| Author |
Message |
Gary Stadler (Boogiethecat)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 30, 2005 - 4:34 pm: | |
My question comes because while I'm on the road or in the boonies, the propane powered fridge I have does just fine. BUT there are many times when I park for a while and would love to not hassle with leveling the bus, and also would like to have a lot more cooling capacity, especially when I park for a while in really hot locations that have shore power avaliable... the adsorption fridge just doesn't cut it as well as I'd like.
I've double insulated the fridge walls and that helped, but it's simply that the cooling capacity of the adsorption unit isn't enough in a really hot environment.
So I'm seriously thinking of adding a small 110 volt compressor and all the associated "stuff" to my propane fridge, to turn it into an "either/or" kind of setting. Basically I'd probably just buy a little bar fridge, take it apart and cram all the parts into my current propane fridge.
Best of both worlds although a lot of fussing around to get it there.
Since I find that things that occur to me have quite often occured to industry already, I thought I'd ask if anyone knows of a commercial unit made like this... two totally separate cooling systems built into the same fridge...???
No, I don't want to use the 110 capability that my fridge already has. It's the cooling capacity and levelling stuff I want to get around, not the ability to hook to 110. Using "only" a compressor style fridge is out of the picture for me, because
I don't have/don't want an inverter big enough to run it while on the road, and there are a lot of places I camp where propane power does just fine, while figuring how to power a compressor for that long would be a nightmare.... |
Jerry Liebler (Jerry_liebler)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 30, 2005 - 7:21 pm: | |
Gary,
I sure understand the refrigerator delima. The typical 120 volt small refrigerator has pretty poor energy efficiency. However the 12/24 volt units that use the Danfoss compressor are 2 or 3 times better and don't require an inverter, just enough battery capacity. I'm going to go with a 12 volt unit from http://www.3rivers.net/~cmac/cmac2.htm.
They have features like 'push buton defrost' to add convinience while staying energy efficient. From talking to them I've learned that a single door refrigerator is the most energy frugal. I figure I can last 4 days just running the refrigerator on my 4 ea L16 batterys.
If you add a compressor there are kits of components that use the Danfoss compressor.
Regards
Jerry 4107 1120 |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 30, 2005 - 7:23 pm: | |
It's almost easier to manufacture a leveling system just for the
fridge. With most, you just have to insure it's level from side
to side, not as much front to back... The general rule-of-piggy
is - if you feel comfortable walking front to rear, it's level enough...
I think you'd be more hard pressed than the ammonia, if you
tried using a compressor with it. The ammonia solution was
designed to be distilled, unlike the freon types that are designed
to be compressed.
That aside, some other options?
http://www.e-marine-inc.com/products/refrigeration/cruise.html
http://www.thenaturalhome.com/servel400.htm |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 30, 2005 - 7:37 pm: | |
Oh--- oops.
Man, I just gotta' learn to read..
You said:
"a little bar fridge, take it apart and cram all the parts into
my current propane fridge..../... two totally separate cooling
systems built into the same fridge.."
(And for some reason ...... aarrgghh ...duh)
Yeah, why not? Two systems? Pop some holes and install
the cooling fins inside, pipe it to where the rest of the parts
are, and away you go. When the thermostat setting is reached,
one (or both) will turn off. Not a bad idea at all. In fact, with
some clean engineering and aesthetic manipulation, it'd be
saleable.
('scuze me, I gotta' make a few call$) |
Geoff (Geoff)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 30, 2005 - 8:02 pm: | |
Humm, I run my 120v apartment refer off the inverter and 4ea Grp 31 batteries for 4 days without spending mega-bucks for a 12v unit. |
bobm
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 30, 2005 - 9:36 pm: | |
I run refrigerant through a coil inside a tank of antifreeze-water mix. tank holds about four gallons and fills about a third of the freezer unit in my house style side by side refrigerator freezer. once frozen solid, about -4 degrees, it will keep my unit cold for three days. I use a small 12 volt fan to circulate air from the freezer side to the refer side with a thermostat set at 40 degrees. I freeze the tank by running the unit on 110 or by circulating the bus a/c refrigerant through the unit while driving. served me well for several years. my generator engine also runs the refrigerant compressor |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 30, 2005 - 9:41 pm: | |
bobm-
That is absolutely awesome! Could you post some pictures and
some detailed directions? |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 30, 2005 - 10:11 pm: | |
This is a clever adaptation of the somewhat more efficient holddown plates developed and used for just this purpose.
Different formula/design for regular vs. freezer sections or applications
They generally get better results from a brine mixture.
Dave Smead discusses them at length in his 12V Books.
If space is critical (not so with a side by side house unit) a regular holddown plate may be worth the expense.
Onward and Upward |
James Maxwell (Jmaxwell)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 30, 2005 - 11:42 pm: | |
Like Geoff, an 11.8 GE pulls 112 watts, costs $300. 11.6 listed, 69 watts, $1370----500% more costs to save 39% in energy----abt. as good a bargain as solar power! |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 31, 2005 - 5:14 am: | |
"Like Geoff, an 11.8 GE pulls 112 watts, costs $300. 11.6 listed, 69 watts, $1370----"
WAtts missing here is the RUN TIME of the different units.
And missing is the system efficency while running.
The fine big buck DC units sense how long the unit ran to reach cut out , and if it was "too quick" , will operate the compressor motor at a lower (more efficent Btu removal per watt).
These DC units WANT to run almost 24 hours a day , as with the speed under controll this uses the LEAST amps per btu , daily.
There a efficent 12/24 volt units made to retrofit into a boats ice box,some of which include a good sized eutetic plate.
