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Guys
I have the old Grunert 12 volt refrigeration that requires that you have shore power or the engine running to come on. When I replaced the Crow converter that served as a battery charger since 1979 I replaced it with an inverter. It makes sense to me that I should just hook the sense wires to the 110 out side of the inverter. Does anyone have experience with this style of hook up?
Help I need to get the beer cold!
Linus
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Linus
I should have tried to answer your question too. I have an engine-driven
system from the same company. There is a 12V soleniod switch on the
receiver assembly. As I recall, 12v power from the reefer circuit-breaker
was routed through a pressure switch on the side of the high-pressure fuel
pump. When the engine started, the pressure switch closed allowing 12v
power to go to the solenoid and close the 12V solenoid switch. A second
wire from the breaker provided power through the solenoid to run the water
pump and actuate the clutch on the engine-mounted compressor. I assume that
your 12V compressor is wired in where the clutch would be tied. I had a
problem with the solenoid switch and replaced the it. You can buy them from
RV stores for less than $20.I’m curious about the questions below. Although my engine-drive system
works well, it has the disadvantage of requiring that the engine run each
day even when tied to a dock. A 12v or 115VAC compressor would work without
the engine being run. The engine-driven compressor is about 3hp whereas
most 12v pumps are fractional HP, perhaps 1/4 hp. If Grunert put in
something in the 1hp range, it would suck power down at the rate of about 80
amps, but would probably work almost as well as the engine-driven system.
You’d need a huge alternator and a huge battery charger. If they put in a
1/4hp compressor, your power consumption would be in the 20A range, but
you’re running time would be extended. I’m curios as to what you have and
how well it works.Hope this is of some help.
RichQuote:
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Linus,
I have a Grunert AR-50 system for my 12V refrigeration. This uses a
Blissfield CE compresssor which is rated at 1/2 HP (thus the “50” in
AR-50 methinks).aThe factory schematic calls for both the 120VAC relay and the oil
pressure switch. Both were removed by PO on my system. I have a
breaker on the main panel for this refrigerator and just use common
sense about managing the battery. It draws about 35AMP if I recall
correctly. I think the relay and oil pressure switch are silly. After
all, it is a _sail_ boat.I also have a SensiStat on the system (which I invented and first tested
on my boat). It automatically tops up the plates when the engine is
running which saves on the running time you might have just to charge
the batteries because the refrigeration compressor ran while the engine
did not. It also provides a much higher (precision) degree of control
compared to the mechanical thermostat. Also provides a digital display
of the actual temperature in the box. The newest version of the
SensiStat also has an over-temperature alarm built-in.Pete
On 5/23/2010 5:29 PM, Linus Martinez wrote:
Guys
I have the old Grunert 12 volt refrigeration that requires that you have shore power or the engine running to come on. When I replaced the Crow converter that served as a battery charger since 1979 I replaced it with an inverter. It makes sense to me that I should just hook the sense wires to the 110 out side of the inverter. Does anyone have experience with this style of hook up?
Help I need to get the beer cold!
Linus
_______________________________________________
maillist mailing listhttps://pearson424.org/mailman/listinfo/maillist_pearson424.org
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PS. I have a scan of the manual if you need it.
Pete
On 5/23/2010 5:29 PM, Linus Martinez wrote:
Guys
I have the old Grunert 12 volt refrigeration that requires that you have shore power or the engine running to come on. When I replaced the Crow converter that served as a battery charger since 1979 I replaced it with an inverter. It makes sense to me that I should just hook the sense wires to the 110 out side of the inverter. Does anyone have experience with this style of hook up?
Help I need to get the beer cold!
Linus
_______________________________________________
maillist mailing listhttps://pearson424.org/mailman/listinfo/maillist_pearson424.org
_______________________________________________
maillist mailing listhttps://pearson424.org/mailman/listinfo/maillist_pearson424.org
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Joe:
Like everything on a boat, that “depends”. You have to get the 50-150 amp-hrs of energy for refrigeration from somewhere. If right now you need to run your engine an hour a day to charge the batteries, you can run your 110v system through an inverter at the same time for “free”. You can also run it dockside. If you were to get a Honda 2000, you may be able to both charge the batteries and run the 110V system at the same time, or at least once the initial charging is finished.
If you put in a 12v system, you will still need to get the energy into the system. If you added a couple hundred watts of solar at the same time, you may be in pretty good shape.
It all comes down to the energy budget for the boat and how you plan to meet it.
What size of compressor is the 110v system?
