Follow Parker Hannifin on social media:
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 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.
All torque values are expressed in ft.lb.
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.
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.
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.
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.
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.
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.
Restrictor, Part #2449-004, may be required to control pump out rate on an inactive condenser.
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.
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.
This check valve is required if lowest operating ambient temperature is lower than evaporator temperature.
Restrictor, Part #2449-004, may be required to control pump out rate on inactive condenser.
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.
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
HVACR Tech Tip: Using Bi-Directional Solenoid Valves for Heat Pumps
HVACR Tech Tip: How to Determine Total Refrigerant System Charge When Using Head Pressure Control
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.
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.
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.
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.
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
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.
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.
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.
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.
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
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
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.
When one has compound cooling compressors or vapor injection be sure to use the subcooled temperature.
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.
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
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.
FAILURE OR IMPROPER SELECTION OR IMPROPER USE OF THE PRODUCTS DESCRIBED HEREIN OR RELATED ITEMS CAN CAUSE DEATH, PERSONAL INJURY AND PROPERTY DAMAGE.
HVACR Tech Tip Article contributed by Jim Eckelkamp, senior application engineer, Sporlan Division of Parker Hannifin
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
With the introduction of ZoomLock Flame-Free Refrigerant Fittings we have come across many people in the HVACR industry that have questions about using it. So here we answer the 10 most common questions about using ZoomLock.
Three different jaw configurations are available to ensure a broad range of compatibility to use with your preferred tool. Options include:
Klauke: 19 kN Crimping Tool MAP2L19
RIDGID Compact Press Tool Models: RP 240, RP 241, RP 200, RP 210, RP 100
Milwaukee: M12™ FORCE LOGIC™ Press Tool 2473-20
No. ZoomLock is different than other industry crimping technology. The jaw must align between the o-ring and outer flange. Grooves in the jaws make it easy to align. The fittings will leak if you do not crimp as stated in the ZoomLock installation instructions. Proper crimping alignment is also illustrated in the photo above.
On average you can achieve 100-150 crimps per charge depending on the size fittings being crimped. Each Klauke Tool kit comes with 2 Makita Lithium-ion 2.0 Ah 18V batteries (BL1820B) and a rapid charge charging system. To prevent any downtime, it is recommended that you have both batteries charged before going to the job site and to have one charging while the other is in use.
Use the depth gauge provided or the minimum insertion depth chart to determine the correct insertion depth. Mark the tubing with a permanent marker to indicate proper insertion depth on every tube.
No, we do not have a specific product designed to crimp over the flared tubing. However, if there is at least 2 inches of straight copper tubing after the flared end and is accessible with the jaws, we suggest that you cut the flared end off and crimp directly to the tube.
No, ZoomLock is specifically designed for copper to copper connections. Connecting to dissimilar metals can cause formicary corrosion issues that could cause a failure.
ZoomLock has been approved by UL-207, ASHRAE 15, International Code Council – Evaluation Service (ICC-ES), International Mechanical Code (IMC), Universal Mechanical Code (UMC), and International Residential Code (IRC). These approvals are all that is needed in most areas. Please contact your local building inspector with questions prior to install.
The o-ring is a highly engineered HNBR Parker o-ring that has been used in HVAC applications by OEMs and suppliers for many years with no issues.
Figure 1 below shows an example of a good tube. Figure 2 is an example of a tube with a bad scratch that requires proper tube preparation. It is very important to follow deburring, sanding and inspection steps 4 to 8 in the installation instructions.
Skipping the installation instructions will cause the tube to leak. It is very important to use the scouring pad and deburr tool included in the kit. Refrigerant gas at the maximum rated 700 psi pressure is more likely to leak than water at a much lower pressure, therefore, following the tube preparation instructions is very important. See the video below for proper tube preparation.
Download our complete list of ZoomLock Troubleshooting and Frequently Asked Questions here.
Article contributed by Parker Sporlan Division.
