2 October 2008

Evaporative cooling in Canberra - worth it?

| madocci
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We are investigating cooling options for our house at the moment. I am wondering what experience fellow rioters have with evaporative cooling, and whether it will keep the place cool enough on those really hot summer days and nights.

We are currently tossing up between evaporative cooling and air conditioning. I can’t seem to find an answer on how cool the inside of a place would be in 40 degree heat with evaporative cooling in a climate like Canberra. The price for installation is comparable with a couple of air conditioner units, but the running costs are so much lower than air conditioning.

Any ideas? What would / did you choose and why?

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Most evaporative coolers hold between 15 and 25 litres and when you run them they operate as a bleed sytem where the water drips at a set rate or you have a dump sytem .The BREEZAIR unit has a timed dump which is set bat 72 hours,unless the water quality is not good,then the water sensor dumps this water.Canberra overall nhas excellent water quality.
most brands dump when turned off.
The salt content of the water affects the life of celdek pads,inthis area they should be changed every 7 approx years.

Im in the process of shopping for something to cool the air in my house at the moment and have been investigating the evaporative vs air con thing for a while. The 10 or 20 odd litres these things dump periodically is a tiny fraction of what they use whilst evaporating water to make cool air. This evaporated water is then shot straight outside through all the open windows, and cannot be reclaimed. There is hardly any information online about actual water consumption, but this report showed that during a mild weather period in victoria average water consumption was between 80 and 300 litres per day, depending on the unit. These units only ran on average for 2.5 hours per day, giving average hourly consumption of between 32 and 120 litres per hour.

http://www.yvw.com.au/NR/rdonlyres/823F5570-98A1-442E-BB67-63781C813576/0/EACReport.pdf

There is huge variation in hourly consumption between brands, however the report also shows that the ones which use more water are on for less time each day, and I assume this is because the high water consumption ones produce more cold air (just like how a small ducted gas heater would use less fuel but it would need to be on for a longer period to provide the amount of heat that a large ducted gas heater can provide).

I still havent made my mind up on what to get, but that sort of water consumption is worrying. If I owned an evaporative system, it would have been on for at least 20 hours over the past 4 days when the temp has been above 35. Based on the consumption of the units in the study this I would have used between 600 and 2400 litres of water in just 4 days, depending on the consumption of the unit. A unit in the middle of this range would surpass the entire average water consumption of my house (average daily water consumption per person in the ACT is 260 litres per day).

sepi, our system is a Bonaire unit 5 or 6 years old.

caf, you are right. I forgot to mention to add the additional evaporation content, so goodness knows how much it is really.

drewbytes: That’s still an underestimate, because a considerable quantity of the water it uses is evaporated and disappears out your windows.

drewbytes – is that an older system? I’m sure we were told ours dumped 20 litres after being turned on and off.

Evaporative is good in Canberra, and is much nicer air than aircon air, and quieter.

Downsides – you have vents in the roof. You have to leave windows open while it runs – not so good at night or if you’re n’t home.

how cool your house gets will depend on the house, and your working hours etc. We had an unbearably hot house and the evaporative cooled it amazingly well, but not as cool as the aircon at work. they recomend turning it on in the morning on really hot days – it is better at keeping the house cool than cooling a hot box. but that is impractical if you are out.

I was impressed with ours and I’d get it again.

Evap coolers use a lot more water than 5-10 litres per day!!

The units themselves typically hold around 50-80 litres which is filled every time you turn it on, and it is periodically dumped throughout the day at set intervals (although some can be programmed – ours is set to only dump when it’s turned off).

Most also have a bleed system where water is constantly trickling out an overflow – this can also normally be adjusted and I have mine on a low bleed level.

I have the overflow and purge of our system hooked up to a wheelie bin which holds 220 litres. Having the system on all day + 1 purge on turn off will typically fill the bin.

So typically we would use around 200 litres per day using our evap cooler. If you don’t trap ALL the water coming from your system like I do you can’t possibly know how much water it uses. Unfortunately they do use a lot of water. However mine all gets pumped on to the garden so it’s not totally wasted, plus I have a 4500 litre water tank which I direct water to when the wheelie bin is full so I don’t feel so guilty about it.

Had a Breezair back in Perth – had a few problems to begin with (temperature control didn’t work and kept turning off after 10 mins). Once it was fixed it was fine, but have to agree that on very humid days don’t bother turning it on. Luckily days like that are very rare in Canberra.

