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Posted by Bipolar Bear on February 18, 2009, 12:44 am
> >> I mentioned the variable speed pump simply because it can save a good
25%
> >> (or more) in electric consumption.
> > That's a blanket statement--any domestic sys with std bladder tank can
do
> > the same thing...all that's needed here now is to modulate flow rate
based
> > on LWT and taking into consideration the initial extraction costs.
> When I had the well drilled it was sized for the geo as well as domestic,
> w/larger casing & pump.
> Variable speed pumps were just hitting the street & my installer wasn't
> anxious to experiment.
Here there is a 300 gal existing tank with the old school float type air
volume control, a 3hp pump the pressure switch setpoints were changed to
cut-in at 40 psi and out at 80
Even at a 15 gpm flow rat the pump doesnt cycle off but but perhaps once per
hour, not a huge drain the sratup inrush IMO
In order to maintain a more constant pressure at the residence, an
additional bladder tank was added having whatever its a flotec about 3 ft x
5 I magine its gives 35 gals reserve for showers toilets etc and is
isolated via check valve from the mains supply--this tends to re-fill at the
end of the main pressure cycle and thus a pressure of ~ 80 psi is maintained
on the domestic side unless someone is wshing a car or some shit.
Hey it works, what can I say.
> The start & stop of a larger single speed pump via a pressure tank uses a
> lot more electricity compared to a variable speed pump that ramps up &
down
> maintaining proper flow for either geo, domestic, or both.
See above.
Would be nice I agree but lots can be done on the fly depending on what you
already have--increasing cutin/out differential and adding a second bladder
and check vlve for instance.
> When targeting flow rates, I try to get 4 gpm or a delta T across the HP
of
> 15dF...
Not sure you may be typing too fast, delta of 10 to 15 is a good ballpark,
but to rate in gpm then your actual tonnage comes to the forefront.
> Newer units will rate themselves w/3gpm or even less. I find these rated
too
> low to trust.
Let me know HERE and Ill send you a private--this is all fairly simple
math--impossible to more heat than exists in the mass flow a basic review is
always good.
> P&D systems often need higher flow rates to avoid LWT dropping below the
> (40dF) "freezestat" that locks out the unit.
I think the clixon is usually at 38 /40 so yes--AND if the controls need
breaker or stat Y disco then it can indeed be troublesome.
Closed loop is a different aminal, you have a mix that doesnt suddenly turn
hard, a slush that undergoes "glass transition" instead --with glycols
generally at ~ 40~60 % IIRC theres charts and those temps are like -50 deg
dunno ask an ice road trucker.
--
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> decent cooling.
> Warmer temps & slower flow, well... you'll figure it out.
> Above 50dF you won't get much & no real dehumidification...
> geothermaljones