Re: SB: Gravity fed domestic water system

["Scott Willing" <willing@mb.sympatico.ca>]

On 18 Nov 2002 at 10:32, David Delaney wrote:

> Problem still remains, though, how do I design
> such a system and spec suitable components?

Dunno. The only thing I've researched to any degree is gravity 
graywater systems, and most of the information comes from warmer 
climes, so not even that is terribly useful.

I have a little bit of real basic information on gravity systems from 
the book "The Home Water Supply", e.g. 2.3 feet of elevation provides 
one lb of pressure (sorry about the imperial figures) so if you 
wanted 20lbs of pressure, the tank has to be 46ft above the highest 
faucet (yeow) so caveat emptor re: pressure expectations if you're 
planning on a tank in the attic.

There are some other little factoids that I wouldn't have guessed 
offhand, e.g. it's the surface height of the water alone that 
determines basic pressure; the size of the tank only determines 
capacity. You can have a 5-gallon tank and a 5000-gallon tank side by 
side, and they'll produce the same pressure if the height of the 
water surface is the same.

One good thing about this is that if, like me, you don't really have 
a good mental picture of what 10 or 20lbs of pressure is like 
actually coming out of a tap, you could stick a 5-gallon pail in the 
attic and run a garden hose downstairs to get a feel for what you're 
going to end up with.

If it turns out that the pressure you're able to get is on the wimpy 
side for your taste, I guess you could consider the possibility of 
adding a pressure pump downstream of the tank to provide typical 
operating pressure when/if desired, without ruling out gravity 
operation. All depends on what your expectations are. Once you add a 
pressure pump, you're pretty much obliged to add a pressure tank as 
well (so that the pump is buffered from the need to react to every 
on/off cycle when a tap is opened).

I dunno, I'm just flappin' my keyboard fingers now... but given the 
basic pressure calculation above, I expect the rest of the system 
would be pretty much standard stuff and pretty easy to get 
information on. If'n it were me, I'd take the same approach to 
plumbing as I would to electrical, i.e. build a standard, code-
friendly distribution system, and put all the funky stuff at the head 
end. That way you have something that can easily be adapted by 
"normal" folks if the house changes hands. OTOH if you distribute the 
funky stuff throughout, then you have something of an albatross 
around your neck.

But here again I haven't a clue what your priorities are. My house, 
at present, is about as funky as it gets, since I still haven't had 
the pleasure(?) of starting from scratch.

Cheers,
-=s

 
> David Delaney, Ottawa
> 
> At 10:17 AM 11/18/02, Scott Willing wrote:
> >David,
> >
> >In Manitoba, a gravity-fed system -- even if the tank is normally
> >filled by an electric pump -- is not considered "pressurized" and is
> >therefore not subject to codes. YMMV.
> >
> >What's the source? (Creek, shallow well, deep well...) Has a 
> >significant impact on the choice of hand pump.
> >
> >-=s
> >
> >
> >On 18 Nov 2002 at 10:07, David Delaney wrote:
> >
> > > Does anyone know of sources for design practices
> > > and components for gravity fed domestic water
> > > systems that would be compatible with 
> > > North American building codes?
> > > 
> > > The system is to be operable by
> > > solar electricity with no batteries, so pumping
> > > would be available only during daylight. Backup 
> > > would be a hand pump operated as necessary to fill
> > > the attic tank. I also need a source for a suitable
> > > hand pump.
> > > 
> > > David Delaney, Ottawa
> > > 
> > >
> 
> 
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