal mass
>> virtues.
>>> or short term use, an external  tank ,with water above pressurized air
>>> ought to suffice. No bladder necessary....just drain and recharge
>> every month or 2.
>>> I've about 300 gallons available for fire fighting like that.
>>> The pump could be electric on a pressure switch..all commonly
>> available and modestly priced...
>>> Or a small solar powered piston pump might suffice as well.
>>> A tank atop a n upright pipe promises the least upkeep and lots of
>> design freedom.
>>> I think you can go to about 30' up with a centrifugal pump. Beyond
>> that you'll want a piston or roller pump.
>>> I've long wanted to build a rigid, flat, black tank with glass
>> covering,
>>>  that would pump with no moving parts, by the daily heating and
>> expansion of the water...
>>> OK the check valve is a moving part.
>>>
>>>
>>> On May 14, 2011, at 3:05 PM, Bruce Freeman wrote:
>>>
>>>> Once again I'm using the broad knowledge base represented by this
>>>> group for an OT problem.
>>>>
>>>> I have just installed rain barrels at all my downspouts, including a
>>>> 250-gallon tank at one of them.  I plan to siphon or pump water
>>>> between them to maximize capacity.
>>>>
>>>> However, none of these are more than 16" above the ground -- two
>>>> cement blocks.  That means that there's little water pressure
>>>> available, making using the water inconvenient.  I could rig a pump
>> to
>>>> go on anytime I need water, but a more elegant solution would be to
>>>> use that pump to keep an elevated tank (water tower) filled between
>>>> limits.
>>>>
>>>> What I'm thinking is to use a fairly small plastic tank -- 15 or 20
>>>> gallons (i.e., ~150 lbs maximum), and to mount it high enough to
>>>> provide reasonable water pressure.  In use, the pump would probably
>>>> come on every once in a while, because the tank would be fairly
>> small,
>>>> but at least it wouldn't be running continuously or with no flow.
>>>>
>>>> Now, to get 15psi I'd need a tower of over 30', and that's out of the
>>>> question.  I'd like something as low as possible and as small as
>>>> possible.  So, the first question is what is the lowest useful water
>>>> pressure for use around yard and garden?  I don't need to run
>>>> sprinklers, but would like to use drip hoses.
>>>>
>>>> Possibly a water tower isn't the proper solution.  What other
>>>> solutions exist?  What I'm aware of is a pressurized system, in which
>>>> the pump fills an accumulator tank, or something of the sort, which
>>>> then discharges for a while before the pump comes on again.  This
>>>> strikes me as expensive, and i'd like to keep expenses low.
>>>>
>>>> If it were possible to do, one potentially elegant solution would be
>>>> an accumulator tank that would be filled either with city water or
>>>> pumped rain water.  There'd have to be a barrier between them, and
>> the
>>>> side that would accept the city water would have to be clean and
>>>> isolated from the rain water side (which must be assumed to be
>>>> contaminated with various environmental contaminants, not the least
>> of
>>>> which would be bird feces).  If I put a check valve to keep the "city
>>>> water" from backing up into the city piping, this might even be
>> legal!
>>>> I toss it out mainly for discussion, as I really don't see much
>>>> advantage relative to an air bladder accumulator.
>>>>
>>>> So, regale me with your wisdom, o metalworkers and artists of
>> reality!
>>>> --
>>>> Bruce
>>>> NJ
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>>
>>
>>
>> --
>> Bruce
>> NJ
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-- 
Bruce
NJ