9.6   Alterations

This section provides a road map and a few relevant summaries that identify the Standards requirements which are unique to alterations. Envelope, mechanical and water heating system alterations must meet all applicable mandatory measures as discussed in Section 9.3; and also must comply with the Standards using the prescriptive or performance approach.  If a building does not meet all applicable prescriptive measures, see Section 9.5.1), then the performance method using of approved compliance software is the alternative, see Section 9.5.2.

Residential lighting alterations need to meet applicable mandatory measures discussed in Section 9.3.3 since there are no prescriptive lighting requirements in residential buildings.

9.6.1    Prescriptive Requirements

Although alterations must meet many of the same prescriptive requirements for new construction and additions, there are several exceptions or special allowances for certain types of alterations.  Table 9-5A provides a detailed outline of envelope requirements for alterations; and Table 9-5B provides a similar outline for HVAC and water heating alterations.  For each type of alteration, the tables list:

1.   The highlights of the mandatory measures applicable to that kind of alteration; and

2.   A summary of the relevant prescriptive measures; and

3.   Key exceptions, exemptions or special allowances to the prescriptive measures; and

4.   The list of prescriptive compliance forms that must be submitted for permit.

9.6.2    Prescriptive Envelope Alterations

Table 9-5A summarizes requirements for the following types of residential envelope alterations:

1.   Adding ceiling or roof insulation to an existing roof; or constructing a new roof on an existing building;

2.   Replacing the roof sheathing of an existing roof;

3.   Replacing part or all of  roof surface of the existing building;

4.   Replacing or adding skylights;

5.   Adding exterior wall insulation; or constructing new walls in an existing building;

6.   Adding raised floor insulation over unconditioned space;

7.   Replacing vertical fenestration: windows, clerestories and glazed doors;

8.   Adding vertical fenestration: windows, clerestories and glazed doors.

Table 9-5A: For Residential Alterations, Summary of Mandatory and Prescriptive Measures

Table 9-5A: Residential Alterations, Summary of Mandatory and Prescriptive Measures (continued)

Greenhouse Windows

Greenhouse or garden windows are special windows that project from the façade of the building and are typically five sided structure. An NFRC-rated U-factor for greenhouse windows is typically quite high and may not meet the mandatory requirements for the fenestration U-factor of 0.58.

The ways to meet this mandatory measure for greenhouse windows are:

Must have a maximum U-factor of 0.58 or better; or

Use the area-weighted average for all new and replacement fenestration with a combined mandatory maximum of 0.58 U-factor as per §150.0(q)2; or

The Exception to §150.0(q)1 for up to 10 ft² or 0.5% of CFA, whichever is greater; or

When using the performance approach Exception 1 as per §150.2(b) - Any dual-glazed greenhouse or garden window installed as part of an alteration complies automatically with the U-factor and meets the requirements as per §150.1(c)3.

9.6.3    Adding Insulation to Existing Roof/Ceilings, Walls and Raised Floors

The prescriptive requirement for alterations is to add the equivalent of the specified level of batt insulation that fits within the cavity of wood framed assemblies:

1.   R-38 in attic spaces in climate zones 1 and 11 through 16; and R-30 in attics in climate zones 2 through 10; or

2.   R-13 in 2x4 exterior walls, and R-19 in 2x6 or greater exterior walls; or

3.   R-19 in raised floors over crawl spaces, over open outdoor areas and over unheated basements and garages. 

9.6.4    Replacing the Roof Surface or Roof Sheathing

STEEP-SLOPED ROOFS (> 2:12)

In climate zones 10 through 15:  if 50% or more of the existing building’s roof surface is being replaced, the minimum cool roof requirement for the replaced steep-sloped roofing area is aged solar reflectance = 0.20, thermal emittance = 0.75 or a minimum SRI = 16. These apply unless any of the following is present which are considered equivalent to the cool roof requirements in §150.2(b)1Hi:

1.   Air space of 1.0" (25mm) between the roof deck and the bottom of the roofing product; or  

2.   Roofing product profile ratio of rise to width is at least 1:5 for >50% width of roofing product; or

3.   Existing ducts in attic insulated and sealed according to §150.1(c)9; or 

4.   Building has at least R-38 roof/ceiling insulation; or    

5.   Roof of attic spaces has a radiant barrier according to §150.1(c)2; or

6.   There are no ducts in any attic space; or

7.   In CZ10 through 15 only: greater than R-4.0 insulation above the roof deck.

LOW-SLOPED ROOFS (< 2:12)

