HTPG Air Cooled Condensers

General Safety Information

1. Installation and maintenance are to be performed only by qualified personnel who are familiar with this type of equipment.
2. Make sure that all field wiring conforms to the requirements of the equipment and all applicable national and local codes.
3. Avoid contact with sharp edges and coil surfaces. They are potential injury hazards.
4. All power sources must be disconnected prior to any servicing or maintenance of this unit. After disconnecting power, allow 5 minutes for capacitor discharge before servicing motors.
5. Refrigerant recovery devices must be used during installation and service of this equipment. It is illegal for some refrigerants to be released into the atmosphere.

Inspection

Check all items against the bill of lading to make sure all crates or cartons have been received. If there is any damage, report it immediately to the carrier and file a claim. Make sure the voltage on the unit nameplate agrees with the power supply available.

Installation - Rigging and Assembly

Leave the units in the carton or on the skid until they are as close as possible to the installation location. Never lift any of the units by the headers, return bends, or electrical boxes. All condensers are provided with lifting points located on the top panel. The actual method of rigging depends on the equipment available, the size of the unit, and where the unit is to be located. It is up to the installer to decide the best way to handle each unit. A spreader bar must always be used and should be at least as long as the distance between the lifting points. Utilize all lifting points. Failure to use all lifting points will void the condenser warranty.

Rig the units as shown in Figure 1 & 2. Unbolt the unit from the skid and lower into normal operating position, making sure the coil surface is not damaged.

Unit Location - General

These units are designed for outdoor applications. All units must be installed level for proper drainage of liquid refrigerant and oil. When units are installed on a roof, they must be mounted on support beams that span load walls. Ground mounted units should be installed on concrete pads. When selecting a location for an air-cooled condenser, be sure to allocate space for maintenance and service work.

Note: A wind load analysis has determined these multi-refrigerant air cooled condensing units are in accordance with ASCE/SEI 7-10, Florida Building Code Fifth Edition (2014) for the following location: Miami, Dade County, Florida.

Space Requirements

All sides of the condenser should be no closer than the width of the unit, B, to a wall or other obstruction. If the unit is surrounded by more than 2 walls, it should be treated as an installation in a pit.

Piping Recommendations

The following are general guidelines for routing and sizing lines to air-cooled condensers. For further information please consult the ASHRAE Handbook or other accepted piping handbooks.

Discharge Lines

Consider the following three issues when designing and sizing discharge lines:

1. Pressure Drop
   Lines should be sized for a reasonable pressure drop. Pressure drop increases the required horsepower per ton of refrigeration and decreases the compressor capacity. Table 2 shows discharge line capacities for pressure drop equivalent to 1° F per 100 feet of line.
2. Oil Trapping
   Lines must be sized and routed so that oil is carried through the system. Normally, sizing according to Table 2 will be satisfactory. However, when the condenser is located at a higher level than the compressor, it may be necessary to take special precautions, especially if the system is designed to operate at reduced compressor capacity. A vertical hot gas line sized to transport oil at minimum load conditions may have excessive pressure drop at full load. If this is the case, a double hot gas riser, as shown in Figure 8, should be used. Size Riser No. 1 for the minimum load condition. Size Riser No. 2 so that the combined cross-sectional area of both risers is equal to the cross-sectional area of a single riser having acceptable pressure drop at full load. Install a trap between the two risers, as shown in Figure 8. During partial load, the trap will fill up with oil until riser Number 2 is sealed off. Keep the trap as small as possible to limit its oil holding capacity.

* Based on Condensing temperature of 105°F. For other condensing temperatures, multiply by the appropriate correction factor listed in table 3.
* Based on pressure drop equivalent to 1°F per 100 ft. of line run.

