Climate Control

To obtain long term system life, it is important to keep contaminants to a minimum. This is particularly true of a heavy duty application such as a heat pump. Therefore, all heat pumps should have at least one filter-drier. Two standard driers are preferred, but where this creates a piping problem, then a single reversing filter-drier provides adequate protection. In this blog we cover the benefits of applying filter-driers on heat pump systems and tips for any problems that may occur. 

  Using two standard driers

OEMs may prefer using two standard driers rather than a single reversible drier. This has several advantages – more desiccant in the system, less complicated drier parts, and lower cost. Field service people should follow the recommendations of the OEM. The use of two standard driers gives protection equal to, or greater than, the use of a single reversible filter-drier, see Figure 1.

Standard driers are often installed directly ahead of the expansion device – one in the outdoor section and one in the indoor section. Another common design is to locate both driers in the outdoor section, where they are easier to service. In this design one drier is ahead of the expansion device, and the other drier is ahead of the check valve. When installed in these locations, the flow through each drier is always in the same direction, see Figure 2. Standard filter-driers will not tolerate flow in the reverse direction. Reverse flow washes out the dirt previously collected, and also tends to result in high pressure drop.

When servicing units in the field, it is advisable to replace the original filter-drier with the next larger size, or the size recommended by the unit manufacturer. Where other information is lacking, the Parker Sporlan C-080 Series Catch-Alls are recommended for use on heat pumps up through 2 tons R-410A; the C-160 Series Catch-Alls are recommended for 2 through 5 tons R-410A; and the C-300 Series Catch-Alls are recommended for systems of 5 to 10 tons R-410A. When replacing the original driers on a unit, standard filter-driers are preferred. If the original unit does not have a drier, a reversible HPC-160-HH style drier is recommended.

 

  Using HPC reversible filter-driers

The simplest way to install a drier on a heat pump system is to use a Parker Sporlan Reversible Filter-Drier. For most A/C systems select an HPC-160-HH Series Catch-All with the appropriate fitting size. This reversible filter-drier series is suitable for heat pump systems up through 5 tons R-410A capacity. These driers are installed in the reversing liquid line that runs between the indoor and outdoor section. Reversible driers should never be installed in the reversing gas line that runs between the indoor coil and the 4-Way valve, or the reversing gas line that runs between the outdoor coil and the 4-Way valve. Installation in this location will not give protection to the close tolerance parts of the system, and may result in excessive pressure drop. If the reversible drier is used on a highly contaminated system, such as after a hermetic motor burnout, it is essential that the old filter-driers be removed, see Figures 3 and 4.

In the past, Parker Sporlan offered several other types of reversible driers. These included the HCG-030 Series, HPCG-030 Series, and the HPC-080 Series. The HPC-160-HH Series are the proper replacements for any of these obsolete types.

Some heat pumps have only one expansion device – a bi-directional thermostatic expansion valve, or special short-tube flow restrictor. These systems are properly protected using a reversible filter-drier in the line between the expansion device and the outdoor coil. In this location the drier receives solid liquid on the cooling cycle, and a mixture of liquid and vapor on the heating cycle. Under these conditions, the Parker Sporlan HPC-160-HH Series Catch-Alls are suitable for use up through 5 tons capacity.

  Clean-up after burnout

Typical recommendations for clean-up after a hermetic motor burnout are as follows:

1. Install the same size drier (or an oversized drier) in the liquid line ahead of each expansion device, and a drier in the common suction line. In units with two liquid line driers, both should be changed.
2. Install an oversized drier in the common liquid line and, if possible, a drier in the common suction line. Run the unit in one mode of operation for a day. Then replace the liquid line drier with a reversible filter-drier.
3. Install a reversible filter-drier in the common liquid line. If possible, install a drier in the common suction line.

