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So to save time, the recovery process is started by removing the liquid part first. While recovering, vapor refrigerant is retrieved from the vapor line in the system. How can you speed up the removal of the refrigerant charge from the system?Removal of the refrigerant charge from a system can be conducted more quickly by; packing the recovery vessel in ice. When first inspecting a hermetic system known to be leaking, you should look for; traces of oil. How long should it take a system to stabilize after adding or removing refrigerant? Allow 10-15 minutes of operation for the approach to stabilize after refrigerant is added or removed. When recovering refrigerant from small appliances you must recover? Technicians repairing small appliances, such as household refrigerators, window air conditioners, and water coolers, must recover:
What is the best method to determine a chillers normal charge?What is the best method to determine a chiller’s normal charge for leak rate calculations? Use the charge stated on the equipment nameplate. Approximately how much refrigerant vapor is left in an average 350-ton R-123 chiller at 0 psig once all the R-123 liquid has been removed? What are the two refrigerant recovery methods?Overview of Recovery Types When recovering refrigerant, there are three basic methods: liquid, vapor, and push-pull. In the liquid recovery method, you are able to transfer refrigerant while it’s still in the liquid state. This method is especially good for transferring refrigerant from one container to another. What refrigerant is very high pressure and does not need to be recovered? Co2 refrigerant R-744 (Carbon dioxide) is a very high-pressure refrigerant and generally does not need to be recovered. What are routine maintenance tasks performed on most refrigerant recycling machines? In general what is one routine maintenance task which must be performed on most refrigerant recycling machines Change oil and filter You can save time recovering the refrigerant from a system by removing as much as possible in the _ phase Liquid When does a refrigerant unit need to be repaired?EPA regulations require that all appliances containing more than 50 pounds of refrigerant (except for commercial and industrial process refrigeration) be repaired when the leak of a unit is not used for several months? 15 Where does the refrigerant go in an operating unit?An operating unit has a receiver/storage tank that requires refrigerant system service. when servicing the unit ________ refrigerant should be recovered in the receiver every refrigerating system shall be protected by ________ a refrigerant receiver the evaporation temperature of R-134a at 0 psig is _______ -15 degrees F When to remove refrigerant from the condenser outlet? Refrigerant should be removed from the condenser outlet when _________ the condenser is below the receiver An operating unit has a receiver/storage tank that requires refrigerant system service. when servicing the unit ________ refrigerant should be recovered in the receiver every refrigerating system shall be protected by ________
I often see new techs asking how to recover or experienced techs asking how to recover faster, so let’s take a look at both. If looking to connect with a strong culture of HVAC technicians, check out the subscription-based HVAC Know It All app. This all originated from some personal trial and error when an air conditioning manufacturer I worked for had a recall, a missing Schrader core at the receiver service valve (king valve) of all things. This was a possible disaster for an unsuspecting tech. Remove the cap expecting a valve core, and well... Not fun. So it was time to install a single valve core in 50 operational units in critical spaces, each holding between 50 and 100 pounds of R-410A. I had a reasonably repeatable situation on my hands, and I had the opportunity to try all sorts of things: recovery cylinder size, hose size, hose type, etc. I’ll cover all this at the bottom of this article, but we’ve got to start with the basics! How do we recover?There are two typical methods, direct recovery and push/pull. You should always familiarize yourself with the equipment you are working with, but I’ve included a simple diagram of how to connect the required equipment and a “step-by-step” guide for the newer techs. Direct RecoveryThis is our typical recovery method, which will be how every recovery task will finish. 1. Start with all valves closed (recovery cylinder, recovery machine, manifold, hoses.) 2. Setup hoses as shown in the diagram. 3. ZERO/TARE the refrigerant scale. 4. Open hose valves, core removal tool valves or service valves. 1. ---The below steps will vary with your recovery machine--- 5. Set the refrigerant recovery machine to recover. 6. Open the high side of the manifold for liquid recovery. 7. PURGE THE HOSES OF AIR, loosen and unseat the hose connected to the recovery tank until the refrigerant is present, and then retighten. 8. Fully open the vapor valve on the recovery cylinder. 9. Turn on the recovery machine. 2. ---The below steps should be standard for most recovery machines--- 10. The manifold high side valve may need to be adjusted to throttle refrigerant flow into the refrigerant recovery machine to avoid liquid slugging. 11. When the liquid recovery is complete, fully open both the high side and low side manifold valves. 12. Many recovery machines will turn off once the system reaches a vacuum. 13. PURGE THE RECOVERY MACHINE – this one can be pretty specific – so check your manual if you’re unsure. 14. Close all valves and recovery is complete! Push/PullThis will be your faster option if the system has 15 or more pounds of refrigerant. The more refrigerant the system holds, the more time you’ll save. Tip: Using an inline sight glass during push-pull recovery will allow you to visually determine when the liquid flow has stopped. 1. Start with all valves closed (recovery cylinder, recovery machine, manifold, hoses.) 2. Setup hoses as shown in the diagram. 3. ZERO/TARE the refrigerant scale. 4. Set the recovery machine to recover. 5. PURGE THE HOSES OF AIR (this is done slightly differently than in direct recovery.) 6. Turn on the recovery machine. 7. When liquid recovery is complete, switch to Direct Vapor Recovery. Now, let’s speed it up...Valve Core Removal Tools• If you were only going to change one thing – this is it! If you’re stuck pulling through valve cores, get two of these. They’ll even help speed up your evacuation. Recovery Cylinder• Make sure the cylinder is clean and has been evacuated to 500 microns or less. And NEVER fill beyond 80%. This allows for the expansion of the refrigerant. Hoses• Avoid hoses with “anti-blowback” or “low loss” style fittings. • Standard hoses are ¼” – using larger diameter hoses will get you faster recovery. They’re often marketed as “heavy duty,” “charging,” or “vacuum” hoses. • Use hoses that are as short as possible. Temperature• Cool down the recovery cylinder– this will drop the pressure of the recovery cylinder. • With many recovery machines, you can use the fan to draw air over the recovery tank. • Water will work even better, but you’ll need water flow. • Cool down the refrigerant! This one tends to be your best bet if you’re dealing with large volumes of refrigerant – there are heat exchangers available for just for this purpose. Filter It!• If you suspect the system refrigerant to be dirty, use an inline filter drier at the inlet to the recovery machine. With methods ranging from nothing new required to a whole new rig for recovery, you’ve got choices to speed up your recovery in just about all applications. Give some of these a try and see how they work for you. Dan Reggi Humber College Professor Follow HVAC Know It All on Instagram, Facebook, YouTube and LinkedIn and LISTEN to the HVAC Know It All Podcast Save 8% on purchases at TruTech Tools with code knowitall (excluding Fluke and Flir products) BACK |