FAQs

Not necessarily. 

An A2L system is evaluated from an RCL-perspective by comparing the system charge to the effective dispersal volume charge (EDVC) permitted by the space volume. 

Mechanical ventilation can be used to connect one or more spaces to create a larger volume, which in turn permits a larger EDVC.

If the system charge still exceeds the allowable EDVC for a particular space, then that space must be constructed to meet the machinery room requirements of ASHRAE 15 sections 8.9.1 through 8.9.4 and section 8.11, which does include a requirement for ventilation. 

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.2.3.4) (source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 8.9)

ASHRAE 15 – 2024, Section 7.5.1.2, defines two criteria for A2L-equipped refrigeration systems in a public corridor or lobby: 1) the systems should be self-contained, unit systems, and 2) the system charge must not exceed an LFL-based maximum charge. The standard gives no consideration for the type of refrigeration system, which implies that both high-probability and low-probability systems must meet this requirement. 

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.5.1.2.)

Like most ducted applications, most UCK air handler / system combinations will require circulation to achieve compliance. Circulation will allow for the consideration of the total ducted space volumes. The upcoming R-32 version of the UCK allows for the connection of third party RDS, which would allow the UCK to energize the fan in response to a potential leak. The manufacturer of the air handler will still be responsible for establishing the approved location of the RDS via UL 60335-2-40, Annex MM.

No, there are currently no plans to integrate third party valves into the mitigation solutions for DVM.

Addendum a to ASHRAE 15-2024 revised the text of section 7.2.3.1.1 Exempted Spaces to reflect that components like valves do not meet the exemption requirements, and as such, the placement of the SVB or MCU must be evaluated to ensure the space volume can accommodate the releasable charge. If the space volume is too small, then the ventilated enclosure approach can be used to ventilate the SVB or MCU. 

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.6.4)
(source: ANSI/ASHRAE Addendum a to ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.2.3.1.1)
(source: UL. 2024. UL 60335-2-40, Annex GG.4DV D1)

This source of confusion has been clarified in the 2024 edition of the standard. Section 7.3.1 still contains RCL calculations but now includes a subsection, Section 7.3.1.1, that explicitly refers to A2L equipment as defined in Section 7.6. A2L equipment will always use LFL for room and equipment sizing.

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.3.1.1)

During a typical OFF state, if the RDS detects a leak, then the indoor unit will be energized. For systems which have been shut down by the Forced Off contact of the central touch, new central touch, and DMS, the indoor unit will remain Forced Off.

DVM Pro calculates the releasable charge at the MCU or SVB as the entire system charge.

The safety shutoff valves are located on the outlet ports of the MCU, in order to limit the leaked charge if a leak were to develop at the indoor unit. For a leak at the MCU or heat pump valve box, the internal leak will be mitigated by the MCU’s ventilation connections and integral RDS.

Typically, when the releasable charge exceeds the EDVC charge, Mechanical Ventilation can be applied in accordance with ASHRAE 15 section 7.6.4. However, when a ventilated enclosure, such as an MCU or SVB, is used to control the leak, no additional ventilation requirements are necessary for compliance. 

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.6.4)
(source: UL. 2024. UL 60335-2-40, Annex GG.4DV D1)

In the U.S., the phasedown of refrigerants is mandated by the AIM act. The next major phasedown milestone is in 2029, but there is no definitive transition by technology type at this time.

When following ASHRAE 15, section 7.2.3.3.2 both ceiling and floor plenums are allowed to be included in the volume calculation, as long as the ducted system contains RDS and the plenum is part of the air distribution system. Similarly, section 7.2.3.3.3 permits the inclusion of supply and return air duct volumes.

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.2.3.3)

Section 9.13.7 requires the certificate-of-test only for systems over 55 lb or more of refrigerant. This section also requires the certificate to include test dates, photographs of the pressure gage at the test pressure, refrigerant designation, test medium, and the test pressures applied to the system during the test.

The test time varies according to the length of pipe in the system being tested, but generally a 24-hour limit will be applied for systems with over 200 feet of piping.