  The suction line drier location

A filter-drier should be installed in the suction line to clean up a heat pump after severe hermetic motor burnout. First, make sure the burnout is “severe” by testing the acidity of the oil from the burned out compressor using the Parker Sporlan TA-1 Acid Test Kit. If the burnout is severe, install a standard “HH” Catch-All in the common suction line. This drier can be installed either before or after the accumulator, but always between the 4-Way valve and the compressor. If some contaminants have remained in the accumulator, then the preferred location is between the accumulator and the compressor. This is usually a crowded location on the unit, and installing the drier may be difficult. In some cases, it may be necessary to re-pipe the suction line so the drier is located outside the cabinet.

Follow the unit manufacturer’s size recommendations if possible. Where this information is not available, use C-140-S-TT-HH Series Catch-Alls in systems up to 5 tons. Select a C-4300-S-T-HH Series Catch-All for units in the range of 5 to 10 tons. The exact model should be selected according to capacities and line size, consult Parker Sporlan Bulletin 40-10.

  If the filter-drier doesn't fit

Most heat pumps are compact, unitary systems, with cramped piping, making it difficult to replace or install filter-driers. Here are some suggestions to solve these practical problems.

1. The reversible filter-drier is usually the simplest to install because it can be installed anywhere in the reversing liquid line leading from the outdoor section to the indoor section. Even when using the reversible filter-drier, it is important to remove any old filter-driers installed on the unit, since they may be plugged if the unit is severely contaminated. If it is not possible to replace the previous filter-driers directly, the best alternative is to remove them. Reattach the line at the drier location, and use a reversible filter-drier to protect the system in the future. The old driers must be removed; they may be severely plugged.
2. The HPC-160-HH Series Catch-Alls are recommended for most field applications requiring a reversible filter-drier. The smaller HPC-100 Series is used by OEMs and can be used on new field built systems. The HPC-100 Series is 1.0” shorter than the HPC-160-HH Series. This difference may make the HPC-100 Series more desirable on systems with cramped piping.
3. The installation of two standard driers is usually easier if both are installed in the outdoor section. One drier is installed directly ahead of the expansion valve in the out-door coil, and the other drier is installed directly ahead of the check valve that leads to the expansion valve on the indoor coil. Each of these locations has refrigerant flow in only one direction at all times. If there is not sufficient space for two standard driers on a particular unit, perhaps satisfactory contaminant protection can be obtained by using only one drier. When there is no room inside the cabinet to install or replace the drier, the serviceman has no choice but to mount the drier outside the cabinet, and do the necessary re-piping.
4. The suction line connection on the 4-Way valve is usually the middle connection, of the three connections on one side. The single connection on the opposite side of the valve is the discharge line connection.
5. Whenever a drier is added to the liquid line of a system that did not originally have a drier, additional refrigerant charge should be added to the unit to fill the interior space of the drier. No additional charge is necessary for a drier installed in the suction line.

  Protect your system

Reversible Heat Pump Catch-Alls are designed for installation in the reversing liquid line. The smaller HPC-100 Series, using the standard Catch-All core, is designed specifically for new installations and for use on OEM equipment. The HPC-160-HH Series uses a larger core which includes activated charcoal for maximum performance in removing all types of contaminants generated from a hermetic motor burnout. Both filter-driers consist of one core in a shell with a check valve at either end. The check valves control the flow so the filtration occurs on the outside of the core, regardless of the flow direction.

The reliability of the check valves used in these filter-driers have passed the most rigid OEM testing – no synthetic materials are used. The check valves have been thoroughly proven in actual field performance over a period of many years. They function well, even in the presence of solid contaminants.

For more information on sizing filter-driers in heat pump systems please see Parker Sporlan Bulletin 40-10. For various HVAC and Refrigeration product information visit www.Parker.com/Sporlan. 

 

Article contributed by Glen Steinkoenig, product manager, Contaminant Controls, Sporlan Division of Parker Hannifin.

 

 

 

 

Additional resources for you:

HVACR Tech Tip: Understanding Heat Pump Systems and Thermostatic Expansion Valves

HVACR Tech Tip: When Should a Catch-All Filter-Drier be Changed?