Liquid Lines

Liquid lines from the receiver to the expansion valve can generally be sized for pressure drop equivalent to a 1° F to 2° F change in saturation temperature. If there is substantial sub cooling, or the line is short, it can be sized at the high end of this range. If the opposite is true, a more conservative selection should be made. A receiver, if used in the system, should be located below the condenser and the condenser-to-receiver liquid line must be sized to allow free drainage from the condenser to the receiver. This line should be sized so the velocity does not exceed 100 FPM. Generous sizing of this liquid (condensate) line is especially important if the receiver is exposed at any time to a warmer ambient temperature than the condenser. It must be large enough for the liquid to flow to the receiver and at the same time allow venting of refrigerant vapor in the opposite direction back to the condenser. The receiver can become vapor-locked under these conditions if the re-evaporated gas is not allowed to flow back to the condenser for re-condensation. All liquid (condensate) lines should be free of any traps or loops.

Table 4 shows liquid line capacity in evaporator MBH. Line sizing is shown for both condenser-to-receiver lines and receiver-to- expansion valve lines. All capacities are for 100 equivalent feet of tubing. The selections based on pressure drop are for an equivalent to a 1° F change in saturation temperature. They can be converted to capacities based on a 2° F equivalent drop by using the factor given below the table. See Table 5 for the weight of refrigerant in liquid, suction and discharge lines.

*Based on 100 FPM refrigerant velocity.
+ Based on refrigerant pressure drop of 1°F per 100 feet of line.

Multiple Condensers

Often two condensers are piped in parallel to the same refrigeration system. It is important that the units have approximately the same capacity so that the pressure drop through each is equal. The piping should be arranged so that the lengths of runs and bends to each are equal on both the inlet and outlet of the condensers. A drop leg should be included from each liquid outlet of sufficient height to prevent backup of liquid into one coil. This will overcome any difference in pressure drop that may exist between the two coils.

Routing of Piping

Piping should be routed to avoid excessive strain on system components or the piping itself. Discharge lines must be supported with rigid pipe supports to prevent transmission of vibration and movement of the line. The discharge line should be well supported near the condenser hot gas connection. Use offsets in inter-connecting lines between two condensers and provide isolation where pipes pass through building walls or floors.

Head Pressure Control Options and Charge Calculations

Flooded Condenser

The Flooded Condenser Head Pressure Control Option maintains adequate condensing pressure while operating in low ambient temperatures. By flooding the condenser with liquid refrigerant, the amount of coil surface available for condensing is reduced. The resulting reduction in capacity ensures proper operation of the thermal expansion valve.

This option requires a modulating three-way valve, dependent on refrigerant discharge pressure, be placed at the condenser outlet. A fall in ambient temperature causes a corresponding fall in discharge pressure. The valve modulates allowing discharge gas to flow to the receiver, creating a higher pressure at the condenser outlet. This higher pressure reduces the flow out of the condenser, causing liquid refrigerant to back up in the coil. Flooding the condenser reduces the available condensing surface and raises the condensing pressure so that adequate high-side pressure is maintained. Various types and combinations of flooding control valves are available. Contact the valve manufacturer for specific recommendations.

A larger receiver and additional refrigerant are required for systems with flooded condenser control. The receiver can be conveniently installed directly under the condenser in most applications. However, if the system will be operational in ambient temperatures below 55° F, the receiver should be located in a warm environment or heated. In this situation, a check valve must be installed in the line between the receiver and condenser. This prevents refrigerant migration from the receiver to the condenser.

The amount of additional refrigerant charge is based on the lowest expected winter operating temperature and the design TD. In addition to the condenser charge, the operating charges of the evaporator, receiver and refrigerant lines must be added to determine the total system refrigerant charge. The pump-down capacity (80% of full capacity) of the receiver must be at least equal to the total system charge.

Table 6 shows the standard summer condenser charge when using R-407A. The additional charge required for flooded condenser operation with a design TD of 15°F is also shown. Additional charge for alternate design TDs can be found using the correction factors in Table 7.

For flooded condenser control only:

Total Charge = Summer charge (Table 6) + additional charge (Table 6) x design TD correction factor (Table 7)

Example: Single Section Unit with Flooded Condenser Head Pressure Control

Given: A RDD030*B2 Condenser with a R-407A summer charge of 26.2lbs. (See Table 5) has a design TD of 10° F and will operate at a minimum ambient of 0° F.

