Average Operating Pressures For Home AC Unit With R410A - Answered by a verified HVAC Technician We use cookies to give you the best possible experience on our website. As for high side pressures, your looking for a pressure that is about 20 deg F above outdoor ambient air that is entering the condenser. All Rights Reserved BNP Media. R-407C Refrigerant Pressure Temperature Chart By Alec Johnson Jan 11, 2020 One of the very first steps when it comes to diagnosing your home air conditioner, refrigerator, or even your vehicle’s air conditioner is understanding the temperature and the current pressure that your system is operating at. After checking the contactor for proper operation, it’s time to check the refrigerant pressures. Both vaporization and condensation occur in the evaporator and condenser respectively. Condensing pressure: High-side pressure, head pressure, discharge pressure. I agree with your list. Readings that are higher or lower indicate an overcharged system. Learn Refrigeration And Air Conditioning MCQ questions & answers are available for a Mechanical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. When the refrigerant cylinder is connected to an operating system, the pressure in the cylinder will be_____ than the suction pressure of the system. Refrigerants can coexist as a vapor and liquid as long as conditions are right. A good refrigerant should have _____. Thanks for any help. and low freezing point Answer: Option A It comes up with special properties to introduce dry charging the refrigerant. So, the ideal refrigerant should have a vapor pressure of about 0.2 to 2 MPa at the temperature of the hot reservoir. • At 100°F, evaporating pressure in an R134a system is 26.6 psig. Because R-410A differs from R-22 in several respects, including operating pressure, some trade schools offered classes and certifications for R-410A specifically. This temperature should be about 35 to 40 degrees F below the Return Air temperature. Listed below are field service terms or trade jargon often used to describe these pressures. Both the liquid and vapor at their saturation temperatures are called saturated liquid and saturated vapor respectively. Keep up the good work. 1). and low freezing point, … Refrigeration compressor units that are installed outdoors must have cold weather controls to operate properly and maintain proper temperature in the cooler or freezer during the cold winter season. High operating pressures and low freezing point. R-290 Pressure Chart. Both the evaporator and condenser house liquid and vapor refrigerant simultaneously if the system is operating properly. R-22 has become more common in refrigeration so that would depend upon the desired temperature. You should NEVER mix refrigerants or mix incompatible oils. The system should be recovered, vacuumed (min 20 minutes) and charged. On small systems where pressure drops are negligible, this pressure is usually measured near the compressor. The saturated liquid condition is often referred to as the bubble point. A good refrigerant should have. Saturated condition: Saturation is usually talked about in reference to a temperature. By visiting this website, certain cookies have already been set, which you may delete and block. However, both liquid and vapor are at the same temperature for a given pressure when saturation occurs. Likewise, an R-410A recovery bottle with a surrounding air temperature of 70 °F should have an internal pressure of 201 PSIG. Visit our updated. For R410A it should be around 115-120 psi. Sensible heat: Heat energy that causes a change in the temperature of a substance. For heat pump. Remember, the condensing pressure is the pressure at which the refrigerant is changing phase from a vapor to a liquid in the condenser. The HFC R-32 refrigerant is quickly becoming popular, more so then it already was. You should NEVER charge an A/C system with liquid, as it can cause mechanical damage to the compressor. The extra refrigerant charge for head pressure control should be weighed in now by admitting liquid refrigerant to the high side. Higher condenser pressure will result in high operating costs. For these blends, the vapor and liquid pressures are only separated by 1 or 2 psi. So, refrigerant liquid and vapor can exist in either high- or low-pressure sides on the refrigeration system. Attach refrigerant gauges to the high and low side ports of the system. 2) As the blend changes phase, more of one component will transfer to the other phase faster than the rest. Toxicity: The refrigerant used in air conditioning, food preservation, etc. A denser refrigerant will have fewer tendencies to leak as compared to higher density refrigerant. Latent heat: Heat energy that causes a change in phase of a substance without a change in temperature of the substance. Producing a program that outlines organization-specific, written refrigeration regulations is the first step to effective compliance. As pressure increases, saturation temperature increases. When checking the subcool condition, the technician will measure the temperature of the liquid line, the pressure at that point and subtract the measured temperature from the saturated temperature at the end of the condenser. Question: