[RE-wrenches] Gen preheat in cold climates

Mac Lewis maclewis1 at gmail.com
Thu Apr 2 20:10:03 PDT 2015


Hi Gary,

We have implemented a preheat strategy that has really worked well at a
site using dual sunny islands.  They have a load shed function built in
with the control relays.  We are using that function to add the block
heater load.  When a generator start is likely (~50% SOC) it triggers a
relay that energized the block heater.  The generator start is then
programmed at a lower SOC (~30% SOC).  It takes some guesswork to know how
many watt hours its going to take to get the block heated up, but we
conservatively chose and have fiddled with it.  I imagine this can be done
with either the Radian or the XW, and you could trigger with voltage
instead of SOC, but SOC is a superior way to do it.

Another way is to use a propane block heater.  This will work well, but
they use quite a bit of propane, and are very expensive (~$1500).

Good luck

On Thu, Apr 2, 2015 at 8:47 PM, Gary Higbee <gary at windstreamsolar.com>
wrote:

> Wrenches,
>
> I'm curious what strategies you use to preheat a propane gen in cold
> climates. This is a large off-grid design in a sub-zero winter climate and
> ideal would be to turn on a block heater an hour or two in advance, then
> run the gen cycle. We plan to use either a Schneider XW or Outback Radian
> configuration (still very interested in which you'd use and why). We could
> set up a logic/relay system to first send the gen request to the heater for
> a while and then turn off and initiate a gen cycle but that would eliminate
> the ability for autostart on short notice. I've read of heat lamps on a
> thermostat, just wondering if you have seen other solutions.
>
> Thanks!
>
> Gary
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-- 



Mac Lewis

*"Yo solo sé que no sé nada." -Sócrates*
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