Thoughts on system

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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #32
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    Re: Thoughts on system

    A rinnai/paloma/takagi demand water heater can be installed in a closet.
    They take up very little space. The caveat is that you have to use a direct vent system, drawing air from outside,,, venting it out either the roof or the side wall. There may be an issue with the gas appliance in a sleeping room closet,,, but that is usually an issue of O2 depletion,, not an issue with direct vent combustion air.

    The outdoor units are fine too, but not for use in any climate that has the threat of freezing. The real answer is a simple solar system,,, either evacuated tube, direct hot water or a closed loop system.

    T
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  • got solar
    got solar Registered Users Posts: 6 ✭
    #33
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    Re: Thoughts on system

    Thanks to all who have responded. The elec. dryer is being swapped for NG, A/C is being replaced with high efficiency unit, water heater going to NG tankless. Those three changes will drop my solar needs quite a bit. I'm also looking into a Propane Fridge. This is a great site with tons of info so I'll continue browsing for ideas.
    Thanks again
    Dave
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #34
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    Re: Thoughts on system

    FYI,

    On a per BTU basis, propane fridges are less efficient that modern energy star compressor fridge. Couple that with the added cost of a propane fridge, (and most propane fridges are quite small,,, and not very well built,, at least the full cabinet type,, danby, pioneer etc.) and I think you risk cutting off your nose to spite your face. Consider a very efficient compressor fridge instead.

    In my own case, I run propane fridges because that is what we have always done. If I got to do it over again,, I would go with a compressor fridge.

    Tony

    PS If you have natural gas available,, if you were to go with a propane fridge you would be buying propane in small quantity and not getting a good price for it. I have a memory of a natural gas fridge but I don't know of any that are readily available.
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  • lorelec
    lorelec Solar Expert Posts: 200 ✭✭
    #35
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    Re: Thoughts on system

    I've used propane fridges for the past seven years and have been very pleased with them. I have a newer Servel (made now by GE I think?) and an older Sibir that came with a place I bought a few years ago. I would like to eventually get away from propane altogether, but in my experience the reliability of the newer gas fridges can't be beat: no moving parts and no seals within the refrigerant loop. The one drawback is that they must be defrosted on a regular basis. The ice that forms on the evaporator in the back (inside) of the fridge will literally envelop and consume items that sit on the shelf if it's allowed to "grow" (for lack of a better term). Several times a year, we transfer the contents of the fridge to cooler and then wheel the fridge outside so that the ice can melt.

    Yes, they are also not nearly as large as a compressor-based fridge, but that hasn't presented any problems for me. A larger fridge, in my opinion, tends to accumulate and waste more food.

    Propane fridges can be converted to run on natural gas with re-jetting, just like other dual-gas appliances (dryers, ranges). It might require some tinkering, though, because I'm not sure if ready-made kits are available. I do believe that Servel makes their gas fridge available in both propane and natural gas varieties...or at least they used to.

    Marc
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #36
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    Re: Thoughts on system

    Marc,

    I am not dissing LP fridges,, I have been using them for more than 50 years,, I've had em all, servels, dometics, sibires, Danbys, etc.

    My point is that on a per btu basis a modern compressor fridge is more efficient. Since the OP is on grid,, it wouldn't (IMHO) to unplug an efficient fridge and turn on a LP fridge in it's place.

    LP fridges are very good at what the can do,, and do have a place. Just pay attention to the energy details.

    Tony
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  • PhilS
    PhilS Solar Expert Posts: 370 ✭✭✭
    #37
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    Re: Thoughts on system

    What Tony said X2.

    I was only on propane refrigeration for 30 years. Performance was lackluster. Periodic maintenance was a pain (cleaning burners, replacing thermocouples and ignitors, etc.). But electric friges weren't very efficient back then.

    But the BIG reason I added solar panels, bought a newer better inverter, and purchased a new efficient fridge:

    The price of propane has skyrocketed, along with other fossil fuels, and my two friges were using between $50 -$75 worth of propane per month. The early years I was spending closer to $15 per month.

    And the price is NOT going down, ever. Try to avoid tying yourself to anything that requres delivery and has an ever increasing cost.

    Phil
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #38
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    Re: Thoughts on system

    Having said all of the above,, let me add that I am engaged in an experiment to use my excess PV capacity to run the electric element on my Dometic. The theory is that when my batteries are nearly charged, the controller will shunt the excess to a dedicated msw inverter to power the fridge. It is not the most efficient way to run a ammonia absorption fridge, but at least I have that option. That heating element uses 325 watts, and on the advice of a Propane fridge expert (RVmobile in Everett WA) we are going to try to reduce that to a 225 watt element,, the size of a similar 12vdc element in a threee way fridge.

    I don't expect that it is going to be very effective,, but I am curious to see if the 225 watt element works. If it does,,, then the idea of adding a couple more Sun panels at $2.50/watt might make some sense.

