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alternative to generator swamp c
Yahoo Message Number: 19196
what is a swamp cooler? also why dont they put rear ac units in mh like mini vans? any one know?
[Life With A Lazy Daze RV] Re: alternative to generator swamp cooler
Reply #1 –
Yahoo Message Number: 19203
Quote
what is a swamp cooler? also why dont they put rear ac units in mh
like mini vans? any one know?

'Swamp cooler' is the slangy, somewhat derogatory term for 'evaporative cooler'. These used to come standard in all LD models, whether or not an air conditioner was ordered. Mounted through a roof vent opening, they spray water onto a porous foam element, and a fan draws outside air through it into the coach interior. As the water evaporates, the change of state to a gas absorbs heat from the air, cooling it about 20 degrees. The disadvantages of this device are the need for a dry climate, increased humidity of the outlet air, the consumption of a notable amount of your water supply over time, and the sloshing of water from its reservoir tray onto the roof if used while driving. Regular cleaning and maintenance are necessary to prevent deterioration of its components. The advantages are low power consumption, and it can be used boondocking without a generator, lower noise than the air conditioner, and the increase in humidity in a desert environment.

Rear A/C units in vans are similar in design to the roof mounted units in motorhomes. Vans simply locate them where they won't be a problem if the headroom is limited. Note if they were used in that location in a LD, significant storage would be lost. You can't compensate by moving the storage to the center of the ceiling. When a 'cleaner' installation or less noise is desired in a motorhome, basement units are used. LD models are low profile, and don't have the room for this option.

Steve
2004 FL
2013 Honda Fit
Re: alternative to generator swamp cooler
Reply #2 –
Yahoo Message Number: 19206
Steve, The KoolerAire that Victor was looking at would act in a similar way to a swamp cooler the not nearly as efficient. I believe he is most concerned with something to help assist the dash air for cooling the rear of the coach during travel and not to cool the rig by itself. I think people are getting the wrong idea as to what Victor's intensions are with using either of the two alternates he was thinking about. I actually think it could do a decent job in helping the dash air but mainly in a dryer climate area, like the mountains in Colorado where he lives and the rest of the Rocky Mountain States and much of the west. It certainly wouldn't be as effective as a "swamp cooler" nor would it cool the whole coach but it can help even if only for the additional airflow from it. As I said earlier also it would give the kids a closer place thanthe fridge to store some cold drinks for in route and they would also help keep them cooler in the rear of the coach.

Mike
Re: alternative to generator swamp cooler
Reply #3 –
Yahoo Message Number: 19208
Mike, my response was not to Victor's post. Note the text I quoted, or go 'up thread'.

Steve
2004 FL
2013 Honda Fit
Re: alternative to generator swamp cooler
Reply #4 –
Yahoo Message Number: 19210
Steve, I realize you were not replying to Victor's original post on the message I replied to or the previous ones you replied to. You and others though have been discussing what Victor brought up as possible alternatives. I just wanted to clarify for everyone that it is my understanding he is merely looking for ways to supplement the dash air during travel without having a generator and using the roof A/C to make the rear of the coach more comfortable for those sitting there and not really trying to cool the entire coach with any of these items.

I believe in hot weather if he wanted to use the A/C with no generator while camping he'd camp in a place with an electric hook- up. I also don't think the added humidity from the KoolerAire would make the dash A/C work much harder than it would normally. In fact by moving more air it should actually offset any increase it might cause due to added humidity. I was also merely pointing out that it would work in a similar way to a "swamp cooler" though not nearly as well but would equally as well traveling or standing still.

I'm sorry if you took my post in any other way because that was certainly not my intention.

Mike
Re: alternative to generator swamp cooler
Reply #5 –
Yahoo Message Number: 19211
Quote
I believe in hot weather if he wanted to use the A/C with no generator while camping he'd camp in a place with an electric hook- up. I also don't think the added humidity from the KoolerAire would make the dash A/C work much harder than it would normally. In fact by moving more air it should actually offset any increase it might cause due to added humidity. I was also merely pointing out that it would work in a similar way to a "swamp cooler" though not nearly as well but would equally as well traveling or standing still.
Mike, when an air conditioner dehumidifies, it must absorb energy from the water vapor to condense it to a liquid - this is separate from the energy required to reduce its temperature. It takes more energy to cool a humid environment than a dry one. This is sort of the 'reverse' swamp cooler effect. The effect is that the unit will run longer to cool the interior by a specified amount as the humidity increases. The KoolerAire, by contrast, does not remove any energy from the interior. It cools uniquely by state change or the medium - ice. The water vapor it produces is thus at a higher energy level than was the ice, and that energy is removed by the air conditioner in simply recondensing it.

