Mini-Split Heat Pumps are Quirky and Still Effective The name "mini-splits" generally refers to heat pump systems with one outdoor unit and one or several smaller capacity air handlers. The efficiency of their operation comes via the inverter compressor and variable refrigerant flow technology, and they are available for single- and multi-family homes, as well as commercial buildings of any size. Here's a general overview of what the systems are and how they work, in case you're not familiar. Compared to conventional heating and cooling equipment, they're very quiet and very efficient. For most folks, ductless mini-splits are what they've heard of, but there is also a concealed ducted option that many of our clients choose to avoid the "wall wart". Over the past several years, I have  pretty well, and like the 2001 Land Rover Discovery II that we drove for 10 years, with it's backwards dashboard and odd noises, mini-splits can be rather quirky. Unlike the Discovery II, though, most of the quirkiness of the mini-splits is good, not just quirky!

At this year's Building Science Summer Camp, Bruce Harley, Technical Director at Conservation Services Group, discussed his experience and the quirkiness of the combination ducted and ductless multi-split heat pump system installed in his Vermont home. split system air conditioner size roomBelow are some of the key takeaways from his presentation with a little commentary from me:auto ac repair orlando fl IMAGE LEFT - Mitsubishi ducted mini- or multi-split heat pump air handler in encapsulated atticIMAGE RIGHT - Mitsubishi 4-ton multi-split outdoor unitvertical window air conditioners canada The Quirkiness of Heat Pumps",(Click title to see entire presentation):ac unit smoke detector

IMAGE LEFT - Mitsubishi outdoor unit mounted on exterior wall of Providence, R.I. homeIMAGE RIGHT - (Left to Right) Gordie (happy homeowner), Ray Bolvin (installer), and Me IMAGE LEFT - Mitsubishi ceiling suspended ducted air handler.ac unit stopped blowingIMAGE RIGHT - Mitsubishi outdoor unit with access panel removed during commissioningbalancing hvac units July 2013 Electricity bill with set backs30 ton hvac unit cost July 2014 Electricity bill when we set it and forgot itwindow ac unit for trailer IMAGE: Mitsubishi Electric MHK-1 Controller is one of the more user-friendly controllersac unit blowing cool but not cold

IMAGE: Slide from Bruce Harley's presentation showing comparison between resistance heat and mini-split heat pump energy consumption. Quirkiness of Mini-Split (VRF) Heat Pump Capacity On the topic of the HSPF (Heating Seasonal Performance Factor, a.k.a. heating efficiency) of VRF heat pump systems, Bruce Harley said, "Be careful about what manufacturers specs you use" and "Adjust for climate using bin analysis for actual equipment and application". installing an ac unit in a windowThis is extremely important! solar air conditioning units reviewsEspecially when it comes to equipment capacity. how to repair ac leak in carIn fact, knowing the rated versus actual capacity of the outdoor unit (heat pump) and the individual air handlers is one of, if not the most critical design considerations with VRF heat pump system.water leaking from furnace ac unit

Capacities are considered "Rated" if their published via testing performed by a third-party and approved by the Air Conditioning, Heating and Refrigeration Institute, or AHRI. AHRI regulates all 3rd-party testing for all types equipment based on standard rating conditions at full capacity.heating and cooling units for condos As mentioned above, mini-split heat pump systems can have a single or multiple indoor units (as many as sixty four (64) ducted or ductless air handlers) connected to a single outdoor unit (heat pump), depending on building or home size, desired zoning, required heating and cooling, etc. home air conditioning repairs brisbaneAlthough equipment efficiency is better and costs can be slightly less to have one outdoor unit serving each indoor unit, it may be more practical to have a single outdoor unit with multiple indoor units connected. air conditioner split system installation cost

The more indoor units there are, the more it makes sense to use a single outdoor unit. Whatever the configuration, the actual capacity of each indoor and outdoor piece of equipment will vary. What factors change the actual capacity?home air conditioning repairs adelaide DESIGN CONDITIONS (Factors that effect system capacity)how does air conditioner work animation Below is a screen shot of the actual capacities based on design conditions (see "Factors" above), generated with a proprietary design software from , one of the leading manufacturers of VRF (mini-split) equipment. auto ac repair south tampaFor simplicity, I'm only showing the first four indoor units, but there are 10 total. handheld ac unit