Wish we installed evap air when we built our house here, instead we got a/c. We hardly ever turn it on during summer – what a waste of money! Though, we’ve got a white colourbond roof which I think helps cool down the house during the warmer months.

Gungahlin Al4:44 pm 17 Mar 09

Oops.

Nothappy: I would contact Master Gasfitters and raise your concerns. Would be very interested to hear their response.

As mentioned in an earlier post, I was very happy with the work they did at my house.

Kramer said :

Nothappy – We might have to take your comments with a grain of salt…. Looking at your email address and the fact that you only just joined – I suspect you could be involved with another service provider in this space? So unless we actually go out and check your installation, or you want to send in photos of the dodgy work?

BTW – did you contact them about your grievances??

LOL!
service provider flaming. different, but only a matter of time…
great to see you are on the ball, kramer.

Nothappy – We might have to take your comments with a grain of salt…. Looking at your email address and the fact that you only just joined – I suspect you could be involved with another service provider in this space? So unless we actually go out and check your installation, or you want to send in photos of the dodgy work?

BTW – did you contact them about your grievances??

Gungahlin Al11:56 pm 16 Mar 09

Brilliant. And with one bit of crappy onsite work, they get themselves an equally crappy google hit for anyone searching around before using them. In this day and age poor service is the death-knell of a business, because now you can tell lots of people about it really easily.

I have just had a Breezaire installed by Master Gas Fitters. The unit seemed to cool very well on the couple of days that we used it.

I was not very happy with their service as there were a large number of problems such as:
– rubbish left on the roof and in the ceiling
– insulation removed from around vents and under ducting
– a few tiles left open and water in the ceiling and house
– ducting over the man hole
– torn outer layer on ducting
– numerous tile chipped on roof

We have Brivis evap cooling and love it. The hottest our house gets is 24 deg. On a cooler Canberra evening you can just put the fan on and push the breeze through your home with out using water. We don’t find it gets too humid in the house when its in cooling mode.

We got ours from Master Gasfitters in Fyshwick, they were cheaper and very helpful.

In response to Barrys comments above, we have lived in climates that are often in the mid 40s and the evap was fantastic. Melbourne is often a humid heat so that is different to here.

Do you work for a air-con company Barry? Or just a climate change sceptic?

Ours uses about 5-10 litres of water a day and I send that water onto the lawn so its not a waste.

Any water that the machine actually uses would be evaporated and so you can’t redirect it any ware. Do you mean it pumps 5-10 litres out it’s overflow/purge/whatever pipe? Cause that sounds like a lot to me… On the other hand, if you have a vegie garden…

Die Lefty Scum4:25 pm 02 Feb 09

Is there any reason why substituting the water in an evaporative cooler with, say, strawberry schnapps could not get you tanked while sleeping?

Welcome Mark “Barry” Taylor.

methinks barry is an air-conditioning salesman.

For the canberra climate evaporative coolers are much better.

unless you need to be in a house that is 17C all the time, the evaporative cooler is far cheaper and provides enough cooling for an average Canberra house.

On the other hand with Canberra’s low humidity one imagines it generally works pretty well.

evaporative cooling – don’t believe the hype;

folks, not sure if you experience the same temps as SA or VIC – but with the recent heatwave that has just gone through (several days above 43 degrees celcius) – evaporative cooling was a total waste of money for a couple of colleagues i work with. they would get home, turn on the evap and all it did was bring down the inside temp to 30 degrees – what a waste of money! one of them said that at one stage his brand new unit was blowing in hot air. suffice to say that his wife has demanded they get a real aircon before next summer so that both her and their new child can have some comfort.

they may be cheaper to run than real air-con (don’t fall for the ‘evaporative air-conditioning’ marketing rubbish) – but if you want ‘real’ relief go a real airconditioner (you can always bump up the temp to 24 degrees if you want to save some money – and also only cool the main room of the house).

this document explains some of the pitfalls of evaporative cooling;
http://www.eduweb.vic.gov.au/edulibrary/public/schadmin/environment/trees/InfoTechSpecifications/Evaporative-coolers-vs-AirConditioners.doc

it is imporant to note these points;

– During periods of high humidity and high temperature, the effectiveness of evaporative coolers is limited (ie, no ‘real’ relief),

– An evaporative cooler reduces control over temperature and comfort (no ‘real’ relief part 2).