Now with the swamp coolers I alluded to, there is an additional problem. They work more effectively than the KoolerAire because they bring in outside dry air - and require an open vent or window. The KoolerAire will begin to saturate the air inside, and stop cooling.
When running the dash air with one of these swamp coolers, you are also fighting the replenishment of the inside air with hot outside reinforcements.

Steve
2004 FL
2013 Honda Fit
Re: alternative to generator swamp cooler
Reply #6 –
Yahoo Message Number: 19212
Steve, I understand how the swamp coolers work and also the way the KoolerAire works. Both will add to the humidity in the air but the KoolerAire will add far less than a swamp cooler as well as being less effective. Even though I don't have a swamp cooler I do know people out west that do or did have one and have experienced them in operation. The KoolerAire uses ice for the cooling agent and as it melts the fan will evaporate some of the water and make the air marginally more humid. I also knew people in NJ that had no A/C and during the summer used ice in a humidifier along with additional fans to cool a room. It did help keep the room cooler than others of equal size and equal airflow in the house so even in a humid environment this does help some.
 I also understand a humid environment takes more time and energy for an A/C to cool and I understand how they work as well. Don't forget I live in Fl (for the past 12yrs) and have lived on the humid east coast all my life. It is certainly more humid here than in your area or in the Rockies and much of the west. I seriously doubt even with a KoolerAire and the small amount of additional humidity it would add that it would make the dash A/C in anyone's coach work that much harder and definitely not as hard as one here in Fl or most of the east coast or Gulf states including Texas in its more humid areas in summer. Our A/C works for much of the year here in Fl and that's especially true with the ones in our cars, but we rarely need to use the heat.
 What I'm getting at is that the KoolerAire Victor had an interest in would be the best choice of the items he had been thinking about for supplementing his dash A/C. I do think he could get away with only a few 12vDC fans and some additional insulation in areas though. That wouldn't add to the humidity at all or make the dash A/C work harder.
In fact it would help the dash A/C so it wouldn't have to work as hard as it probably did last summer on his trip. It sounds to me like he mainly feels the need for a generator to run the rooftop A/C in route and these were ideas for not needing one in the coach. He could always get a Honda portable and keep it in a toad in route. He wouldn't need to lose limited cargo capacity in the coach and could use it when stationary for whatever he might need one for. It wouldn't be as loud or give the vibration of a coach mounted one as well.

Mike
Re: alternative to generator swamp cooler
Reply #7 –
Yahoo Message Number: 19214
This humidty discussion is amazingly interesting.  It had never occured to me that the a/c works harder in humid conditions.

The statement about the KoolerAir unit adding humidity, does that assume the ice is directly exposed to air?  If you used frozen plastic soda jugs or ice sealed in plastic, that would not add any humidty to the air, right?
 BTW, to clarify, I just want to cool the coach while in transit.  We have always stayed at places with hookups.  I guess that could change if we had a genset.

-Victor
Re: alternative to generator swamp cooler
Reply #8 –
Yahoo Message Number: 19216
I really wouldn't be too concerned with the small amout of added humidity you'd be likely to gain from the KoolerAire. It is very unlikely it would add very much additional stress to the dash A/C and I'm sure the A/C units here on the east coast work that hard most of the time. I'd also bet that your A/C unit worked harder last summer without onet than it would have with one.
 The statement of it adding to the humidity is due to the evaporation of the water as the ice melts and the amount evaporated would not be very significant. The cooling effect would cetainly more than make-up the difference. Even in a humid environment like here in Fl it would not add a significant additional load on the dash A/C and would more likely aid it. If you used plastic soda jugs or other containers filled with water and frozen or the "blue ice" packs they wouldn't add any humidity. You would get condensation on them but that would only be from the humidity already present in the air. The problem is how do you keep enough of them frozen and replenish them and still have room in the freezer section for things you really want and need to have? Use of regular ice would be the most practical, at least IMO.

Gensets have their pros and cons. I've camped with and without them for long enough that I feel often the cons outweigh the pros. That's just my opinion though. The fact is most people run their genset so little due to the cons that it is often not worth having one. I do like the option of having it when I want to use one though. They do come in handy at times! The Honda portable units that can be placed several feet away from the rig are much nicer in many respects but again there are pros and cons with that scenario. The question you must ask yourself is what works best for you and your family? What's best for me, or Steve, or anyone else in this group may not be what is best for you. You need to do what you feel is best for you and only you know what that is!

Mike
Re: alternative to generator swamp cooler
Reply #9 –
Yahoo Message Number: 19218
Quote
This humidty discussion is amazingly interesting.  It had never occured to me that the a/c works harder in humid conditions.