HVACR Tech Tip: Where Should the TEV External Equalizer Be Installed?
HVACR Tech Tip: Principles of Thermostatic Expansion Valves
Customers have complained of hydraulic hammering noises on heat pump systems for years. Field people refer to it as the “knock-knock” noise. The complaints usually surface at the end of the heating season. The noise apparently occurs following a heating cycle during the light load part of the year. This means it could occur sometime in March or April and reportedly is most noticeable in the early hours of the morning. The compressor cycles off after a heating cycle and the hydraulic hammering or “knock-knock” noise commence shortly thereafter.
Hydraulic hammering can occur with abrupt impedance (a valve closes) to non-compressible fluid flow (liquid). This can create an initial shock wave which can then resonate through the system piping. During the heating mode, the internal check valve in a thermostatic expansion valve (TEV) would normally be in the open position on the indoor coil with reverse flow through the valve. The check valve on the indoor coil’s TEV would tend to close after the compressor cycles to the off position. However, gravity would tend to hold the check valve in the open position if the TEV was in a vertical position with the thermostatic element assembly (also known as the power head in general industry vernacular) pointing down towards the earth even after the compressor cycles to the off position. This could promote normal forward flow through the indoor coil TEV during the system pressure equalization process. Forward flow through the check assembly does cause the check valve to close by design. This could account for the necessary abrupt change that must take place to create the initial shock wave thus creating the hydraulic hammering phenomenon. If this theory has any merit, repositioning the TEV to eliminate the force of gravity would reduce or curtail the hydraulic hammering problem.
Refer to Figure 1; the Type CBBI valve is depicted with the check valve in both a Closed and an Open position.
Previous field trips to supposed trouble job locations yielded negative results, meaning no objectionable noise was ever observed, much less repeated. That was about to change with this trip. The trouble job was located in a historic home (1870 vintage) in South Central Texas that had been restored and remodeled with the input of an architect. It was fitted with acid washed concrete floors, stone walls, hardwood accents and a relatively new heat pump system supplied by one of the major equipment manufacturers.
The heat pump system utilized R-22 as the refrigerant and was fitted with the CBIVE-2-GA on both the indoor and outdoor coils. The air handling unit and indoor coil were mounted in the ceiling in close proximity to the bedroom; the equipment was relatively new and had been supplied and installed via reputable means. If this system exhibited the so-called “knock- knock” noise, it would certainly reverberate through-out this structure of hard surfaces.
A scroll type compressor with a discharge line check valve was deployed on this unit; the discharge line check valve is intended to prevent the compressor from running in a reverse direction following an off cycle. The system was originally installed with the TEV in a horizontal position in the indoor coil. The line set was within the OEM’s specified requirements regarding size and design. The piping was routed through the attic and above grade.
The unit had been previously re-charged with R-22 to confirm system integrity and removal of non-condensable contaminants. The system was checked for proper superheat and sub-cooling performance while we were at the site. Superheat was approximately 12°F and sub-cooling was approximately 11°F. These numbers were all within OEM specifications. The system heated and cooled adequately and there was never a complaint regarding this aspect of performance.
Based on the theory, we decided to first remove the Chatleff style piston assembly in the distributor. We speculated that perhaps the piston which serves as both a check valve for reverse flow and a nozzle assembly for forwarding flow was contributing to the hydraulic hammer perhaps in conjunction with the TEV’s check valve. The system was pumped down and the piston assembly was removed. The system charge was not modified.
Even with the piston assembly removed from the distributor, the hydraulic hammering noise could reliably be produced; however, the time duration of the noise was shortened considerably. We reinstalled the piston assembly in the Chatleff distributor.