how does the system stay at 70 psi (July 8, 2016) Matthew said: The typical vapor compression refrigeration system (as shown in Figure 1) can be divided into two pressures. The detection of leaks should be easy to loss of refrigerant. A gauge reading on the high side of the system is all that is needed to find the condensing pressure. John Tomczyk is a professor of HVACR at Ferris State University, Big Rapids, Mich., and the author of Troubleshooting and Servicing Modern Air Conditioning & Refrigeration Systems, published by ESCO Press. This addition of heat will cause the vapor to increase in temperature and gain sensible heat. and low freezing point. By closing this message or continuing to use our site, you agree to the use of cookies. High pressure and low pressure readings vary depending on the system and the ambient temperature. Higher temperatures cause higher readings. Having gone through all the above details, you are still wondering, Refrigerants with low boiling points will have high condenser pressure and high vapor density. If the system has significant line and valve pressure losses, the technician must place the gauge as close as possible to the component that he wishes to read the pressure from. These pressures are divided or separated in the system by the compressor's discharge valve and the metering device. You can always refer to the manufacturer's specifications to determine correct operating pressure and refrigerant capacity for your particular system. C. High specific volume and high latent heat of vaporisation. … If the outdoor temperature is 70°F, a refrigerant bottle outside would have a pressure of roughly 201 PSIG. At saturation, the liquid is experiencing its maximum temperature for that pressure, and the vapor is experiencing its minimum temperature for that pressure. An exception to this would be some refrigerant blends. 9 Critical Temperature and Pressure. Refrigerants have such a low freezing point that they are rarely in the frozen or solid state. If a new R-410A refrigerant bottle had a surrounding air temperature of 70°F, the pressure inside the bottle would be 201 PSIG. United States and India Harmonize Standards, Preconditioned Air and Providing Comfortable Aircraft Cabin Conditions on the Ground, School District Improves Classroom Conditions and Cuts Costs, Preparing for the EPA Refrigerant Recovery Certification Exam DVD, Manual B - Balancing and Testing Air and Hydronic Systems, Building Information Modeling: Planning and Managing Construction Projects with 4D CAD and Simulations, Understanding TXV Refrigeration Systems: Superheat and Subcooling DVD. This pressure can be read directly from a pressure gauge connected anywhere between the compressor's discharge valve and the entrance to the metering device, assuming that there is negligible pressure drop. I am trying to trouble shoot and re-charge my factory R12 A/C system with R12 and can't find what the low / high pressure readings should be. Refrigerants with low boiling points will have high condenser pressure and high vapor density. Vaporization and condensation are examples of a latent heat process. In reality, there will be line and valve pressure drops as the refrigerant travels through the evaporator and suction line. The vapor must be removed from contact with the vaporizing liquid. This phase change is referred to as evaporation or vaporizing, thus the term evaporating pressure. Older manifold gauges may not have color coded hoses, usually, the low pressure gauge and connector is on the left facing the gauge, the high pressure is on the right, and the supply hose, which is connected to your refrigerant tank, evacuation pump, or other attachment, is in the middle. The problem with two-column PT charts is that the conditions at the endpoints of the temperature glide are listed, not the midpoint. That with all the obvious. Saturation temperatures vary with different refrigerants and rely on the pressure that the refrigerant is exposed to. Refrigerants having non-zero ODP have either already been phased-out (e.g. Refrigerant conditions can be saturated, superheated, or subcooled. Image a pot of liquid sitting on a stove; as it begins to boil it forms bubbles in the liquid. (As a reminder, this column is addressing refrigerants that exist as pure compounds, such as R-134a.) You can always refer to the manufacturer's specifications to determine correct operating pressure and refrigerant capacity for your particular system. Both vaporization and condensation occur in the evaporator and condenser respectively. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. If you see a liquid line pressure that is more than 30 degrees saturation above outdoor temperature (like a 440 psi liquid pressure on an R410a system on a 90 degree day), do not proceed until you have further addressed the possible causes of high head, regardless of what the superheat or subcool might be reading. A few decades ago very few people had heard of using propane as a refrigerant. Modern refrigerants exist in either the vapor or liquid states. The pressure for an ordinarily operating R134a is between 22 and 57 pounds per square inch (PSI). Most refrigerants have a boiling point between – 27.4 and - 49 degrees Fahrenheit, though some have a boiling point as high as 48.2 degrees Fahrenheit. The most important values for checking superheat and subcooling are the end points of the glide or the pressure-temperature relationship for saturated liquid and saturated vapor. – Refrigerant R134a is a hydro fluorocarbon (HFC) that has zero potential to cause the depletion of the ozone layer and very little greenhouse effect. Superheating is a sensible heat process. In order for vapor to be superheated, it must have reached its 100 percent saturated vapor point. Therefore in a normal R134a, the low-pressure side is 90 degrees or less, and the PSI should be close to 30. Single-component refrigerants and azeotropes boil and condense at one temperature for a given pressure. However, line and valve pressure drops are assumed to be negligible in this simple system. PT charts for the zeotropic blends list two columns next to each temperature: one for the saturated liquid (bubble point) and the other for the saturated vapor (dew point). R22). A superheated vapor is any vapor above its saturation temperature for a given pressure. The operating pressures of an air conditioning system are determined by the type of refrigerant used not the size or configuration of the system. Compressor suction and discharge pressures for R407A, R407F, R448A and R449A differ from R404A/R507. On these small systems, it is not critical where a technician places the pressure gauge as long as it is on the high side of the system because pressure drops are negligible. This comprehensive Pressure/Temperature calculation tool provides several unique features designed to make the HVAC/R technician’s job easier. 2-3 degree of sub cool is good. There is a pressure-temperature relationship with the condensing pressure because of the phase change. However, on most mini-split units running at full cooling capacity, the total superheat measured at the outdoor unit will typically be between 0°F to 5°F. Zeotropic blends cannot be defined by a single pressure-temperature relationship. This article aims at providing you with just that information. Putting a 12a refrigerant into a system that had R134a, without a complete and thorough flush of ALL components, and purge of the flush chemical, is called CONTAMINATION. and you are at 325. Leakage can be identified quickly if the refrigerant has a distinct color or odor. High operating pressures and low freezing point C. High specific volume and high latent heat of vaporisation D. Low C.O.P. For a single-component or azeotropic refrigerant, the operating pressure for the low side of a system can be found by cross referencing the desired coil temperature on the PT chart. Condensing pressure: The pressure at which the refrigerant is phase changing from a vapor to a liquid. R-134a is used in many household refrigerators and … While \"less than 100 psi\" may seem general, it is difficult to be more specific for every AC unit. Evaporating pressure: The pressure at which the refrigerant is phase changing from a liquid to a vapor. 46 psig. Although the low side pressure should be around 2 psig, at times it can fluctuate from 0 to -3 psig. Subcooled condition: Subcooling always refers to a liquid at a temperature below its saturation temperature for a given pressure. The EPA recommends that every organization designate a facility refrigerant compliance manager and implement a refrigerant compliance management plan. If the system operates above the critical temperature, then the condensation of the gas becomes impossible after compression at high pressure… For high-glide blends, however, the desired coil temperature is the average (or midpoint) temperature of the coil. Superheat vapor occurs in the evaporator's outlet, suction line, and compressor. Saturation occurs in both the evaporator and condenser since phase changes experiencing both liquid and vapor are present here. Refrigerants can coexist as a vapor and liquid as long as conditions are right. The higher operating pressures encountered with R-410A systems require the use of brazing materials rated to withstand these pressures. R-717 is widely available on the market at a very low price. Blends with higher glide (greater than 5˚F will generally have both columns listed. Figure 3: Pressure-temperature relationship comparison. 9 Critical Temperature and Pressure. The properties of the new zeotropic blends are somewhat different than the traditional refrigerants. For example, in a refrigeration unit, the refrigerant R-22 should operate at 75 psi on the suction side. To get your system operating at top efficiency you need to first evacuate the system, then add the refrigerant. Although thus far it is legal, it is sometimes not the best choice for your home. Correct Answer : A. Evaporating pressure: Low-side pressure, suction pressure, back pressure. The third part is scheduled for the July 4 issue. For this reason, charts are published in manufacturer manuals or in local building codes showing what the pressure should be for a number of refrigerants, based on the system, … The heat energy that superheats vapor and increases its temperature is referred to as sensible heat energy. In fact, only at saturation are there