    But,,, the bottom line is that if I add up all the costs,, buying the fridge(s) the panels/inverter capacity etc,, I would be way ahead if I could have bought a new energy star compressor fridge in the beginning. As with so many things,,, once you have committed to any given technology, you are in bed with it and make the compromises going forward.

    If I run my LP fridge on electricity it will use an estimated 2.6 kw/day where a new energy star will use ~.5kwh/day. That extra ~2kw/day would need ~500 watts of panel and battery,,,at a cost of ~$2,000,, including batteries. My current fridge is bought and paid for,, (and the space it uses is too small to fit a conventional fridge,,, Doh!) but for the ~ $500 it would take to buy a conventional,,, I can buy a lot of propane,,, at $.40/day,, about 3.5 years,,, not a bad pay off,,,, when you think aobut it. But since I only am home ~ 200 days/year it would be more like 6 years,,,hmmm!
    Now if my 225 watt experiment reduces the LP need to say $.30/day it takes even longer.

    Tony
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  • lorelec
    lorelec Solar Expert Posts: 200 ✭✭
    #39
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    Re: Thoughts on system

    Tony & Phil,

    I agree that from an efficiency standpoint (and also one of reliance on a fossil fuel), the propane fridges aren't the best choice. But that ultra-efficient compressor model at 500Wh per day is about equal to my total daily energy demand (from solar) right now, so in effect I would be doubling my electricity demand by adding an electric fridge. I also like the option of being able to control my energy usage; at night there are no loads on here at the house. This is especially important to me during those long, dark, snowy weeks during winter when I barely have any sun.

    So as with anything, there are compromises to be made. I would love to get away from propane, but since I have other appliances that also use it, I think I'm stuck with it for the time being. Propane has come down in price since last summer. I can get it for about $1.65/gallon undelivered right now. Last summer I paid over $4 delivered.

    Marc
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #40
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    Re: Thoughts on system

    Marc,

    You got it spot on! I use ~600wh day,, going to a compressor would double my consumption. The reality is that you're going to consume the energy one way or another. The compromise comes with how much solar we can afford, or how much LP (or other energy) we wish to buy. You are also right about sizing a system for the worst times of the day/year etc.

    Tony
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  • PhilS
    PhilS Solar Expert Posts: 370 ✭✭✭
    #41
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    Re: Thoughts on system
    icarus wrote: »
    Having said all of the above,, let me add that I am engaged in an experiment to use my excess PV capacity to run the electric element on my Dometic. The theory is that when my batteries are nearly charged, the controller will shunt the excess to a dedicated msw inverter to power the fridge. It is not the most efficient way to run a ammonia absorption fridge, but at least I have that option. That heating element uses 325 watts, and on the advice of a Propane fridge expert (RVmobile in Everett WA) we are going to try to reduce that to a 225 watt element,, the size of a similar 12vdc element in a threee way fridge. Tony

    Tony,

    My plan was EXACTLY like yours. I was working toward enough solar power so that on sunny days I could run the fridges on excess electric (two Dometics mounted together in the kitchen). Summer before last I had one of them on 115V most of the summer.

    Then I saw this at another forum I frequent (and I post with the same name):

    http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/18592867.cfm

    It references a recall by Dometic and if you have the patience to read through an 824 post thread you can learn much more. Basically the 325W electric element causes a weak spot in the tubes to split, spewing ammonia that CAN catch fire if a flame is present. Dometic's recall just consists of an extra shield around the flame, nothing about the actual defect.

    In MY situation, with two fridges.. one on electric, one on propane, if the one leaked I had the ignition source on the other. SCARED me too much! Went back to propane immediately and started planning for the electric fridge.

    By your using the smaller heater the problem could be solved. But I wanted to make sure you were aware of the situation IF you have one of the many affected Dometic models. I believe I've seen posts by RVmobile there too but I could be mistaken.

    Phil
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #42
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    Re: Thoughts on system

    Phil,

    Thanks for the link. I am pretty on top of the Dometic recall situation I run a whole series of Dometics ranging from small under the counter rigs, to older 3 ways, to two modern Rm2852's. The 2852s would be subject to the recall except one of them is too old, and the other has a replacement cooling unit so that it is not subject.

    I have never run any of my Domtics on 120vc or 12vdc for that matter.

    For those that are interested there is a very good forum for Lp fridges of all stripes,, sponsored by RVMobil in Everett WA. I think that TJ who runs the place is as good a Propane fridge guy as there is: http://rvmobile.com/wb/default.asp?action=10&boardid=2&fid=2


    Personally,, having seen a number of fridges lose their charge over the years,,, I am not really worried about a fire due to a cooling unit failure, perhaps I should be.