– The air from an evaporative cooler is not “cleaned” as well as with an air conditioner (forget the marketing hype about ‘stale’ air being recirculated).

– An evaporative cooler needs to have open windows or vents to outside (what if you want to go our for a few hours – do you leave the house open?).

– An evaporative cooler adds moisture to the air and damp air can cause doors and wood furniture to swell (cold or flu anyone?).

– An evaporative cooler requires more maintenance than an air conditioner.

the way i see it – if evaporative cooling was any good, most places of work would have them installed – they don’t and for good reason.

Another big YES vote for Breezair and Scania in Fyshwick’s professionalism.

The guys showed up on time to install ours in our 3br single level house and took from 8am till 3pm to do all work. all tradies intriduced themselves and asked plenty of questions to make sure we got exactly what we wanted.

We even got a discount deal for November from Breezair knocking some cash off and adding 3 years extra warranty and an upgraded controller for free.

Very impressed in the performance of Scania and Breezair unit (6 ducts used – 2 more available for future expansion – 170 model). They didn’t mention it but u even get a nice Feng shuish very faint trickling water sound when outside but no fan noise to report outside or inside so = happy neighbours and very happy us.

Now we just need some weather worthy of the awesome new cooling !

ta to rioatacters who recommended both too !

just one thing – it seemed the brivis link mentions only a refrigerated cooling unit, not evap.

Maybe I missed an extra link ?

Woody Mann-Caruso said :

<snipI have Brivis gas heating but I doubt it would integrate but not overley concerned.

Gord0 – we had Brivis heating before we got the evap cooling. They put in a new controller to replace the one for the heater, and now it controls both. You probably can’t use the same ducts – Brivis said it was possible with some units, though (see here: Brivis Add-On Cooling).

We got the top-of-the-line Brivis system (Countour?) for about $4K installed in early 2007.

Awesome – thanks heaps ! using existing ducting probably cuts down on a lot of labour $$ too…

Woody Mann-Caruso11:12 am 03 Oct 08

Fired it up last night (fan only, didn’t need the wet part) – feels like summer already.

But if you use electricty to run cooling devices won’t a polar bear drown?

Yeah, but not if you’ve got 100% GreenChoice electricity 😛 Now, I’ve got to go soak some lentils for lunch.

tylersmayhem11:02 am 03 Oct 08

Nice WMC – cheers for that mate! Looks like you’ll be revving up the cooling this weekend *knocking on wood*

Woody Mann-Caruso4:20 pm 02 Oct 08

Extremely happy with both our Brivis heating and cooling. The heating has had one glitch in nine years, and it just happened to show up when we were on the bus to catch an international flight. House sitter called me, I called Brivis on the mobile, they sent a tech out to fix it that day, said we could fix them up when we got back six weeks later. The unit was well and truly out of warranty by then, but they seemed genuinely horrified that something had gone wrong. That was 2003 – haven’t heard a peep out of it since.

your , not you’re .. shesh

Interesting. We got the insulation, whirlygigs and ducted evap cooling installed at the same time. The house was noticeably cooler even with the aircon off. Does this mean it’s actually the whirlygigs doing the work rather than the insulation?

Can’t say. There are some on that envirotalk site who are dead against whirly-gigs, but as you say your insulation and whirlys make it cooler so they must make a difference.

I think the point is that the R-values for bulk insulation are not valid for very hot roofspaces subject to radiative heating. It still does something, but RFL alone would do better (at least according to those that know).

We in Canberra still need bulk insulation for winter however, so you’re money was not wasted.

tylersmayhem4:11 pm 02 Oct 08

Do Brivis seem reliable WMC?

Woody Mann-Caruso4:04 pm 02 Oct 08

Interesting. We got the insulation, whirlygigs and ducted evap cooling installed at the same time. The house was noticeably cooler even with the aircon off. Does this mean it’s actually the whirlygigs doing the work rather than the insulation?

Doesn’t really matter I guess – the insulation does the trick in winter keeping the ducted gas heating in, so it’s not like we wasted the money (which wasn’t a lot anyways).

I have Brivis gas heating but I doubt it would integrate but not overley concerned.

Gord0 – we had Brivis heating before we got the evap cooling. They put in a new controller to replace the one for the heater, and now it controls both. You probably can’t use the same ducts – Brivis said it was possible with some units, though (see here: Brivis Add-On Cooling).

