| Author | Message | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Hi all, I'm about to get a refrigerator and I'd like your thoughts. My bus will be used by my wife and I for travel with some boondocking, mostly overnight at Walmarts, but ocasionally for a week or so (like at a rally or EAA convention), far from full timing. I detest absorbtion refrigerators so I'm opting for a 12 volt DC unit. I have 780 amp hours of battery so I can use about 390. I'm leaning toward a 4.6 cu ft. Marine unit that's rated to use 1.2 amps average. This would give me 13+ days of refrigeration if that was the only power used. I like the size of this unit as I can put the microwave above it and raise it 22" off the floor for less bending & more cupboards. But is 4.6 cu ft enough? I'm scrambling to fit as much as I can in 35 foot of bus. Regards Jerry 4107 1120 | ||
| H3-40 Rating: N/A |
Jerry, we are doing our kitchen now and we thought about putting our convection oven over the fridge too but after talking to some friends, they made a good point that once it is above the fridge, you can't really see in it and when removing hot foods they could actually spil on you and cause harm. Just keep this in mind as you plan your kitchen! Ace | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Ace, Thanks for the caution but. Aparently you have a lot more head room than I do. Where my microwave will be (bottom is 55" above the floor) is almost exactly at eye level and BTW almost exactly the same height from the floor as the one over the stove in our house. Regards Jerry 4107 1120 | ||
| H3-40 Rating: N/A |
Jerry, sorry I forgot the 4107 is a little lower than our H3 and I even had one once! How soon you forget!  Ace | ||
| David Hartley (Drdave)
Rating: N/A |
The new Norcolds and Dometics are available with the 12 volt compressor systems. So unless you have a serious size/space limitation one of the new units would work great. They are expensive but available in most capacities up to or above 10 cu/ft. Marine stuff is way over priced in most cases. | ||
| gabby
Rating: N/A |
If you have a generator or solar you can put in a regular 120 volt frig. I have a 15 cu foot frig and solar panels. If it is cloudy and I dont get enough solar I use a 1k watt generator to run the thing and the TV. Power consumption of the frig is 345 KW a year or less than 1 kw a day. We have had it in for 2 years and no problems. Cost about $300.00 | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
David, The Norcold DE0061 could fit but it's bottom would be about 3" above my floor. It is 7.0 cu. ft. but it uses 3.2 amps average. If I can live with 4.6 cu ft it's like I have 2.66 times the battery life. The advantage of the marine units is they have more insulation and use less power, for example an 8 cu ft marine unit is rated at 2.5 amps avg vs 3.2 for the Norcold 7 cu ft. For even better energy frugality I'm planning to add 1" (r7) of urethane foam on 5 sides of the box. Believe it or not the prices are actually very close. Regards Jerry 4107 1120 | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Gabby, What I'm looking at is about 126KWh/ year and you'd need to factor in inverter efeiiency, less than 90% to properly compare. 345/0.9= 383 so you do use less power per cu. ft.(by about 7 %) and your's is certainly a lower cost option. But do I really need all that refrigerator? I know I'll use the extra cupboard space. Regards Jerry 4107 1120 | ||
| Ron Frazier (Ron_4104)
Rating: N/A |
Jerry, You did not mention what brand name you are looking at or pricing. You mention the marine unit has more insulation. Would this be the tundra compressor type? I have a ac-dc norcold that is old enough that there's no parts available, so if something goes it's either jury rig or replace. If I replace it will be compressor. We live about 4 or 5 months in our bus each year and I would hate to get along with much less than our current size which is about 8 cubic feet.I don"t care for the absorption type either, but some do, hence they make both kinds and both seem to do the same thing. | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Ron, Tundra is very similar but I am actually looking at an Isotherm CR130. I had an 8 or so cu. ft. absorbtion unit in a stick and staple and it sure was almost always less than 1/2 full even on our longest trip which lasted over 3 weeks. But If the temperature outside was 90 about the best it would do is 45 inside and even parking for 30 minutes, at a rest stop, without leveling would raise the interior temperature and that was after I added a 12 volt fan to boost the airflow over the condensor. Regards Jerry 4107 1120 | ||
| John MC9 Rating: N/A |
There is absolutely nothing in it's size class (7-9cf) that is more economical, than an absorption type refrigerator running on propane. And I can't imagine any serious boondocker (full-timer or not) getting by with a freezer/fridge smaller than 7cf (I know we couldn't). Battery banks are great, as well as inverters, to provide 110v (or 12v) to electric powered refrigerators. But along with the battery bank, comes the cost of the batteries and the cost of the electronics to maintain them. With propane, all you do is keep propane in the tank. When you want refrigeration, turn it on; there's nothing more efficient. Used/reconditioned 7-9 cf units are available at the right price, if you shop around. | ||
