will shading outside HVAc compressors help at all?

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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #32
    Re: will shading outside HVAc compressors help at all?
    BB. wrote: »
    It sounds like that is what the newer window units are doing--Slinging (oops) condenser onto the evaporator (from earlier posts) and sometimes making a leaky mess.

    -Bill
    It's the condenser coils that you want to cool down, not the evaporator coils. Note that in very humid conditions, wetting the condenser coils with water which is at ambient temp won't help much because evaporation is slow to nil. The reason it worked for us in Peru was that we threw a lot of water on the coils and the water was cooler than the coils; it didn't depend on evaporation.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #33
    Re: will shading outside HVAc compressors help at all?
    ggunn wrote: »
    It's the condenser coils that you want to cool down, not the evaporator coils.

    Let me see....
    The condensate comes from the evaporator and evaporates at the condensor. That can certainly lead to some confusion. :-)
    The difference is between inside the system where the refrigerant evaporates in the evaporator and condenses in the condensor and outside the system where water in the air does the opposite.
    SMA SB 3000, old BP panels.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #34
    Re: will shading outside HVAc compressors help at all?
    inetdog wrote: »
    Let me see....
    The condensate comes from the evaporator and evaporates at the condensor. That can certainly lead to some confusion. :-)
    The difference is between inside the system where the refrigerant evaporates in the evaporator and condenses in the condensor and outside the system where water in the air does the opposite.
    By George, you've got it! :D
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  • SteveK
    SteveK Solar Expert Posts: 387 ✭✭
    #35
    Re: will shading outside HVAc compressors help at all?

    When we bought our HPWH we were told by two different sources that each gallon of condensate represented 1KWH of energy savings. I wonder if the same would be true with this mister?
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  • rollandelliott
    rollandelliott Solar Expert Posts: 834 ✭✭
    #36
    Re: will shading outside HVAc compressors help at all?

    "HPWH"???? what does that stand for?
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #37
    Re: will shading outside HVAc compressors help at all?

    Heat pump water heater
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #38
    Re: will shading outside HVAc compressors help at all?
    rollandelliott wrote: »
    "HPWH"???? what does that stand for?

    I am guessing Heat Pump Water Heater. (http://www.bpa.gov/Energy/N/HPWH.cfm)

    I am not sure just how the condensate comes into the picture though. Since the pump is heating the water, the air coil will be the evaporator and will be condensing moisture from the ambient air. Possibly the source was saying that it would be more efficient working with humid air since that would increase the working temperature of the coil?

    Where they can be used, they are more energy efficient than just using resistance heating. And in some cases they are combined with A/C units to get additional savings over resistance water heating.
    (Savings are realized over straight heat pump A/C only if you really need all of the hot water they produce and would be heating it via resistance heating otherwise.)
    SMA SB 3000, old BP panels.
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  • Ken Marsh
    Ken Marsh Solar Expert Posts: 114 ✭✭✭✭
    #39
    Re: will shading outside HVAc compressors help at all?

    They have been splashing the condensate on the condensing coil of window units for at least 50 years.
    Is anybody here is old enough to remember having to plumb drain lines to window units?
    Hate to admit it but I remember.

    OK, I will take a stab at the equations.
    Don't think this editor will generate equations so will just talk about it.

    The power used by a window unit goes two ways.
    First is the fixed power used by the compressor motor for core loss, overcoming core hysteresis, friction and fan motor.
    The variable power draw, by Carnot's equation, is linearly proportional to the temperature difference.
    Lowering the condensing temperature will not change your fixed power draw but it will effect the variable power draw.
    A general estimate of fixed power loss on a small single phase compressor motor will be around 40% of full load.
    This leaves 60% of the power to be effected by temperature difference.

    Small window units will typically run 40 deg F evaporation and 100 deg condensing making 60 deg delta T.
    So, if you are successful in lowering the condensing temperature one degree this would be 1/60 difference of 60% of the load.
    Condensing temperature for small changes is directly linked to cooling air in temperature,
    Power savings will be around one percent per degree F that you reduce the cooling air temperature.

    There used to be stacks available for top discharge condensing units.
    I remember specifying them to get discharge air above the eves.
    It can be beneficial by reducing recirculation, particularly in installations using multiple condensing units.
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #40
    Re: will shading outside HVAc compressors help at all?
    rollandelliott wrote: »
    Some of the Cool n save reviews metion that it sprays so much water that it turned thier lawn into a muddy mess. I can just image a poorly drained lawn turning into a pond with 100 to 700 gallons of water being poured on it weekly.

    Ideally you'd have a HUGE drain pan under neath the units and a small pump to move the water back to the rainwater tank.


    I have heard that the condensed water is not safe to drink. perhaps it picks up some of the metals used to coat the tubing? I wanted to use it to water plants, but members here cautioned against it
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #41
    Re: will shading outside HVAc compressors help at all?

    Untreated condensate water is a good place to breed diseases such as Legionnaires' disease (warm, moist, lots of dust/debris/microbes moving through)...