In climate zones 13 and 15:  if 50% or more of the existing building’s roof surface is being replaced, the minimum cool roof requirements for low-sloped roofs are aged solar reflectance = 0.63, thermal emittance = 0.75 or a minimum SRI = 75 per §150.2(b)1Hii. These apply unless any of the following is present which are considered equivalent to the cool roof requirements in §150.2(b)1Hii:

1.   There are no ducts in any attic space; or

2.   The aged solar reflectance can be traded off with additional insulation being added  at the roof deck as specified in Table 150.2-A

Table 9-6 Aged Solar Reflectance Insulation Trade Off Table

ROOF SHEATHING

In climate zones 2 through 15: if roof sheathing over an attic space with a continuous radiant barrier is being replaced, a continuous radiant barrier must be re-installed.

9.6.5    Replacement Fenestration

If any fenestration (i.e. windows, skylights, clerestories, and glazed doors) that is being removed and replaced in an exterior wall or roof, it is considered “replacement fenestration”. 

Replacement fenestration is an area of new fenestration which replaces an equal or greater area of glazing removed in the same existing wall or roof area.  It is labeled as “altered” fenestration, and it need not occur in the same exact openings as the glazing being removed as long as it is being installed in the same existing wall or roof surface which remains a part of the existing building.  Any added fenestration area that is larger than the total altered glazing area) is labeled as “new”.

9.6.6    New Fenestration in Alterations

The 2013 Standards have relaxed some of the prescriptive restrictions on new vertical fenestration for alterations in existing dwellings.  When new vertical fenestration is added in existing dwellings, up to 75 square feet are not required to meet the overall total fenestrations limit (20 percent of the CFA) and the west-facing area limit (5 percent of the CFA).  This provides for additional flexibility to meet the Standards requirements using the prescriptive approach, without having to resort to the performance approach.  However, this additional fenestration must meet the prescriptive U-factor and SHGC requirements of Package A or meet the U-factor and SHGC requirements of Exceptions 1 and 2 to Section 150.2(b)1B.

9.6.7    Prescriptive HVAC System and Water Heating Alterations

The Standards apply to alterations of the heating and cooling system whether or not the alterations correspond to an addition to the building. This section describes the conditions where compliance is necessary and describes the corresponding prescriptive requirements.

If the heating and cooling system is left unchanged as part of an addition or alteration, then compliance with the requirements for altered HVAC systems is not necessary. Extension of an existing heating and cooling system, such as extension of a duct is not considered a change to the existing heating and cooling equipment therefore the existing heating and cooling system components are unchanged (except the ducts) and do not need to meet the Standards requirements. However, the extensions of the duct systems must meet mandatory requirements described in Section 9.4.2; and prescriptive requirements described below.

9.6.8    HVAC "Changeouts"

The Standards make a distinction between two types of HVAC "changeout" situations:

1.   Entirely New or Complete Replacement Space Conditioning Systems;

2.   Altered Space Conditioning Systems.

The differences in the requirements for these two types of HVAC changeout situations are discussed in the following sections.

9.6.9    Entirely New or Complete Replacement Space Conditioning Systems

When an Entirely New or Complete Replacement Space Conditioning Systems is installed, the system must meet all applicable mandatory measures, including:

§150.0(h)– Space conditioning equipment loads, design, installation, etc.;

§150.0(i) – Thermostat requirements;

§150.0(j)2 – Refrigerant line insulation thickness;

§150.0(j)3 – Refrigerant line insulation protection;

§150.0(m)1 – California Mechanical Code(CMC) compliance;

§150.0(m)2 – Factory fabricated duct system UL requirements;

§150.0(m)3 – Field fabricated duct system UL requirements;

§150.0(m)4 – Duct R-value minimum ratings;

§150.0(m)5 – Duct insulation thickness and R-value;

§150.0(m)6 – Duct labeling requirements;

§150.0(m)7 – Backdraft damper requirements on vent systems;

§150.0(m)8 – Gravity ventilation system dampers;

§150.0(m)9 – Protection of insulation;

§150.0(m)10 – Prohibition of using porous inner core;

§150.0(m)11 – Duct system sealing and leakage testing for new systems;

§150.0(m)12 – Air filtration requirements;

§150.0(m)13 – HSPP/PSPP, mandatory return duct sizing (or diagnostically tested airflow and fan efficacy);

§150.0(m)15 – Requirements for zonally controlled systems;

These systems must also meet the prescriptive requirements found in:

§150.1(c)6 – Allowed heating system types;

§150.1(c)7 – Space heating and cooling system minimum efficiencies and refrigerant charge verification in climate zones 2, 8 through 15.