Paul
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Lets say that your alternator can put out 150A. One might think that you could put 150AH into your battery by running your engine for one hour. It doesn’t work that way. Your batteries won’t accept a charge at that rate. Even with the best smart regulator and a huge alternator you’ll be lucky to get an average of 50AH into your battery bank assuming that your bank is a typical size. So what can you do with that extra 100A that your alternator could provide that’s not going into your batteries? Run a 115v compressor through your inverter of course! That’s not going to take all of that extra alternator capacity but it will use some of it. I have an engine-driven system so that extra alternator capacity doesn’t go anywhere unless I run the microwave.
I would think that a 115v holding-plate system would have the best of both worlds. I’ve never had the opportunity to compare it with my system but on paper it should work. It might take more running time than an engine-driven system but would eliminate the rubber hoses and engine-mounted compressor which are maintenance items. It could also work off a generator or shore power.
My engine-driven system still consumes about 15A DC when running. This is what the water pump and clutch consume. I’d like to replace the water pump with something smaller. The original pump died many years ago and I replaced it with a big washdown pump. That’s all I could find.
Regards
Rich
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My previous cruising sailboat had what I consider the ideal fridge set-up, a
single-plate Grunert holdover system powered by a big 12V compressor. The
engine-is-running sensor was disconnected so the unit came on whenever I
turned it on, or else automatically if I left it on and the box temp rose
above some set number. Of course, I had a hefty battery bank, too. To
generate the daily 80-100 amp hours the Grunert required I employed a
variety of recharging systems – wind, solar, a big alternator on the engine
and another on a separate 4 HP Yanmar that could (like Pete’s system) also
be used to refill SCUBA tanks and/or whatever. Often while sailing, and
sometimes at anchor in the trade winds, the wind generator alone kept the
batteries charged enough to feed the fridge, lights, nighttime radar
underway, etc, etc. Re-creating that set-up on my 424 is a near-future
project.IMHO, any refrigeration system that requires a fossil-fueled engine to
operate is less than ideal, especially for liveaboard cruising.Tor
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Silver Heels, P-424 #17
http://www.silverheels.us
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From previous discussions on this subject I think most of us agree that the
most important component of the refrigeration system is the box itself. The
type of compressor is secondary. If you have a box like friends have on
their custom-built boat – the compressor comes on every two days in the
tropics to maintain the freezer at 0F – it really doesn’t matter what type
of compressor is driving the system. However most of us are living with a
box somewhere between mine (original Pearson) or one to which additional
insulation has been added. In my case I have to run either my engine drive
or AC (via the shore power or generator) compressor twice a day. I think
those who have upgraded their boxes can probably get by with once a day. My
system works fine dockside or on a passage, but sucks when anchored for an
extended period. Running the engine or generator twice a day keeps me from
spending extended time ashore unless I put into a marina. Also both of my
compressors are water cooled, which means for haulouts I have to shut down
the refrigeration. I blame my over weight condition on those “eat the
contents of the frig” days before a haulout :).
One other lesson I’ve learned – if you want to modify the box, do it before
you move onboard. Once you have set up residence on the boat, changing
anything in the galley becomes a major life style impact item.This coming winter I plan to move off the boat for a month or two and try to
do some upgrades to the frig and a few other items. Making major changes to
the box may not be on the project list. I have the original L-Galley
configuration with the box outboard of the sink and about 1/2 the size of
the box in the U-Galleys. So adding insulation to the inside of the box
will cut down on the volume significantly. Of course a smaller box might
solve my overweight issues, but I’m too old to make those kind of life-style
changes.So my frig upgrade may be adding an air-cooled 12v compressor (I’ve worked
out a solution with SeaFrost) and a wind generator. I don’t think I can add
sufficient solar panels to a 424 Ketch to get enough energy to maintain my
freezer at 25F and still not still have to run the engine or generator twice
a day. A wind generator on the mizzen mast might allow me to get it down to
once a day or maybe skip a day on occasion.On Mon, May 24, 2010 at 4:15 PM, wrote:
Quote:Lets say that your alternator can put out 150A. One might think that you
could put 150AH into your battery by running your engine for one hour. It
doesn’t work that way. Your batteries won’t accept a charge at that rate.