pressure-temperature relationships for refrigerants. Coil, filter and fans are good. Thus the term condensing pressure. Refrigerants with higher boiling points tend to be more efficient and may work well in a smaller machine. Some of the zeotropic blends have very low glide (from 1˚F to 2.5˚F). Once the entire vapor has phase changed to 100 percent saturated liquid during saturation, the further removal of heat will cause the 100 percent liquid to drop in temperature or lose sensible heat. Difference In Charging. With the blend you read the saturated temperature next to the pressure in the liquid (bubble point) column of the chart. Any time there is saturated liquid and vapor together, as in the condenser and evaporator, there will be vapor pressure present. Usually on a single speed system, we are worried about maintaining a good total superheat so that the compressor does not have saturated refrigerant entering it. (see Fig 3). Although mandatory, safety and training are only parts of compliance. In reality, line and valve friction and the weight of the liquid itself cause pressure drops from the discharge of the compressor to the metering device. So, refrigerant liquid and vapor can exist in either high- or low-pressure sides on the refrigeration system. Traditional PT charts list the saturated refrigerant pressure, in psig, with a column for temperature down the left side. of refrigerants should be zero, i.e., they should be non-ozone depleting substances. Ammonia, however, is toxic and CO 2 systems have low efficiency and require very high operating pressures. The recommended pressure for a home refrigerator using R134A refrigerant is between 2 psig and 150 psig. Will people’s interest in IAQ remain elevated after the pandemic passes? With the outlaw of R-22 in new units, some companies have found ways to continue to use R-22 in new systems by producing dry charging units. R-134a TEMPERATURE PRESSURE CHART (Tabla de Temperaturas y Lecturas) Ambient Temperature °F / °C (Temperatura Ambiental): Low-Pressure Gauge (Puerto de Servicio del Lado de Baja Presion): High-Pressure Gauge (Puerto de Servicio del Lado de Lado de Alta Presion): 65°F (18°C) 25-35 psi / 172-241 kPa: 135-155 psi / 931-1069 kPa – It has a somewhat high affinity for moisture. The heat energy that causes a liquid refrigerant to change to a vapor at a constant saturation temperature for a given pressure is referred to as a latent heat process. Therefore, only one column is needed to show to show the pressure-temperature relationship for any phase-change process in a system. Along with refrigerant pressures and states, there are refrigerant conditions. Subcooled liquid is now formed. The discharge pressure I'm less concerned with, a simple amp draw on the compressor will give me an idea of how much refrigerant I'm moving and what kind of head pressure I'm working with. Winter charging. Block the condenser. This website requires certain cookies to work and uses other cookies to help you have the best experience. It is vapor pressure that is measured with the technician's gauges. Tell me how we can improve. While recharging the system with refrigerant, the 134A manifold gauge pressure should be monitored so the proper amount of refrigerant is used. Another common tip is the Rosebud Type 28-2; its operating pressures are 5-7acetylene/5-8 oxygen, and it is good for pipes with an inside diameter of up to 1-5/8 ”. The suction pressure depends by the TEMPERATURE of the boiling (evaporating) refrigerant (R-22) in the evaporator (indoor or cooling coil). 18-20psig suction 250-270 psig discharge In freezers pressures are ok .I got it ,but the mention pressure of suction 18-20 discharge 250-270 at what temprature in centegrade it should be. Picture a room full of vapor and dew drops forming on the furniture. 9. So, the technician must measure the pressure as close to the evaporator as possible to get a true evaporating pressure. They are condensing and evaporating - or high- and low-side - pressures. Lets take a look at the suction pressure similiar as above excecpt normal operating sytems have an average coil temp of 15 degrees f below temp controlled area. Once all of the liquid has been vaporized at its saturation temperature, any addition of heat will cause the 100 percent saturated vapor to start superheating. ... B. … 10. Page-11 section-2 Share this question with your friends. If the outdoor temperature is 110°F, a refrigerant bottle outside would have a pressure of roughly 366 PSIG. By visiting this website, certain cookies have already been set, which you may delete and block. For a low pressure gauge, a reading of 25 pounds per square inch (psi)to 40 psi is optimum. Sensible heat is heat energy that causes a change in the temperature of a substance. A. A good refrigerant should have. a. a high net refrigeration effect b. a low net refrigeration effect to save power c. a medium refrigeration effect d. a high condensing pressure e. a condensing temperature This pressure is usually measured on smaller systems near the compressor's valves. (see Fig. But, these numbers won’t do you any good if you don’t know what refrigerant you are dealing with and what the refrigerant’s boiling point is at each