With ducted or ductless mini-split systems, you only pay for and use as much or as little heating and cooling as you need at any given time in any given room? How does it work? In technical terms, there are three primary components to making this possible. 1. An inverter-driven scroll compressor inside the outdoor unit (a.k.a. condenser, compressor) that adjusts its rotation speed, and the electrical draw, to precisely match the load requirements within each zone of the house or building. 2. Quiet, low-wattage fans in the “mini” air handlers and outdoor units modulate their speed to match the need of individual zones (air handler) and whole system demand (outdoor unit) 3. Dual electronic linear expansion valves (LEV) that adjust the amount refrigerant being delivered to all air handlers, and within each air handler, based on what each zone or all zones are calling for. In practical terms, it’s similar to a pay-as-you-go cell phone, where the user only pays for the minutes used.

No more, no less. With this technology, the users heat and/or cool as much or as little as they want, and only pay for what they use. The inverter-driven scroll compressor in the outdoor unit adjusts the amount of electricity, and the linear expansion valves adjust the amount of refrigerant, the hot and cold liquid that is used to condition the air being supplied to each zone, to deliver exactly the amount of heating and cooling needed at any given time in any given room and/or zone. The system only uses the energy it needs to do this, whether its a little or a lot. The mini air handlers (a.k.a. indoor fan coils), which range in capacity from 6,000 btu/h to 24,000 btu/h for residential, and up to 96,000 btu/h for commercial applications, are selected through a process that is based on the heat loss and gain calculations, a.k.a. load calculations.  How many air handlers, how much air needed, and how that air is delivered to each room or zone, are the remaining steps in the  process.

Outdoor units can have as few as one (1), and as many as eight (8) air handlers in residential applications, and up to sixty-four (64) units in commercial. This is what gives these systems their name “mini-split” heat pumps, since conventional split systems have one outdoor unit and one indoor unit to serve individual or multiple zones. The “mini” refers to the multiple air handlers that are not only smaller in capacity, but also in physical size. IMAGE LEFT – Typical Wall-Mounted Ductless Air Handler IMAGE RIGHT – Typical Concealed Ducted Air Handler The air handlers can have ductwork and be concealed in a ceiling, attic or floor cavity to serve up to three or four rooms. OR, they can deliver the air without ducts with wall-mounted or recessed (in wall/ceiling) ductless units. Either way, these air handlers deliver air with a fan that is generally quieter than a human whisper. Everything about these systems are variable, efficient, quiet, great for good indoor air quality, and extremely effective.

What more would you want in an HVAC system? Contrary to what you might be thinking, or know, these systems can and DO work in all climate zones. They’ve been used in Europe, Asia, Canada, and South America for decades, and have proven themselves to be reliable. HVAC companies rave about how few call backs and/or repairs that there are with these systems. Generally, they can be as much as 30%-50% more efficient than conventional systems. Though they’re rated efficiency (at full capacity) ranges from 14 to 20 SEER, they rarely ever run at full capacity. ac ground power unitThis makes their real world efficiency seem higher. best buy ac wall unitsIn fact, an alternate efficiency rating, called Integrated Energy Efficiency Ratio (IEER), is used to more accurately factor the variability of the equipment in to the rating.top 10 split unit ac

A final technical note: Conventional outdoor units (heat pump or air conditioner) draw about 25-40 amps of electricity when in use. The maximum amp draw on mostresidential mini-split outdoor units is 18-20 amps. Again, because of the variability, and the fact that the system is never on full capacity, the amp draw is usually much lower…maybe around 10 amps or lower…. To the left is a graph showing just one of the many ways that the mini-split systems are better at minimizing energy use. If you need more information about these systems, or are considering them for your new or existing home, don’t hesitate to contact us. We have experience with these and many other types of systems, and can a system that suites your needs…precisely. written by Chris Laumer-Giddens, Architect, HVAC Designer, Residential Builder, HERS Rater, Building Science Professional, EarthCraft TA Post Tagged with building science, ducted or ductless, energy efficient, good design, hvac design, mini split heat pumps, mini-split