| FAST FRED Rating: N/A |
Check on the Glacier Bay website, for the latest in high efficency. Most of the really smart DC compressor stuff will cost about as much as the propane units, in other words a week of quiet camping with cold beer & ice cream will always be a $1000. The problem with a long stay like at Sun & Fun is the bat-set will be "Almost" fully to the 50% empty point for days. That's Sulfation territory. Of course you could pull out from the Quiet Zone over to the empty treeless field ,"Death Valley" and run the noisemaker all night one time. Other choice would be a drive , with the coach 200A+ alt and a smart regulator , for a bunch of hours. Solar refills are usyally out as the early birds get to be under the trees, rather than basting in the sun. Any box can be made more efficent with more insulation glued on , but the Sunfrost has good insulation 4 inches thick from the factory. Its only a bit more pricy . FAST FRED | ||
| Don/TX
Rating: N/A |
I am a proponent of the household refrigerators, but for the EAA convention, I cannot imagine getting by with anything other than a propane fridge. I had a three way fridge there this year, and anything other than propane would have been a worthless drill. | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
I just may change my mind and go with a household unit now that I found one that's pretty energy frugal. The particular unit is a Summit CM 117. It is 8.8 cu ft. , uses 230 kwh/year and is 56 3/4 tall so I can still put my microwave over it. It will save a bit of money too as I can get it delivered for $420. With an added inch of r7 foam on 5 sides I might get 10 days & , if I got ambitious, for another $400-500 I could swap the compressor for a Danfoss BD50f which would eliminate the inverter's losses and just may even use less energy. Regards Jerry 4107 1120 | ||
| FAST FRED Rating: N/A |
By dividing 230W by 365 you will get the watts used per day. At 90% efficency for a good inverter you can then figgure the endurance, to 50% discharged house batts. FAST FRED | ||
| Art Gill (Sandcastle)
Rating: N/A |
Jerry, if you use a 120v frig, you may want to consider one that has the freezer inside the refrigerator door. They don't use a fan to move the cold air from the freezer to the refrigerator and you can save on the energy. Also, these are on the low end of refrigerators the idea of adding insulation may also be a energy saver. Art Eagle 20 NJT | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Art, I've used this data to make my selection. http://www.ftc.gov/bcp/conline/edcams/eande/appliances/fridge.htm I've settled on the Avanti 651 because of it's freezer size and energy use, 254kwh/yr. Ill add 1" of urethane foam under it, on the sides and over it and possibly on the back if the condensor coils can be moved. I rejected the larger Avanti RM901 (230kwh/yr) because it really doesn't have a freezer section and I eat mostly frozen vegetables. I frankly doubt that the marine units are any better and the added insulation should make up for the inverter losses and hopefully even more. Ignoring the added insulation and using 90% for the inverter efficiency I come up with 32.2 watts for the refrigerator or about 6 days to use 1/2 the rated capacity of my battery bank. Regards Jerry 4107 1120 | ||
| FAST FRED Rating: N/A |
"I frankly doubt that the marine units are any better " Glacier bay and others that Mfg modern DC equippment claim different. The newest DC stuff pulses the juice just enough so the unit uses the Least amount of current , and learns the boxes requirements as it works,gaining Efficency in time. The house stuff is single speed with no brain. Cost in electric? up to 50% less for the modern DC units. Weather it pay$ is up to you & your battset FAST FRED | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Fred, Take a look at the Isotherm CR220, which uses the Danfoss BD50 with compressor speed control, and compare it to the Avanti 651wt1. They are very similar in size with the Avanti,single speed no brain, being ever so slighty larger. Isotherm uses 2.5A @ 12 volts or 720 wh/day while the Avanti uses 696wh/day. The price difference $1495 vs $259 almost pays for the inverter. In some cases 'throttling' actually lowers efficiency. I once won an 'economy run' in a VW by holding the pedal on the floor and in 4th gear acelerating from 20 to 55 then coasting, with the engine off, in neutral till I got down to 20 again & repeating. I averaged over 100 mpg for the 100 mile course. Regards Jerry 4107 1120 | ||
| FAST FRED Rating: N/A |
