I have a Cape Cod with 1000 ft2 on the first floor and an apartment in the attic. In a few years I may get rid of the apartment and build up a second story + attic. Both the first floor and the attic currently have window AC units. The heat is hot water radiators and the boiler is on gas. Does it make sense to install high-velocity AC in the crawl space for the first floor and later, when I build up the second floor, add another AC system in the new attic to cool it? Or is that going to be too expensive? I'm thinking that a dual zone system would be nice anyway. Are two AC systems twice as expensive than a single dual-zone one? Or what is the ratio? Also, what are the prices of such systems? A dual-zone system is one heating element and/or AC coil serving two separate ductwork segments. The extra cost of a dual-zone system as opposed to a single-zone system is in the dual-zone temperature monitoring/control panels, and a system-controlled diverter that sends the air to the side of the system that needs it (or both).

One interior and one exterior unit to buy/maintain. Drastically reduces most routine maintenance costs and generally increases MTBF. Easier to balance your home's ventilation; you don't have to worry about the relative heating/cooling capacity of two units versus the space they're expected to cover. Dual-zone systems usually have a "master/slave" control panel arrangement allowing the "master" panel to control both zones while the "slave" panel can either also control both or only control the secondary zone, possibly with additional restrictions like max/min temperature that can be set on the master panel.if something on the one unit goes, there is no heated/cooled air anywhere in your home. Impossible to differentiate the electric costs of you versus an upstairs tenant. Longer ventilation runs to the second zone, depending on home design; the second zone needs vents and returns run from the main unit to a usually distant part of the home. These longer runs will not be as efficient.

To supply ample heated/cooled air to both zones at once, the unit must usually be a bit beefier than a comparable single-zone system, to compensate for inefficiencies and maintain desired airflow when both zones are being ventilated. You cannot have the heat on in one zone and the A/C on in another. The entire system must be set to heat or cooling, meaning if your tenant likes it substantially warmer or cooler than you do, the ability of the system to provide the proper temperatures can be limited at times. A dual-unit system will have two separate single-zone HVAC units each controlling one area of the home (upstairs-downstairs is common in new construction, as is having a second HVAC for a new addition). Having a backup system means at least some of your house can still be heated or cooled in the event of a failure of one unit. Vent runs can usually be shorter, as the units can be strategically placed in new construction for the most efficient ductwork layout to each zone.

Each unit can be smaller than a single unit for the whole house would have to be, meaning the exterior units can be located in tight spaces or more easily hidden behind shrubs. By hooking the second HVAC along with all upstairs circuits to a sub-meter, you can easily determine (and sever) the electrical costs of an income property. More expensive to put in than a single unit, even a dual-zone. How Many Yards For Shower CurtainTwo 1-ton units will cost more than a 2-ton.Warehouse Floor Vacuum Cleaners Maintenance costs also increase; Whimsical Beach Wedding Dresseswith two units the MTBF of a single unit in the home is halved, meaning on average you'll have to call the repair guy twice as often.There are some nice thermostats that can communicate wirelessly (usually as part of a whole-house automation/alarm system), but basically each unit will be its own completely separate system and to balance the temperature in the whole house you must go upstairs and down to fiddle with settings.

If your living in an area that doesn't get below -20c I would look very closely at the geothermal units they have. These units can be used for heating and ac. They are basically a heat pump designed to reverse depending on the demand. Because they use the ambient air to pull heat and not an electric element they are extremely efficient. They sell both ducted systems and ductless. We have had them installed in a community hall I look after and so far they have been great. I live in North okanagan and we have seen temps down to -25 so far this year and they have had no problems. here is a link. Here is a links that will do better justice to the explanation. How Heat Pumps Work What It boils down to is, it is a lot cheaper to transfer heat than it is to create it.Browse other questions tagged hvac or ask your own question.LG Ductless Mini-Split Systems LG ductless mini-split air Conditioners and heat pump models include the LG art cool mini-split line, standard mini-split air conditioners for a single zone, and multi split air conditioners for dual and tri-zone.

These LG mini-split systems vary by function, look, and output. ***NOTE: LG mini-split systems should be installed by a certified technician. Single Zone Mini-Split Air Conditioners LG Mini-Split Standard systems utilize the same duct-free technology as Art Cool un Art Cool Mini-Split Air Conditioners The slim, contemporary styling of the Art Cool models will appeal to today’s di Flex Multi-Split Ductless Air Conditioners Flex Multi-Split Systems The larger, Flex Multi-Split systems operate two, three inte LG Mini Split Parts This category contains various LG Mini Split parts such as Thermistors, boards, remotZoneline Packaged Terminal Air Conditioners Zoneline Packaged Terminal Air Conditioners with Makeup Air Zoneline Vertical Air Conditioners Shop All Zoneline Air Conditioners Our New ZonelineQuietest in the Industry Learn about the Industry's quietest PTAC See how GE Zoneline, produced in Louisville, KY, has been reinvented to meet the changing needs of America’s hotel industry.