13,803 posts, read 19,510,664 times 7,939 posts, read 9,881,502 times Originally Posted by nybbler 1,256 posts, read 2,453,055 times Standardized at 120 V. Electricity suppliers aim to keep most customers supplied between 114 and 126 V most of the time. Originally Posted by sullyguy 14,196 posts, read 40,490,832 times I'll make it even more complicated. You can have 120 at the outlet, plug your AC in and have it drop to 110. No need to thank me. From the consumer point of view, if the socket fits, the appliance can wear it. 5,037 posts, read 5,971,651 times If you blow your place up Dawn, you could stay with us. Originally Posted by harry chickpea Mr. Garbanzo, "more complicated" makes my head hurt. And I'm thanking you anyway! Originally Posted by CheyDee We'll be there soon, even if I don't blow anything up. 4,576 posts, read 6,642,738 times 45,038 posts, read 45,640,403 times I've always thought P = U * I (units watt, volt and ampere, respectively), but I ran across this discussion on a forum:

If you look in your panel there are 2 “hot wires coming in from the1 is the 120v A phase and 1 is the 120v B phase. you need a hot leg from each one to make 240V. if you have a machine drawing 20 amps on 120V it is drawing it from 1 phase. If you have the same machine drawing 10 amps on 240V it is drawing 10 from the A phase and 10 from The easiest motor for me to read the name plate on is a 1.5 HP 3450It was on the shelf. It states at 115V it drawsnext it states 230V it draws 6.6 amps. “amps x volts = watts” 6.6 x 230 = 1518 no matter what you do it will draw the same amperage total. To me this explanation contradicts itself since it says that the motor draws both the same current and the same power. Is the motor actually drawing 6.6 A from each hot wire (for a total of 13.2 A), or is it drawing 3.3 A from each hot wire? If it's 6.6 A from each hot wire, it seems the classic "current x voltage = power" equation is misleading for 240 V "single-phase" circuits.

Update: to clarify, this question applies to 120 V and 240 V current in the US. A 240 volt motor will only be connected to the two live wires, not to neutral, so your example draws 6.6 amps at 240 volts. If it is connected to operate at 120 volts, it will be connected between one live wire and neutral, and will draw 13.2 amps at 120 volts. I think it is misleading to say that, in the 240 volt case, the motor draws 6.6 amps from each live wire. A more correct description would be that it draws 6.6 amps from one live wire, and returns that 6.6 amps through the other live wire. Using the same terminology, in the 120 volt case, the motor will draw 13.2 amps from the live wire, and return that 13.2 amps through the neutral wire. It is written in a confusing way, but well. The one phase motor has only one phase from which something is drawn, the other one is bound to ground. You use a one phase motor because you don't have three phases. That means using phase-phase voltage on it wouldn't make sense, you should be using a three phase motor instead.

The 120V vs. 240V is not related to phase to phase voltage(or live wire to live wire) as that would be \$120\sqrt(3)\approx 207V\$. It is a refference to the outlet voltage for different countries. 120V 60Hz (for example US) 240V 60Hz (for example Brazil) 240V 50Hz (for example Europe) The other ratings you read were for people in other regions of the world that want to use the same motor. You need a bit more of data in the question, and clarify it so that I really know what you are talking about. I'm now doing my best guess at what you really wanted to ask. I would suspect that you will be metered on both phases and the current you are charged for is the sum of currents in the hot wires. So although the physics says it's the same 6.6A current coming in one phase and going out the other on one circuit across 240V, the accountants charge for it twice. Is the motor actually drawing 6.6A from each hot wire (for a total of 13.2A), or is it drawing 3.3A from each hot wire?

A phrase like "drawing from each hot wire" is unclear. For the 120V circuit, there is one hot wire and one neutral wire and the motor is between the two. The current is the same in both the hot and neutral. For the 240V circuit, there are two (out of phase) hot wires and the motor is between the two. The current is the same in both hot wires. Just as you do not add the currents in the hot and neutral for the 120V case, you do not add the currents in the two hots for the 240V case. Perhaps a drawing will help. simulate this circuit – Schematic created using CircuitLab In the left hand circuit, the load "draws" current from 1 hot wire and the current "returns" through the neutral. In the right hand circuit, the load "draws" current from 1 hot wire and the current "returns" through the other hot wire. Assuming the power is the same for both loads above, the current in the 240V circuit is half that of the 120V circuit. You can think of it this way: the motor is using the same amount of power regardless of the voltage.