how big is your ducted refrigerated unit?

Damon · Apr 28, 2008 9:55 pm

hi
i am building a 29 squares PD 4 bedroom house at the moment.
the living area to be cooled is 101m2 and bedroom area is 61m2 .

what confused me most is that i have 3 quotes form 3 contractors. just for living area, one quoted 19kw , other said 15kw will be more than enough , one even say 13-14kw , all of them got my floorplan to do the cool load calculation so i am very confused about how big i should go for.

i understand a house at this size need zoned system as cooling 160m2 at once could need ~20kw or bigger

therefore, may be i can get some users feedback / rough idea here if you can reply by stating
1) how big is your floor area to be cooled
2) what power is your installed ducted refrigerated unit
3) does it work well ? e.g. does it struggle to cool ? or does the compressor keep turning on and off all the time?

my previous little research ( single case study ) already shown a 2-zoned 15kw Brivis ICE can get a PD 30 squares house well under control

thank you so much
Damon

PhoenixStar · Apr 28, 2008 10:32 pm

Damon

hi
i am building a 29 squares PD 4 bedroom house at the moment.
the living area to be cooled is 101m2 and bedroom area is 61m2 .

what confused me most is that i have 3 quotes form 3 contractors. just for living area, one quoted 19kw , other said 15kw will be more than enough , one even say 13-14kw , all of them got my floorplan to do the cool load calculation so i am very confused about how big i should go for.

i understand a house at this size need zoned system as cooling 160m2 at once could need ~20kw or bigger

therefore, may be i can get some users feedback / rough idea here if you can reply by stating
1) how big is your floor area to be cooled
2) what power is your installed ducted refrigerated unit
3) does it work well ? e.g. does it struggle to cool ? or does the compressor keep turning on and off all the time?

my previous little research ( single case study ) already shown a 2-zoned 15kw Brivis ICE can get a PD 30 squares house well under control

thank you so much
Damon

Our unit is the CDU18A-9 (17.1 kw) with 3 phase power to 12 points and zone motors as discussed via PM. Total floor space is 249.6m2

House isn't finished yet so can't tell you but will keep you informed.

Let us know how you go?

3timesbuilda · Apr 29, 2008 1:24 pm

From a previous post of mine (I'm getting lazy)

Quote:

Non invertor air conditioners work as follows. Whe the unit is switched on, the unit runs at full capacity (power use) until a certain set temp is reached. Once reached, the unit switches off (although the fan may still run) until the temp rises to a certain level above the set temp and then it switches on again. This repeats with the unit switching on and off.

Invertor air conditionerswork as follows. When the unit is switched on, the unit runs at full capacity until a certain set temp is reached. Once nearly reached, the unit slows down (uses less power) and gently increases or decreases the power use as needed to keep as close as possible to the desired temp. This means that the tempreature is more even - no hot and cold all the time. In a well insulated house, the temp is very even. This method also uses less power. This is because the unit is more efficient when it is not running at full power.

I recommend an inverter unit, with high efficiency >250% and one that is somewhat overspecced (claims to cool a larger area) for the area. This will allow you to cool colder on hot days, use less electricity and have more even tempreatures

Remember that by quoting for a smaller system, you will come in at a lower price and have a better chance of winning the job. Best to get a quote for a size that you specify and then go from there.