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 9.13.7)

The International Mechanical Code applies a requirement that refrigerant piping penetrating two or more floor/ceiling assemblies must be enclosed in a fire-resistance-rated shaft enclosure. ASHRAE 15 applies a requirement that shafts which contain A2L refrigerants must be mechanically or naturally ventilated. However, Addendum B makes the installation of shafts optional, and if used, it allows an exception to the ventilation of shafts if there are no hot surfaces exceeding 1290°F in the shaft and the refrigerant piping, including joints and connections, are tested in accordance with Section 9.13. UMC defines the requirements for refrigerant piping that penetrates a floor. In some cases, this piping must be enclosed in a shaft but note that the UMC does not apply a requirement to ventilate such a shaft.  

(source: ICC. 2024. International Mechanical Code. Washington, DC: International Code Council, Section 1109.2.5)
(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 9.12.2.2)
(source: IAPMO. 2024. Uniform Mechanical Code. Ontario, CA: International Association of Plumbing and Mechanical Officials, Section 1109.3)

The IMC typically operates on a 3 year code cycle, with the most current edition being 2024. The next edition is 2027.

Similarly, the UMC also operates on a 3 year cycle and is expected to be updated in 2027.

The current ventilated shaft requirements of ASHRAE 15-2024, section 9.12.2.2 do not actually require any control of the system(s) whose pipe runs through the shaft. Logically, there may be many systems with piping in the shaft, and it would be impossible to determine which system is leaking using only the RDS.

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 9.12.2.2)

The current sequence of operations for Samsung products will shut the system down upon detection of a leak by the RDS at the MCU or valve dox.

However, if the RDS in an indoor unit connected to the MCU or valve box detects a leak, then only the associated zone will be shut down.

After 10 years, the sensor must be replaced. Safety standards restrict the in-field calibration of refrigerant detection sensors.

When calculating compliance for a given volume, the effective dispersal volume charge is compared against the releasable charge, Mrel. The releasable charge used for this calculation is the largest releasable charge downstream of independent shut-off valves.

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.3.4.2)

No, the shutoff valves inside the MCUs and SVBs do not double as typical service isolation valves with Schrader ports.

No, the SVB heat pump valve boxes will not be compatible with DVM Mini heat pumps systems. Later in 2026, a single-port SVB will be introduced with compatibility to DVM Mini.

There is no plan to use safety shutoff valves with FJM or CAC systems at this time. The total system charge for these systems is relatively low, making them suitable for most applications without requiring shutoff valves.

The existing range of port-quantities will be retained when applying safety shutoff valves for R-32.

The MCU’s and valve boxes are designed as ventilated enclosures per UL 60335-2-40, Annex GG. They have a duct connection for exhaust air flow, which should be a minimum of 12 CFM, and they must maintain a negative pressure of minimum 0.08 in wg (20 Pa) and maximum 1.4 in wg (350 Pa).

(source: UL. 2024. UL 60335-2-40, Annex GG.4DV D1)

There is no specific requirement for an alarm on the thermostat as part of the standard mitigation actions in ASHRAE 15, section 7.6.2.5.

If an external alarm is requested, an MIM-B14U I/O board can be installed to supply a dry contact output when a leak is detected at the indoor unit.

The RDS sensor in the unit does not itself generate an alarm sound, nor is there a code or standard requirement which requires an audible alarm.

No, the RDS location for all air handlers must be validated by testing in accordance with Annex MM. Each air handler manufacturer will establish the compliant location.

When a chiller or condensing unit is installed indoors, and the system charge exceeds the allowable EDVC for the equipment room, then the machinery room must include ventilation and a refrigerant detector, per ASHRAE 15-2024, section 8.11.6. There are various requirements for the ventilation outlined in Section 8.11.11, two of which imply that the condensing unit fan would not be a suitable mechanism for machinery room exhaust:

• Inlets to the exhaust openings or ducts shall have their bottom edge within 1 foot of the floor
• Electric motors shall not be placed in the duct, and fan rotating elements shall be non-sparking.

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.4.3)
(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 8.11.6)
(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 8.11.11)

There are various error codes associated with leakage that will go to BACnet. However, there is not a separate object for related to RDS leakage detection; the integrator will need to parse out error codes in order to take specific action related to A2L leakage error codes.

The R-454B Hylex features an ACU which has been upgraded to receive an input from the third party AHU’s RDS outputs. Then the Hylex’s internal sequences can generate the appropriate error code and energize the AHU fan.

