mini-splits using AS A primary heating source Locating effective evaporator and condenser locations is critical to ductless heating success.

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1 using mini-splits AS A primary heating source Locating effective evaporator and condenser locations is critical to ductless heating success. BY JAMES BOWMAN Unless specified, images courtesy of RectorSeal Corp. L ocation, location, location are the three key words for real estate and ductless mini-split heating installations. Location is important in mini-split air-conditioner installation, but it is even more critical when the unit is also a primary heating source. For example, wall-mounting an evaporator coil over a bookshelf, kitchen cabinetry, curio cabinet or other tall-standing home furnishing will inevitably lead to poor circulation and short-cycling in the mini-split s heating mode. Many minisplit installers may not realize that the louvers on most evaporator brands default to outward or downward air-flow direction when in cooling or heating mode, respectively. In cooling mode, the louvers direct the air out across the ceiling so it will descend toward the floor and displace warmer air toward the ceiling. Therefore, a 6-ft-high curio cabinet positioned under a wall-mounted evaporator does not affect the air flow in cooling mode. However, in the heating mode, the louvers automatically direct air flow down toward the floor so that the heated air then rises and more evenly tempers the air from floor to ceiling. Thus, an air-flow blocking curio cabinet deflects the air toward the unoccupied ceiling zone and then short-cycles, because the thermostat senses setpoint temperature. The result is an undesirable occupied zone temperature. The condenser location and positioning for ductless heating 22 RSES Journal DECEMBER 2015 In the heating mode, a ductless heating evaporator automatically adjusts louvers down toward the floor so that the heated air then rises and more evenly tempers the air from floor to ceiling. Wall-mounting these units over anything that can deflect the air toward the unoccupied ceiling zone can short-cycle the unit because the thermostat senses setpoint temperature. is also critical in terms of weather, environment and human interaction. The outdoor condenser must be raised 4 in. above the grade, as per most manufacturers recommendations and some jurisdictions code requirements. Northern installations must consider a condenser mounting above the snow line that is determined by local code requirements and seasonal snow accumulation expectations. To endure extreme sub-zero cold weather, the condenser should be positioned so that the house blocks typical winter highwind direction. Condenser baffles, which are available from some mini-split brands, can also be used to throttle wind infiltration into the condenser and allow the unit to perform with better heat transfer. Likewise, a house built in a flood zone and susceptible to springtime ice melts will need its ductless heating mini-split condenser mounted to an appropriate height. There are several condenser-mounting strategies that go beyond concrete pads. HVAC accessory manufacturers have

2 The condenser location and positioning for ductless heating is also critical in terms of weather. Northern installations must consider a condenser mount above the snow line, depending upon local code requirements that are based on snow accumulation forecasts. Image courtesy and copyright of South Mountain Co., West Tisbury, MA. Besides snow and flooding, drainage is another reason manufacturers require condensers raised a minimum 4 in. above the slab, roof line or grade. developed load-bearing metal brackets designed especially for most mini-split condensers challenges. Some of these include: ga wall mount for any height; ga pad mount to raise the condenser up to 4 in.; gan adjustable mount to level the unit on sloped roofs; ga slab support to install above grade; and ga soffit mount for hanging. Besides snow and flooding, drainage is another reason manufacturers require condensers raised a minimum 4 in. above the slab, roof line or grade. In heating mode, the evaporator and condenser swap roles in winter operation via a valve that reverses refrigerant flow. When the reversing valve is activated, heat is rejected indoors and condensate occurs outside and drains through the condenser s cabinet bottom. If not raised, the condenser s condensate can become blocked or frozen and will not drain properly away from the unit. Accessory manufacturers have designed footing mounts, sometimes made of recycled tire rubber, with channels that accommodate two legs of a mini-split condenser. Equipment mounts and footings are made to be more aesthetically pleasing than concrete blocks and they do not require extra labor that cutting and weather-treating wood does for outdoor use. These same footings are also invaluable for getting condensers up and away from flat-roof drainage patterns without damaging sensitive roof materials, such as the white reflective membrane. They also attenuate sound and vibration transmission into the home. Outdoor positioning should also be considered for direct salt spray from ocean properties. Using the home to block anticipated high winds and salt spray can extend the life cycle of the condenser. Additionally, high crime or sports and landscape areas need condensers positioned out-of-reach of thieves, errant balls and weed whackers and projectiles from lawnmowers. DECEMBER 2015 RSES Journal 23

3 Accessory manufacturers have designed footings, sometimes made of recycled tire rubber, with channels that accommodate the two legs of a mini-split condenser. In addition to their aesthetics, they work well for equipment footings on flat roofs and help get the condenser above the roofline without the use and extra weight of a concrete pad. They also attenuate sound and vibration transmission into the facility. New codes affect ductless heating Today s HVAC accessory manufacturers make mounting easy with wall brackets that can elevate ductless heating condensers out of reach of weed whackers, projectiles from lawnmowers and other dangers from landscaping and lawn care. Image courtesy and copyright of South Mountain Co., West Tisbury, MA. 24 RSES Journal DECEMBER 2015 The 2015 International Residential Code (IRC) (Section ) now mandates a trap or a check valve be installed in-line with all gravity drain lines in ductless mini-splits. A 3-in.-long, in-line check valve designed for push-fitting into 5/8-in. drain hoses might be a better choice than a trap. Many traps are originally designed for conventional unitary equipment and will cause a drain restriction on mini-splits. Many manufacturers also call for a trap or check valve to be a minimum of 12 in. away from and below the drain pan so that enough water weight can open the one-way door. The 2015 IRC is not expected to be adapted by most jurisdictions until 2016 or 2017, however some states, such as Delaware, have already incorporated it. Florida is close to incorporating it (or will have incorporated it by the time this feature is printed). In the heating mode, drain-line check valves are critical for preventing: cold-air infiltration for energy efficiency, allergen infiltration for indoor air quality, evaporator coil cleanliness for lower maintenance costs, and insect infiltration protection, according to code review committee explanations. Today s tightly sealed homes have helped attract more air infiltration through the condensate drain hose. Mini-split installers should not use vinyl tubing when gravity draining, because it is prone to kinking and mold growth. A better alternative is a corrugated, kink-resistant polyethylene