Use of Suction Line Filter-Driers for HVAC Clean-up After Burnout

HVACR Tech Tip: What You Need to Know About Flooded Head Pressure Control

 

Manufacturers have been successfully applying Parker Sporlan Thermostatic Expansion Valves on Heat Pump Applications for many years. Parker Sporlan's large diaphragm and durable welded element result in unmatched thermostatic expansion valve quality and life. In this blog we discuss using thermostatic expansion valves on different types of heat pump systems.

 

Conventional thermostatic expansion valve on heat pumps

Many variations and matches of expansion devices have been used to regulate flow to the evaporator coils of a heat pump system. Optimum control is achieved by employing two thermostatic expansion valves, one to feed each coil as shown in Figure 1. Each valve can be tuned to control desired super­heat for uniquely different coils and operating conditions.

The durable construction of the standard Parker Sporlan valve is ideal for heat pump applications. It is recommended that the external equalizer be connect­ed to the common suction line, as shown in Figure 1. The underside of the diaphragm will be exposed to high side pressures if the equalizer is connected to the suction line ahead of the reversing valve. Parker Sporlan diaphragms can withstand these pressures but discharge pulsations are a possible source of problems. Discharge pulses can be dampened but the OEM tests should be performed to prove reliability. When using a thermostatic expansion valve to con­trol flow in one direction only, as shown in Figure 1, there are two options available:

1. Employ a standard Parker Sporlan valve and install a bypass check valve for reverse flow.
2. Install a Parker Sporlan valve which incorporates an internal check valve that minimizes reverse flow pressure drop. There are two Parker Sporlan valves which incorporate this check valve feature. The RC valve and the CBBI valve. The CBBI valve is only available to OEM customers whereas the RC valve is also available to wholesalers. These valves are available for capacities through a nominal 6 tons, R-410A. 

 

Bi-Directional thermostatic expansion valves on heat pumps

The "Bi-Directional" Thermostatic Expansion Valve has successfully been used to replace two expansion devices as shown in Figure 2. It controls refrigerant flow to either coil when the coil is serv­ing as the system evaporator. The Bi-Directional valve is generally applied on packaged units with close coupled components. The bulb and external equalizer are mounted to the common suction line. The suggested flow direction for the Bi-Directional valve is with the valve flowing in its normal direc­tion when the system is in the heating mode. This flow direction will normally result in a lower superheat in the heating mode. The preferred flow direction for each application should be verified by test­ing. There are two valves which have been designed for Bi-Directional applications. The ER valve which is available to wholesale customers and the BBI valve which is only available to OEM customers. These valves are available in capacities through a nominal 15 tons, R-410A.

 

For more information on Parker Sporlan Thermostatic Expansion valves please see Bulletin 10-10. For selecting your appropriate valve configuration, visit our webpage.

 

For more information on applying filter-driers in the same heat pump system please see Bulletin 240-10-2.

 

HVACR Tech Tip Article contributed by Jason Forshee, application engineer,  Sporlan Division of Parker Hannifin

 

 

 

 

 

Additional resources for you:

HVACR Tech Tip: What You Need to Know About Flooded Head Pressure Control

HVACR Tech Tip: Guidelines for How to Size Solenoid Valves for Split Condensers

HVACR Tech Tip: Guide to Servicing Blended Refrigerants

 

Working in the HVAC and Refrigeration industry there are many times when you are going to have applied torque when working on a particular job. In this blog, we help you understand the basics of torque and a method of applying torque. A bolt that has been over tightened can be just as disastrous as one that hasn't been tightened enough. A bolt that has been tightened beyond recommended torque specs can easily break in service.

 

Torque Specifications

Torque is measured as a unit of force acting on a rotating lever of some set length. North American made hex head cap screws have radial lines on their heads that indicate their tensile strength. When replacing a fastener, use a quality at least equal to or greater than the original fastener used on the machine. The more marks on the head, the higher the quality. Thus, bolts of the same diameter vary in strength and require a correspondingly different tightening torque or preload. Remembering that torque is the turning effort or force applied to the fastener to preload it, or place it in tension, and is normally expressed in inch-pounds (in.lb) or foot-pounds (ft.lb). A one pound weight or force applied to a lever arm one foot long exerts one foot-pound or twelve inch-pounds of torque. Note: Where possible always use OEM torque values which may differ from the table below.