We got the top-of-the-line Brivis system (Countour?) for about $4K installed in early 2007.

I should also point out that bulk insulation in your roof might not actually do that much good stopping heat gain in summer, for that you need RFL (shiny foil stuff):

http://forums.envirotalk.com.au/Roof-Insulation-t7772.html

tylersmayhem3:20 pm 02 Oct 08

I would draw a little ASCII stick figure of me rubbing my crotch against my ducted evaporative cooling system but I’m no artist.

Haha, my chuckle for the afternoon. thanks WMC!

aidan said :

The portable evap units I have tried are crap — there is no comparison with the rooftop coolers which work very well.

Agreed, but I am poor.

Woody Mann-Caruso2:25 pm 02 Oct 08

I would draw a little ASCII stick figure of me rubbing my crotch against my ducted evaporative cooling system but I’m no artist. Pair with R4 insulation in the roof and a couple of whirlygigs and my place is like the inside of an esky in the middle of summer with the doors and windows open. Ours is a Brivis, got it installed by Luxaire (near Zierholz in Fyshwick) – top blokes.

Another vote for Breezair. We don’t notice the electricity or water usage on our bills.

The centrifugal fan is very quiet except when you have it on full and this is only when we arrive home and the house has been closed up and got stinking hot.

It is nice to have the windows and doors open, we don’t have to yell at the kids to close the door.

Evaporative cooling pretty much doesn’t work at night, as the relative humidity rises rapidly when the sun goes down and the temperature drops. But that is largely the point, the temperature has dropped so you can just pipe in the fresh air outside. It is great when a cool easterly sweeps in. You can make the outside and inside temperature pretty much the same within minutes.

Most of last summer the temperature in our house was between 23 and 25 even on those 38 degree days. The portable evap units I have tried are crap — there is no comparison with the rooftop coolers which work very well.

Best part about evap is after getting sweaty and hot outside, opening an external door a crack and standing on the outside in a torrent of cool fresh air

tylersmayhem1:49 pm 02 Oct 08

Any recommendations on co’s to use or avoid yet?!

Who say’s I;m impatient. Next this I’ll be called annoying, or even a douche!

+1 vote for (ducted) evaporative cooling.

It takes about 10 degrees off the temp but the breeze makes it feel like more.

One tip is that if its forecast to be warm then turn it on in the morning and let it run all day. It won’t work well if you turn it on when it feels hot in the house already.

You need to have windows open – I installed window locks and lock our windows open a few centimetres.

Ours uses about 5-10 litres of water a day and I send that water onto the lawn so its not a waste.

We gradually did insulation, then the roof whirly things, blockout blinds, new doors etc, and eventually gave in and got cooling. Some houses are just hot boxes and face the wrong way with too many windows.

we have the whirly thing, and decent insulation, but have a heap of vents from the days of the old oil heater. gotta get around to blocking them up…

Our Breezair was about $4200 fully installed I think. Would cool a 4 bed house.

You may not need it if you do some sensible prevention work on your house first. Try keeping the sun off windows in the first place by eg putting up awnings. I’ve got ones with modern materials that is transparent one way, ie allows me to see out to the street, but blocks out the sun and stops anyone looking in (amazing tekernology). Also, try keeping curtains closed during the hottest part of the day and opening the house up at night to let cool air in. Keep green space around your house instead of paving or concrete. Put a whirly gig in the roof to let hot air out. Put in top rating insulation in the ceiling and wall cavities. I have also just replaced a western facing front door with a glass one that uses ‘Comfort Plus Glass’ which is specially designed to repell heat while letting the sun in. We haven’t needed air con or other cooling since.

Count me in with another vote for evap. I *love* the cool breeze feeling rather than stuffy refrigerated air that ends up leaving you feeling to cold. My dust mite allergy is less noticable and my skin is not as dry.

We bought a Breezair unit about 3 years ago – installed by Scandia Air Con in Fyshwick and they did a great job – their after sales support is also excellent as I called on a Saturday once and the guys called me back from a WEDDING and the glitch was fixed first thing Monday morning. We chose this brand because it is super quiet and we have neighbours with a double story so didn’t want to bother them at night. I’ve found you can only hear the unit if it is really cranked up – which you would only do on a really hot & humid day. We paid a little extra to get the next capacity model in case we ever extended the house and so find that 90% of days we have it sitting on 2 bars – barely cranking and totally silent.

