How are you sizing up your AC system?

Hi,

Can anyone share their experiences with selecting the correct size AC systems?

Daikin (3phase) has served us very well for the past 17 years. But with a KDR in the mix I'm exploring the optimal options.

Traditionally the AC is sold to cool/heat the entire house quickly but this is rarely ever needed.

And with more 'zoning requirements' than ever before; are we over compensating for handful of times when the AC system is 'pushed' to capacity??

Considering 90% of the time if will 'either be set to living areas OR bedrooms'.

With this in mind, should we be sizing the system to accommodate for the larger of the 2? And as a result, is buying a ducted system for the entire house overkill and an additional cost for a system that would mostly run at say 50% capacity?

That being said, with more zones and AC Systems improving their efficiency to the point they can ramp down based on zones they need to service, could this again lead to smaller systems that are appropriately size to service the largest of the combined 'active zones'?

Please let me know your thoughts.

Cheers
GLO

I just finished a ducted system with a mate for his place where I assisted him to size it to do living areas as one zone and bedrooms as the other


Traditionally ducted systems were sized for worst case scenarios of those few times of year where the system is running at 100% to condition your house as you've stated.


Some installers will push to sell a system that conditions the entire house at worst case scenarios where as others will sized it in conjunction with how the homeowner intends to use it and making them aware that with the smaller sized system you may struggle those dozen times a year when the smaller system won't condition their house to what they're used to.


This is the theory behind all the VRF/VRV systems whereas not every zone served by individual indoor units will be requiring 100% capacity all the time so a smaller sized system could serve more zones.

We went Actron single phase for 37 square area, we mostly run 2,maybe 3 of 4zones,handles it easily, if we had a 40 degree day, would run 3 zones, which is pretty much all house, bar spare bedroom and study, which we never ever use.

17kw Actron single phase.

H Joker,

You are in continental Victoria or in Melbourne? Do you think bigger unit will be needed for Sydney?

WBR,
Alex

No ,unit size can depend on design,quality of ducts,how efficient your home is,get best installer,even if a little more expensive,get him down in price a little,but be fair,the quality of design and install is just as important as is unit choice,maybe,even more important.

I'm in Geelong,Victoria,our summers can hit early 40,s,and be humid and or dry,works well no matter what.