Joined on April 16, 2013
Last Post on March 11, 2014
@ July 24, 2013 4:17 PM in I know now why I quite coming to the wallIt is my firm belief that 4/3 of us are highly educated.
@ June 23, 2013 9:02 AM in why would Compressor vibrate?Again, check pressures and amp draw against nameplate. Sounds as if you're running hot has anyone checked, really checked, the condenser coil?
@ June 21, 2013 5:56 PM in why would Compressor vibrate?If this is a start-up and you have a scroll compressor, it might be running in reverse. If this is the case, switch around the power legs at the disconnect until it quiets down and your pressures look normal, or if you have a phase monitor, the LED will be green when it is happy.
@ June 21, 2013 5:45 PM in why would Compressor vibrate?Attach your gauges to see their readings as compared to the factory charts. Under operation, measure the compressor amps on the COMMON lead. Compare your amps to the nameplate. If your vibration is not a broken mounting spring and your amp reading is 15% or more above the nameplate, that would certainly indicate damaged bearings.
@ June 21, 2013 5:36 PM in why would Compressor vibrate?Do you have a hermetic (sealed) compressor, or a semi-hermetic (looks like a small car engine)?
@ June 21, 2013 11:58 AM in why would Compressor vibrate?Some manufacturers put large compressors on springs. If this is your case, after hundreds of hours of operation, a spring or springs can break, throwing the compressor off-balance. Kits are available for replacement.
@ June 15, 2013 10:25 AM in High subcoolSorry I didn't respond last night. I was charging myself to a full shot glass.
With the new coils so tall you need a bucket truck to get to the compressor, as long as the manufacturer doesn't object, putting the drier at the service valve sure makes it easier to install, read temperature and pressure across the body, and change the core if needed. I'm still at a loss as to why Rick's units have them, yet they are there, and the PDs are out of line on a couple of them at least.
@ June 14, 2013 6:24 PM in High subcoolFor the same reasons you place an air filter as close as possible to the blower inlet. Plus, the makers of the driers recommend it for best results.
@ June 14, 2013 2:56 PM in High subcoolLook at Unit 3. Your head pressure converted to temperature and the ambient are dead on target! I'm going for air flow or overcharge. Send us your ESP and the CFM at that figure from your blower performance chart in the IOM manual that came with your indoor unit. Along with the load test, we will nail this thing.
@ June 14, 2013 2:47 PM in High subcoolFirst lets review the test. As I mentioned earlier, condensers below ambient shouldn't be. Hook up your head pressure gauge and turn the system off. Place a quality thermometer at least 6" from the coil, but not in direct sunlight. After at least 20 minutes, your head pressure converted to temperature and the ambient should be the same. If still lower I am concerned that your ambient and the inside temperature are too close, causing liquid stacking in the outdoor unit. Only a load will tell at this point, other than recovering some refrigerant, which I'm sure you would rather not do right now. It's 72 outside, yet in the 50's and low 60's inside, so your system is loafing. That being said, your SC would still be correct with the correct charge. Since you have sight glasses installed and there seems to be a tremendous temptation to charge to a clear glass for reasons I'll never understand, I'm betting on too much refrigerant. Turn the 'stat to "pizza oven" and see what happens to your SC. We'll save the SLD mystery for later.
@ June 14, 2013 12:32 PM in High subcoolLets look at #1 first. You listed your static at 180, which means your condenser is 9 degrees colder than ambient. This should not be the case! I'm going to guess that since your RAs are in the 50's, you are stacking liquid in the condenser because you have no load. That also makes sense as your SH is not that far out of line, if at all. Three things still bother me; why is there an SLD, why is it not next to the compressor where it belongs if it is really needed, and the PD is too high. Disregarding the SLD for the moment, I would crank on the furnace to raise the indoor temperature to the 80's. Even though it would be all sensible load, at least you would see if your SC comes up. If it doesn't, checking for an overcharge may be the next logical step. All of this is assuming your air flow is correct, of course.