§150.1(c)9 -  Duct insulation requirements;

§150.1(c)10 – Central fan integrate systems added or required as part of an addition or alteration must meet the 0.58 watts per cfm requirement.

These requirements are discussed in detail in Chapter 4, HVAC Requirements.

Note: Completely New or Replacement Duct Systems in multifamily dwelling units shall meet the 12% (total leakage protocol), or 6% (leakage to outside protocol) criteria used for newly constructed systems (may also use the smoke test protocol if the system does not meet these criteria).  Otherwise, altered duct systems in multifamily dwelling units shall meet the 15% (total leakage protocol), or 10% (leakage to outside protocol), or smoke test criteria given in 150.2(b)1Dii(b).

A system installed in an existing dwelling shall be considered an Entirely New or Complete Replacement Space Conditioning System when:

1.   the air handler and all of the system heating/cooling equipment ( e.g. outdoor condensing unit and indoor cooling or heating coil for split systems; or complete replacement of a package unit),are new, and

2.   the duct system meets the definition of an Entirely New or Complete Replacement Duct System (including systems less than 40 feet in length).

An altered duct system installed in an existing home shall be considered an Entirely New or Complete Replacement Duct System when:

1.   at least 75 percent of the duct material is new, and

2.   any remaining components from the previous system are accessible and can be sealed.

Altered duct systems that do not meet the definition of Entirely New or Complete Replacement Duct Systems shall be considered an Extension of an Existing System. 

Space conditioning systems that do not meet the definition of Entirely New or Complete Replacement Space Conditioning Systems shall be considered Altered Space Conditioning Systems.

9.6.10  Altered Duct Systems – Duct Sealing Requirements

Entirely New or Complete Replacement Duct Systems must meet the mandatory requirements of:

§150.0(m)12 – Air filtration requirements, and

§150.0(m)13 – HSPP/PSPP, mandatory return duct sizing (or diagnostically tested airflow and fan efficacy).

These requirements are discussed in detail in Chapter 4. 

Entirely New or Complete Replacement Duct Systems must also be sealed to the criteria for “new duct systems” found in Table RA3.1-2, discussed below.

Because Entirely New or Complete Replacement Duct Systems can also include the original air handler, which may leak substantially more than new equipment.  An attempt should be made to seal the duct system to meet the 6 percent (of nominal system central fan airflow) leakage rate criteria.  If the 6 percent leakage rate criteria cannot be met, a smoke test should be performed to verify that the excess leakage is coming only from the furnace cabinet (air handler cabinet), and not from other accessible portions of the duct system.  Note that the protocol for Smoke Test of Accessible-duct Sealing given in Reference Residential Appendix RA3.1.4.3.7 makes an exception for the furnace cabinet (air handler cabinet).

Note that this will satisfy the sealing requirement and does not cause the system to no longer meet the definition of an Entirely New or Complete Replacement Duct Systems.

Altered duct systems that do not meet the definition of Entirely New or Complete Replacement Duct Systems shall be considered an Extension of an Existing System.  These duct systems are required to meet one of the leakage criteria for “altered existing systems” cases in Table RA3.1-2.

Because duct sealing is a mandatory measure, alterations to an existing duct system, such as adding or replacing sections of duct, will trigger duct sealing.  However, cost-effectiveness must also be taken into account.  Having to seal an entire system because one foot of duct is being removed may not be cost effective all by itself.  The standards set the length of 40 feet of duct as a criterion to trigger this requirement. 

If 40 feet of duct are being added or replaced, this work alone can trigger the requirement for duct sealing and field verification.  The system would have to meet one of the leakage criteria for “altered existing systems” cases in Table RA3.1-2. 

