Sizing of units

[AC&R Jersey]

Hi there guys. Just wondering if anyone could help me out. I have been installing Air con and refrigeration for the past 9 years and I have decided to start my own company, problem is the boss always sized up the equipment we used so could anyone please tell me the correct formula for sizing up of air conditioning units. I know all of the relevant factors to be considered but I'm not to sure of the calculations with the measurements.

Thank you.

[Brian_UK]

There is quite a lot of free 'sizing' software out on the web, have you tried any of those or are you wishing to do it be hand.?

[AC&R Jersey]

hi thanks for the reply. I have seen some sizing information on the net, but no down loadable software. where would i find such software.

[Toosh]

hi thanks for the reply. I have seen some sizing information on the net, but no down loadable software. where would i find such software.

Hi Ac go to the danfoss site and download coolpack its free

Norm

[beagle]

Also, don't forget you can lean on your suppliers for this kind of support, unless it's an urgent one (ie: immediate) or you need a quote together out of office hours most suppliers can turn a full quote round pretty quickly these days.

[Prince Vaillant]

http://www.ryanairconspares.com/cooling_calculator.php

[AC&R Jersey]

Thanks very much for all you help guys. Time to get some work now.

[Greengrocer]

Thanks very much for all you help guys. Time to get some work now.

Knowing roughly what load to expect as a double check is also invaluable. Software is great but like all PC based stuff if you put "rubbish in you get rubbish out".

For a general office A/C 100watts/m2 = competitive selection.
130-140watts/m2 for south/west facing more densly populaated and a cover your ar** selection.

[Contactor]

Don't rely on software, it will give you a rough idea in offices but is hopeless for other quotes e.g shops(door always open), restaurants with open kitchen, small industrial units etc etc etc

The NVQ level 3 is a good starting point for design work.

If you're asking this with a view to offering quotations, as long as you are about right with your sizing you can worry about calculations after the order comes in because most of your costs will come from elsewhere anyway, eg materials, labour, access etc etc. This will save lots of time!

I've never used suppliers for this either, I avoid Daikin like the plague, the 15 year old Neanderthal Sloths working the telephones can't even grunt properly and only operate the handset after it's been ringing for 15 hours.

[Prince Vaillant]

LOL he only asked for some help! you see thats whats wrong with this industry, no one wants to help anyone!

[Contactor]

Unqualified suppliers should not be offering this kind of help, they put up crap software to improve sales.

[puddleboy3]

Unqualified suppliers should not be offering this kind of help, they put up crap software to improve sales.

Am I missing somethng here! No disrespect but installing for nine years aged 24. So right out of school, apprentice for four years to learn your trade and then many years to master your trade.

One question I would ask are you a qualified A/C fridge installation engineer?

[WINJA]

, I avoid Daikin like the plague, the 15 year old Neanderthal Sloths working the telephones can't even grunt properly and only operate the handset after it's been ringing for 15 hours.

This must be a daiken world wide policy.



http://www.aircondition.co.nz/pump_calculator.htm

the above calculator is quite good , beware it maybe country specific

[paul pursehouse]

hi,I was in the same situation,
Rule of thumb 100-110w sq metre as a check back.We used what was known out here as the arema survey form it is **** hot but you need to take a lot of measurements,I have recently bought a commercial program from a fellow in melbourne australia for sizing single room or whole of house/zoning up to 3 zones very cheap. it works well and is recognised by the CSIRO in australia.If you are interested I can pass this on so that you may be able to buy a copy your self
I found all the free stuff is too basic to put your name behind if you want to have a good bussiness

[beagle]

Unqualified suppliers should not be offering this kind of help, they put up crap software to improve sales.

The "crap software" you mention is likely just a graphic representation of the rule of thumb calculations 99.9% of engineers use when tentatively pricing a potential job, I can't see anything wrong with that at all as long as it's used in the manner it's supposed to be used and if it isn't, the user really only has themselves to blame as all of these sorts of simple software programs carry a disclaimer.

Blanket statements like yours aren't at all helpfull, I know guys working for suppliers that have an absolutely mind boggling wealth of knowledge at their disposal, of course I've known some plonkers as well but the trick is to find one you get along with, can rely on and have a decent working relationship with and you'll never look back.

The strain that the technical sales guys can take off of their customers can be invaluable if used in the right way. Of course it's a two way street though and we're all human, put a bit of business their way, be nice and you'll find they'll be as helpfull to you as it would be if you had your own technical sales guy sitting in your own office.

[Contactor]

Those of you without qualifications can get your suppliers to do your maths for you if you must, in fact go ahead as we professionals get paid to clear up your mess.

[beagle]

Well I'd take experience over qualifications anyway and ultimately, the guys on the front line for the suppliers work with their kit day in, day out and will more often than not have a better understanding of it than anyone, in some cases even the manufacturer themselves. As I said before, there's some good and some not so good but if you choose to ignore that as a potential resource, it's your loss in my opinion.

[Contactor]

This thread is about 'sizing of units' Beagle. However I agree with your (somewhat obvious) observations on manufacturers technical data.

As for 'experience over qualifications' this person has 'NINE YEARS' in the trade and yet is being told to call manufacturers and use free software to calculate cooling loads.