    However, if a window A/C system is operating correctly, it is moving several gallons of water through it every day, it is probably OK.
    The water that drips from air conditioners is probably even safe for drinking. (It's certainly more potable than the drinking water in many countries.) Still, for the reasons mentioned above, it's best not to tilt your head back for a draft. If you're looking for a better use for your air conditioner's condensate, the Explainer recommends using it to water your plants.
    However, since nobody takes apart their A/C unit to look for stagnant water and/or cleaning and sterilizing, would not recommend drinking if other, known good, sources are available.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • rollandelliott
    rollandelliott Solar Expert Posts: 834 ✭✭
    #42
    Re: will shading outside HVAc compressors help at all?

    "It(vertical stacks) can be beneficial by reducing recirculation, particularly in installations using multiple condensing units. "

    I have 2 outside compressors One for lower floor and other one for upper floor of a big house. They are about six feet apart. I could make a duct work out of some sheet metal, wonder if it woudl be beneficial?
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #43
    Re: will shading outside HVAc compressors help at all?
    rollandelliott wrote: »
    "It(vertical stacks) can be beneficial by reducing recirculation, particularly in installations using multiple condensing units. "

    I have 2 outside compressors One for lower floor and other one for upper floor of a big house. They are about six feet apart. I could make a duct work out of some sheet metal, wonder if it woudl be beneficial?

    You can get a quick idea of whether this even needs further investigation by measuring the air temperature around the upper condensor to see if it is being heated by the lower condensor. A difference of a degree or two probably will not justify the extra work, but at least you will have something to go on. The other thing to look at, of course, is whether the temp of the air being pulled into the lower unit is higher than the air temp 6 or more feet away from it. (Be sure not to be confused by reading with the thermometer in direct sunlight.)
    SMA SB 3000, old BP panels.
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  • rollandelliott
    rollandelliott Solar Expert Posts: 834 ✭✭
    #44
    Re: will shading outside HVAc compressors help at all?

    I got the cool n save device and I've been running it for about a month just using my well water (which is around 12 grains hardness) I already have white calcium film on everything. I'll deffintely need to switch to rain water next year. It will probably be fine for another 6 weeks and then the weather will be cool enough not to need it. I have not run any power usage tests, but it seems to work fine.
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  • fixitmanarizona
    fixitmanarizona Registered Users Posts: 4
    #45
    Re: will shading outside HVAc compressors help at all?

    All the newer window A/C units I've seen do this (discharging condensate water to the "hot" side,) and there IS no water leaking out anywhere. I don't think that's what this thread is dealing with, though.
    Here in Phoenix, many people still use the 'swamp' cooler, which is pretty efficient (when it's not humid) and typically doesn't use a lot of water. This is ancient technology, adapted for the arid southwest, but also in use in other parts of the country where you really don't need much in the way of cooling besides ceiling fans and good attic insulation. My house in Flagstaff, for instance (similar to the climate in Colorado) had no cooling at all, and stayed under 80F even on the hottest days (I think it got up to 96 once.)
    In a "swamp cooler" (or evaporative cooler) water is constantly in motion (unless you leave the unit undrained, and off in the winter) and most people use treated city water and so you get very little problem with mosquitos, mold, etc. The hard water here poses a problem, but that's usually dealt with by leaving a small amount of the recirculated water to drain out to plants, etc, or into a sewage drain.
    The idea behind this type of unit is simply to blow air through wet pads. This puts cooler (seeming) wet air into the house, rather than dry, hot air, which you would get if you simply put a fan in the window. Some of the water evaporates off the pads, cooling them.
    The older "swamp" units from when I was young, did NOT have a pump, the water was just turned on, and wet the pads. When you turned the motor off, you had to remember to turn off the water as well, or you were just basically watering the side of your house all the time.
    There's also a new idea used in a unit called the "Coolerado" (check their website) which uses no refreigerant, and
    it uses very little power since there is no pump, nor is there a compressor which is the best idea yet. The heat is discharged in steam. They're based in Colorado (no surprise considering the name.)
    Basically the best cooling solution is to live in a climate where you need none. Failing that, going underground, or having a LOT of ceiling and wall insulation, or thermal mass, will keep things well within the bearable upper limit of 85 to 90 F inside even without AC. Walls, especially, in newer homes, are way too thin to have any thermal mass, for instance, no matter how much insulation you put in them. Walls should be a minimum of a foot thick, and solid, either in log, or stone or masonry. Here in Phoenix they build them 4 inches thick with drywall on the inside, particle board and foam on the outside, and a thin sprayed-on layer of "stucco" and paint over that. Often there isn't even any fiberglass in the hollow parts... That's all. VERY poorly built.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #46
    Re: will shading outside HVAc compressors help at all?

    Coolerado is pretty "COOL" to bad no residential products.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #47
    Re: will shading outside HVAc compressors help at all?
    fixitmanarizona wrote: »
    The idea behind this type of unit is simply to blow air through wet pads. This puts cooler (seeming) wet air into the house, rather than dry, hot air, which you would get if you simply put a fan in the window.
    It doesn't just seem cooler, it is cooler. Delta heat of vaporization is removed from the air when it passes through the mats, and if the air is very dry, the temperature differential can be quite substantial. If the humidity is high, of course, it just makes everything wet.
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