In 'addition to the duct sealing requirements, the added or replaced ducts must also meet the air distribution requirements of §150.0(m) and the duct insulation requirements of §150.1(c)9. Note that the air distribution and duct insulation requirements must be complied with in all climate zones; however, these requirements apply to only new or replaced ducts, the existing and unaltered ducts do no need to comply with these requirements.

Installing 40 feet or less of new or replacement ducts alone will not trigger the sealing requirements described above; however, the new ducts and connections must still meet the air distribution and duct insulation requirements of §150.0(m) and §150.1(c)9.

9.6.11  Altered Space-Conditioning Systems - Duct Sealing and Insulation

Existing duct systems must be sealed and verified by a HERS rater when portions of the heating and cooling system are altered. The requirement applies in all climate zones.

9.6.12  An air handler is installed or replaced.

Ducts must be sealed (as described below) under any of the following circumstances:

1.   An outdoor condensing unit of a split system air conditioner or heat pump is installed or replaced;

2.   A cooling or heating coil is installed or replaced;

3.   More than 40 feet of new or replacement ducts are installed in unconditioned space

The requirements apply to the duct system that is affected by any one of the alterations 'listed above. If a residence has more than one duct system, only the ducts connected to the altered equipment need to be sealed and verified.

There are three options for showing compliance for existing duct systems 'listed below.  The rater or installing contractor must at least attempt compliance with the first option (15 percent leakage); then any of the other options can be utilized:

a.   Total leakage is less than 15 percent of nominal system fan airflow (RA3.1.4.3.1);

b.   Leakage to the outside is less than 10 percent of system fan airflow (RA3.1.4.3.4);

c.   If the first option (15 percent) leakage target cannot be met, then compliance can be achieved by sealing all accessible leaks verified by a HERS rater inspection.  When using this option sampling is not allowed (RA3.1.4.3.5-7).

d.   HERS field verification is required for all options 'listed above. For options 1, and 2, verification can be accomplished through sampling as described in Sampling for Additions or Alterations below. For option 3, sampling is not allowed; a certified HERS rater must do the visual inspection and the smoke test on every house that chooses option 3.

e.   Since test equipment must be set up for the first three options, it may be most efficient to test and record the results for the existing system and then attempt to meet each option sequentially until compliance is achieved.

f.    There are a few cases where duct sealing and duct leakage verification are not required.  These exceptions include the following:

g.   Ducts that have already been sealed, tested, and certified by a HERS rater;

h.   Duct systems with less than 40 ft of duct in unconditioned spaces;

Duct systems that are insulated or sealed with asbestos.

9.6.13  Accessible Ducts

Several code sections and protocols require a smoke test to demonstrate that all accessible leaks have been sealed. 

Accessible is defined Joint Appendix JA1 as “having access thereto, but which first may require removal or opening of access panels, doors, or similar obstructions.”

Ducts located in an attic or crawlspaces are generally considered accessible because code requires access to those spaces.  Access is usually gained by opening a door, hatch, or other moveable panel.  If this can be done without causing damage that would need to be repaired, this is considered accessible.  It is not expected that drywall sections have to be cut or damaged to gain access,

Some judgment is required in determining if ducts are accessible or not.   The local code enforcement agency will have the final say when it is not immediately obvious. 

For example:

If the ducts are buried under insulation, and gaining access to the leaks in these ducts would require substantially disturbing the insulation this is probably not considered accessible;

If a leak in the duct system is in too small a space between framing members for an average size person to be able to reach the joint to seal it, then this is probably not considered accessible;

If ducts are suspended far above the ground and reaching them would require scaffolding or special equipment other than normal ladders, then these are probably not considered accessible;

If sheet metal ducts are wrapped with insulation and a smoke test indicates multiple small leaks along the lengthwise seams in the ducts in many locations, it is probably not cost effective to remove the insulation to find and seal these leaks.  However, if one or more location shows a very obvious and substantial leak, it should be sealed.

All other portions of the duct system for which a smoke test identifies the presence of leakage must be sealed in order to comply. The exemption for inaccessible portions of the duct system is applicable only if the other criteria for duct leakage compliance cannot be met.

The installing contractor may perform a smoke test to locate and seal accessible leaks, or assess whether or not the duct leaks are accessible. However, compliance by smoke test and sealing all accessible leaks must be determined by a smoke test that has been conducted by a HERS rater.

