Ductless mini-splits (sometimes referred to as Variable Capacity Heat Pumps) are an attractive alternative to conditioning a home.
In this post, we will review the requirements for ductless mini-splits that are required as part of the 2019 Energy Code. For a completely detailed reference of all requirements for variable capacity heat pumps, please refer to Appendix B, Eligibility Verification Protocols published by the California Energy Commission.
On page 2 of a CF1R, there is a HERS feature summary which lists many features that must be field-verified by a HERS rater as a condition of meeting the modeled energy performance for the analysis. An example of this is provided below.
I'll list the most common HERS features that pertain to ductless mini-splits and discuss each in more detail.
Verified Refrigerant Charge
This is standard for all new systems and is executed based on procedures within RA3.2 that apply to nearly all new systems. This is typical for all new air conditioning systems and won't be discussed at length here, but more information can be found here.
Airflow in Habitable Rooms
Procedure SC3.1.4.1.7 (below) will be used to confirm that your ductless mini-split provides sufficient airflow to all habitable spaces.
Procedure SC3.1.4.1.7 - Verification of Space-Conditioning System Airflow Supply to All Habitable Spaces
A visual inspection shall confirm that all habitable spaces in the dwelling unit receive space-conditioning system airflow either by use of a ductless space-conditioning system indoor unit located on the wall, ceiling, or floor of the habitable space, or by use of space-conditioning system air supply registers located in the habitable space that use ductwork connected from the register directly to the supply air outlet of a ducted space-conditioning system air handling unit. Refer to Standards Section 100.1 for the definition of habitable space. Transfer fans that move air from one space in the dwelling to a different space in the dwelling, but do not heat or cool the air transferred, do not meet the requirement for providing space-conditioning system airflow.
Verified Heat Pump Rated Heating Capacity
This is a verification to make sure the BTU/Hr specified on your CF1R matches the system you installed.
A Wall-Mounted thermostat in Zones Greater than 150 sqft
You need to have permanently installed wall-mounted thermostat(s). This will be verified by procedure SC3.4.5 (below).
Procedure SC3.4.5 - Verification of Wall-Mounted Thermostat
When compliance requires verification that a wall-mounted, thermostat has been installed to control a space conditioning system's indoor unit operation, the system's indoor unit thermostat(s) shall be verified according to the following procedures. If a system has more than one indoor unit, then all of the system's indoor unit thermostats shall be verified according to this procedure.
(a) If the conditioned floor area (ft2) of the zone served by an indoor unit is not a criterion for determining the compliance requirement for wall-mounted thermostats, then skip to subsection (b) below.
Otherwise, if the conditioned floor area (ft2) of the zone served by an indoor unit is a criterion for determining the compliance requirements for wall-mounted thermostats in the zone, then record the conditioned floor area served by the indoor unit.
i. If the zone area size (ft2) criterion indicates that a wall-mounted thermostat is not required for the zone, then the indoor unit complies and no further thermostat verification is required for the zone served by the indoor unit.
ii. If the zone area size (ft2) criterion indicates that a wall-mounted thermostat is required for the zone, then perform the remaining steps that follow.
(b) If possible, locate the wall-mounted thermostat that controls the indoor unit, and verify whether or not the thermostat controls the indoor unit by setting the thermostat to a cooling setpoint that is less than the room temperature, or alternatively by setting the thermostat to a heating setpoint that is greater than the room temperature.
If there is no wall-mounted thermostat installed in the zone that controls the indoor unit, then the indoor unit does not comply. If there is a wall-mounted thermostat installed that controls the indoor unit, but it is not located within the zone served by the indoor unit, then the indoor unit does not comply.
(c) For a wall-mounted thermostat installed in the zone that controls the indoor unit located in step (b), by visual inspection determine if the thermostat is mounted permanently to the wall. Wall-mounted brackets or other means that facilitate non-permanent attachment of handheld thermostats to the wall do not meet this requirement.
If the thermostat is not permanently mounted to the wall, then the indoor unit does not comply.
Ductless Indoor Units Located Entirely in Conditioned Space
This will be verified by procedure SC3.1.4.1.8 (below) which will visually confirm that all of your indoor ductless units are located entirely in conditioned space.
Procedure SC3.1.4.1.8 - Verification of Ductless Space-Conditioning System Indoor Units Located Entirely in Conditioned Space
A visual inspection shall confirm that ductless indoor units are located entirely in conditioned space in accordance with the following requirements:
(a) Ductless indoor unit types that mount entirely on the interior surface of dwelling unit walls, ceilings, or floors shall be considered to be entirely in conditioned space. Penetrations in the wall, ceiling or floor surface necessary for the indoor unit refrigerant piping, condensate drain, or electrical connections shall be allowed, provided the penetrations are well sealed.
(b) Ductless indoor units that penetrate the interior surface of dwelling unit walls, ceilings, or floors, and protrude through cut-out openings in the dwelling unit walls, ceilings, or floors shall be inspected to determine whether the indoor unit is installed inside both the thermal boundary and the air barrier of the dwelling as follows:
i. If the ductless indoor unit protrudes through the air barrier into unconditioned spaces such as attics, crawl spaces, garages, or outdoors, the indoor unit shall not be considered to be located entirely in conditioned space.
ii. If the indoor unit protrudes into indirectly conditioned spaces such as drop ceilings, or floor assemblies in a single-family or multifamily multi-story building, that are wholly inside both the thermal boundary and the air barrier of the dwelling, then the unit shall be considered to be located entirely in conditioned space. Verification at an early stage of building construction may be necessary in order for this visual verification to be possible.
If field verification according to SC3.1.4.1.8 determines the installed system's ductless indoor units are not located entirely in conditioned space, then the system does not comply with the VCHP compliance option eligibility requirements.
References
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