"In some cases 'throttling' actually lowers efficiency." However it does not in refrigeration as the limit is frequently how fast the heat can travel thru ice (your frozen food) to get to be removed. Unfortunatly ICE is an insulator. If only a few hundred BTU can be coaxed out of a cool box , its a waste to provide more cooling. Also the newer breed of DC units with controlled pulsing will spin slower and "softer" when less than max cooling are required. Most off grid folks and sailors figure a 5X saving on every amp thats not required to be made , stored in a batt , used and resupplied. MAX Amps when operating can not be compared as the cycle time , as well as amps used will vary considerably with each box. FAST FRED | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Fred, As a thought experiment let's say the refrigerator is empty and the doors have been closed for several days. The compressor will still be cycling every so often. A watt hour meter in the power supply to the refrigerator will record more watts/hour while the compressor runs and much less when it's not running (the Danfoss system uses over a watt when the motor is not running). If we read the watt hour meter at the same time each day the difference in those readings will be the watt hours/day. If we divide watt hours/day by 24 hours/day we will have average watts used to remove the heat that crept in, through the insulation and air exchange through leaky door seals. To reduce the watts we have but two choices: 1. reduce the heat flowing in (more or better insulation and/or better sealing of the door) 2. find a more efficient way of removing the heat. After observing what looks like a very similar amount of insulation in comparable sized refrigerators from Indotherm and Avanti I seriously doubt that the Danfoss compressor system is even 10% more efficient. The $1000+ price difference buys a lot of insulation or even batterys. | ||
| FAST FRED Rating: N/A |
" or even batterys." No question but the noisemaker time it takes to properly refill a bboat att set is HUGE! Most offshore folks with DC fridges accept the problem and simply cycle the battset between 80% full and 50%. Which is what many folks do (unintentionally)with a short 3 or 4 hours of noisemaker recharge a day Of course this reduces the batt life and capacity a great deal , but the cost of full batt replacement is still FAR less than the engine time to actually refill the house set , even with 4 stage regulation and a huge alternator. Different methods will still get to the same goal, at different costs in noise or dollars. Cold BEER & frozen Ice-cream!! FAST FRED | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Fred, I'm going to try to quantify, by experiment, the improvement in energy use of the refrigerator I just bought. Toward that end I just splurged and bought a cute little watt hour meter from Backwoodssolar. Here is the experiment. In my heated basement where the temperature stays right at 65 f. I'll set up the refrigerator as received and run it with the door closed for a day then record the kwh used over the next 24 hours. Then I'll add the insulation and run the same test on it with insulation. My insulation plan is for 1 1/2" on the sides and back (if I can space the condensor coils out an additional 1 1/2"), 3" on top (where the freezer is) and whatever I can fit on the bottom. The insulation I'll use is in 1/2' sheets and is rated at r7/inch. The data from the before test will tell if the manufacturer was honest or not. Regards Jerry 4107 1120 | ||
| FAST FRED Rating: N/A |
However refrigeration service is different in the real world , where folks open the door a couple of dozen times a day , and frequently place warm items in the box. Your test will tell if extra insulation helps (it should), but tell little of the overall efficency of a dumb cheap compressor compared to a smart super efficent modern DC system. FAST FRED | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Fred, If you want to supply the Danfoss compressor I'll install it and run the same test with it. The Danfoss peaks at an EER of 2(metric units). It is no longer legal to sell air conditioners that have such a poor EER, today's minimum is about 3 (metric units). While small compressors are usually less efficient, there are many air conditioners sold today that are TWICE as efficient as the Danfoss. It is very likely that a 120 volt energy star refrigerator has a more efficient compressor than the Danfoss. In fact I have a heat pump that moves 10,000 BTU/h by using 620 watts, that is an EER of 4.65 (metric) but, regretably, it uses r22 and that won't get cold enough. It is very likely that the Japanese at the likes of Matsushita or Sanyo have figured out how to build a better r 134a compressor than the ten year old Danish design. Regards Jerry 4107 1120 | ||
| John MC9 Rating: N/A |
"It is no longer legal to sell air conditioners that have such a poor EER" Say what? What's that, some new Kalifornia legislation? | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