We then repositioned the indoor coil TEV so as to be totally upright; i.e., in a vertical position with the thermostatic element pointing towards the sky. We were able to accomplish this by simply rotating the TEV as enough “slack” existed in the system piping. Again, this was performed without disturbing the system charge in any way. This solved the problem on this trouble job. Merely rotating the TEV to prevent gravity from opening the check valve following the heating mode cycle prevents the hydraulic hammering noise. We then attempted to reproduce the noise over the course of two days and were unable to reproduce it while prior to repositioning the TEV it could easily be done.
The problem occurs only when the necessary system conditions exist. It appears the indoor coil TEV needs to be upside down or at least on its side and TEVs must be present on both the indoor and outdoor coils for the noise to occur. It may also be necessary for the discharge check valve on the scroll compressor to have some associated leak rate; it is speculated this may contribute to the necessary system conditions for noise to occur.
Refer to Figure 2 for recommended TEV positions when equipped with the internal check valve. These recommendations pertain to TEVs equipped with internal check valves that are installed in the valve body so as to be parallel to a vertical line through the center of the TEV. The Sporlan Type CBI and CBBI thermostatic expansion valves are examples of this type of construction.
The hydraulic hammering noise would not surface with any other expansion device on the outdoor coil; both the indoor and outdoor coils must be equipped with a thermostatic expansion valve. If the outdoor unit was fitted with a fixed tube orifice of any kind or a TEV with a bleed port, the noise didn’t occur. Apparently, this provides a “vent “or release for the pressure differential after the compressor cycles to the off position and the shock wave never occurs. In all cases, the problem can occur with conventional and balanced ports alike and includes most any competitive product that utilizes a gravity influenced check valve for reverse flow for a bypass around the main port.
Furthermore, the noise issue is not a valve malfunction. The thermostatic expansion valve controls superheat at the bulb location in spite of the noise issue. The problem only occurs when the necessary system conditions exist. It appears the indoor coil TEV needs to be upside down or at least on its side and non-bleed style TEVs must be present on both the indoor and outdoor coils for the noise to occur. It may also be necessary for the discharge check valve on the scroll compressor to have some associated leak rate.
And finally, with the TEV in a vertical position and the thermostatic element pointing towards the sky, the noise will not occur.
For more information about TEVs see Bulletin 10-10 Thermostatic Expansion Valves.
Article contributed by Jim Jansen, senior application engineer, Sporlan Division of Parker Hannifin
Additional resources on HVACR Tech Tips:
HVACR Tech Tip: Understanding and Preventing Superheat Hunting in TEVs
HVACR Tech Tip: Troubleshooting Solenoid Valves in Refrigeration Applications
Condenser coil cleaning is one of those subjects in which there is much misdirection and misinformation being propagated by some manufacturers/distributors that has caused unfortunate confusion in the industry. Addressed below are answers to common questions to set the record straight on the use of these products.
Condenser coils depend on a chemical reaction between the aluminum fins and either a strong acid or alkaline solution to clean the coils. This chemical reaction produces heat and several fumes and gasses (primarily hydrogen) which causes the coil cleaner to foam and push out the dirt loosened by the wetting and heating process. If a foaming condenser coil cleaner is used and does not foam, it means that aluminum is not in the coil (possibly a steel or copper coil), or grease, oil, paint or some other substance is keeping the cleaner from contacting the aluminum and creating the reaction. Due to the fumes given off in this process, these types of cleaners are not suitable for use inside. Evaporator coil cleaners are specifically formulated for indoor use and, although probably not as effective as the foaming condenser coil cleaners, they are effective cleaners on the types of dirt commonly found on evaporator coils.
In the past, acid based condenser coil cleaners were the standard. There really was no other option. The primary acid of choice was hydrofluoric acid (HF) because it reacted well with aluminum to create the desired foam. It was common knowledge that HF was a serious chemical and needed to be used with a certain amount of caution. One of the peculiar things about HF is that if it comes in contact with skin, it typically does not create a burning sensation immediately. Instead it can soak into the skin and later cause the user pain. By this time, skin and tissue damage is advanced and may require a trip to the doctor for a neutralizing injection.