Solution: The additional charge needed to operate at 0° F can be found in Table 5 (69.0 lbs.). Because the unit has a design TD of 10° F, the additional charge must be multiplied by a correction factor of 1.04 as shown in Table 7. Therefore, the required additional charge is: 69.0 × 1.04 = 71.8 lbs. The total operating charge for a minimum ambient of 0° F and a 10° design TD is 26.2 + 71.8 = 98.0 lbs.

Example: Multi-Section Unit with Flooded Condenser Head Pressure Control

Given: A RDS012 condenser split into two sections. One section has 22 face tubes of R-404A at a 10°TD and the other section has 14 face tubes of R-407A at a 15°TD. The unit will operate at a minimum ambient of 20° F.

Solution: To calculate the winter charge for each section, the summer charge and additional charge for low ambient must be found. The summer charge can be calculated by multiplying the number of face tubes in the section by the charge per face tube value in Table 6. Next, divide the number of face tubes in the section by the total number of face tubes and multiply by the additional charge required for a minimum ambient of 20° F. Make sure to apply correction factors for design TDs other than 15° and for refrigerants other than R-407A. Adding the summer charge and additional charge for low ambient will yield the total winter charge.

For the R-404A section, the summer charge is 22 tubes × 0.25 × 0.92 lbs. (404A correction factor) per face tube = 5.06 lbs. The additional charge equals the ratio of tubes in the section to total tubes times the additional charge at 20° F with a 15° FTD times the TD correction factor from Table 6, or 22/36 × 20.8 × 1.05 × .92 = 12.26 lbs. The winter charge is 5.06 + 12.26 = 17.32 lbs.

For the R-407A section, the summer charge is 14 × 0.25 = 3.5 lbs. The additional charge calculation also requires the use of the correction factor. The additional charge is 14/36 × 20.8 = 8.08 lbs. The winter charge is 3.5 + 8.08 = 11.58 lbs.

† Based on 90°F Condensing Temperature

For refrigerants other than R407a, 448a, and R449a us the multipliers below:

• *For R22, multiply by 1.04
• *For R134A, multiply by 1.06
• *For R410A, multiply by 0.94
• *For R404A, multiply by 0.92

Splitting Controls

Condenser splitting controls assist in maintaining head pressure while minimizing the amount of refrigerant required for the system. A single condenser is split into two parallel circuits, allowing half of the condenser to be removed from the refrigerant circuit during low ambient operation. This is achieved by installing a three-way solenoid valve at the condenser inlet, regulated by either a temperature sensing controller or pressure switch. Additional controls are required for the Splitting Control Option on double wide units to shut off the fan motors on the unused portion of the coil.

Fan Cycling Control Option

The cycling of condenser fans provides an automatic means of maintaining condensing pressure control at low ambient air temperature conditions. It also results in substantial fan motor power savings in lower ambient. Temperature sensing thermostats or pressure controls determine whether the motor is on or off. The minimum ambient temperatures for units with the Fan Cycling Control Option can be found in Table 8.

The Fan Cycling Control Option consists of a weatherproof enclosure, fan contactors, and either ambient thermostat(s) or pressure control(s). The enclosure is factory mounted and completely factory wired. Power must be supplied from a fused disconnect switch to the power circuit terminal block; control circuit power must be supplied to the control terminal block.

Table 9 shows the recommended temperature set points for the thermostats. The recommended cut-in and differential settings for fan cycling using pressure controls are listed in table 10. Thermostat 1 is for the second fan from the header end, Thermostat 2 for the third fan from the header end, etc. The fan(s) nearest the header end must run continuously, and cannot be cycled.

*Based on approximately 90°F condensing temp.

Thermostat set point is the temperature at which the fan(s) will shut off due to a fall in ambient temperature. Fan(s) will restart when the ambient temperature rises 3 to 4° above the set point.

Fan Speed Control Option

Variable fan speed control is designed to enhance the performance of the Fan Cycling Control Option by reducing the RPM and air volume of the lead (header end) fan motor(s) after all other (lag) fans have cycled off. The lead fan(s) must run continuously, even in the lowest ambient temperature. By reducing their CFM, adequate head pressure can be maintained at lower ambient temperatures without resorting to flooded condenser head pressure controls.