 

SAE Bolt head markings

              Maximum torque table

All torque values are expressed in ft.lb.

 

Method of applying torque

Always run fasteners up snug (do not over tighten) with a regular wrench and then observe the following four steps unless OEM instructions are available.

1. Run each fastener in the proper sequence up to 1/3 of their recommended torque setting.
2. Repeat the process running up to 2/3 of the required torque setting.
3. Repeat the process again, running every fastener up to full torque.
4. Repeat step #3 to be positive you have not missed a fastener.

For various HVAC and Refrigeration product information visit www.Parker.com/Sporlan. 

 

Article contributed by Glen Steinkoenig, product manager, Contaminant Controls, Sporlan Division of Parker Hannifin.

 

 

 

 

Related, helpful climate control content for you:

HVACR Tech Tip: What You Need to Know About Flooded Head Pressure Control

Six Reasons Why CDS Conversion Reduces Costs

HVACR Tech Tip: 12 Solutions for Fixing Common TEV Problems

Today more and more applications are utilizing “heat reclaim” as a means of providing a supplementary or even a primary heat source. Heat reclaim can significantly lower energy costs. Heat reclaim is best described as the process of reclaiming heat that would normally be rejected by an outdoor condenser. Typically, the refrigerant is diverted to an air handler in an area that requires heat. One of the older applications of heat reclaim is in a supermarket since a supermarket has a constant supply of heat removed from the many refrigerated display fixtures and coolers. Today there are many cost-effective applications of heat reclaim in refrigeration, air conditioning, dehumidification, and heat pump systems.

While the most popular application of heat reclaim is air, water heating is popular in supermarkets, convenience stores, and restaurants, which all use considerable amounts of hot water. Essentially any application that requires heat can recover the heat from a refrigeration or air conditioning system. The energy efficiency of recovered heat will almost always be more efficient than any other purchased heat source. The common sense question is “Why reject heat to the outdoors when additional heat is required in any other moderate temperature application within the system or building?” 3-Way refrigerant heat reclaim valves make it convenient to recover rejected or waste heat.

 

Application

Valves may be installed in either a horizontal or vertical position. However, it should not be mounted with the coil housing below the valve body.

Series Versus Parallel Piping Schematics

Figures 2 & 3 show typical piping schematics for the two basic types of piping arrangements, series and parallel condensers. The selection of the piping arrangement will depend on the sizing of the reclaim coil and the control scheme of the system.

If the parallel piping arrangement is used, the reclaim condenser must be sized to handle 100% of the rejected heat at the conditions and time at which the reclaim coil is being utilized.

If the series piping arrangement is used, care and safety measures should be taken to prevent the mixing of subcooled refrigerant with hot gas vapors. These safety measures could include pressure or temperature lockout controls and time delay relays.

For both parallel and series piping, when the idle condenser is pumped down to suction pressure, a small solenoid valve can be used to pressurize the idle condenser prior to the 3-way valve shifting. This may reduce the potential for stress and fatigue failure of the refrigerant piping.

Heat reclaim with or without a bleed port

3-Way Heat Reclaim Valves with 3-way pilot valves are available in a variety of different sizes. These valves are available with an optional “bleed” port, see Figure 1. The bleed port allows the refrigerant to be removed from the heat reclaim coil or heat exchanger when it is not being used. There are two reasons why the refrigerant is removed from the heat reclaim coil. One is to maintain a proper balance of refrigerant in the system (i.e., refrigerant left in the reclaim coil could result in the remainder of the system operating short of charge). A second reason is to eliminate the potential of having condensed refrigerant in an idle coil. When an idle reclaim coil has condensed or even subcooled liquid refrigerant sitting in the tubes there is a potential for a problem. When refrigerant liquid, either saturated or subcooled, is mixed with hot gas refrigerant, the reaction of the mixing can cause severe liquid hammer. Hot gas mixed with liquid can create thousands of pounds of force and has the potential of breaking refrigerant lines and valves.