Due to this danger, coil cleaner manufacturers developed alternative acidic cleaner formulas that did not contain HF directly, as well as non-acid (alkaline) coil cleaners whose primary ingredient was either sodium hydroxide or potassium hydroxide, both of which are very similar chemically. These chemicals do cause a burning sensation when in contact with skin and the discomfort will encourage the user to rinse the cleaner off before serious skin and tissue damage occurs. It should be noted, however, that neither type of cleaner should be called safe. Both the acid and alkaline condenser coil cleaners can cause serious skin and eye damage, and the vapors, especially those during the cleaning process, can cause serious lung and throat problems and should be used with caution. Due to the change of ground pH, both types of cleaners can kill grass and other foliage immediately around the condenser coil. Both types of coil cleaners are technically biodegradable. Both types are for outdoor use only. Both types should be rinsed thoroughly from the coil and surrounding area when the coil cleaning process is complete. These are serious chemicals and demand serious respect.
Both acidic and alkaline cleaners continue to have roles in your arsenal of coil cleaning products. The acid based Acti-Brite remains the cleaner of choice for removing corrosion by-products and scale build-up. Alkaline-based Alki-Foam is recommended to remove excess dirt, grease and grime.
One of the interesting things that has come about in recent years is the push for cleaners with more and more foam generation. This begs the question “how much foam is really enough?” The idea to keep in mind is that you need enough foam to push out the quantity of dirt down in the coil. More foam does not necessarily mean that the unit is getting any cleaner. Clean is clean - anything more is too much. Before cleaning the condenser coil, the coil should be inspected to determine how dirty it really is. In the vast majority of cases, the coil just has a light coat of dirt and dust covering the surfaces and really just needs a light cleaning. Using super-high foaming cleaners straight out of the bottle is overkill. In most applications, a good coil cleaner such as Acti-Brite or Alki-Foam mixed to a dilution ratio of between 1:2 and 1:4 is usually adequate for most cleaning jobs. The reality is that most technicians love to see thick foam and tend to use the cleaners straight. We discourage this practice because it usually is not needed, can result in damage to the fin stock and results in unnecessary amounts of chemicals that are transferred into the ground. If inspection determines that a condenser coil is very dirty with grease or other difficult dirt, then a dilution ratio of 1:1 will usually result in a very thick foam and enough chemical to clean virtually any application. If the coil remains dirty after one application, then rinse it off and reapply at a 1:1 ratio.
Before cleaning a condenser coil, make sure to break power to the unit. Perform an inspection of the coil to determine how dirty it is. This should entail disassembly of the unit to the extent that if there are multiple rows of coils, you can inspect between the rows to determine the depth of dirt. On multiple row coils, it is not uncommon to have a quantity of dirt make it through the outside row of coils and block the inside row of coils. The unit may look clean from the outside, but airflow is blocked.
If accumulations of dirt, dust, cottonwood or other contaminants is matted on the face of the coil, it is a good idea to use a coil brush similar to the one discussed in the evaporator coil section to quickly brush the condenser coil face. This will aid in the penetration of the coil cleaner and speed up the job considerably. After inspection, mix your coil cleaner in a low pressure sprayer to a ratio appropriate for the amount of dirt on the coil (1:1 to 1:2 for heavily soiled coils, 1:3 to 1:4 for light to medium soiled coils). It is recommended that due to the nature of these chemicals, chemical impervious gloves, goggles and apron are worn. Always make sure to put the water in the sprayer first, then add the appropriate amount of cleaner. Wet the coil with water first as this will aid penetration of the cleaner into the coils. Apply the cleaner to both the inlet and outlet side of the coil, saturating the coil with cleaner. Caution should be taken on windy days as condenser coil cleaners can etch glass and remove paint from vehicles, as well as cause harm to anyone standing downwind. Do not allow the cleaner to rest on other system components. Sprayers with foaming tips are not recommended as pre foaming the cleaner will hinder penetration into the coils. The foam generated is a chemical reaction with the aluminum, not from a spray tip.