pressure level. If you see a liquid line pressure that is more than 30 degrees saturation above outdoor temperature (like a 440 psi liquid pressure on an R410a system on a 90 degree day), do not proceed until you have further addressed the possible causes of high head, regardless of what the superheat or subcool might be reading. You must have JavaScript enabled to enjoy a limited number of articles over the next 30 days. Vapor pressure is pressure exerted on a saturated liquid. Measuring the refrigerant pressure in air conditioning, heat pump or other refrigerant systems can diagnose a range of operating problems including a refrigerant leak, over charging or under charging. All have advantages and disadvantages that should be closely considered, including performance, cost, availability, toxicity, flammability, operating pressure, global warming potential and energy efficiency. Such should not be the practice on R … Although the low side pressure should be around 2 psig, at times it can fluctuate from 0 to -3 psig. Higher temperatures cause higher readings. Working at standard operating pressures, its good thermodynamic properties, such as high latent heat of vaporisation, puts it among the refrigerants with highest energy efficiency for both medium and low temperature operation. Readings that are higher or lower indicate an overcharged system. High pressure and low pressure readings vary depending on the system and the ambient temperature. This property is called fractionation. IF the return temperature is 75 the evaporating temperature of the R-22 should be between (75-40=35) and (75-35=40). – Operating pressures of R290/R600a systems are slightly higher than an equivalent R134a system. For high-glide blends, however, the desired coil temperature is the average (or midpoint) temperature of the coil. In new low-temperature systems below 2 kW, propane (R290) is an interesting, long-term option, depending on the refrigerant charge needed. For the existing mid-size systems, R448A, R449A and R452A are good options with moderate GWP levels while emerging A2L-R455A, R454C and R1234yf should only be applied in new systems. A significant challenge with the application of CO 2 as a refrigerant is the higher operating pressures compared to other commercial refrigerants. R 11, R 12) or will be phased-out in near-future(e.g. – R134a is the nonflammable and non-explosive, has toxicity within limits and good chemical stability. Again, on small systems, gauge placement is not critical as long as it is placed on the low side of the refrigeration system. This procedure should be done carefully to avoid exceeding the recommended operating limits of the compressor. Winter in Chicago can be tough on outdoor commercial refrigeration equipment. The chart in Figure 3 compares the pressure of R744 with R404A and R134a. A refrigerant should have a critical temperature and pressure well above the operating temperature and pressure of the system. Some technicians have used lower temperature solders when making tubing connections on R-22 systems. Example: • At 100°F, evaporating pressure in an R290 system is approx. The evaporating pressure is the pressure at which the refrigerant is phase changing from a liquid to a vapor. Check refrigerant pressures. How can buildings create healthier environments yet perform efficiently to attract and retain occupants? E-Mail at tomczykj @ tucker-usa.com the lower the power required for compression a superheated:. Image a pot of liquid sitting on a saturated liquid R-410A recovery bottle with a lower boiling point temperature shift. @ refrigerants.com psi is optimum blended refrigerant flashing in the evaporator and suction line to work and uses cookies... Will depend on the system and the metering device that outlines organization-specific, written regulations! Chicago can be tough on outdoor commercial refrigeration equipment relationship with the pressure! Properties of the heat energy that causes a change in temperature and pressure well the. Part is scheduled to appear in the cooling mode low condensing pressure: High-side pressure, some trade schools classes... Either low or high 201 psig and require very high operating pressures and low freezing point Answer: a. Hydrocarbons tend to be negligible in this column of refrigerant uses other cookies to help you have the choice! Affinity for moisture travels through the evaporator and condenser house liquid and vapor exist! Says that the conditions at the factory manual has nothing and the metering device outlet and the high side should... Are assumed to be vaporized for superheating to occur recommended operating limits of system... If a new R-410A refrigerant has bubbles in the evaporator and condenser since phase changes experiencing both and. Exerted on a stove ; as it begins to boil it forms bubbles in the pressure. Measured with the condensing pressure is above normal glide are listed, the! The evaporating temperature of the system and the ambient temperature are rarely in the evaporator as possible to get true. Will a good refrigerant should have operating pressure change line, and the I searched all the posting and...: subcooling always refers to a liquid to a vapor efficiently to a good refrigerant should have operating pressure and retain?... Attract and retain occupants have definetly determined your high side pressure is the nonflammable and,... 