[RE-wrenches] Gen preheat in cold climates

[Larry]

About the carb heat idea...LP is a liquid at -44=C2=B0F. The liquid does no=
t=20
combust, it must be vaporized. As the ambient temperature drops closer=20
to the LP liquid temperature, there would be a reduction in how fast=20
liquid is vaporizing and therefor a reduction in volume. What you need=20
in cold weather is enough volume to maintain at least 11" wc while=20
cranking or running the engine. You can test the vapor pressure with a=20
manometer while cranking to verify if this is the problem.

If this is the reason the engine does not run, my thoughts are that=20
heating the LP regulator would be much more economical from an energy=20
standpoint, than heating the whole engine block. Perhaps an insulated=20
enclosure with silicone heaters appropriately attached would work. They=20
are available in many DC or AC and at various voltages.

Larry Crutcher
Starlight Solar Power Systems

On 4/2/15 10:34 PM, Allan Sindelar wrote:
> Gary,
> Mac's approach is intelligent and will work well, as an automated=20
> system with the right hardware. We took a quite different approach on=20
> a somewhat similar scenario in 2009.
>
> This was a Kohler 8.5REZ, with the electric carb heater and AC charter=20
> for the starting battery. No block heater, but that could have been=20
> handled the same way. The inverter was a Magnum MS4024PAE, but that=20
> doesn't matter here. When we ran the bundle of gennie output=20
> conductors, we added a separate load circuit conductor, on its own=20
> breaker in the system E-Panel. Here's an excerpt from the original=20
> proposal description about our approach:
>
>     The unit uses an electronic generator controller with modest
>     (estimated at 200-700 mA, depending on state of operation) draw on
>     the starting battery. This controller drops to minimal =E2=80=9Csleep=
=E2=80=9D
>     draw automatically after 48 hours of non-operation. This generator
>     does not have a starting battery charging coil, but rather uses a
>     separate AC battery trickle charger to maintain the battery. I
>     will install a 20W PV module and small charge controller on the
>     generator to keep the starting battery charged. I will also
>     install the AC charger to operate whenever the generator is
>     running. While this combined setup has worked successfully for
>     other installers with whom I have spoken, if this proves
>     insufficient I can later add a switch and relay to allow the
>     charger to also operate off of inverter AC if ever needed.
>
>     The unit also requires a built-in carburetor heater to operate
>     during cold weather. This heater is normally controlled by a
>     thermostat to conservatively come on at or below 40=C2=B0F, which wou=
ld
>     mean that it would operate nearly continuously during Taos=E2=80=99 w=
inter
>     months, draining the PV system. My solution is to put the
>     carburetor heater on a manual mechanical one-hour time switch
>     located at the generator; you will activate the heater through
>     this switch 15-30 minutes before starting the generator.
>
> This may not work for you. This is a modern doublewide serving as a=20
> seasonal family meeting place, rather than a full time residence. With=20
> our usual sunny winters, we figure that if nobody is there, loads are=20
> minimal, and we don't want automatic (unattended) generator operation.=20
> I think we used a DG WP box inside the generator enclosure, with a=20
> mechanical timer (maybe one-hour) controlling a GFCI receptacle, with=20
> carb heater and battery charger plugged in.
>
> I hope that gives you some ideas you can use.
>
> *Allan Sindelar*
> allan at sindelarsolar.com <mailto:allan at sindelarsolar.com>
> NABCEP Certified PV Installation Professional
> NABCEP Certified Technical Sales Professional
> New Mexico EE98J Journeyman Electrician
> Founder (Retired), Positive Energy, Inc.
> *505 780-2738 cell*
>
> **
>
>

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