Allow the cleaner to work for a maximum of five minutes. During this time, foam should form and dirt should be visibly carried out on the foam. Smoke or other vapors may be visible during this time which are a side effect of the chemical reaction and is not something to be concerned about. Begin rinsing the coil from the top down, taking care not to splash the cleaner on yourself or other surfaces as damage may occur. Continue to rinse the coil until no more foam is visible coming out the bottom of the condenser coil. Be sure to rinse all of the cleaner out of the coil as the cleaners may cause coil damage if left to dry on the coil. Rinse the surrounding area thoroughly with water, reassemble the unit and restore power to the condenser. Always be sure to rinse out the sprayer when finished as the chemicals may cause damage to all but the best sprayers over time.
Article contributed by Chris Reeves, product manager, Contaminant Control Products, Sporlan Division of Parker Hannifin
For more articles on climate control:
HVACR Tech Tip: Coil Cleaning Basics for the HVACR Service Technician
HVACR Tech Tip: How to Clean Evaporator Coils for Preventive Maintenance
HVACR Tech Tip: When Should a Catch-All Filter-Drier be Changed?
When it’s time to provide your customer's preventive maintenance don’t forget to pay particular attention to system components that are out of sight within the system cabinet or air handler enclosure. The unit’s evaporator coils are among the more important of these hidden components. Problems can develop with dirty evaporator coils as it can effect the system's performance and efficiency. This can also lead to damage and/or breakdowns. Here is some basic information on effectively cleaning evaporator coils.
Evaporator coils are probably the most difficult to clean. They are usually packed tightly inside a blower compartment that are usually difficult to service. They may be located over bathtubs, in tight dark closets, on rooftops in commercial applications, in a hot attic or a myriad of other places that are usually cramped, dark and uncomfortable. Due to these inconveniences, evaporator coils are often left alone and not cleaned until a system problem emerges. An evaporator coil should be inspected every six months and may need to be cleaned every six months to four years, depending on environment and filtration.
Make sure to disconnect the power to the unit while cleaning the coil. This will prevent a potential electrical hazard. Disassemble the unit to the extent that both sides of the coil can be accessed. For applications that have matted hair and dirt on the intake side of the coil, it is important that they be carefully brushed clean. Failure to do so will severely limit the penetration of the coil cleaner and dramatically reduce its effectiveness. There are several disposable types of coil brushes available from different manufacturers that do a very good job of cleaning the surface dirt off while keeping your hands away from the filth and fins. One note of warning - the fins on a/c coils are very sharp and can cause severe cuts to skin. Be sure to avoid contact with the coil with your hands, arms, etc. It’s advisable to wear gloves, face mask and apron during this procedure since potential organisms growing on the coil and contact with lungs, skin, eyes or clothing may transmit disease. Once the surface dirt has been removed, a good evaporator coil cleaner, such as Acti-Klean should be mixed in a low pressure sprayer with water in a dilution ration of between 3:1 to 1:1, depending on the condition of the coil and the type of dirt encountered. Acti-Klean is a concentrated set of soaps and surfactants (wetting agents that help the cleaner penetrate the coil fully). The coil should then be sprayed liberally from both sides of the coil with the coil cleaner solution. This coil cleaner will not create the foam that condenser coil cleaners do, so don’t be shy applying the coil cleaner. Make sure that the liquid does not fall onto electrical components in the system. The cleaner will cut through grease and oils, as well as dislodge any dirt, dust and hair that may be trapped in the coil and rinses them down the condensate drain. An alternative option would be Virginia Coil Klean aerosol coil cleaner. This product will foam out dirt and dust and is certainly more convenient in the aerosol container, although it is more costly than cleaners like Acti-Klean. When the coil is clean, it is recommended that where possible the coil be rinsed off. This will aid in removing any remaining dirt from the coil. If this is not possible, then the condensate created by running the a/c system will rinse off any remaining cleaner. Depending on temperature and humidity conditions, the unit should run for between 15 minutes to 1 hour to ensure all cleaner is rinsed off the coil.