Recall that the RDS location must be identified by the AHU manufacturer and verified according to UL 60335-2-40, Annex MM.

It’s not feasible to field test the RDS, and currently there is no test feature to engage the safety shutoff valves. It’s not recommended to spray R32 on the sensors, as exposure to R-32 and other chemicals can reduce the sensor’s effective life.

ASHRAE 15, Section 8.12 contains open free area calculations for natural openings. If large enough, no other ventilation is required. The minimum required free area depends on the amount of refrigerant in the system.

This also requires that the refrigeration system is located more than 20 ft from building openings.

In the AIM act, the manufacture/import ban for chillers began Jan 1, 2025. The chiller sell through period is established to be three years, ending Jan 1, 2028. However, there are several State regulations that prohibit installation of Chillers.

There is no indication in the standards and codes that exhaust fans used for shaft ventilation need to be spark resistant or connected to an explosion proof motor.

The DMS will not close the shut-off valves in the system. The DMS can be used for other types of emergency shut down, but should not be used for fire safety applications.

The units indicated are the standard units-of-measure for these two values.

ASHRAE 15-2024, section 4 defines the following occupancy classifications: Institutional; Public assembly; Residential; Commercial; Large mercantile; Industrial; Mixed.

With respect to refrigerants limits, the Institutional occupancy type is the outlier, requiring mandatory RDS for A2L systems as well as applying a correction factor when making compliance calculations. All other occupancy types are treated the same.

(source: ANSI/ASHRAE. 2024. Standard 15: Safety Standard for Refrigeration Systems. Atlanta: ASHRAE, Section 7.6.2.3)

R-410A indoor units and outdoor units for DVM S2 will continue to be produced after the phase-down, to be sold as components for repair-only in existing systems.

Parts for R410A units will be available for as long as the longest warranty requires, which is 12 years.

Systems can be registered:

1.  Using the Samsung HVAC Mobile App
2.  Under the Training & Support menu tab on samsunghvac.com
3.  In Samsung HVAC Dealer Link*
4.  In Samsung HVAC B2B B-Link*

*Limited access

Email registrations@samsunghvac.com with the registration confirmation number.

Registering the product within 60 days of installation will secure the enhanced warranty on eligible systems.

Systems can be registered:

1.  Using the Samsung HVAC Mobile App
2.  Under the Training & Support menu tab on samsunghvac.com
3.  In Samsung HVAC Dealer Link*
4.  In Samsung HVAC B2B B-Link*

*Limited access

Warranty claims must be submitted by a dealer in Samsung HVAC Dealer Link or by a distributor or spec rep in Samsung HVAC B2B B-Link.

Email warranty@samsunghvac.com with the warranty claim confirmation number.

Warranty parts are generally processed and shipped in 1 business day.

Installation and service manuals are located in the Tech Documents section under the Training & Support tab.

No, because of the inverter compressor ramping up and down, pressure and temps will fluctuate. If a charge issue is suspected, weigh out the charge and verify the factory charge on the side of the unit. If low, find and repair the leak. After the leak is repaired, perform a pressure test, vacuum down under 500 microns and weigh in factory charge.

You will need a computer with the SNET Pro software and a service tool. The process will require a 60-minute recording in test mode and a 60-minute recording of normal operation.

Yes, you will need to download the certificate or you will continue to receive the error when connecting to the gateway. The DMS 2.5 instruction manual shows a step-by-step procedure for downloading the certificate.

You will need a 410A adapter. It converts ¼ (standard) to 5/16 (410A specific).

New indoor boards do not come programmed and will need to be programmed with a wireless controller once installed. The option code procedure is in the service manual. Service manuals are located in the Tech Documents section under the Training & Support tab.

Samsung requires 16/2 stranded shielded cable for all communication wiring grounded at the outdoor unit only.

Option 1

Check voltage at the sensor terminal. If the board does not read between .5 - 4.5 vdc, the board is defective.

Option 2

Check the DC link voltage on pins 1 and 3 (red and black wires) on the BLDC fan connection on the PCB.

The reactor improves the power factor of the inverter power supply, reduces harmonics, and suppresses external surges.