Check out Adler Barbour for "cold machine" or sinilar.
Also go to Glacier Bay for a good tutorial on low energy cooling.
"Humm, I run my 120v apartment refer off the inverter and 4ea Grp 31 batteries for 4 days without spending mega-bucks for a 12v unit."
And this includes HOW MANY hours of noisemaker time per day?
FAST FRED |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 31, 2005 - 7:55 am: | |
Fast Fred: That is really great information about running the compressor slower on the DC units. The A/C gurus tell us that the condenser, evaporator and expansion valve have to closely matched to work properly and give good effieciency.
Do you know how they compensate for the reduced compressor output? This opens up a whole new area to explore for bus A/C systems. Maybe running an electric motor on the bus 10 ton unit at reduced speed could provide 2 or 3 tons efficiently. |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 31, 2005 - 9:11 am: | |
hmm..
http://www.rifledair.com/old/about11.htm
http://www.crtech.com/docs/papers/C599-061.pdf
and
http://www.crtech.com/docs/papers/vtms2001.pdf
What it says, is that air conditioning is a bit more complicated,
than to just simply run a compressor slower to get less cooling.
There's evaporator fan speed, condenser fan speed, etc, that
all must be adjusted for a difference in compressor speed, and
vice-versa.
If you've never had a roof-top AC unit freeze up and cease
to work, you don't know what you're missing... like the
water cascading out your door when it finally melts...
I enjoy reading of all the efforts to quickly re-design something
that took engineers and manufacturers years and piles of cash
to design. It's great for all of us, when the feat's accomplished
and the information is provided to us.
But man..... I just want to build an RV out of a bus body as
quick as I can (preferably before the hurricanes hit)(again),
and as inexpensively as I can.
By the time these major re-designs are worked out, the price
to do it is near staggering, compared to using products that
have already been designed and sold commercially for years.
In the time spent to make a better mousetrap, the mouse has
eaten, moved on, and probably left behind a few thousand kids.
Used, broken rooftop AC units and mobile home AC units
are a dime a dozen. I'd rather see some information on how to
fix and modify units for mobile use. |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 31, 2005 - 9:50 am: | |
My Gosh, Are we finally getting both pragmatic and practical?
(JTNG, just to make a point "at large", no slight intended, nice job, wish I was so eloquent!) |
James Maxwell (Jmaxwell)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 31, 2005 - 10:49 am: | |
I don't argue w/the efficiency factor of some of these units; it certainly exceeds that of high production household models in most cases, but not all. My point is the ECONOMIC and UTILITY "efficiency". The total cubic space of these units far exceeds that of comparable inside cabinet space of household types, not to mention the inside designs and space utilization are generally poor in comparison. And, it's a waste of time to do price comparisons.
The GE runs btwn. 15 and 25 minutes of the hour, depending on the ambient temp. and loading within the refer. Sanyo makes a comparable unit that is slightly more efficient. Both of them are priced at nearly $1k less than any of the corporate designated "efficiency" models. |
Gary Stadler (Boogiethecat)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 31, 2005 - 10:52 am: | |
Funny how the thread gets so far off topic from the original question...
...So from what I read above, I guess my thought of ripping up a little under-the-counter fridge and stuffing the parts into my 2-way is the way to go.
If I do it, I'll report in. I probably will. |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 31, 2005 - 5:18 pm: | |
Gary-
Yeah man, why not? There's no reason it won't work. It sounds
like a helluvan easy was to get the redundancy you desire. And
bobm's way sounds interesting also...
Easy and cheap is always good. |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 01, 2005 - 5:28 am: | |
May have located a simple solution (not a Cheap solution) for ya,
Defender industries 1-800-628-8225 shows a Waeco "do it yourself " kit.
This is a quality Danfoss DB35F DC air cooled package that installs thru a hole cut in the side of the box,9Dx10Wx14H.
Its designed as a retrofit for boats that only had iceboxes , but should suppliment the propane unit for quicker freezdown.
item 401988 model CS-CN-15 $529.
For a TEC camper this unit with a good homebuilt box ,
4 inch sheet freon blown urathane and good door and seals should be as good as the Sun Frost , which are the off grid Standard , but HUGE for a coach.
May work for you,
FAST FRED |
Gary Stadler (Boogiethecat)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 01, 2005 - 1:59 pm: | |
Very cute item!
http://www.defender.com/ProductDisplay?id=323775
This would certainly work, although you're giving the boat store half of what it's worth, and it's a bit big sticking out the side of the fridge. But basically the right idea.
I still think I'll just get a little fridge at a second hand place for $30, take it apart and rebuild it's guts into my fridge. I have all the reefer equip and some freon left over from the old days, so it should be simple...
Thanks Fred!!
Gary |
Bill Endres
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 02, 2005 - 2:16 am: | |
Gary: They make a temp controlled 12V fan that mounts up on top by the roof vent it really helps the air flow over the condenser coils, on at 110 off at 90 Deg. W/On/Off sw. Propane refrigs need a lot of cooling especially 90 Deg. days, they struggle to maintain 40 Deg. internally.
Bill ragingbull@wcoil.com |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 02, 2005 - 6:04 am: | |
Bill has the right idea , most hassles with propan fridges I have seen were from NOT following the instalation instructions to the "T".
Cooling iseldom a problem if the unit vents properly, with the proper vent cap etc.
The 12V helper fan does work , (good place for tiny solar cell) but proper instalation works even better.
Fridges made before thew 1980 era have to be near level, after that they just burn more gas if off level.
If you can stay in bed , its level enough.
FAST FRED |