John, No! it's a Federal requirement, an outgrowth of our last 'energy crisis'. Minimum EER, for residential air conditioners, depend on size and application, generally ranging upward from 10BTU/h/watt(US units) but all are above the 7 (US units) that Danfoss gets, at it's best. Unfortunately RV air conditioners, I believe, are exempt which is why the roof warts are at about 9 but still above the Danfoss. Regards Jerry 4107 1120 | ||
| John MC9 Rating: N/A |
Jerry - Holy schumtzville. I turn my back for a few years, and bingo, more gubberment intrusion: --------------------------------------------------- In 1992 Congress established a federal standard EER of 8.9 for air-conditioners. In November 2004, ANSI member the Air-Conditioning and Refrigeration Institute (ARI) and the American Council for an Energy-Efficient Economy (ACEEE) signed a consensus agreement on air-conditioner efficiency standards that calls for the most common type of equipment to use an EER of 11.2 as of January 1, 2010. The U.S. Department of Energy (DOE) recently announced the enforcement of a 13 SEER standard for residential central air conditioners. This standard, which will take effect in January 2006, increases the SEER standard that applies to current models by 30 percent. The widespread usage of SEER 13 or higher air-conditioners will also contribute to lower peak electricity demand during the summer months, which can represent as much as 70% of peak demand in some states. http://www.ansi.org/news_publications/media_tips/A_C_standards.aspx?menuid=7 ---------------------------------------------------- And as I follow the $$$ trail: http://www.taxalmanac.org/index.php/Sec._25C._Nonbusiness_Energy_Property Oh well. We mind as well be taking orders from a Queen. | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
"Fred, If you want to supply the Danfoss compressor I'll install it and run the same test with it." Holy simolie, sounds like another 2D offer. LOL Richard | ||
| FAST FRED Rating: N/A |
The Danfloss is now 2 or 3 generstions out of date , although still a price leader. The newer stuff from Glacier Bay is in a different leage. FAST FRED The Micro HPStm (Hybrid Plate System) represents an entirely new kind of marine refrigeration system. The most significant advancement in marine refrigeration technology in the past 30 years, and winner of the 2003 NMMA Innovation Award, the Micro HPS blurs the line between small, hermetically sealed DC constant-cycle units and large, high-powered DC holding plate systems. The result is a clean, compact, reliable system of unprecedented power and performance. Here are just a few of the Micro HPS unique features and advantages: ► Powerful - Masterflux® rolling piston compressor give 7x more cooling power than any other hermetically sealed DC compressor. Cool your refrigerator, freezer and even air condition all with only one Micro HPS condensing unit. ► Efficient - The first 100% hermetically sealed system to offer the energy efficiency of Glacier Bay's large, open-shaft compressor systems. ► Quiet - Engineered for silence. Unique, glass-filled panels absorb radiated compressor noise while a floating rubber-mounted base isolates vibration through the mounts. ► Compact - At only 12" deep, 13" wide and 9" high there has never been a refrigeration system this powerful and this small. ► Lightweight - The fully charged condensing unit weighs in at under 38 lbs (17 kg), less than 1/2 the weight of other systems of similar cooling capacity. ► Reliable - From the brushless DC compressor to the integrated suction accumulator to the 31 tube cupro-nickel heat exchanger, the Micro HPS may well outlast your boat. ► Arctic Airtm compatible - Run a 6,000 BTU/Hr air conditioning "zone" directly from your refrigeration system with Glacier Bay's patented Arctic Air option. ► OSSA Powerlite® compatible - High voltage versions are available for integration into Glacier Bay's revolutionary integrated lightweight power system. One look at the new Micro HPS tells you that it is like no other refrigeration system in the world. The clean lines and electro-polished stainless steel illustrate the quality and attention to detail which has become the hallmark of Glacier Bay products throughout the world. However, as you might expect, the beauty is more that skin deep. To really see the Micro HPS shine you need to turn it on. The heart of the system is a Masterflux brushless DC rolling piston compressor. This quiet and highly efficient compressor was developed by Glacier Bay and is now produced by the Masterflux division of Tecumseh Products Corporation, the world's largest compressor manufacturer. Weighting less than 12 lbs, the compressor is 100% hermetically sealed and has 7x the refrigerating capacity of other DC compressors. The Masterflux compressor is just one of the technologies that give the Micro HPS an unbeatable edge over the competition. Gone are the days when you have to compromise on size, weight and noise to gain power and efficiency. With the Microtm HPS you get it all - tiny size, light weight and super quiet operation. These breakthroughs don't come by assembling standard off-the-shelf refrigeration components. The Micro HPS is chock full of technological advancements you'll find no where else. FF |