An alternate method of removing the refrigerant from a heat reclaim coil is to use a separate normally open solenoid valve and an optional fixed metering device, see Figures 2 & 3. The separate solenoid valve allows the flexibility of pumping out the reclaim heat exchanger as a liquid instead of a vapor. There are two benefits to pumping out the reclaim coil as a liquid: (1) Removal of any oil that may be present in the reclaim heat exchanger. (2) The refrigerating effect of the liquid can be used to lower the superheat of vapor entering the compressor, instead of cooling the heat reclaim heat exchanger. Sporlan recommends that recognized piping references be consulted for assistance in piping procedures. Sporlan is not responsible for system design, any damage resulting from system design, or for misapplication of its products.

Note: A check valve should be installed in the heat reclaim pump out or bleed line whenever the reclaim heat exchanger is exposed to temperatures lower than the saturated suction temperature of the system. This will prevent migration of refrigerant to the coldest location in the system.

Series condenser typical piping schematic

1. Use optional solenoid valve and piping if pump out is required and “C” model Heat Reclaim Valve is used, see Note 4. It is optional to omit this solenoid valve and piping on systems using “B” model Heat Reclaim Valve.

2. Restrictor, Part #2449-004, may be required to control pump out rate on an inactive condenser.

3. The pilot suction line must be open to common suction whether or not Heat Reclaim Coil is installed at the time of installation and regardless of Heat Reclaim Valve model/type.

4. Proper support of heat reclaim valves is essential. Concentrated stresses resulting from thermal expansion or compressor vibrations can cause fatigue failure of tubing, elbows and valve fittings. Fatigue failures can also result from vapor propelled liquid slugging and condensation induced shock. The use of piping brackets close to each of the 3-Way valve fittings is recommended.

Parallel condenser typical piping schematic

1. Use optional solenoid valve and piping if pump out is required and “C” model Heat Reclaim Valve is used, see Note 4. It is optional to omit this solenoid valve and piping on systems using “B” model Heat Reclaim Valve.

2. This check valve is required if lowest operating ambient temperature is lower than evaporator temperature.

3. Restrictor, Part #2449-004, may be required to control pump out rate on inactive condenser.

4. Pilot suction line must be open to common suction whether or not Heat Reclaim Coil is installed at time of installation and regardless of Heat Reclaim Valve model/type.

5. Proper support of heat reclaim valves is essential. Concentrated stresses resulting from thermal expansion or compressor vibrations can cause fatigue failure of tubing, elbows and valve fittings. Fatigue failures can also result from vapor propelled liquid slugging, and condensation induced shock. The use of piping brackets close to each of the 3-Way valve fittings is recommended.

For additional information on 3-Way Heat Reclaim Valves download Parker Sporlan Bulletin 30-20 or visit the product page here.

 

HVACR Tech Tip Article contributed by Jim Eckelkamp, senior application engineer,  Sporlan Division of Parker Hannifin

 

 

 

 

 

 

Additional resources:

HVACR Tech Tip: Using Bi-Directional Solenoid Valves for Heat Pumps

HVACR Tech Tip: 12 Solutions for Fixing Common TEV Problems

HVACR Tech Tip: How to Determine Total Refrigerant System Charge When Using Head Pressure Control

 

 

The design and operation of Parker Sporlan Head Pressure Control Valves are discussed thoroughly in Bulletin 90-30. Installation and service is covered in Bulletin 90-31. This Climate Control blog will provide complete charging instructions, from determining the correct amount of refrigerant to actually charging the system.

If the manufacturer of your equipment provides charging information it should be used. However, if it is not provided, the following procedure is suggested.

Determining the amount of charge

When “refrigerant side” head pressure control is utilized on a system, one of the most important factors is determining the total system refrigerant charge. While on most packaged units the amount of charge is listed on the unit, the required charge for a field built-up system cannot be listed by the manufacturer. The charge is usually added when the system is started up until “proper” system performance is reached. However, this is not satisfactory and if the system is to function properly year-round, the correct amount of extra charge must be calculated ahead of time.

