Joined on April 16, 2013
Last Post on November 24, 2013
@ April 21, 2013 8:03 PM in vacuumI only mentioned the old way in case the tech does not yet have a set like the ones in the picture, which I now use as well. No more fried digits or valve cores down my shirt!
@ April 21, 2013 11:18 AM in vacuumBy sending this picture, the tech is showing us that he uses them. By using them, this seemingly tiny little issue speaks volumes about the quality and performance of his work in the field. I'll bet his air conditioner and heat pump installations last 20 years!
@ April 21, 2013 10:55 AM in vacuumGood question; love it! Here are a couple of ways: (1) Install a core removal tool with side ports for vacuuming. When you are happy with your evacuation, push down on the plunger and screw them back in. (2) If you don't have the above tool, don't forget we are allowed de minimus release of refrigerant into the atmosphere, so introduce just enough refrigerant to break your vacuum. If you're quick enough, you can get the core in before all of the pressure is released so you don't disturb your vacuum or burn yourself. Then repeat the process for the other line. It may sound crazy, yet I have done this hundreds of times before the days of the above mentioned tool. The trick is getting the core in before the refrigerant empties.
@ April 21, 2013 10:37 AM in subcoolThe problem is not you. It is others who use them as charging devices. I cringe when I hear someone who charges a system to "a clear sight glass". Yikes! Plus, since it is so hard to get all of the moisture out of an R-410A system, I rely on the LLD temperature drop as a moisture indicator. As pipe joining appears to be a lost art, one less component means two less potential leak sources.
@ April 20, 2013 12:13 PM in vacuumCommonly called Shrader valves, they look like the valve in a tire. You cannot pull a quality vacuum with them in the service valve.
@ April 17, 2013 7:50 PM in dry charged condensor changeoutYou are putting yourself and the equipment in a tough situation with any type of fixed metering device. Quality-driven makers of the dry units assume you will be using a TXV. You have possibilities from the easy to the extreme: (1) Locate an R-22 coil that will "match" the unit you propose; (2) Remove the orifice and pipe in a TXV; (3) Check other makers to see if they have an "N" coil that may be less tall; (4) Determine if the furnace is approved for horizontal application and change the configuration, or; (5) Replace the furnace, giving your customer higher efficiency, the advantage of R-410A, and the long life expectancy that comes with AHRI certified combinations.
@ April 17, 2013 8:57 AM in vacuumIf you are working with R-410A, it is a real challenge to get the moisture out, so try not to leave the system open to atmosphere for more than 15 min. Always remove your valve cores to vacuum, and use a vacuum hose, not refrigerant hoses. Run your pump (with clean oil) to 200-300 microns and isolate the pump. If your micron gauge rises to 500 microns and stays, job well done. Continuing rise means moisture is still in the system, or you have a leak. With R-410A, it is near impossible to get all the moisture out, so if your microns rise to 750 for example, and you have done a triple evacuation, you have done the best you could under the circumstances. Again, minimize exposure to atmosphere and oversize your LLD as a matter of practice. On your annual maintenance calls, check the temperature drop across the drier. Anything more than 3 degrees, out it comes!
@ April 16, 2013 3:37 PM in subcoolSounds as if you are slugging liquid with your high sub cooling and low TD at the evaporator. Your unit is not designed to operate below 55 degrees, so go back on a warmer day. You may have to create a load by running the furnace for a half hour or so if the ambient is still around 60 degrees. Hint: weigh in your charge per factory specifications in cold ambients, then go back in May to fine-tune. Never use a sight glass with R-410A.
When you go back, just to make sure all of the moisture was taken out at installation, do a static test. Hook up your head pressure gauge (the system must be off for at least 20 minutes) and check the ambient temperature. It, and your head pressure converted to temperature, should match. If your condensing temperature is higher than ambient, you may have non-condensables in the system, such as moisture or remaining nitrogen. If you do, the 1st thing that will occur is high sub cooling. Remember, R-410A POE oil is a sponge!