4 A plastic wall sleeve will help seal an outdoor wall penetration and prevent cold-air infiltration during ductless mini-split heating. Some wall sleeves are adjustable and can telescope to span most wall widths or a combination of sleeves can be used in tandem to cover wider walls. Today s tightly sealed homes have helped attract more air infiltration through the condensate drain hose. vinyl drain hose designed specifically for mini-split condensate. There is little danger of freezing when running drain hose through an unconditioned space, because there is little condensate production indoors during winter months. However, that same unconditioned space in summer months can produce sweating on drain hoses and surrounding area moisture damage. An insulated drain hose will minimize sweating. Another cold-air infiltration concern is the hole made in the wall to allow lineset and drain-hose access. Therefore a plastic, properly-sealing wall sleeve will help close WHAT YOU DON T SEE IS WHAT YOU GET C155 LIMITED EDITION 5-Year All Inclusive Warranty* EOS Long Life Sensors Complete Combustion Kit U E i C a m o H a t ** QUANTITIES LIMITED C155KIT Camouflage Limited Edition: part # C155LE Camo Combustion Analyzer, Infrared Thermal Printer, Flue Probe, 2 K-Type Temperature Probes, 2 Static Pressure Hoses, True Draft Probe, Gas Pressure Probe, AC Adapter, Hard Carrying Case, Thermal Paper Roll, Particle Filter, Inlet Tube/Probe Connecter, Quick Start Guide, Owners Manual, 5-Year All Inclusive Warranty* and UEi Camo Hat**. *5-Year All Inclusive Warranty requires product registration. **UEi Camo Hat sent from UEi upon receipt of product registration. Quantities limited. Camouflage patterns vary by analyzer. For complete details see participating distributors or contact UEi Test Instruments: Copyright 2015 UEi Test Instruments All rights reserved Circle Reader Service No. 54 DECEMBER 2015 RSES Journal 25

5 The 2015 International Residential Code (IRC) (Section ) now mandates a trap or a check valve be installed in-line with all gravity drain lines in ductless mini-splits. A 3-in.-long, polyethylene vinyl inline check valve designed to be push-fit into 5/8-in. drain hoses might be a better choice than a trap, which may not fit inside a mini-split evaporator. the penetration to any outdoor infi ltrations. Some wall sleeves are more universal in that they are adjustable and can telescope from 4 in. to 7 in. to span most wall widths. Two wall sleeves can be paired together to cover walls wider than 7 in. Cleaning for ductless heating Like the cooling mode, heating requires a clean evaporator coil for optimal wintertime heat transfer. Too many consumers think mini-splits are exclusively for air-conditioning and do not realize homes depending on a mini-split as a primary heating source must be clean to start the winter season. A dirty evaporator during the heating season could overheat and potentially shut off the unit. Condenser mounts like this sloped-roof version, help accommodate job challenges confronting ductless minisplit installers. Startup during a new construction project could also get the coil dirty, as excessive dirt and dust can be drawn through and deposited on the evaporator. Cleaning minisplits, whether it is for summer or winter operation, requires special care, techniques and cleaning agents that are different than conventional unitary equipment coils. Cleaning agents should be safe for the aluminum, copper and metal alloys of sensitive evaporator coil tubing, as well as fins and plastic housing 26 RSES Journal DECEMBER 2015 covers on all mini-split brands. Cleaning agents should also be safe for use with mini-split piston, diaphragm and peristalticstyle mini-split condensate pumps, which are code-mandated accessories on interior wall evaporator coils that are not able to gravity drain condensate outdoors. Outdoor condensers should be outfitted with a tamperproof refrigerant port locking cap that can only be removed with a special tool available at HVAC wholesalers. The emergence of teenage deaths from huffi ng refrigerants from outdoor condensers has prompted the IRC-2015 (M1411.6) to mandate locking caps on any new installation and now any existing unit that is opened for service. Contractors should consider two things when installing mini-splits. Cooling and heating modes are decidedly different and require well-thought locations to accommodate both functions. James Bowman is the National Technical Manager HVACR for RectorSeal Corp. (Houston, TX), which offers mini-split installation accessories. Prior to joining RectorSeal, Bowman was a service tech at several HVACR service contractors. He is EPAcertifi ed, NATE-certifi ed, holds a Class A contractor license in Texas, and has installed and serviced dozens of ductless minisplits representing most brands. For more information, visit or jamesb@rectorseal.com. Ductless (Mini-split) Heating Evolution When ductless mini-splits first emerged in the United States 30 years ago, they were used for cooling only. When heat-pump models later arrived on the scene, except in southern regions, they were not used as the primary heating source. The emergence of the inverter-controlled compressor as well as other technological advancements have been responsible for the surge of ductless heating. Recently, the technology has improved ductless heating capacity and made the relatively new HVAC category suitable as a primary heating source, even in temperatures well below 0 F. The inverters and onboard microprocessors allow for the adjustment of blower and fan rpms, refrigerant flow and even the compressor speed via variable-frequency drives to maintain heating capacity with decreasing outdoor temperatures. While many HVAC contractors concentrate on the cooling side of ductless mini-splits, the heating side must also receive careful attention, especially in locating them in the best possible areas of the home for the highest efficiency and performance.