9.6.14  Refrigerant Charge Verification

In climate zones 2, and 8-15, when a refrigerant containing component of an air conditioner or heat pump is replaced or installed in an existing building, §150.2(b)1F requires systems that do not have a CID installed to have refrigerant charge field verified in accordance with all applicable procedures specified in Reference Residential Appendix Sections RA3.2.2, or Reference Residential Appendix RA1.

The RCV procedures in RA3.2 are not intended to replace the equipment manufacturer’s charging procedures and specifications. The installer must first charge the system according to the manufacturer’s instructions and specifications. It is important to know that the procedures in RA3.2 are not procedures for charging a system; rather, they are procedures for verifying proper charge. HERS Raters are not allowed to adjust the refrigerant charge in systems that they are verifying. Raters are also prohibited from performing the weigh-in charge verification procedures. However, when specified by the Standards, a Rater may observe the installer while the installer performs the weigh-in procedure to verify compliance as specified in Section RA3.2.3.2 (described below).

A.   Charge Indicator Display. As an alternative to RCV the installer may install a special device called a charge indicator display (CID).  This device provides real-time monitoring of the air conditioning system and will show a warning visible to the home’s occupants when the system is either over or undercharged, or if the system airflow rate does not meet the minimum requirement.  The display unit must be located within one foot of the thermostat.  §150.1(c)7Aib states:

(When applicable, systems shall) be equipped with a charge indicator display (CID) device that provides a clearly visible indication to the occupant when the air conditioner fails to meet the required system operating parameters specified in the applicable section of Reference Joint Appendix JA6 for the installed CID technology. The CID indication display shall be constantly visible and within one foot of the air conditioners thermostat. CID installations shall be confirmed by field verification and diagnostic testing utilizing the procedures specified in Reference Residential Appendix RA3.4.2.

Minimum Airflow. When refrigerant charge verification is required for compliance, the system must also comply with the minimum airflow requirement specified in RA3.2.2.7 if the airflow verification protocol in RA3.3 can be applied to the system.

Altered HVAC systems must meet the minimum 300 cfm/ton airflow rate compliance criterion; example include but not limited to replacing the outdoor condensing unit, replacing the furnace or air handler, and entire replacement of the duct system.

Entirely New or Complete Replacement Space Conditioning Systems, as specified in §150.2(b)1C, must meet the minimum 350 cfm/ton airflow rate compliance criterion or the duct design alternative specified in 150.0(m)13.

Alternative to Refrigerant Charge and Verification requiring at least 300 cfm per ton of airflow. If the altered HVAC that requires RC&V is not able to comply with the 300 cfm per ton of airflow required under subsection Reference Residential Appendix RA3.2.2.7.2, the HVAC installer may choose the alternative procedure outlined in Reference Residential Appendix RA3.2.2.7.3, Alternative to Compliance with Minimum System Airflow Requirements for Altered Systems, provided that the system thermostat is an Occupant Controlled Smart Thermostat (OCST) which conforms to the requirements of Reference Joint Appendix JA5. 

Under RA3.2.2.7.3, installer must take a series of remedial steps, including but not limited to cleaning filters, removing obstructions from registers and dampers, replacing crushed or blocked ducts, cleaning the evaporator coil, making sure that the air handler is set to high speed and conforms to manufacturer specifications, and enlarging/adding the return duct and the return grill.  These steps must be HERS verified by a HERS rater.  Again, as mentioned above, when the installer chooses this option, the system thermostat must be an OCST.

B.   Applicability of the protocols. The refrigerant charge verification (RCV) protocols in RA3.2 and RA1 are applicable only to air-cooled air conditioners and air-source heat pumps.  Equipment types such as ground source, water source, and absorption air conditioners and heat pumps cannot be verified using the protocols in RA3.2 and RA1. When a system other than an air-cooled air conditioner or air-source heat pump is installed, the requirements in Standards §110.1 may provide further direction for compliance. 

If an aspect of the RA3.2.2 or RA1 verification protocol is not applicable to the system, alternative requirements may be specified by applicable subsections of §150.2(b)1F, however the procedures in RA3.2.2 or RA1 that are applicable to the system shall be performed. 

