Browse Forums Heating, Cooling & Insulation 1 Jan 26, 2009 10:45 am Hi All
We are still in the throws of trying to sort out issues with our home, - been in just over 6 months now Was wondering if anyone knows the Australian Standard for ducting and vent sizes for ducted system. We have an 18kW Daikan installed by M. We believe the duct and vents are not correct sizing but need the Aust Standard to back us up. Daikan are not interested in helping. Thanks in adv Anne Grandview 36 on Beautiful Bribie Site Start Dec 5th 2007 Projected completion May 12th 2008 NOPE Handover 24th June 2008 Moved in 11th July 2008 Wating on one final thing - Still - Oct 2009 Re: Aust Stand for Duct and Vent sizing 2Jan 26, 2009 1:45 pm I dont know if aus standards exist. However 200mm duct should do 17square meters. But there is more too it then that.
Does the system work properly?? It doesnt really matter how it is designed in the end as long as it work properly. Just a note that refridgerated cooling uses smaller duct size than evap. Re: Aust Stand for Duct and Vent sizing 4Jan 30, 2009 5:33 pm Thanks for the reply's, no I don't hink it is working properly, our main bed which is the longest run takes a very long time to get cold and my boys room which are very close to the return air vent are too cold even with the vents closed most of the way. M advertising is a crock - "Ducted air conditioning solutions made to measure." - rubbish
I am just not sure if there is an Aust stand or calculations per system Any experts know where to point me? Anne Grandview 36 on Beautiful Bribie Site Start Dec 5th 2007 Projected completion May 12th 2008 NOPE Handover 24th June 2008 Moved in 11th July 2008 Wating on one final thing - Still - Oct 2009 Re: Aust Stand for Duct and Vent sizing 6Feb 28, 2009 9:58 pm Rooms with smaller runs have less resistance. e.g. a 3M duct run will get more air than a 9M duct run. Sounds like all the system needs is a few strategically placed inline manual dampers to restrict some airflow to the kids bedrooms that will push more airflow to your master bed. Re: Aust Stand for Duct and Vent sizing 7Apr 08, 2009 8:42 am I used to work as a designer for a company that designed industrial aircon systems. It is a specialised field that uses engineers to do calculations. Not my area however I can tell you that there is a very basic handheld slide ruler measurement tool, that helps them determine duct size according to length of duct required, size of room, cubic meter of air to be moved. It sounds like the main bedroom duct is too narrow and therefore the air is taking the path of least resistance. If you simply install dampers it will cause the fans to work harder, Id say increase size of main bedroom duct ans see how it goes. Re: Aust Stand for Duct and Vent sizing 8May 19, 2009 5:10 pm Sounds like you need to call the Installing company and ask if they can do an air balance. This should have been done at commissioning stage. They will be able adjust the amount of air to different rooms, more to some, less to others. This should sort out the problem. Cheers Re: Aust Stand for Duct and Vent sizing 9May 24, 2009 8:42 pm You may need to upsize the duct to the master bedroom, and/or put manual dampers on the kids bedrooms that are getting too much air.
Re: Aust Stand for Duct and Vent sizing 10May 25, 2009 9:42 pm Thank you all for your replys. Yes you would think the situation should be easy to fix alas not. Our builder and the installation company refuse to take responsibility for it. We affectively have a $14k+ white elephant. This is the result of two major issues. Our outdoor unit does not comply with EPA guidlines for noise and therefore can not be run at all. Even after the manufactuers"fix" that we waited months for. There fore it is "not fit for purpose." Secondly ducting, vents and valves in our home do not appear to be appropriate for our home as per the engineering guidlines that we believe should be being used. We have asked for the air con plan for our home, and the design calcuations showing that what has been installed is correct. The builder/installer is either unwilling or as we belive unable to give us these. We believe they do not exist. Considering the advertising that comes with this option we thik they have a case to answer. We are currently at the beginning of the process with the Office of Fair Trading and QBSA. Only time will tell Grandview 36 on Beautiful Bribie Site Start Dec 5th 2007 Projected completion May 12th 2008 NOPE Handover 24th June 2008 Moved in 11th July 2008 Wating on one final thing - Still - Oct 2009 Re: Aust Stand for Duct and Vent sizing 11May 26, 2009 11:58 am coljacqld We are currently at the beginning of the process with the Office of Fair Trading and QBSA. Only time will tell I have heard (but would need an expert to confirm) that the majority of AC companies are hacks and think installing a unit is as simple as cutting some holes in the ceiling and connecting the ducts in. Most don't do a proper heat load calculation or an engineered design. Whilst organisations such as AIRAH provide a lot of technical guides they are not involved in policing the industry. Which actually sounds like a large proportion of construction in general. Re: Aust Stand for Duct and Vent sizing 12May 26, 2009 4:51 pm Nice comment Dymonite69 Based on what you've heard? Dymonite69, You have confirmed you don't have a clue. You have no idea! This comment is baseless and undermines the good work that most air conditioning contractors do! Re: Aust Stand for Duct and Vent sizing 13May 26, 2009 6:23 pm Fridgy This comment is baseless and undermines the good work that most air conditioning contractors do! Absolutely. On the other hand, is