    Tony
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #43
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    Re: Thoughts on system

    One issue I would question is running a propane fridge in an air conditioned space... Since they are less efficient (generate more waste heat) than a good electric fridge--you may end up paying more for A/C costs in summer.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #44
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    Re: Thoughts on system

    A good trick to do with a absorption fridge is to build a sealed box behind the fridge, with outside air being let in at the bottom, warm air exhausted at the top. (fan cooled is even better) In the winter I close the outside vents and let the fridge draw from the room and vent to the room,, summer I reverse it. (The flue vent always vents outside!) I suppose it is not a bad strategy with a conventional fridge as well.

    Tony

    Welcome back Bill.
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  • PhilS
    PhilS Solar Expert Posts: 370 ✭✭✭
    #45
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    Re: Thoughts on system
    icarus wrote: »
    A good trick to do with a absorption fridge is to build a sealed box behind the fridge, with outside air being let in at the bottom, warm air exhausted at the top. (fan cooled is even better) In the winter I close the outside vents and let the fridge draw from the room and vent to the room,, summer I reverse it. (The flue vent always vents outside!) I suppose it is not a bad strategy with a conventional fridge as well. Tony Welcome back Bill.

    I certainly agree on your method. In the pic I posted above, what might not be obvious is the 6" space built in above and behind the fridges that exhausts through a roof vent. At one time there were a couple of little fans with their own little solar panel to help, but after a couple of years listening to the fans change speeds as clouds passed overhead, I removed them.

    The new electric fridge still vents through that roof outlet. I toyed with the idea of closing off the vent during the winter to keep heat in the house, but put it into the "round tuit" bin and now it's getting warmer so it'll stay there for the time being.

    Glad you are familiar with the Dometic problem, as I guessed you were. That situation scared me big-time, knowing I could come home from work anyday and find ashes where the house used to be. However, it all worked out OK since it prompted me to buy 3 more panels, the Magnum inverter, and the Kenmore fridge. On hindsight that was the best solution but I'd not have done it if the problem with Dometics hadn't surfaced.

    Phil
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  • PhilS
    PhilS Solar Expert Posts: 370 ✭✭✭
    #46
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    Re: Thoughts on system
    icarus wrote: »
    Personally,, having seen a number of fridges lose their charge over the years,,, I am not really worried about a fire due to a cooling unit failure, perhaps I should be.Tony

    Tony...

    I would have NEVER even thought ammonia could/would burn. I would have bet $$ on that assumption. I've lost bets on surer things.

    Dometic's problem isn't as serious for most others. If the unit fails while on AC, there's no flame present. No flame: no fire. But I can understand that a cooling unit could be severly weakened by the electric heater, then fail while it was on propane power--- but what are the odds?

    In OUR kitchen tho, you could have seen the blood drain from my face as I realized the potential hazard I'd created installing the fridges side-by-side and then running one on propane and the other on electric.

    I apologize to got solar for straying from your original questions in this thread.

    Phil
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #47
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    Re: Thoughts on system

    I assume the propane fridges use Anhydrous Ammonia... Here is one MSDS on the subject.
    Fire and Explosion Hazard Data
    Flashpoint: None
    Flammable Limits in Air: LEL/UEL 16% to 25% (listed in the NIOSH Pocket Guide to Chemical Hazards 15% to 28%)
    Extinguishing Media: Dry Chemical, CO2, water spray or alcohol-resistant foam if gas flow cannot be stoppedAuto Ignition Temperature: 1,204°F (If catalyzed), 1,570°F (If un-catalyzed)

    Special Fire-Fighting Procedure
    Must wear protective clothing and a positive pressure SCBA. Stop source if possible. If a portable container (such as a cylinder or trailer) can be moved from the fire area without risk to the individual, do so to prevent the pressure relief valve of the trailer from discharging or the cylinder from rupturing. Fight fires using dry chemical, carbon dioxide, water spray or alcohol-resistant foam. Cool fire exposed containers with water spray. Stay upwind when containers are threatened. Use water spray to knock down vapor and dilute.

    Unusual Fire and Explosion Hazards
    • Outdoors, ammonia is not generally a fire hazard. Indoors, in confined areas, ammonia may be a fire hazard, especially if oil and other combustible materials are present. Combustion may form toxic nitrogen oxides.
    • If relief valves are inoperative, heat exposed storage containers may become explosion hazards due to over pressurization.

    Chemical Reactivity
    Stability
    Stable at room temperature. Heating a closed container above room temperature causes vapor pressure to increase rapidly. Anhydrous ammonia will react exothermically with acids and water. Will not polymerize.