Retrofit precautions

When changing refrigerants on a retrofit, be sure to calculate the refrigerant charge required for the new refrigerant. The density of the alternate refrigerants varies considerably from their CFC predecessors. In other words, if you remove 10 pounds of R-12 from a system being retrofitted to R-401A, do not charge the system with 10 pounds of R-401A. Typically, an R-401A system would only need approximately 90% of the R-12 previously required.

There are two methods of calculating the extra charge necessary to flood the condenser if the condenser manufacturer does not publish this data.

1. Completely Flooded Condenser

The easiest method is to calculate the volume of the condenser coil and then use the density factor of the refrigerant shown in Table 1 on Page 4 of Bulletin 90-30-1 to figure the pounds of refrigerant necessary to completely flood the condenser coil at the appropriate ambient. The factors involved in calculating the extra pounds of refrigerant are:

a. Length of tubing and return bends in condenser

b. Minimum ambient temperature at which systems will be required to function 

c. Tubing size and wall thickness

d. Refrigerant

The primary point to remember in selecting the proper density factor is that when the liquid drain valve (ORI, OROA, or LAC) is throttling, the refrigerant temperature will be at the same temperature as the ambient.

EXAMPLE: Calculate the extra refrigerant charge necessary for a Refrigerant 22, roof-top, air conditioning unit (40°F evaporator and a minimum condensing temperature of 90°F) with compressor unloading to 33-1/3% of full compressor capacity. To determine the equivalent length of tubing in a condenser proceed as follows: First, count the number of tubes and multiply this by their length.

Example: 150 tubes x 7.55 feet = 1132.5 feet

Next, count the return bends and multiply them by the factor shown in Table 1.

Example: 150 bends x .250 for 1/2 inch bends = 37.5 feet

Then add this 37.5 feet to the 1132.5 feet for a total of 1170 feet

The system uses a 30 hp condensing unit with a condenser coil containing 1170 equivalent feet of 1/2 inch tubing (tubes and return bends). Assume a design temperature of minus 20°F minimum ambient. From Table 1 we find the density factor necessary to calculate the pounds of extra refrigerant to completely flood the condenser at minus 20°F: 1170 feet x .102 pounds/foot = 119 pounds.

2. Partially Flooded Condenser

On many systems it isn’t necessary to completely flood the condenser to maintain sufficient operating head pressure (equivalent to approximately 90°F condensing temperature) because of a milder climate than Method 1 assumes. Therefore, a second method is available. The additional information found in Tables 2 and 3 on Page 8 of Bulletin 90-30-1 can be used to figure more closely the charge necessary to properly flood the condenser for sufficient head pressure at various minimum ambient temperatures. (The multipliers are applied to the extra refrigerant charge that was calculated in Method 1 to completely flood the condenser.)

EXAMPLE: Our example calls for a compressor equipped with unloaders. Since the compressor would unload at the low ambients this must be taken into consideration. This is necessary since as the compressor unloads, the condenser’s capacity increases and additional flooding is required. Using the same roof-top unit as in the earlier example (40°F evaporator and minus 20°F minimum ambient), a multiplier of .79 is shown in Table 2. And since we have unloaders (33-1/3%), this .79 is used to enter Table 3 to find a multiplier of .95. This final multiplier is applied to the 119 pounds calculated earlier to arrive at the final extra charge requirement: 119 x .95 = 113 pounds. This is added to the normal system charge to arrive at a total system charge.

Since the majority of “low and medium suction” condensing units are already flooded 75% or more for any minimum ambient temperatures below 20°F, no data is supplied for these units even when they use unloaders. The normal procedure is to recommend flooding from 90 to 100% for these units when they have unloaders.

Refrigerant charging procedures

Normally this information is supplied by the equipment manufacturer. And when it is available, it should be followed. When it is not available from the equipment manufacturer, the following suggestions are recommended.

