[Guite]

Originally Posted by tj123

Room Coolers work on a simple principle of evaporation of water removing heat.

Is the cooling effect of a room cooler more if it is mounted on a window (like window AC) than if the cooler is just placed inside a room? If yes, I would like to hear some scientific explanation than just some personal impression.

[anupmathur]

Originally Posted by Guite

Is the cooling effect of a room cooler more if it is mounted on a window (like window AC) than if the cooler is just placed inside a room? If yes, I would like to hear some scientific explanation than just some personal impression.

The only correct way to mount a cooler is to have the 'pads' outside the room (sucking in outside air) and the front facing into the room. ie. mounted like a window AC.

And this is where the similarity ends. For the cooler to do a good job there has to be throughput of air in the room while an AC will work best on re-circulation.

A cooler does 'one-shot' or 'single pass' cooling.
Water evaporates from the large surface area of the pads and this causes cooling. The air passes through these pads and gets cooled. The 'residence' time of air in passing through the pads is also important - the pads should have some thickness. When viewed from inside there should be virtually no outside light visible through the pads (ie packing thickness of about one inch).

Evaporative coolers work best in low relative humidity conditions and serve practically no purpose once the RH has gone above 40% or so.

Delhi these days has typical RH figures of 10 to 15% and my large cooler at home is keeping the entire house at a very comfortable 23 to 25°C.
This is a 5½ feet tall cooler, 3 feet square cross section and has a 24 inch GE low speed exhaust fan doing duty. It is consuming close a hundred litres of water during the 12 hours that we are running it each day. The need for night duty has not been felt yet. Night temps are 24°C or so.

[Guite]

Thanks Anup, your inputs in this thread and the AC thread are invaluable. When drawing hot air from outside, does the hot air generate more evaporation at the pad, and hence more cooling? Some manufacturers mention imported pads. I suppose it is critical for evaporation rate. Is it?

I keep one cooler on trolley and move it around inside the house and find it is better than none. BTW, is your cooler a DIY?

[anupmathur]

Haha, thanks, Guite.
Hot air will absorb more water of course. But the way it works is that the water gets cooled progressive more during the first few minutes of operation. The colder water is now eveaporating and helping to cool the air more than before. Till a steady state or equillibrium is reached. And this is related to the dew point at that particular moment.

For my cooler with a water tank capacity of about 60 ltrs it takes about 20 minutes to reach full cooling.
The water tank of the cooler is essential; cooling would be radically impaired without a tank. Intersetingly, you can give a further boost to the cooling by adding ice to the tank; provided you have access to tons of ice! You can beat the dew point limitation this way, hehe!

My cooler is not exactly a DIY in the strict sense.
You buy the 'box' of the size you want, you select the pads you want, an exhaust fan and a pump and you get it all put together. A stool to place it at the desired height, and it's good to go.
BTW, the best pads are the wood shaving pads. Preferably a wood that absorbs some water. The synthetic pads simply do not match up.

The job that this cooler does cannot be matched by the 5 tons of air conditioners that I will be running once the dry heat days are over!
The ACs send you to the cleaners!

[Guite]

Hi Anup, thanks again. I have a lot more questions and if I were to go post all you might get bored and we will be hogging the thread. In office work we discuss things over the phone and when detailed discussion is required a physical meeting is called. So the discussion in this thread is like telephonic discussion...

[pradipk]

Originally Posted by knp

I am also looking for air cooler in bangalore, and would someone please post the prices of models available? especially usha, symphony, kenstar?

Hey I too vote as SPARKled and other's suggestion. When it's Air Cooler, never go for any brand. Always go for locally made real "Giants". The rule of thumb is Bigger the Better. All branded one comes smaller and rather cooling it increased humidity a lot. I have experienced the same. However bad thiing is I haven't seen any such locally made coolers in Bangalore. May be till date it's not required but considering the summer since last couple of years, it's time to have some local brands.

[iamback]

Don't know about you guys but I brought a Kenstar cooler on 2000 and till now its working fine. Never had any problem. I just clean it twice a year.

[anupmathur]

Originally Posted by pradipk

.... All branded one comes smaller and rather cooling it increased humidity a lot. ......

Pradip, are you keeping the cooler in the room?
It HAS to be mounted with the pads outside so that all the air is drawn from outside and none from the room.

[pradipk]

Originally Posted by anupmathur

Pradip, are you keeping the cooler in the room?
It HAS to be mounted with the pads outside so that all the air is drawn from outside and none from the room.

Inside the room. I had symphony tower model.

[anupmathur]

Originally Posted by pradipk

Inside the room. I had symphony tower model.

I am sorry and sad that unethical makers deliberately and knowingly misguide customers and sell such crap.

A cooler kept in a room is like a humongous humidifier doing duty diligently!

[di1in]

Reviving this thread with the all important question for 2012: "Please suggest a good air cooler"!

Is there any problem using a 200sq ft rated for a 600 sq ft room? Slow cooling is not a problem.

[smartindboy]

I have a 1.4KVA inverter, what wattage air cooler should be ok? and any recommendations?

I plan to use it for my hall 25x15 ft at day time.

[bluevolt]

Originally Posted by smartindboy

I have a 1.4KVA inverter, what wattage air cooler should be ok? and any recommendations?

I plan to use it for my hall 25x15 ft at day time.

All air coolers consume around 150-250 watts and even a 800 VA inverter will run it. I guess 1.4KVA is more than enough for a cooler.

[rakirank]

I have 2010 Kenstar.

The cooling so far has been fair. Defnitely helps as compared to just the fan.

Unfortunately I am having a foul smell from the same & I seem to get no where in terms of A.S.S.

Each time I am assured that I will get a call and no one does.

Wanted to put this down for people who may be looking to buy a new cooler.

[fine69]

Would the coolers that are available in the market for 4-5k good enough if to be used in a 125 sqft shop? It doesn't have any window and is closed from all sides with the front having a wooden/glass door.

We don't want to get an AC right away as this business is an experiment and I don't want to splurge too much just in case it doesn't work out later on.

Would the cooler do any justice in a closed room? Ours is a ground floor shop with no direct sunlight anytime of the day.