there a method of verifying the credentials of the company or be presented with their methods and calculations prior to installation? I contacted AIRAH who are an impartial organisation but they were not able to suggest how I could confirm that I was going with a reputable installer. When presented with the plans by two separate companies - one were at pains to avoid placing grilles near windows (presumably to prevent convective losses through the glazing), whilst the other had grilles furthest away from the doors (to encourage air flow through the room). Similarly, one technician advised not to open internal doors to operating zones whilst I have been otherwise told this will prevent air returning to the unit (and resulting in overpressure and exfiltration). Why all this contradictory information. Aren't there standards and who is reading or following them? As a consumer this is very confusing. Re: Aust Stand for Duct and Vent sizing 14May 28, 2009 12:50 pm My understanding was that the policeman (for lack of a better word) are the QBSA for the technical side of things. I have had some fantastic dealings with a couple of air con installers in Brissy, non more so than Snowdonia and Tony Redsell Air Con. I tried getting advice from AIRAH but they didn't return my phone calls. Oh to have my time over again Anne Grandview 36 on Beautiful Bribie Site Start Dec 5th 2007 Projected completion May 12th 2008 NOPE Handover 24th June 2008 Moved in 11th July 2008 Wating on one final thing - Still - Oct 2009 Re: Aust Stand for Duct and Vent sizing 15May 25, 2022 8:25 am This is a very old topic, however I am certain it is just as relevant today so thought I'd add an update for anyone who lands here later. I work in a related industry with a lot of crossover so thought I'd add some professional input. The installation requirements are basically State regulated, although some requirements are part of the BCA. My experience is strictly NSW, however the installation issues are probably very similar Australia-wide. System specification, design & installation forms part of air-conditioning trade training but real world conditions overtake optimal application of best-practice principles. Like all businesses, time & money are the real driving factors in the industry and these ultimately shape the quality of installations. The issues quoted by Dymonite69 are commonplace. Despite the license-holder for a particular business being trained often the guys actually doing the job are not and they simply make it up as they go along. Basics such as where to place outlets and the Return Air are often confused (part of this is the dynamics of heating & cooling are different but the system needs to do both usually) and some installers simply don't know how to do it or have received erroneous instruction from senior colleagues or their employers. In general terms outlets should be near windows on external walls which are opposite or at least as far away as practically possible from the door to the room. This is simple physics, the major temperature differential is usually near a window and the exit point for the air in the room is the door to the rest of the house - so the outlet goes near the window(s) to minimise the temperature differential and allow the air to fill the room as much as possible before exiting the door under the draw from the RA. In R/C installs the Return Air should be centrally placed and as low down as is practicable (close to the floor preferably) - this is because cool air falls so being drawn along the floor makes no practical difference, whereas in heat mode warm air rises so you don't want the airflow along the ceiling but down towards the floor. They should always be filtered as well, they are much bigger but then all airborne debris stops at the filter pad rather than being circulated through the ductwork. The Thermo/wall control should not be close to the RA as there is a zone of temperature difference around the inlet, it should be centrally placed in the largest common area which forms part of the Common Zone. This will allow it to sample the largest area of average temperature and hopefully achieve the best overall temperature balance through the house. Duct sizing, routing & connection are usually the biggest issue (after under-sizing of units for energy output & airflow) as this is really where the rubber meets the road. Because a lot of these systems are installed in ceiling spaces (especially as retrofits) the installers often shortcut this part of the job to make their lives easier, it's no fun having to lie on your face in fibreglass insulation etc so the path of least resistance is very attractive. Air has a lot of similarities to water so the same principles apply as in Hydrodynamic design, you need to manage pressure and flow to ensure even distribution with minimal restriction. In regards to Coljacqld's specific issues, I'd be very interested to know how her action through DFT & QBSA went. In my experience these organisations 'talk the talk' but definitely don't 'walk the walk' when it comes to enforcement of the Consumer Guarantees. Generally speaking if you aren't willing to undertake legal action yourself, you'll get very little traction if the business at fault resists or ignores the bureaucrats. 10https://www.homeone.com.au/member/coljacqld Re: Aust Stand for Duct and Vent sizing 16May 25, 2022 12:20 pm Greendragon I would agree with the most, but placing outlets is also of the question of the comfort, e.g. placing outlet over your working desk or over your bed can be a problem. What do you know about draught free aircon systems with smaller ducts such as Airsmart? 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