This option includes an inverter and pressure transducer. All components are factory mounted and wired. The controller decreases fan motor RPM as head pressure decreases.

See Table 8 for minimum ambient temperatures for units with both the Fan Cycling Control Option and Fan Speed Control Option.

Flooded Condenser Option With Fan Cycling

Fan Cycling can also be used in conjunction with the Flooded Control Option to greatly reduce the required operating change typical of flooded condenser operation. The additional charge needed for condensers equipped with the Fan Cycling and Flooded Condenser Controls operating in low ambient temperatures can be found in Table 11. For refrigerants other than R407A, R448A or R449A, see correction factors in the footnotes.

*Based on approximately 90°F condensing temp.

For refrigerants other than R407a, 448a, and R449a us the multipliers below:

• *For R22, multiply by 1.04
• *For R134A, multiply by 1.06
• *For R410A, multiply by 0.94
• *For R404A, multiply by 0.92

Wiring Diagrams

The following diagrams illustrate the electrical connections for the HTPG Air Cooled Condensers. These diagrams cover motor control signal wiring, main power circuits, and fan cycling control components.

Start-Up Procedure

1. Make sure the condenser is wired as shown in the Field Wiring section of this bulletin and in accordance with applicable codes and local ordinances.
2. Make sure all electrical connections are tight.
3. Make sure the piping to the condenser is in accordance with the Refrigerant Piping information section of this bulletin and good piping practice.
4. Make sure all motors are mounted securely and all fan setscrews are tight.
5. Make sure all fans rotate freely.
6. Make sure the unit is located so that it has free access for proper air flow, see the Unit Location section of this bulletin.
7. After start-up, make sure all fans are rotating in the proper direction. Fans should draw air through the coil.

Maintenance

General

Air-Cooled Condensers require very little maintenance. Keeping the coil surface clean and free of debris is important for extended life, peak performance, and corrosion resistance. It is also important to periodically check all electrical connections to make sure they are secure. All motors have permanently sealed ball bearings which do not require any maintenance.

Condenser coils should be cleaned every three months in coastal or industrial environments and every six months in all other environments.

ALWAYS BE CERTAIN THAT POWER TO THE CONDENSER FANS IS SHUT OFF AND LOCKED OUT BEFORE PROCEEDING WITH MAINTENANCE AND CLEANING!

Remove all large debris from the area under and around the condenser. Inspect the inlet face of the coil for damage caused by blowing debris. Comb out any bent fins with a fin coil.

Apply clean water from a garden hose with a spray wand to the outlet side of the coil, after using a soft-bristle brush or vacuum cleaner to remove dirt or other fibrous material. The use of high velocity water or compressed air could bend the coil surface, resulting in a decrease in performance. The use of coil agent cleaning agents is not recommended. If a cleaning agent is used, make sure it is non-acidic or non-caustic. If the coil is coated, make sure the cleaner is compatible with the coating.

Be certain that all tools have been safely stowed away and that fans, guards and panels are in place and secure before returning the condenser to operation.

Hinged Venturi Panels

Cleaning the coil or servicing the fans or motors is easier on units provided with hinged venturi fan panels because they can be raised by removing bolts with self-retained nuts. The hinged panels are provided with gas struts that hold them securely in the upright position. With the panels raised, the coil can be cleaned by washing it down from the top. Service access to the fans and motors is greatly improved.

Motor Replacement

Motors can be easily replaced by removing the fan blade and (4) four nuts. The studs will partially retain the motor for re-installation.

Dimensional Drawings

Vertical Air Discharge

The following diagrams show various configurations for Vertical Air Discharge condensers, detailing their lengths and widths. All dimensions are in inches.

Horizontal Air Discharge

The following diagrams show various configurations for Horizontal Air Discharge condensers, detailing their lengths and widths. All dimensions are in inches.

Replacement Parts and Service Record

Refer to the contact information below for replacement parts. A service record section is provided for documenting maintenance performed.

Replacement parts: www.parts@htpgusa.com

Contact Information: 201 Thomas French Drive, Scottsboro, AL 35769 PHONE (256) 259-7400 FAX (256) 259-7478 www.htpgusa.com