The statement about the KoolerAir unit adding humidity, does that assume the ice is directly exposed to air?  If you used frozen plastic soda jugs or ice sealed in plastic, that would not add any humidty to the air, right?
Victor, the KoolAire apparently works two ways - it moves the cool air surrounding the ice to your proximity, displacing the warm air.
This would happen anyway, of course, just by the natural convection in the vicinity of the ice - but less quickly. The energy involved in cooling you in this case is just that consumed by the icemaker that produced the ice.

The second cooling effect is due to the melting, evaporation, or sublimation (ice to vapor directly) which all absorb energy from the air. Although you will get some benefit from this using sealed containers, the thermal transfer will be poor compared to the vapor being dispersed through the cabin interior. If the containers are NOT sealed, the change of state energy acquired by the water vapor in the cooling process will reduce the effectiveness of your dash air by the same amount as the cooling effect achieved.

It would certainly be cheap enough to test the effectiveness of sealed containers with ice - put them in an open cooler, train a small fan on them, and see what you get. That will just be a 'coolness' tranfer system, but it may be enough for spot comfort cooling in your situation.]

Steve
2004 FL
2013 Honda Fit
Re: alternative to generator swamp cooler
Reply #10 –
Yahoo Message Number: 19225
Quote
It would certainly be cheap enough to test the effectiveness of sealed containers with ice - put them in an open cooler, train a small fan on them, and see what you get. That will just be a 'coolness' tranfer system, but it may be enough for spot comfort cooling in your situation.]
Steve, I haven't thought about this in years, but when I read your comments above they reminded me of some stories my Mother-in-law used to tell.  They lived in New Orleans back in the late 40's.  They didn't have air conditioning of course.  So during the worst of the hot weather they would take a towel, soak it in cold water, wring most of the water out, hang it from the doorway of the room, and then set a fan to blow across it.  It at least made the heat bearable.  It's the same basic "coolness transfer system" you mentioned above.

Whew, makes me glad I'm a little younger.  I barely remember those days before air conditioning!

Charles.
Re: alternative to generator swamp cooler
Reply #11 –
Yahoo Message Number: 19227
If you wanted a portable "swamp cooler", aka evaporative cooler, a while back I was looking at coolers too and I ran across a web site that sold coolers made for RV, cars, etc. that ran off of 12V, some could be plugged into the cigarette lighter (or for us any 12v outlet).  It looked interesting, so I thought I'd pass it along. I'm not recommending the products since I've never used them: http://www.nvo.com/southwestsolar/productcatalog/list.nhtml

They don't use foam to hold the water, they use something called a Celdek pad, which they claim is the "most efficient evaporative cooling media in the world".
 The cheapest one looked like around $199, and they claim it cools 200 cubic feet per minute, with the usual caveats about it working best in low humidity.

They looked decent, but since I got my LD cooler working in my '84 Multiplan, and they don't seem to be much use in my area anyway, I didn't look into the ones on the website. (Dallas area has relatively high humidity, don't beleive anyone who tells you North Central Texas has "dry" heat).

I sometimes wondered if replacing the foam in my cooler with this Celdek stuff would make any difference.

Chuck.
 
Re: alternative to generator swamp cooler
Reply #12 –
Yahoo Message Number: 19241
Quote
I sometimes wondered if replacing the foam in my cooler with this Celdek stuff would make any difference.

Chuck.
Chuck, although we call the Recair element 'foam', that is a pretty catch-all phrase for what includes the specialized material used for this element. The key to good cooling is saturating the pad and achieving good airflow through it.  I have used mine in ideal circumstances and am convinced it works like a champ, so I really doubt if any unit would work noticeably better. But, if the humidity exceeds 40%, it becomes nearly worthless - or worse - and no pad design will alter them apples.
 SoCal urban/suburban areas have become noticeably more humid since I moved here in '69, without any increase in average precipitation.
Whatever experts may say, I attribute this to more people and more water use, and swamp coolers are no longer viable most of the year in our area, either. Luckily, most of our major trips take us to or through areas where the device is still useful.

Not for travel, though. On a trip home once from Phoenix during a spell daytime temps were >100F and dry, we started at the crack of a cool dawn with just ventilation and open windows. Later, I switched on the cooler - with about 1/4 tank of fresh water. We stopped briefly in San Bernardino a few hours later, and the pump was running dry. Most of the water had sloshed out enroute across the roof. I then switched on our hapless, ineffective dash air for the last 100 miles. Its blower fan blade exploded with a crash in Pasedena, making me miss our interchange and nearly need a clothing change. We finished the drive with our tongues lolling and our heads out the window.

BTW, I discovered in the A/C repair process an incorrect blower fan was the cause of poor A/C performance. It now does a decent job keeping the whole interior comfortable, if suplemented with the interior oscillating fans.

Steve
2004 FL
2013 Honda Fit