Equalize charge - SW4024 [RE-wrenches]

[allan]

John,
    RE the EQ: It's [another] design/software weakness in the SW.  If you
set the generator menu to EQ, the NEXT time the inverter auto-starts the
generator it will go through the EQ procedure.  That's OK if the generator
is routinely started by the inverter (which I suppose it will be up in
Vermont in the winter).  It doesn't work if the array keeps up with the
load.  The other way is to set the generator menu to EQ, then manually start
the gennie at the gennie; watch when you reach EQ voltage, then wait X hours
(according to your preferred EQ time duration) and turn it off.  You can let
the inverter do the process (which includes bulk charge to EQ setpoint, hold
for set duration; drop to float) but you still have to watch the process to
know when to manually shut off the gennie.  Wrenches: I believe that I have
all this right--any dissent?
On the pumps: When you say DC250, do you mean T240?  By all means, control
the T240 on the primary side to avoid phantom loads.  We have done a 3/4hp
240 well pump with a standard open-coil relay with 24VDC coil voltage
(Grainger 3X749), letting the control circuit (float switch or pressure
switch) operate the DC coil; worked great, and even let us series in a DC
timer (App. Pwr #52-112 with 52-117 step-down resistor).
The T240 is rated 4.5kW, so whatever the inverter will handle, the T240 will
too.  If you have trouble (lights flicker, computers crash, etc.) with the
surge from starting both pumps at once, you could try a second time-delay
relay (Grainger 4A368 in 24VDC) to control a DC coil AC relay.  Sounds
complicated, but relays are actually pretty simple and reliable.
I suspect your client will complain about lights flickering when the pumps
start.
By the way, how are you running the hydronic system? A standard AC system
will kill batteries, it's such an energy hog.  We use all-DC stuff we have
developed.  Respond if interested...

Allan at Poz E
-----Original Message-----
From: John Blittersdorf, Cent. VT Solar & Wind <cvsolar at aol.com>
To: RE-wrenches at topica.com <RE-wrenches at topica.com>
Date: Monday, October 16, 2000 7:11 PM
Subject: Re: Equalize charge - SW4024 [RE-wrenches]


>Kurt,
>   Thanks for the EQ info.  We will try the AUTO mode initialization and
see
>what happens.  We have their system metered well so they won't have to
>babysit watching for it to happen (even though they probably will as they
>love to watch it run).
>This system is my flagship off grid job.  It's a new passive solar, energy
>efficient house with radiant floor heat, solar hot water.  The GC for the
job
>was a real perfectionist and everything including the utility room was done
>looking real sharp.  He is now convinced that solar works so I am hoping
this
>will lead to more solar in new homes in this area.  The owners of this
house
>are real efficiency nuts so it has been a pleasure to work with them.  I
have
>put a lot of extra time into this one at no charge just to have a top notch
>shining example of my work to show people with money.
>
>The EQ problem was the only one with the system.  They also had a problem
>when the septic pump installed was 240 and we had planned on a 120 vac
pump.
>The engineer said that the piping in the mound would have to be changed if
we
>went with a 120 pump (GC slipped on this detail- he knew we only had 120)
We
>ended up hooking both pumps to one DC250.  Has anyone done this..  Trace
says
>that the loads are OK even if both pumps start at the same time (both pumps
>are 3/4 hp)  We are still waiting to see if the sewer pump shuts off before
>the well pump all the time.  If so, we can use the pressure switch on the
>well pump to activate the transformer.  If the flows don't work out right,
we
>will have to have the DC250 on all the time.  Hadn't planned on that with
our
>load analysis.
>
>John
>CVSolar
>
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