    Conditions to Avoid
    Anhydrous ammonia has potentially explosive reactions with strong oxidizers. Anhydrous ammonia forms explosive mixtures in air with hydrocarbons, chlorine, ethanol, fluorine and silver nitrate. Anhydrous ammonia reacts to form explosive products, mixtures or compounds with mercury, gold, silver, iodine, bromine and silver oxide. Avoid anhydrous ammonia contact with chlorine, which forms a chloramine gas, which is a primary skin irritant and sensitizer. Avoid anhydrous ammonia contact with galvanized surfaces, copper, brass, bronze, aluminum alloys, mercury, gold and silver. A corrosive reaction will occur.

    Hazardous Decomposition Products
    Anhydrous ammonia decomposes to hydrogen and nitrogen gases above 450°C (842°F). Decomposition temperatures may be lowered by contact with certain metals, such as iron, nickel and zinc and by catalytic surfaces such as porcelain and pumice.
    Read the whole thing... Anhydrous Ammonia is nothing to play with and the normal reaction of putting water on the "fire" is not a good idea without a respirator/hazmat suit.
    CAUTION: ADDING WATER DIRECTLY TO LIQUID SPILLS WILL INCREASE VOLATILIZATION OF AMMONIA, THUS INCREASING THE POSSIBILITY OF EXPOSURE.
    In summary--get out if there is a leak.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • PhilS
    PhilS Solar Expert Posts: 370 ✭✭✭
    #48
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    Re: Thoughts on system
    BB. wrote: »
    In summary--get out if there is a leak. -Bill

    I will now admit that my biggest fear was for the animals IN our house that wouldn't be able to escape, NOT that the house would burn.

    Bill.... when are you gonna be in our area and able to stop by for a cold one?

    Phil
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #49
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    Re: Thoughts on system

    Phil,,

    I did follow your link, and read through page 21 on that forum. I am left with the conclusion that this whole issue is a mountain our of a mole hill. Ammonia absorption fridges have been around for almost a century,,, AND they have had leaking cooling units since then. Now in reference to Bill's admonishment about ammonia releases,, the fact on the ground are that the advice has always been,, if you smell ammonia get out and air out the room/RV. The likely hood of fatal inhalation is so small in the event of a major failure as to be effectively nil. Most cooling unit failures in my experience are slow and manifest themselves only when people realize the fridge doesn't get cold any more. Investigation then reveals the telltale yellow sign of failure. I have never,, in 50 years of fridge experience seen one fail all at once.

    As for the issue germane to the fire potential with this specific Dometic cooling unit. I think that once again, the chances of all the elements coming together at the same time to cause the fire is extremely remote. That said,, I think that it is clear that the issue is with potential defective cooling units,,, potentially aggravated by a heating element that is too large an therefore may cause the cracking in the cooling unit as suggested. If you use your fridge in a RV setting, mostly on 120vac then I would be a bit more concerned than if you use it on LP like Phil and I do.

    In my somewhat limited,, but not completely limited experience with these fridges,, the biggest cause of failure is operator error,,, primarily running them out of level. Most people have no real idea how these units work. They expect to plug them in, or light them, and expect them to get cold. (No an unreasonable assumption) The reality is that they are a bit quirky, but if they are used properly they are safe and reliable. (I do think that this production run of cooling units seems to have a higher than average failure rate anecdotally. It would be curious to see the real numbers).

    Tony
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  • PhilS
    PhilS Solar Expert Posts: 370 ✭✭✭
    #50
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    Re: Thoughts on system
    icarus wrote: »
    Phil,,

    I did follow your link, and read through page 21 on that forum. I am left with the conclusion that this whole issue is a mountain our of a mole hill. Tony

    Yeah, Tony, I've understood from the get-go that this whole problem was pretty remote. But so is my home. Meaning... if it were to catch on fire, it'd burn to the ground before any response team showed up. I would see the smoke on the horizon from where I sit now.

    I hope you'll be able to stop in with Bill for awhile and compare stories! We DO have guest quarters, tho I don't know if Bill snores or not, but there IS a Norcold fridge in that RV.

    I hope EVERYONE is gonna have a wonderful Easter. The weather looks to be excellent here.

    Phil
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #51
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    Re: Thoughts on system

    Phil,

    I didn't mean to diminish your concern. Since you have (had?) two of them burning side by side your concerns are warranted. I myself am now going to pay attention over the next little while,, and begin to look at alternatives if and when the current fridge fails.

    I, like you am my own fire dept. Our fire department consists of a Wajax high volume/high pressure forest fire pump sitting on the lakeshore. Problem is,, I have to be there. No fire dept for 150kms.

    We have had several lightning caused forest fires nearby over the years,,, and curiously enough,, I can get a chopper and a water bomber in here is less than an hour,,,, if they are not really busy! http://www.mnr.gov.on.ca/en/Business/AFFM/2ColumnSubPage/252319.html If you follow the link, there are some really cool picture of water bombers in our neighbourhood.

    Watching these guys work is really cool! Sometime I will find some of my file pictures of my experiences.
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