For example, if a system does not have both a high side and low side refrigerant access port, thus cannot conform to the subcooling or superheat refrigerant charge verification procedure, but is a ducted system that can conform to the airflow measurement protocol; the system must comply with the minimum airflow requirement specified in RA3.2.2.7.  Similarly, if the outdoor temperature is below 55°F which precludes use of the RA3.2.2 protocol for verification of the charge, and if the RA1 protocol cannot be used, then the weigh-in charging procedure in Reference Residential Appendix Section RA3.2.3.1 shall be used, and the minimum system airflow rate shall be verified as required by RA3.2.2.7.

The installer must determine which procedures are applicable to a system and verify compliance accordingly. 

C.   Thermostats. When an existing system has a refrigerant containing component added or replaced, the thermostat must be upgraded to a digital setback type that meets §110.2(c)

Package Units. Package units are typically pre-charged at the factory prior to shipment. When a new package unit is being installed or is replacing an older unit it may not require RCV if the installer can document that the manufacturer certified correct refrigerant charge at the factory. The installer must submit a certificate of installation documenting this and third party verification of refrigerant charge by a HERS rater is not required. This only applies to new equipment shipped from the manufacturer. Any modification to existing equipment that adds or replaces refrigerant containing components voids the manufacturer’s certification. It is also important to note that this does not relieve the contractor from the requirement to verify that the system meets the minimum 300 cfm per ton airflow rate requirement.

D.   Mini-Splits and Other System Types. Some air-cooled air conditioning systems and air-source heat pumps cannot use the standard charge verification procedure, as specified in RA3.2.2, due to the design or construction of the system components. These include certain types of “mini-split” systems and variable speed condenser systems. In these cases, the installer must use the weigh-in charge procedures, as specified in RA3.2.3.1, and these systems must be HERS verified using the, as specified in RA3.2.3.2 procedure for HERS Rater observation of the weigh in charge procedure. These systems must also be equipped with an Occupant Controlled Smart Thermostat (OCST) which conforms to the requirements of Reference Joint Appendix JA5.

It is therefore important that the installation of these types of systems be coordinated with the third party verification. When these systems are ducted, they are still subject to the minimum system airflow requirements.

1.   Winter Refrigerant Charge Verification. Most systems will normally be verified using the RA3.2.2 standard charge verification procedure to demonstrate compliance. However, when the outdoor temperature is less than 55^oF, and the Standard Charge verification procedure cannot be used, the installer may elect to use the weigh-in charge method to demonstrate compliance.  Compliance with HERS verification when the outdoor temperatures are less than 55^oF can be demonstrated using one of two alternatives:

A.   The installer may use the weigh-in charging procedure, but elect to have the system verified by a HERS rater using the RA3.2.2 Standard Charge Verification procedure at a later time when the temperature is warmer; however, this option can delay the project; or

B.   The EXCEPTION to Section 150.2(b)1Fi provides for an alternative HERS verification procedure if the weigh-in method is used. This exception allows the installer to elect to utilize the HERS Rater verification procedure in Reference Residential Appendix Section RA3.2.3.2 in which the Rater observes the installer while the installer performs the weigh-in charging procedure. However, when the HVAC installer elects this procedure for verification, as specified in RA3.2.3.2, the system thermostat must be an Occupant Controlled Smart Thermostat (OCST) which conforms to the requirements of Reference Joint Appendix JA5.

C.   Weigh-in Procedure During Warm Weather. The installer may also opt to use the weigh-in procedure when the outdoor temperature is at or above 55^oF, but in this case the rater must use the standard charge verification procedure.

D.   Weigh-in Procedure Description. The weigh-in procedure involves charging the system by determining the appropriate weight of refrigerant based on the size of the equipment and refrigerant lines rather than by actual performance of the system.  Systems utilizing the weigh-in procedure by the installer for any reason may not be third party verified by using sample groups.

There are two basic variations of the weigh-in procedures.  One involves the adjustment to the amount of refrigerant in a system by adding or removing a fraction of the refrigerant as specified by the manufacturer (weigh-in charge adjustment).  The other involves evacuating the entire system and recharging it with the correct total amount of refrigerant, by weight (weigh-in total charge).

The weigh-in charge adjustment procedure may only be used when a new factory-charged condenser is being installed and the manufacturer provides adjustment specifications based on evaporator coil size and refrigerant line size and length.