Wireless Controllers

Enter the product code by following the steps found in the service manual. Service manuals are located in the Tech Documents section under the Training & Support tab.

Ducted IDUs Without a Factory Wireless Receiver

Using a direct coupled wireless receiver kit, plug the display connector in the main PCB and manually input the product code located in the service manual. This process should be performed multiple times to ensure successful operation.

1. Confirm that 12 vdc are present at the controller
2. Verify the number of terminals on the controller

• MWR-WE10N (2 terminals) 2 wire connection (F3,F4) 
• MWR-WE10 (4 terminals) 4 wire connection (RAC, FJM - V1, V2)

Product code information is located in the installation and service manuals. Installation and service manuals are located in the Tech Documents section under the Training & Support tab. 

Dip Switches

The dip switches should remain in the default position (ON) for auto addressing. The first dip switch should remain down (OFF) for manual addressing.

Rotary Dial

The rotary dial must be set to the total number of indoor units connected. (Ex. 3 indoor units, set the outdoor dial to 3).

E201 indicates the number of indoor units connected do not match the rotary dial setting at the outdoor unit.  Make sure the dial is set to the number of indoor units connected. 

Check all communication wiring and power wiring.  If any single indoor unit is not powered properly or the communication wire is broken or spliced, the outdoor unit may lose communication to that indoor unit.

Note: Communication wiring will not function properly if wire nuts or splices are present.

E199 is indicating the system is communicating and ready for the start-up procedure (pipe check). Simply press the K1 button once to initiate the pipe check. The outdoor display will show “K5” on the screen. The pipe check typically takes 15-20 minutes in cooling mode and can take up to 60 minutes in heating mode.

Compressor winding

U, V, and W reading should be equal

Compressor to ground

Should have an infinity reading (OL)

The model number is located on the back of the wired controller. It will start with the letters “MWR."

Because the foil surrounding the wires acts as a shield to protect the wiring from harmful external interference that could disrupt the signal. Also, it is very important to connect only one end to a ground connection in the unit. If both ends are grounded it creates a continuous path for the interference and will cause communication problems.

Triple evacuation is a three step process to remove moisture from the system. This process will help prevent compressor failure.

Step 1

• Evacuate down to 5,000 microns
• Pressurize with dry nitrogen to 3 PSI
• Hold pressure for 10 minutes
• Release nitrogen

Step 2

• Evacuate down to 2,000 microns
• Pressurize with dry nitrogen to 3 PSI
• Hold pressure for 15 minutes
• Release nitrogen

Step 3

• Evacuate to below 200 microns
• Hold pressure for 60 minutes

Always refer to the detailed menus found in the installation manual for each wired controller. Installation manuals are located in the Tech Documents section under the Training & Support tab. 

Refrigerant calculator factors can be found in the installation manual. Installation manuals are located in the Tech Documents section under the Training & Support tab. 

Installation and service manuals are located in the Tech Documents section under the Training & Support tab.

No, because of the inverter compressor ramping up and down, pressure and temps will fluctuate. If a charge issue is suspected, weigh out the charge and verify the factory charge on the side of the unit. If low, find and repair the leak. After the leak is repaired, perform a pressure test, vacuum down under 500 microns and weigh in factory charge.

You will need a computer with the SNET Pro software and a service tool. The process will require a 60-minute recording in test mode and a 60-minute recording of normal operation.

Yes, you will need to download the certificate or you will continue to receive the error when connecting to the gateway. The DMS 2.5 instruction manual shows a step-by-step procedure for downloading the certificate.

You will need a 410A adapter. It converts ¼ (standard) to 5/16 (410A specific).

New indoor boards do not come programmed and will need to be programmed with a wireless controller once installed. The option code procedure is in the service manual. Service manuals are located in the Tech Documents section under the Training & Support tab.

Samsung requires 16/2 stranded shielded cable for all communication wiring grounded at the outdoor unit only.

Wireless Controllers

Enter the product code by following the steps found in the service manual. Service manuals are located in the Tech Documents section under the Training & Support tab.

Ducted IDUs Without a Factory Wireless Receiver

Using a direct coupled wireless receiver kit, plug the display connector in the main PCB and manually input the product code located in the service manual. This process should be performed multiple times to ensure successful operation.

