Zone Cooling Replacing Whole Home Air Conditioning

A lot of people get confused over the difference between zone cooling and whole home cooling, so this article sets out to explain what each of these is and how they differ from one another.

Air conditioning in the home or workspace can be an expensive necessity with rising fuel costs, so it makes sense to try and cut costs by having your system run as efficiently and economically as possible.

The Whole House Air Conditioning Problem

The main problem with a typical whole house or central home AC is that it cools the entire home, whether certain rooms are occupied or not. It's just like having a single switch that turns on or off all the lights at the same time.

zone air conditioningThis situation may have been acceptable many years ago when electricity costs were very cheap. But now that prices have gone through the roof and continue to rise year out, it simply does not make sense to waste so much money and natural resources.

It would make much more sense to be able to only cool those rooms in the house that are actually occupied by people, while leaving unoccupied rooms untreated until someone decides they want to go in there. Of course, the convenience-minded person would argue that a room should be ready cooled before they enter it.

If they had to turn on a cooler in as they entered, they would need to wait for it to cool down.

Mini Split AC Addresses the Problem

A sensible alternative to whole house cooling is the mini split AC system (also called ductless units). They are being promoted extensively but unfortunately they cost 3-4 times as much as central systems per ton to buy and install.

This solution is far better because it uses a smaller packaged air conditioning unit in each room with remote control for ease of use and they don't take up much space. It is a better solution than opting for even the best portable air conditioners which require floor space in each room and venting through an open window.

Window AC Units

A similar alternative is the window AC, but you need to mount them on the outside of a window if you do not want see or hear them. They also require an external window to be present which is not always possible.

By using sound damping material mounted in flexible ducts or rigid ducting, it is possible to allow these units not to run more quietly and not be so easily heard from inside a room. This is a perfect way to cool your bedroom on those hot summer nights dropping the indoor temperature to a cool 75F.

When they are mounted in this way, there is a clear advantage as it's simply a case of turning on the zone you happen to be in. Window AC units can be purchased from a discount eBay seller for example for as a low as $200 for a 12,000 BTU unit (British Thermal Unit), rather than paying top dollar in local hardware stores.

The advantages of using this approach are:

  1. You never need to replace an old central AC costing over $10,000 as with a typical high SEER AC home system upgrade
  2. If a single, smaller, standalone zone AC unit fails, the replacement costs are around $200 and there's no need to hire an expensive HVAC contractor to install the new one.
  3. On those rare, very hot days (like when it hits 110F) there's still the old central AC that you can turn on first for a while until the smaller zone units take over the cooling load.
  4. If your home has a typical, modern solar power system, powering 3 to 4 smaller zone ACs should be possible during the day. This kind of system would certainly not be able to run a large, 4 ton central AC installation!

The Benefit of Installing Zone Systems

The main benefit of this type of setup is cost saving and greater efficiency on a room-by-room basis. You only cool occupied rooms and save on electricity costs by having unoccupied rooms closed off and their mini-split units turned off.

You can solve many cost and sizing problems with a zone damper system by a company like Honeywell. For each zone, you can install dampers at the air handler then run a thermostat to each zone to drastically improve each zone's dynamic cooling requirements.

This solution can be a lot cheaper than having to buy and retrofit a lot of window units and far less expensive than refitting a central AC system.

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