The weigh-in total charge may be used for any weigh-in procedure but still requires manufacturer’s adjustment specifications.

E.   Standard Charge Procedure Description. The standard charge verification procedure also has two basic variations.  One is for systems that have a fixed orifice and the other is for systems that have a variable metering device such as a thermostatic expansion valve (TXV) or electronic expansion valve (EXV).

Both procedures, whether performed by the installer or the rater require that adequate airflow be confirmed prior to verifying charge.  If the airflow is less than the minimum requirement of 300 cfm per ton, the system is not operating near its designed capacity or efficiency and the standard charge verification procedure is not valid.

The standard charge verification procedures involve taking refrigerant line temperatures and pressures, calculating equipment performance parameters and comparing those to targets either provided by the manufacturer or obtained from standard tables.  All temperature and pressure measurements must be taken using calibrated digital meters.  Analog gauges are no longer allowed for refrigerant charge verification procedures due to a lack of accuracy and precision.

In systems that have metering devices, the proper installation and performance can be verified by similar measurements and is an important part of the standard charge verification procedure for systems that have metering devices.

F.   Verifying Minimum System Airflow. The procedures for measuring total system airflow are found in RA3.3.  They include plenum pressure matching using a fan flow meter, a flow grid, a powered flow hood and the traditional (non-powered flow hood).  The airflow verification procedures for refrigerant charge verification no longer include the temperature split method.

If a system does not meet the minimum airflow requirements, remedial steps may be required to bring the airflow up.  More airflow is generally better for systems with air conditioning.  Not only does this allow proper refrigerant charge to be verified, but it also improves the overall performance of the system.  When able to be performed on a system, regardless of the refrigerant charge verification procedure, minimum system airflow must always be verified.  Note that §150.2(b)1F states that systems must be installed with “all applicable procedures”.  This includes the minimum system airflow requirements.

In some cases, improving airflow may be cost prohibitive and there is a process for documenting this in RA3.2.2.7.3.  When this option is used, verification by sample groups is not allowed.

G.   Temperature Measurements. To properly perform the standard refrigerant charge verification procedure, a means of taking an accurate return air dry-bulb temperature must be provided by the installer.  In most systems, this is accomplished by drilling a 5/16” measurement access hole (MAH) in the return side of the air handler or return plenum as shown in Figure RA3.2-1.  In some cases the correct location for these holes may not be accessible and an alternative location may be provided as long as an accurate return air temperature measurement of the air as it enters the return side of the equipment can be made.

In other cases, taking the return air dry-bulb temperature at the return grill may be appropriate.  This is true when the return is located entirely within conditioned space and not subject to leakage or conduction that may change the temperature of the air after it passes through the return grill and before it enters the evaporator coil.  This may also apply to equipment where the return grill is an integral part of the air handler, such as enclosed soffit-mounted air handlers (aka, “pancake units”).

E.   Maintaining 70°F Return Air Temperature. During the data collection portion of the standard charge verification procedures, the return air dry bulb temperature, as measured at the MAH, must remain at or above 70°F.  This is to ensure proper refrigerant charge conditions, including but not limited to preventing the moisture on the coil from freezing.  This requirement may be problematic during cooler outdoor conditions (above 55°F but below 70°F).  The return air temperature can be maintained above 70°F by utilizing the home’s heating system or supplemental heaters is permissible.  <refer to Blueprint language on this topic>.  Note that the weigh-in method is always an option for the installer in these cases.

F.   Airflow and Fan Efficacy

In all climate zones when an entirely new or replacement duct system (refer to section 9.6.9, above) is installed, the central forced air fan of all ducted air conditioners and heat pumps must simultaneously, in every zonal control mode, demonstrate an airflow of greater than 350 CFM/ton of nominal cooling, and a fan watt draw of less than 0.58 W/CFM in accordance with the procedures in Reference Residential Appendix RA3.3.  

As an alternative to the field verified air flow and fan efficacy requirements, the system’s return ducts can be sized according to Tables 150.0-C or 150.0-D.

In 'addition to either the airflow/fan efficacy or return duct sizing alternative, the system installer must provide in the supply plenum, a hole for the placement of a static pressure probe (HSPP) or a permanently installed static pressure probe (PSPP), downstream of the evaporator coil that meets the specifications of Residential Reference Appendix RA3.3.1.