1. Confirm that 12 vdc are present at the controller 
2. Verify the number of terminals on the controller

• MWR-WE10N (2 terminals) 2 wire connection (F3, F4)

"UP" indicates that the system has not performed the auto trial operation portion of the start-up. 

To initiate the auto trial operation, press the K1 button for a few seconds. The left-hand screen will display digital “KK” and the right-hand screen will be blank. This process will last for 20 - 60 minutes.

Triple evacuation is a three step process to remove moisture from the system. This process will help prevent compressor failure.

Step 1

• Evacuate down to 5,000 microns
• Pressurize with dry nitrogen to 3 PSI
• Hold pressure for 10 minutes
• Release nitrogen

Step 2

• Evacuate down to 2,000 microns
• Pressurize with dry nitrogen to 3 PSI
• Hold pressure for 15 minutes
• Release nitrogen

Step 3

• Evacuate to below 200 microns
• Hold pressure for 60 minutes

The model number is located on the back of the wired controller. It will start with the letters “MWR."

Always refer to the detailed menus found in the installation manual for each wired controller. Installation manuals are located in the Tech Documents section under the Training & Support tab.  

U200 E201

The outdoor (ODU) unit cannot find either the exact number of indoor units (IDU) or MCU’s that it has been told to find.  The MCU’s have to be manually addressed before the ODU is told to communicate with them.   

C10x E216 

The MCU (addressed as “x”), wasn’t addressed to attach a specific port. You have to determine which IDU (based on the address it was manually assigned or by the outdoor unit auto assigning) does not have an indoor unit(s) on one or more of its ports.  

Field correction is needed to address the IDU’s to match what the MCU is expecting at each port.

Refrigerant calculator factors can be found in the installation manual. Installation manuals are located in the Tech Documents section under the Training & Support tab.  

Od Nd

The installation manuals for the new version “2AA” VRF condensing units describe how the outdoor unit has not been defined (Od Nd) as either a MAIN or a SUB (SUB1 or SUB2*) unit.  

Id Nd

Is stating that the indoor unit quantity is not defined (Id Nd). The manuals will explain the use of the K1, K2 and K4 buttons at the main PCB to determine and save the quantity of indoor units it has to manage.

Installation and service manuals are located in the Tech Documents section under the Training & Support tab.

*DVM S Eco utilizes MAIN only.

VRF stands for Variable Refrigerant Flow. VRF HVAC systems consist of outdoor units connected to multiple indoor units via refrigerant piping to provide cooling and heating to individual zones. The outdoor units can modulate capacity based on the requirements of the individual zones, thus saving energy by not always running at 100% capacity and improving occupant comfort by maintaining temperature as needed in each individual zone.

Service manuals are located in the Tech Documents section under the Training & Support tab.

Yes, you will need to download the certificate or you will continue to receive the error when connecting to the gateway. The DMS 2.5 instruction manual shows a step-by-step procedure for downloading the certificate.

Samsung requires 16/2 stranded shielded cable for all communication wiring grounded at the outdoor unit only.

• Lookup the error code in the controller installation manual for details and directions.
• Note that the first time a DVM S system is started up that wired controllers will not turn on until addressing is completed.  If there are addressing errors the first time power is applied to the system, wired controllers may remain unpowered until the proper addressing/commissioning steps have been completed. 

Most Samsung wired controllers sold in the USA and Canada are configured for °F by default.  To change to °C, refer to the detailed menus found in the installation manual for each wired controller. Installation manuals are located in the Tech Documents section under the Training & Support tab.

The model number is located on the back of the wired controller. It will start with the letters “MWR-".

Using the direct connection into the gateway through its CAT 5 port to a laptop, use the built in interface software to complete the following steps: 

1. Select system settings
2. Locate BACnet gateway information
3. Select Recipient List Initialize

Once complete, the BMS system can share the Samsung system data.

If there is a communication error between the indoor unit and the wired controller (E604) be sure the correct wired controller is being used. Always refer to submittals if there is any uncertainty. Submittals are located in the Tech Documents section under the Training & Support tab.

2 Wire controllers (F3, F4) are used for Residential (RAC), Multi-zone (FJM), Light Commercial (CAC) and Commercial (DVM S, DVM S Mini).