Ours – and I expect all current models – use a computer to monitor water quality – so it only dumps waters when it needs to. I think we go at least 3 or 4 days before the water is dumped and replaced. Very efficient.

Running costs are supposed to be the equivalent of a 60w light globe – so 20c a day sounds about right.

tylers, ill have to go home and have a look @ paperwork – its been about 3 years and Mrs Danman is more cluey on our expenditure than me.

tylersmayhem12:51 pm 02 Oct 08

@Danman: Sounds like a great system man! Can you say how much it cost you back then and can people recommend, or not recommend good companies to install them?

Cheers!

We had it in our last house – it was fabulous. The cool breeze is nice and fresh, unlike aircon which is dry and stale.

A downside is you have to leave windows open for it to run – which makes some people nervous at night. Each time you power it up it suck up 20 litres of water, so it is better to leave it on and turn the fan right down, than to be turning it on and off all day. Also you need to manually shut all the ducts during winter, to avoid losing all your heat to the roof space.

Upsides are it does the whole house at once, is cheap, and nicer air.

You can’t usually integrate it with existing heating ducts. And try to get the model where when you turn it off, you can let the remaining water pour down a hose onto a part of the garden rather than into the gutters – some models don’t allow for this.

and make sure you get the model

We have breezaire – Our neighbours up the hill can see and hear it, no dramas there, our downhill neighbours have the same unit – we can see and hear it outside – but its not noisy – just background noise – evaps are notorious for noise though – so if you like your neighbours, do your homework.

Definately the route I’m going (evap).

Several friends have it and love it.

One warning from them was to check the noise level of the fans they use in evap. One is a drum config and is apparently much quieter than a more conventional bladed fan design. Either way seems like the smart way to go.

any brand recommendations ? I have Brivis gas heating but I doubt it would integrate but not overley concerned.

I’ve measured our evaporative cooler and it costs 20 cents per day to run. The only downside is that it does attract flies who like the cool humid air. They can also be a bit noisy. A full throttle our system roars but as we are usually staying inside due to the heat we don’t notice it – our neighbours might have a different view however.

Whilst they do need regular maintenance to prevent crud building up, they are much simpler and less expensive to repair then refrigerative cooling when something goes wrong.

DarkLadyWolfMother9:40 am 02 Oct 08

I’ve used portable evaporative coolers and find they make the room too humid and sticky, even on dry days. This may well be due to the dumb room design that means even with windows and doors open, there isn’t enough airflow to help shift anything.

Evaporative coolers work a treat in dry air climates, having several times had to spend a day sobering up in Wagga at midsummer.
I keep my living areas at home cool in summer with a cieling fan and one of the old evaporative box blower units.

Downside is they’re a bit water thirsty and maintenance hungry.

SCIENCE WARNING: Something about humid air having a higher specific heat capacity than dry air, so is able to acquire more heat energy (or seem more ‘cool’) for a given temperature. (i think)

Having moved from Brisbane to a house here fitted with ducted evaporative cooling I have to say it is great! We can leave the windows and doors open and get a lovely fresh breeze blowing through the house. If we crank it up to full the breeze even comes out on to the deck which is prefect when relaxing with a beer on a hot summer day!

I have evaporative cooler and it is fine for Canberra. On really hot days you can put it on high. If there is a really humid day then air conditioning might be a little better, but in my opinion not worth the huge extra running costs. In the last few years there have probably been 1 or 2 days a year like this if any at all, and it is not completely ineffective on those days just slightly warm ie a lot cooler than outside.

And you get to leave the windows open for fresh air too!

We got evap and would fully recommend it.
Canberras snap dry heat is well suited (As said above) to evaporative cooling.
In the 3 or so years that we have had it, only 2 or 3 really humid days have left us stranded.

Evap also had a bonus of cooling our patio area by means of th eopen doors (You have to open doors and windows for evap cooling to work efficiently)

We have a breezaire rooftop model. Self cleaning, self purging maintenece – free.

The only downside of evap cooling is that it curls up teh pages of books if they are left near a draft – but i findthat air con drys me out too much so prefer the evap..

They consume less electricity as well, becausee essentially they are just a fan that sucks air through wet sponges.

Insulation and evaporative coolers are much more suited to Canberra’s climate than air con. Air con’s just overkill.

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