<Insert Diagram>

These requirements are mandatory measures and cannot be traded off by using the performance approach.

These requirements are discussed in more detail in Chapter 4 of this 'manual.

Heating-only space-conditioning systems are not required to meet the prescriptive cooling coil airflow and fan watt draw requirements.

G.   Sampling for Alterations

When compliance for an alteration requires field verification and diagnostic testing, the building owners or their agents may choose to have testing and field verification completed for the dwelling unit alone, or as part of a closed sample group of dwelling units for which the same installing company has completed work that requires testing and field verification for compliance.

Registration of the compliance documentation is required and the procedures for registration of compliance documentation must be followed as described in Chapter 2 of this Residential Compliance Manual, and in Residential Reference Appendix RA2.

Notes regarding sampling for alterations:

1.   The sample group shall be no larger than seven;

2.   The installing company may request a smaller group for sampling; 

3.   Homes in a sample group must all have the same set of features to be verified (duct testing, airflow/fan efficacy, refrigerant charge, etc.);

4.   Homes with systems utilizing the weigh in method for refrigerant charge verification by the installer cannot be sampled;

5.   Whenever the HERS rater for the group is changed, a new group will be established; 

6.   Field verification and diagnostic testing shall be completed by the HERS rater for at least one randomly selected dwelling unit in each group; 

7.   Re-sampling, full testing and corrective action shall be completed if necessary, as specified by the Residential Reference Appendix RA2.6.3;

8.   The installing contractor must self test and register certificates of installation for all features to be tested prior to the rater choosing a home for verification by sampling.

H.   Third Party Quality Control Program

An approved Third Party Quality Control Program may serve some of the functions of HERS raters for field verification and diagnostic testing purposes but does not have authority to sign the Certificate of Field Verification and Diagnostic Testing (CF-4R) as a HERS rater, as specified in Residential Reference Appendix  RA2.7.

When a Third Party Quality Control Program is used, the HERS rater must still submit completed, signed, registered copies of the CF-4R to the enforcement agency, the installing contractor, and the builder or building owner for all dwellings that must demonstrate compliance.

I.    Setback Thermostat

When a split system air conditioner or heat pump is altered by the installation or replacement of any refrigerant containing component and the existing thermostat is not a setback thermostat, then a new setback thermostat must be installed as described in Chapter 4 of this 'manual and as specified in §150.2(b)1F.

J.   Fuel Switching

For prescriptive compliance, new electric resistance heating systems are prohibited in alterations unless the system being replaced is an electric resistance heating system. If the existing system is gas, propane, or LPG, then new electric resistance systems are not permitted. However, changing from a gas, propane, or LPG space heating system to an electric heat pump is allowed as long as the heat pump efficiency meets minimum efficiency standards, and the heat pump installed size is shown to result in no more TDV energy use than the standard design heat pump using the performance method as specified in §150.2(b)1C.

Table 9-7 – Acceptable Replacement Heating System Fuel Source(s)

Table 9-5B summarizes requirements for the following types of residential mechanical and water heating system alterations:

1.   New or complete replacement space conditioning system: all new equipment and all new ducts with more than 40 linear feet of ducts in unconditioned or indirectly conditioned space;

2.   Altered space conditioning system with forced air ducts;

3.   Altered mechanical cooling system;

4.   Altered duct systems: when more than 40 linear feet of new or replacement ducts are installed in unconditioned or indirectly conditioned space;

5.   Installed a zonally controlled central forced air system;

6.   Replacing water heaters and altering hot water pipes.

Since there are some overlaps in Table 9-5B between a few mandatory and prescriptive measures depending on the kind of alteration, it is important to accurately identify the type(s) of alteration within the permitted scope of work.  For example, duct sealing and HERS testing is a mandatory measure when there is a new or complete replacement space conditioning system and greater than 40 linear feet of ducts in unconditioned space.  However, when only new or replacement ducts are being installed, and there is no new space conditioning equipment involved, duct sealing and HERS testing is a prescriptive measure.  A key to using Table 9-5B effectively is to have a good understanding of the scope of the proposed alterations.

Table 9-8 Summary of Prescriptive HVAC & Water Heating Alterations

Table 9-9: Residential Alteration, Summary of Mandatory and Prescriptive Measures