Once the amount of extra refrigerant charge is calculated, care must be taken in charging the system to ensure the proper total amount of refrigerant getting into the system. This is especially true if the ambient temperature is below 70°F and the liquid drain valve (ORI, OROA, or LAC) is throttling the refrigerant flow from the condenser. A step-by-step procedure is given below for the two possible situations that can exist. And depending on the ambient temperature at the time the system is charged, each should be carefully followed to ensure proper system operation in both summer and winter. In either case, a liquid seal must be established in the receiver before the system can start to function correctly.

NOTE: While charging any system with head pressure control, the outdoor ambient temperature must be known. And if the system has compressor unloaders, it is important to know if they are functioning during the charging procedure. To keep this procedure as simple as possible, it is recommended that the unloaders be locked out (compressor fully loaded) during charging.

Charging of Systems with Parker Sporlan Head Pressure Control in Ambients ABOVE 70°F (After normal evacuation procedures) Before Starting System

1. Connect refrigerant cylinder to a charging or gauge port on the receiver outlet valve.

2. Open the receiver valve approximately one-half way (so receiver and liquid line are connected to charging or gauge port).

3. Charge liquid refrigerant into the high side of the system. Weighing the charge is recommended with the initial charge consisting of approximately 2.5 pounds per system ton.

4. Remove the refrigerant drum and connect it to the suction side of the compressor. 

5. Charge refrigerant vapor into the low side until the pressure is above atmospheric pressure. Do not admit liquid refrigerant into the low side.

6. Start the system. 

7. Observe See•All moisture and liquid indicator (at receiver outlet) to see if system is properly charged for normal refrigeration cycle. CAUTION: Bubbles in the See•All can be caused by flashing due to pressure drop from pipe or accessory losses, etc. 

8. If the See•All shows bubbles, more refrigerant should be added, while allowing sufficient time for the refrigerant to stabilize and clear the See•All.

9. The extra refrigerant charge for head pressure control should be weighed in now by admitting liquid refrigerant to the high side. 

Charging of Systems with Sporlan Head Pressure Control in Ambients BELOW 70°F (After normal evacuation procedures)

NOTE: When charging in ambients below 70°F the procedure is very critical. Be sure to adhere to the following steps without fail. Failure to do so will result in overcharging the system.

1. Follow instructions 1 through 7 above. 

2. If the ORI, OROA, or LAC valve setting is correct for the system being charged, it is quite likely that some refrigerant will be backed up into the condenser and the See•All will indicate bubbles in the liquid line. 

3. Add more refrigerant, while allowing sufficient time for the refrigerant to stabilize and clear the See•All. 

4. At this point, the system is correctly charged for this type of head pressure control at the ambient temperature that exists while the charging procedure is taking place. 

5. If the system is designed to operate at ambients below the ambient that exists during charging, an additional charge will have to be added now. 

6. To calculate the additional charge required, follow the examples outlined under “Refrigerant Charge” except remember that the “head pressure control charge” is partially charged already. Refer to Tables 2 and 3. The difference in percentages between the minimum design ambient temperature and the ambient temperature at the time the system is charged gives the percent of extra charge still needed in the system. E.g., if this system was charged at an ambient of 50°F, we have approximately 40% of the extra charge in the system. This holds true as long as the compressor unloaders were not operating during charging. Therefore, the additional charge required is 95 minus 40 or 55% of the total extra charge calculated previously. This is .55 x 119 or 65 pounds.

Since good system performance during low ambient operation depends on proper refrigerant charge, it is very important that this phase of the installation procedure be done carefully. Many times, poor system performance will be due to too little or too much charge. And in many cases this will be the last item suspected.

 

HVACR Tech Tip Article contributed by Jason Forshee, application engineer,  Sporlan Division of Parker Hannifin

 

 

 

 

 

Additional resources:

HVACR Tech Tip: What You Need to Know About Flooded Head Pressure Control

HVACR Tech Tip: Guidelines for How to Size Solenoid Valves for Split Condensers

HVACR Tech Tip: Guide to Servicing Blended Refrigerants

 

As most of us know, sizing solenoid valves for split condensers seem to be more of an art, than a science. Many tangibles affect the calculations. This Climate Control blog will provide some guidelines for sizing solenoid valves for split condenser systems. While it is not perfect, it should help in sizing valves to match the capacity requirements. This is not intended to replace existing sizing methods used by our customers. It is intended to be used where no other information is provided and/or double check for selections. The goal is to match the proper valve to the proper capacity to provide the best system operation. In sizing these valves consider both system design conditions and low load winter conditions as well.