@ June 12, 2013 3:44 PM in Sight glass againI am just as much against overcharging as undercharging; hence, my reliance on manufacturer's prescribed methods and nomos in the unit. Overcharging does not create saturation. Overcharging creates overcharging. Saturated refrigerant is what you see on your manifold gauges. In its purest form, saturated means adding heat changes liquid to vapor; taking away heat changes vapor to liquid. That is why the actual liquid line temperature must always be colder than its saturated temperature, which you see as pressure on your manifold and then convert to temperature. A classic example of this is Ingersol Rand; after the last circuit through the condenser coil, you will find an extra pass of tubing upstream of the LLD and service valve. This is a "sub cooling loop." The thought process is that if the refrigerant is allowed to stay in the ambient just a little longer, then the extra time is assurance that as much superheated vapor has been condensed as possible and feeding the TXV with only liquid. That overcharge has to go somewhere, so it will stack in the condenser. Since the condenser must be exactly that, and not a receiver, then the resultant capacity loss from the OD coil not being allowed to do its job is a risk not worth taking.
@ June 12, 2013 2:38 PM in Sight glass againIf my charge is correct, and my sub cooling is correct, how could the refrigerant in the liquid line possibly be saturated? It was 7 degrees below that point; the range where the factory wanted us to be. 100% liquid into the TXV. That's what sub cooling is!
@ June 12, 2013 9:26 AM in Sight glass againI can't speak regarding low-temp, but for residential DX cooling, I know of no maker who supports charging to a clear sight glass.
In an experiment with an HVAC tech school, we had an R-410A machine stamped 9 pounds one ounce of factory charge. Since the manual told us that was for the OD unit and a 15' lineset, we installed a 15' lineset and the AHRI smallest rated coil. The conditions at the time required 8 degrees of sub cooling (+/- 3 degrees). We had 7, so we were happy with that. We then removed the refrigerant, installed a sight glass, and added refrigerant until the glass was clear. Removal of the refrigerant this time revealed ten pounds three ounces. Proof enough.
@ June 11, 2013 11:15 AM in Heat loss Calc, correct wi ndow measurmentsCorrect! Then, once you have your type and size, take into account blinds, shading, awnings, orientation, and whether or not the glazing is flat against the wall (as opposed to a bay, bow, skylight, or garden window) and you're in pretty good shape. If you're wondering about the different grades of windows, glazing insulation value is shown in a "u" factor. "R" and "u" are a reciprocal; 1/R = u, and 1/u = R. For example: if your window has a u-factor of .36, then insulating value is equal to R-2.8.
@ June 10, 2013 4:15 PM in High subcoolSomething is amiss here. Your static test should not indicate your condensing temperature is 10 degrees COLDER than your ambient, and with an abnormally high SH, it is impossible your condensing temperature would be colder than ambient. Unless you have a heat pump operating in heating mode, of course. Also, your PD across the SLD is too much.
@ June 10, 2013 9:11 AM in Heat loss Calc, correct wi ndow measurmentsWhen you are working with load calculations with respect to windows, you are working with "fenestration." It is a term used to describe all types of glass (windows, doors, skylights, etc.). The term applies to the entire assembly of glazing, sash, and framework that fits into a rough opening.
@ June 9, 2013 9:40 AM in High subcoolToo cool! There are two things I really dislike; losing my car keys and losing compressors. And, I'm sure you will agree that after what we see in the field, someone lost their car keys in the compressor.
I've really enjoyed being on "The Wall." With the security check, my math is getting better. Sometimes, I don't even use a calculator.
@ June 9, 2013 7:55 AM in High subcoolIf you are using this device for ONLY checking moisture or oil condition, then I'm with you. However, I remain a proponent of the static test for non-condensables for one small issue and one huge issue. The small issue is two extra potential leak sources. The huge issue is with a static test, there is no way anyone before or behind you can use it a a charging method.
@ June 7, 2013 5:03 PM in High subcoolYour step-by-step plan of attack, in #5, states: "pressure test to 400." I like your plan, yet personally I would use factory test pressure. It might be 400 PSIG; it might not be. After all of this, I would hate to see you create your own leak.
@ June 7, 2013 4:52 PM in High subcoolOK, I'm with you. But what does it matter what is in there? It has to come out anyway, so who cares if its water, nitro, or Jack Daniels? If the removal process is done correctly, you get it all, or at least enough to get the percentage of nasties to a tolerable level. With R-410A for example, we will probably never get all of the moisture out, yet a well-done evacuation and an oversized LLD at least gives us the satisfaction of doing the best we can with what we have.
@ June 7, 2013 4:25 PM in High subcoolI humbly and respectfully disagree with your statement. Your head pressure converted to temperature and the ambient must be equal. A change of more than 3 degrees indicates non-condensables (provided you have checked for a restricted condenser). Head pressure converted to temperature most certainly involves a refrigerant gauge and a PT chart, having no correlation to water pressure. What it is, be it moisture, nitrogen, etc. matters not. It has to come out.