Noisy Braemar air conditioner

[Tiger]

I don't know much about air conditioners but with the recent heat and projections of a hot summer i am contemplating getting one. A couple of townhouses have been built 18 months ago approx. 40 to 50 metres from us. They both have identical air conditioning units which are mounted on the roofs but one unit is very noisy, how can this be? Can see that the brand is Braemer, the air con units must be fairly currrent. The air con units are cube shaped and measure about 600 to 700 mm across each dimension.

[Chief Tiff]

Evaporative air coolers - nasty things only enjoyed by those who would rather live in a yurt, weave their own yoghurt and wear shoes made from bark. Absolutely essential for those who wish to farm mould.

What noise comes from them? There is really only a fan and a water pump; if the fan is running billy-oh then that'll make a bit of a noise. The only other thing I can think of is if the whole assembly isn't mounted properly and is making the whole roof vibrate.

[Tiger]

Thánks Chief for that simple and eloquent explanation. Why do you say they're orrible? I don't know if there are many other choices at my place but if they're going to make as much noise as the one i'm hearing now it might be portable fans throughout the house.

[Big Shed]

Evaporative air coolers - nasty things only enjoyed by those who would rather live in a yurt, weave their own yoghurt and wear shoes made from bark. Absolutely essential for those who wish to farm mould.
..........

Perfectly true where you live Chief, but not where the OP lives, slight difference in relative humidity most of the time between the southern states and Qld, especially as you get higher up.

Also totally useless in Darwin etc.

But in Melbourne and Adelaide they work very well indeed at least 85+% of the time and are very much cheaper to run than a reverse cycle aircon.

Many a time we ran ours in Adelaide 24/7 days on end.

[Tiger]

I understand now that these work with minimal humidity, my house is not that large, is there a big difference between 12kw and 16kw and could that account for any noise difference?

[Chief Tiff]

I understand now that these work with minimal humidity, my house is not that large, is there a big difference between 12kw and 16kw and could that account for any noise difference?

The power rating relates to the power consumption rating of the fan and to a lesser extent the water pump. Refrigerated air con power refers to the actual cooling effect of the system at maximum and generally means more when expressed in BTU rather than kw. But 12-16kw sounds way too much!

Evaporative air con works by using warm outside air to blow through a very coarse filter which has water soaking through it. The water wants to be carried off by the air but to evaporate it requires heat energy which it acquires from the air itself. So, warm air goes in and cooler air comes out.

But...

If the air is already quite cool then its water carrying capacity is reduced. If the air already has a high relative humidity level then again, it can't hold much more water and the cooling effect is reduced. Finally the air cannot be recirculated; it has to come into the house via the box on the roof and must be exhausted through windows, doors or purpose built vents. So if you live somewhere with high humidity they're useless. And any cold surfaces in the house immediately soak through with condensation, remember that having absorbed this water the air has a much higher relative humidity than the air already in the house, if it gets chilled down any further then it can't hold its moisture and dumps it onto the cold surfaces. Mould. Yay. And wind whistling through house all the time.

Refrigerated air con has the opposite effect, passing the air across the evaporator coils cools it down and causes it to dump its moisture which is why the head units always have drains leading water away. So you get cool dry air blowing around the room. The air gets recirculated and if your house is well insulated the cooling effect is more efficient. They simply work better but they come with a high running cost which can only be reduced by improving the insulation of the house. Evap systems are very cheap to run but only work really well if you live in a dry climate.

Personally I had an evap system when I lived in Rockingham WA, hated it with a passion and found cheap $20 pedestal fans dotted around the house were more effective and MUCH quieter. When I lived in Aspindale Gardens in VIC we had nothing so we froze in winter and cooked in summer. And in Darwin we had both ceiling fans and split system air con so I can speak with a little bit of experience here but obviously its merely my opinion.

If you feel you have a compact place perhaps a centrally placed large split system would be best, if you leave the room doors open it can chill down a house quite soon. You just need to stop external heat from coming in so close the curtains and insulate your roof! And come the winter you run it as a heater with the same conditions for slowing down heat transfer.

[ian]

Evaporative air coolers -

also known as swamp coolers

nasty things only enjoyed by those who would rather live in a yurt, weave their own yoghurt and wear shoes made from bark. Absolutely essential for those who wish to farm mould.

What noise comes from them? There is really only a fan and a water pump; if the fan is running billy-oh then that'll make a bit of a noise. The only other thing I can think of is if the whole assembly isn't mounted properly and is making the whole roof vibrate.

[bsrlee]

Compressor type air conditioners can be noisy, specially if the owner can't be bothered maintaining them - lots of screws, grills and fans to come loose and rattle about and they make good homes for small animals when turned off.

In NSW at least it is also an offence under the various noise abatement regulations to run air conditioners after a certain time - you may want to enquire with your local council inspectors if they are running the air day and night - even a polite enquiry from the council may 'encourage' the occupants to do some maintainance even if they do run them late at night.

If its a rental property then a complaint to the managing agent should work as I think they get a percentage based on cost of maintaining the property so it is in their interest to get the thing fixed or replaced.

[Tiger]

Thanks for your help guys, I've got a better understanding of these things now and what I have to do.

[Glenn.Visca]

I had an evap unit in a 2 storey house in Melbourne and loved it. Prior to having it we would cook in the upstairs bedroom, after having it, almost all nights were cool and required a light doona.

Advantage of these is you can focus the cooling to a particular area by opening windows/doors in THAT area only, regardless of the location of the outlets.

You can't do that with refrig cooling.

Different house now, and 2 large refrig aircons make the house beautiful even on stinkers. $$$ to run though.