Even with the best smart regulator and a huge alternator you’ll be lucky to
get an average of 50AH into your battery bank assuming that your bank is a
typical size. So what can you do with that extra 100A that your alternator
could provide that’s not going into your batteries? Run a 115v compressor
through your inverter of course! That’s not going to take all of that extra
alternator capacity but it will use some of it. I have an engine-driven
system so that extra alternator capacity doesn’t go anywhere unless I run
the microwave.I would think that a 115v holding-plate system would have the best of both
worlds. I’ve never had the opportunity to compare it with my system but on
paper it should work. It might take more running time than an engine-driven
system but would eliminate the rubber hoses and engine-mounted compressor
which are maintenance items. It could also work off a generator or shore
power.My engine-driven system still consumes about 15A DC when running. This is
what the water pump and clutch consume. I’d like to replace the water pump
with something smaller. The original pump died many years ago and I replaced
it with a big washdown pump. That’s all I could find.Regards
Rich
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John,
You’re absolutely right that “the most important component of the
refrigeration system is the box itself.” Pearson built these boats as New
England weekenders, not tropical liveaboard cruisers. Now it’s up to us to
make them into what we want them to be. I have the L-galley, too. Even with
the considerable insulation I added last summer (and WOW, what a difference
THAT made!), I still only really fill the box with food when provisioning
for a long offshore passage, with crew. The rest of the time, when I’m
hanging out in islands where I can go grocery shopping once a week, it’s
half empty all the time. This does not include sectioning off a large
freezer compartment – when I eventually do that it’ll be just big enough.
Also, my boat is provisioned with dry goods enough to last a year, and mung
& alfalfa sprouts for fresh greens no matter what, so there’s no
malnutrition here. Trust me, the box is still plenty big enough after
re-insulating. Doing it is a bitch, but it’s the necessary foundation for
everything else that follows.Incidentally, I was living aboard at anchor when I did the fridge
insulation. I borrowed a big Igloo cooler and bought block ice every other
day from the local fuel dock to keep things reasonably civilized during the
project. It worked out just fine.Tor
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Silver Heels, P-424 #17
http://www.silverheels.us
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Agreed re fossil fuels…
I think of the engine refrigeration system as 1) my backup and 2) great
for when the engine is running.Pete
On 5/24/2010 3:06 PM, Silver Heels wrote:
Quote:My previous cruising sailboat had what I consider the ideal fridge set-up, a
single-plate Grunert holdover system powered by a big 12V compressor. The
engine-is-running sensor was disconnected so the unit came on whenever I
turned it on, or else automatically if I left it on and the box temp rose
above some set number. Of course, I had a hefty battery bank, too. To
generate the daily 80-100 amp hours the Grunert required I employed a
variety of recharging systems – wind, solar, a big alternator on the engine
and another on a separate 4 HP Yanmar that could (like Pete’s system) also
be used to refill SCUBA tanks and/or whatever. Often while sailing, and
sometimes at anchor in the trade winds, the wind generator alone kept the
batteries charged enough to feed the fridge, lights, nighttime radar
underway, etc, etc. Re-creating that set-up on my 424 is a near-future
project.IMHO, any refrigeration system that requires a fossil-fueled engine to
operate is less than ideal, especially for liveaboard cruising.Tor
~~~~~~~~~~~~~~~~~~~~~~~
Silver Heels, P-424 #17
http://www.silverheels.us
~~~~~~~~~~~~~~~~~~Quote:
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Linus
If your inverter comes on automatically when your engine starts, just
running the 115v relay should work.Something doesn’t sound right. Your batteries are charging whenever you
have shore power or whenever your alternator is running. Running the
inverter to actuate the 115v relay should work, but I bet there’s a pressure
switch on your mother that’s supposed to close the solenoid switch too.
Maybe the switch is bad or there’s a loose wire.I have a copy of the Dashew’s book here on the shelf. The 12v system with
holding-plates is what they recommend. I would guess that a 1/2hp 12v motor
must be pretty big and probably a maintenance item. I’d rather have a 115v
motor and run it off an inverter, but AC motors can be hard to start off an
inverter.Rich
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I figured that typo out but Mom does have a pressure switch. I don’t trip
it now as much as I used to but I know that it’s there.
I am still finishing up the repower that is why the switch is not on the
engine. I have been doing without refrigeration but now I would like to
hook it back up. I thank everyone for the input. It seems to me that I can
just put a manual switch in where the pressure switch was and do away with
the AC sensor. I will have to adapt my battery management to be more
vigilant once the refrigeration is running. I do have a Honda for times
when I am at anchor which is not all that often yet. I’m hoping to get a
few weekends in this summer at least, but I’m never that far from a bag of
ice.Thanks
Linus
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Pete
Do you have any photos of your sensistat install. Where did you mount the
panel? I downloaded the manual from the Sailors Solution web site and now
this looks like a product that will do what the original installation was
trying to do.Linus
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I mounted it in the panel forward of the sliding doors in the galley.
On 5/26/2010 1:49 PM, Linus Martinez wrote:
Quote:PeteDo you have any photos of your sensistat install. Where did you mount
the panel? I downloaded the manual from the Sailors Solution web site
and now this looks like a product that will do what the original
installation was trying to do.Linus
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