The project is a custom home on a small island near Great Exuma, Bahamas. Yes, it's hot and humid. Maybe one day of the year it drops below 80...to 79.9. We decided to go with the  line from Mitsubishi, a commercial product that requires three-phase power, for this project, but everything I'm about to show applies to all VRF equipment. window ac unit shelfIt doesn't matter if it's residential-type, commercial-type, any other manufacturer, or if the project is in Anchorage or Timbuktu.air conditioning unit split type price In this configuration, I selected a 10-ton (120,000 btu/h) outdoor unit to serve all but the guest house. hvac unit not runningThe model number and actual capacities at design conditions (see "Factors" above) for the outdoor unit are in the top left corner of this screen shot. temp hvac units

(blue = total cooling, red = total heating). All of the indoor fan coils (air handlers) are concealed ducted, and their model numbers are directly above each image (to the right) of the air handler (starting with PEFY). outdoor ac unit padThe two numbers after the dash represent the nominal capacity (24 = 24,000 btu/h, or 2-ton), and to the right are actual capacities based on manufacturer testing at the design conditions.how much does an ac unit scrap for If I move the house to Fargo, North Dakota, with design temperatures at 71 degrees F in Summer and -23 degrees F in Winter, here's what happens to the capacities.sharp ac unit manual The AHRI certificate below shows the rated capacities of the outdoor unit is 114,000 btu/h cooling and 129,000 heating at their standard rating conditions which is different that design conditions most of the time. removing window ac unit winter

If you look back to the first screen shot, the actual capacity is higher for heating and lower for cooling. That has a lot to do with the design temperatures of rated vs. actual. It is normal to have actual capacities differ from rated capacities with all types of equipment, conventional or mini-split, but now let's see what happens when I change some of the other design conditions, like number of air handlers, line-set length and number of 90 degree bends in the lines.portable ac units in stock In the screen shot above, I've added two more 8,000 btu/h air handlers to the Bahama configuration, still using a single outdoor unit. one ton air conditioning unitThe outdoor unit (OU) capacity has increased by about 6,000 btu/h and the indoor unit (IU) capacities have decreased by as much as 1,500 btu/h. hvac blower motor testing

The reason the OU capacity goes up is that I did not have 100% connected capacity (nominal capacity of indoor units = nominal capacity of outdoor unit) in the original configuration. So, when there is less than 100% connected to VRF equipment, the capacity of the OU will match the total of the indoor units.portable ac units ratings As for the indoor units, the more units that are connected to the OU, the more the capacity of the indoor unit decreases. federal tax credit for ac unitHow much it decreases also depends on the size of each added unit. air conditioner split ac price listThis is fairly logical, since they all have to share the same OU, but it's critical to know so there's enough capacity to match the load of each zone.what size ac unit do i need for 1900 sq ft

The above screen shot shows what happens when I changed all the line-set lengths from the original configuration (10 air handlers) to fifty (50) feet from some of them being over 130 feet, and changing all of them to have only one bend. central air conditioner prices orlandoSee how much the outdoor unit capacity goes up? installing ac unit windowFrom 99 kbtu/h to 110 kbtu/h. ac unit alarm sensorSo, the closer the air handlers are and the fewer bends, the more capacity the system will have. ac unit heat stripYou see, it's not just temperature that effects capacity.4 ton ac unit york You can also compare the actual capacities of the indoor units with their rated capacities in manufacturers published performance data. guardian ac unit

Here is an example of the PEFY-P24NMAU-E3, the first indoor unit (air handler) shown in the configurations above. It also states the rated conditions. See the difference, and see why it would be important to know the capacity?rv ac unit price "If I Had More Time, I Would Have Written a Shorter Letter" - Mark Twainwindow ac unit no drain I know this is a long post, but it's an important topic that needs to be known. convert window ac unit portableI hope it's clear and useful to you and your life. cost of hvac classesIf you have any comments or questions, please post them below. how to clean mold from an ac unit