 

Helpful tips

1. When a Medium Temp rack subcools a Low Temp rack, the subcooler load will drop off during winter operation. When sizing these valves for this application, the removal of this subcooler load must be considered.

2. When one has compound cooling compressors or vapor injection be sure to use the subcooled temperature.

  To calculate the line capacity follow the rules below:

• Take the total evaporator load x 110% then divide by the number of split condenser valves.

• For split suction racks the total evaporator load is equal to the combined evaporator load of each suction.

  To calculate the liquid line temperature follow the rules below:

• For suction groups or standalone racks that are externally subcooled use the subcooled liquid temperature.

• For suction groups or standalone racks that are self‐subcooled take the design condensing temperature minus 20°F.

• For suction groups or standalone racks that are not subcooled take the design condensing temperature minus 20°F.

• For split suction racks follow the above rules and calculate the liquid temperature for each suction group then find the weighted average liquid temperature using the formula below.
  
  Suction 1 Evaporator Load = SQ1       Suction 1 Liquid Temperature = ST1

Suction 1 Evaporator Load = SQ2       Suction 1 Liquid Temperature = ST2

Total Evaporator load = TQ                  Weighted Average Liquid Temperature = WALT

[(SQ1/TQ) x ST1] + [(SQ2/TQ) x ST2] = WALT

 

To calculate evaporator temperature follow the rules below:

• For single suction group or standalone rack use the design suction evaporator temperature.

• For split suction racks calculate the weighted average evaporator temperature using the formula below.

Suction 1 Evaporator Load = SQ1       Suction 1 Liquid Temperature = SE1

Suction 1 Evaporator Load = SQ2       Suction 1 Liquid Temperature = SE2

Total Evaporator load = TQ                  Weighted Average Liquid Temperature = WAET

[(SQ1/TQ) x SE1] + [(SQ2/TQ) x SE2] = WAET

The above information will provide a general guideline if no other information is available.

One psi pressure drop is required for proper operation of pilot operated solenoid valves. As a guide, try to achieve a 2 psi pressure drop during summer conditions. Where possible using a larger pressure drop will provide more of a cushion for valve operation.

For more information on Solenoid 3-Way Valves see Parker Sporlan Bulletin 30-20.

 

User Safety Responsibility Statement 

FAILURE OR IMPROPER SELECTION OR IMPROPER USE OF THE PRODUCTS DESCRIBED HEREIN OR RELATED ITEMS CAN CAUSE DEATH, PERSONAL INJURY AND PROPERTY DAMAGE. 

• This document and other information from Parker-Hannifin Corporation, its subsidiaries and authorized distributors provide product or system options for further investigation by users having technical expertise. 
• The user, through its own analysis and testing, is solely responsible for making the final selection of the system and components and assuring that all performance, endurance, maintenance, safety and warning requirements of the application are met. The user must analyze all aspects of the application, follow applicable industry standards, and follow the information concerning the product in the current product catalog and in any other materials provided from Parker or its subsidiaries or authorized distributors. 
• To the extent that Parker or its subsidiaries or authorized distributors provide component or system options based upon data or specifications provided by the user, the user is responsible for determining that such data and specifications are suitable and sufficient for all applications and reasonably foreseeable uses of the components or systems.

 

HVACR Tech Tip Article contributed by Jim Eckelkamp, senior application engineer,  Sporlan Division of Parker Hannifin

 

 

 

 

Additional resources:

HVACR Tech Tip: What You Need to Know About Flooded Head Pressure Control

HVACR Tech Tip: Considering a Refrigeration System Retrofit? Part 1

HVACR Tech Tip: Considering a Refrigeration System Retrofit? Part 2

HVACR Tech Tip: Considering a Refrigeration System Retrofit? Part 3