In recent years, indoor air quality receives a lot of attention. Often a case of “black mold” in some air conditioning system is reported in the news and the entire building must be evacuated and sanitized. It is a good idea after cleaning the coil that an EPA registered bacteriostat be used on the coil and surrounding ductwork and insulation to ensure that any minor growths and odors are eliminated. Doing so provides your customer a valuable service by ensuring that mold and other growths do not develop throughout the system. It is important the technician pays close attention to the volume of dirt and other growths coming off the coil. It is not uncommon for release dirt to block the opening of the condensate drain line and restrict the draining of water. If this is observed, the blockage should be removed before the drain pan overflows.
While cleaning the coil, it is a good time to clean the drain pan as well. Simply clean out any rust and deposits that may be sitting in the bottom of the pan with a towel, rag or other means. Once again, be careful not to rub your hand across the coil as the edges are quite sharp. Protective gloves are recommended.
For more information see Catalog G-1.
HVACR Tech Tip: Obtaining Oil Samples in a Refrigeration or Air Conditioning System
Cleaning air conditioner condenser and evaporator coils is a basic need for proper system maintenance. In fact, it is probably the number one performed maintenance task by air conditioning service technicians. It seems however, that with the entrance of so many manufacturers and packagers of coil cleaners, that some of the facts about coil cleaning has been lost. As a premier supplier of coil cleaners for the trade we will discuss in general terms why coils need to be cleaned. The discussion is with aluminum-finned air conditioning applications, but the principles apply to refrigeration applications.
Both condenser and evaporator coils are made for one purpose - to transfer heat. The evaporator coil (indoor coil) is generally designed to pick up heat from the inside air, and the condenser coil (outdoor coil) is designed to give off this heat to the outside air. The exception is a heat pump application in the heating mode where the functions are reversed. As dirt, hair, lint, grass, grease and other contaminants coat the fins and tubes of the coils, the transfer of heat is reduced and system problems increase. A dirty evaporator coil causes less air movement over the coil which results in less heat pickup for the refrigerant.
If the heat pickup is not sufficient to vaporize the refrigerant, then one of two things typically occurs: 1) Liquid refrigerant travels back to the compressor and will either wash the lubricant off the bearings and lock the compressor or cause the rotor to drag on the stator and cause a compressor burnout, or 2) liquid refrigerant travels back to the compressor cylinders and the hydraulic pressure breaks valves, typically the suction valves. In the case of a dirty condenser coil, the reduced heat transfer results in higher than normal head pressure and discharge temperatures. This condition causes the compressor to work harder to pump against the higher pressures. The end result is the compressor motor overheats and wears out prematurely.
In either case, a dirty condenser or evaporator coil, the compressor is the component that is usually affected the most, not to mention that in both cases the cooling capacity of the system is reduced, resulting in higher electric bills. For these reasons, it is important that both condenser and evaporator coils be cleaned at regular intervals.
Accumulated dirt, dust and grease insulate against heat transfer. Dirt prevents the condenser coil from rejecting heat as it was designed and elevate head pressure. When head pressure rises, so does electricity because of power requirements.
Higher head pressure also reduces system BTU capacity, by as much as 30%. A 10 ton unit may now only be capable of providing 7 tons of cooling. This causes an increase in run time and inadequate comfort cooling or refrigeration.
Increased amperage draw combined with longer run time adds up to much higher energy bills. A 10 ton A/C system operating for 1500 hours could use as much as 37% more power when the coils are dirty. With a kWH cost of 8.3 cents this would cost the owner $618 more to operate (or $62 per ton more with dirty coils).
For more information see Catalog G-1 Chemical, Lubricants and Accessories.
Compressor Overheating is the Number One Refrigeration Problem