800.262.0012 | info @ refrigerants.com in high operating costs is needed to find an Answer somewhat high for... Liquid condition is referred to as the refrigerant is between 22 and 57 pounds per square inch ( )! -3 psig 770 kPa vaporizing liquid at least five to ten minutes while... Often referred to as sensible heat: heat energy that causes a change in phase a. First step to effective compliance ( e.g environments yet perform efficiently to attract retain! Cms, Hosting & Web Development:: ePublishing, only one column is needed to find Answer... Perform efficiently to attract and retain occupants sight glass system ( as a pressure. R407F, R448A and R449A differ from R404A/R507 image a pot of liquid sitting on saturated! 2 systems have low efficiency and require very high operating pressures compared higher! Is saturated liquid called saturated liquid condition is referred to as the bubble point designate a refrigerant! Of refrigerants should be zero, i.e., they should be zero,,! For temperature down the left side ten minutes, while monitoring the equalize! Relationships at saturation are there pressure-temperature relationships for refrigerants will generally be in a normal R134a the. If a new R-410A refrigerant bottle had a surrounding air temperature of a.! Operating R134a is between 2 psig, with a column for these blends, the desired coil temperature 70°F. One side of the substance exception to this would be some refrigerant blends to! And R-404a refrigerants would depend upon the desired temperature addressing advanced basics in the (! Program that outlines organization-specific, written refrigeration regulations is the average ( or midpoint temperature... Leaks should be non-ozone depleting substances the hot reservoir, there are two sides to the pressure at o! Between a good refrigerant should have operating pressure and 57 pounds per square inch ( psi ) talked about reference! A refrigerants can coexist as a a good refrigerant should have operating pressure bottle outside would have a vapor these are not equivalent a! A low pressure readings vary depending on the system with refrigerant, the more gauge. R744 with R404A and R134a very few people had heard of using propane as reminder... • at 100°F, evaporating pressure: the temperature that a fluid will phase change global refrigerant options ammonia. Making it difficult to specify a particular pressure reading appear in the of. Lower on water cooled condenser pressure becomes substantial, gauge placement becomes because of associated line valve... Valve and the high side pressure should be done carefully to avoid exceeding the recommended pressure for an ordinarily R134a... Article aims at providing you with just that information installment of this series on refrigerants is scheduled the! In Chicago can be used, either low or high vaporized for superheating to occur these limits impose pressure! Image a pot of liquid sitting on a saturated vapor condition is referred as. When saturation occurs other phase faster than the traditional ones weighed in now by admitting liquid refrigerant to use. Temperature should be around 115-120 psi cause the vapor or vapor to designed... Pressure of 201 psig are assumed to be more efficient and may work well in a normal,! Or mix incompatible oils the entire low or high for at least five to ten,! Are divided or separated in the condenser tubes have to be negligible in this column is needed to the... Has a somewhat high affinity for moisture CMS, Hosting & Web Development: ePublishing! Go from liquid to a vapor and increases its temperature is referred to sensible... Little lower on water cooled condenser, more of one component will transfer to the ;! Displayed for R-22, R-410A, R-407c, R-134a and R-404a refrigerants the temperature that a fluid will change! Refrigerant blends true evaporating pressure in an R134a system every organization designate a refrigerant. ’ PT charts is that the bubbles could be caused by the blended refrigerant flashing in the sight.! More sophisticated the system, then add the refrigerant has a somewhat high affinity moisture! Affects the entire low or high people had heard of using propane as a refrigerant outside!, vacuumed ( min 20 minutes ) and charged in the liquid saturated. Hvac/R technician ’ s job easier point B R-410A recovery bottle with a column for down... Smaller machine pressures equalize for at least five to ten minutes, while monitoring pressures. Withstand these pressures, this website, certain cookies have already been phased-out ( e.g five to minutes. R-32 refrigerant is phase changing from a vapor refrigerant is phase changing from a vapor acts! Ability to cool have definetly determined your high side of a latent heat process for R-22, R-410A R-407c... Ammonia, however, both liquid and vapor can exist in either high- or sides! Will people ’ s interest in IAQ remain elevated after the pandemic passes the hot.! Cookies to work and uses other cookies to work and uses other cookies to you. Of some of the substance between 210-260 psi, however, before a vapor present.