<html><body><span style="font-family:Verdana; color:#000000; font-size:10pt;"><div>OBTW, I do have one off grid customer that has the water jacket from his diesel genny plumbed into his heating system. So no only can he dump heat from the engine into his thermal storage tank, he can also treat the engine as a zone and heat it from the wood furnace.<br></div><div><br></div><div>db<br></div><div><br>Dan Brown<br>Foxfire Energy Corp.<br>Renewable Energy Systems<br>(802)-483-2564<br><a href="http://www.Foxfire-Energy.com">www.Foxfire-Energy.com</a><br>NABCEP #092907-44</div><div><img id="sigimg0" title="signature image" src="cid:sigimg0@139c8f0e7a0bd28ed442cbc57519e077" alt="" border="0"></div><div><br><br></div>
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-------- Original Message --------<br>
Subject: Re: [RE-wrenches] Gen preheat in cold climates<br>
From: <a href="mailto:drake.chamberlin@redwoodalliance.org">drake.chamberlin@redwoodalliance.org</a><br>
Date: Fri, April 03, 2015 10:32 am<br>
To: "RE-wrenches" <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><br>
<br>
We are dealing with a generator that absolutely won't start when cold, so<br>
I was considering a block heater. Below 20 deg F it has proven worthless,<br>
and we can see -20 F on occasion.<br>
<br>
My concern is using power from a low battery on a cold cloudy day to heat<br>
a generator. How long does it take to make a difference? Has this method<br>
proven 100% reliable?<br>
<br>
Thanks,<br>
<br>
Drake<br>
<br>
<br>
> Hi Gary,<br>
><br>
> We have implemented a preheat strategy that has really worked well at a<br>
> site using dual sunny islands. They have a load shed function built in<br>
> with the control relays. We are using that function to add the block<br>
> heater load. When a generator start is likely (~50% SOC) it triggers a<br>
> relay that energized the block heater. The generator start is then<br>
> programmed at a lower SOC (~30% SOC). It takes some guesswork to know how<br>
> many watt hours its going to take to get the block heated up, but we<br>
> conservatively chose and have fiddled with it. I imagine this can be done<br>
> with either the Radian or the XW, and you could trigger with voltage<br>
> instead of SOC, but SOC is a superior way to do it.<br>
><br>
> Another way is to use a propane block heater. This will work well, but<br>
> they use quite a bit of propane, and are very expensive (~$1500).<br>
><br>
> Good luck<br>
><br>
> On Thu, Apr 2, 2015 at 8:47 PM, Gary Higbee <<a href="mailto:gary@windstreamsolar.com">gary@windstreamsolar.com</a>><br>
> wrote:<br>
><br>
>> Wrenches,<br>
>><br>
>> I'm curious what strategies you use to preheat a propane gen in cold<br>
>> climates. This is a large off-grid design in a sub-zero winter climate<br>
>> and<br>
>> ideal would be to turn on a block heater an hour or two in advance, then<br>
>> run the gen cycle. We plan to use either a Schneider XW or Outback<br>
>> Radian<br>
>> configuration (still very interested in which you'd use and why). We<br>
>> could<br>
>> set up a logic/relay system to first send the gen request to the heater<br>
>> for<br>
>> a while and then turn off and initiate a gen cycle but that would<br>
>> eliminate<br>
>> the ability for autostart on short notice. I've read of heat lamps on a<br>
>> thermostat, just wondering if you have seen other solutions.<br>
>><br>
>> Thanks!<br>
>><br>
>> Gary<br>
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