Evaporative Cooling

S

smiffy

Hello All

Well with summer on its way i am pricing some evap cooling. The best price system is the Bonair at the moment however it seems the saleman have conflicting advice.

Two salesmand are advising to vents in one room - kitchen and diner whilst the other two are saying one will be enough.

Going by the grid the saleman supplied is the amount of air needed for size of the room which is 94 cubic metre I will need two vents. The reason I am hesistant is our house has beautiful ceilings and two vents wouldnt do it justice. We already have two vents for the ducted heating.

Does anyone know much about Evap cooling?

They advise to put the following vents in to bring it past the 94 cubic metres.

16 inch vent = 56 m3
14 inch vent = 43 m3

Would the one vent be sufficient?

Is this a standard measurement?

He also quoted on metalised ducts? Are these better then the plastic?

Help please - novice evap cooler......
 
OK a lot may depend on where that room is situated and how used and ventalated it will be?? Ie, if its in a corner with the door closed most of the time, it might be worth going the two....if its a throroughfair through the house and there are vents well placed in the adjacent rooms, one larger vent may be enough.

Didn't know they had metalised ducts, i'd only think they would be weightier, but they may be more austetic.
 
Forget Evaporative, get something that really cools the place on a hot day, go refrigerated .. plus it can come out the same ceiling vents as your ducted gas heating.

My experience is that while evaporative is much cheaper to run, it does not work well over about 32degrees .. in fact some hot days I walk into a house with it on and it is more humid inside than out.

Lots and lots of houses with Evaporative cooling also have one or more split systems innstalled in the house as well.

just my thoughts

RightValue
 
Refrigerated and evaporative units cool in very different ways.

Evaporative units work best when the weather is hot and dry as it cools air by the evaporation of the water on the pads. It's theoretical lowest temperature is the "wet bulb" temperature of the day. The more humid it is, the higher the wet bulb, the less effective it is. It also relies on the windows being open to allow the supplied cool air to leave the house.

You cannot have an evaporative unit that recycles it's own air as it will not give any cooling once the air is saturated with moisture.

Evaporative units are therefore great in dry, hot areas, but ineffective in humid climates.

You cannot have a refrigerated and an evaporative working together as the air that the refrigerated one is cooling is being thrown out the window by the evap.

My guess is the splits are a backup for humid days and for heating in winter.

@RightValue, if your house is just becoming humid on hot days, I would suggest that you may have an undersized unit or supply ducting. Also could be that windows are not open or fan is on a low setting - either way the air changes/hour in the house is insufficient to cool it effectively.

As far as duct sizes and quantities... The salesmen know better, I've not got the engineering experience - it's not hard, I've just not done it before.

Blitzkrieg
(he's back, don't you know?)
 
Blitzkrieg said:
@RightValue, if your house is just becoming humid on hot days, I would suggest that you may have an undersized unit or supply ducting. Also could be that windows are not open or fan is on a low setting - either way the air changes/hour in the house is insufficient to cool it effectively..

Blitzkrieg
(he's back, don't you know?)
Click to expand...



I did say .. when I walk into a house..

I walk into about 6 -8 different houses each day.. if I meant my house I would have said my house.

BTW .. I have a split system.. best $2,500 I ever spent.

Come what may .. evaporative cooling does not condition air it just humidifies it.

I don't think I can remember any house that I have been into on a hot day that uses evaporitive cooling having the windows open, if that is required for the units to work effecively then that just means that few people use them effectively

I stand by what I said, abouve about 32 degrees evaporitive cooling is as useful as .. well something on a bull comes to mind.

cheers

RightValue
 
Then indeed they are not being used correctly.

Agreed that refrigerated is the way to go. I prefer it.

Having said that, evap has it's place. Some people don't like closed up houses.

Though those "portable" evaporative coolers that people wheel around rooms to try spot cooling are as useless as your previous proverb. As I mentioned above, you CANNOT recirculate evaporative air, once it is saturated with moisture, it needs to exhaust.
 
RightValue said:
I stand by what I said, abouve about 32 degrees evaporitive cooling is as useful as .. well something on a bull comes to mind.
Click to expand...

Personally, I disagree. As a qualified Refrig. Tech, Elec Fitter & Mech Engr, my choice for hot "dry" climates is usually Evaporative...

I have installed/designed numerous systems and in my own homes I have had both, in similar areas. I must say though, it does depend a lot on the home design/layout/orientation and ceiling height.

My last home in Melbourne had ducted evaporative and it worked fine... even that day when it 46C outside. OK, inside wasn't like a fridge, but if that is the climate you seek, move to Antartica.

Rerigerated systems come into their own in more humid environs and are the only option for the tropics, as they de-humidify the air. This is why you get thirsty on planes and they keep handing out water. Refrigerated systems also cost more to run.

That's my 2 cents ;)
 
Have to throw my support behind the evap units as well.
Make sure you have a large enough unit and plenty of ways for the air to escape and they are more than adequate.
You should only get humidity problems if there is insufficient air flow out of the house.
 
had evap ducted in the last rental i was in, massive 2 story place and my bedroom was in the north west corner. Provided you turned it on early and had sufficient windows open it worked like a charm. Through last summer i never ever had issues sleeping the house was also a nice 20ish degrees and the power bills didn't go nuts. I would get it install in melbourne weather no question!
 
from my experience evap coolers are useless in humidity, they just wont work effectively, only ok in hot/dry conditions..........only one way to go to cover all weather patterns, splitties....
 
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