In lieu of getting to work on the MUA, I followed these two hood links and have the following comments. The claim that accelerating the air in the perimeter hood makes it quieter cannot be true. High velocity air has more turbulence and hence emits more sound. Having less air flow may be what makes it quieter. This perimeter gap is very small, and the amount of air that can flow through it without sounding like a vacuum crevice nozzle will be low. Also, the front to back dimension seems too small to overlap the rising effluent plumes. Mesh filters are specified for the perimeter design. While these can be as effective large particle grease filters as baffles, they also catch and retain dust, hair, lint, etc., and require routine washing to keep from gagging the air flow (such as it is in this case). Both claim the same cfm for the motor power (I can barely resist attacking this terminology), but I would bet that the actual flow at actual pressure losses will make the perimeter unit flow less air than the baffle unit. I would think that the baffle unit would be better at capture than the perimeter unit due to its aperture size. What the perimeter unit captures will surely be contained, but that should be true of the baffles also. One problem with the baffles is that they appear to be horizontal. Tilted baffles drain grease to places where it can be collected. Maybe they anticipate modest grease removal and hence periodic washing will be sufficient to avoid drips. On the other hand, dripping could function as an automatic warning for cleaning. If the perimeter insert is deemed very desirable for aesthetic reasons, then perhaps two inserts mounted so that the non-lamp edges meet would provide enough capture depth. One technical issue is that the perimeter slots have very little influence more than a few gap widths away. Hence rising effluent that hits within the insert perimeter gap has to travel sideways to be captured. This would work if the effluent velocity were small, as in, say, rising cigarette smoke. But the velocity is around 3 ft/s from a hot pan or cooking surface. It will hit the metal and rebound following the law of conservation of momentum. I consider it unlikely that that part of the effluent will be captured. Earlier in this thread I commented on the conflict that arises between cost, aesthetics, and function, and that also applies here. Sometimes one has to use a less functional hood to meet the limits of the other criteria. I prefer to embrace the opposite perspective, albeit still subject to those limitations, which is to ask: How close to the functionality of a commercial hood can I come without exceeding cost or ugliness budgets. kas

First of all, you need to find that leak. If it leaks out just a little, you won't have the proper level of pressure causing the system to have a lower degree diffriential which in turn causes the unit to run alot longer leaving you with higher electrical bills! It's also ruining the system because the compressor isn't cooling properly causing it to overheat! If the Return air duct (existing Temp.) is 75 degrees then it should always be blowing out on the air supply 20 degrees colder which would be 55 degrees. That is showing that the system is taking the heat out! Your going to have to request an experienced technician to find and seal the leak where ever it could be.. If you don't fix it Now, you are going to waste money & time.

what are- amp draw, refrig line sizes and linear length,(i dont think ive EVER seen a 15ft lineset) indoor coil size, type of metering device? if there was a drier id say it might be installed backwards or you didnt purge with nitrogen as you welded your joints and got some trash on the screen at the metering device. (btw you should really put a drier on it) sorry bud, but not installing a drier kinda screams inexperience to me as well. or as daddo said maybe you stacked metering devices and the piston needs to be removed. when you opened the first service valve on the unit did you notice if the other, still-unopened, valve's gauge pressure came up close to equalized? does the unit pump down when you close the liquid valve? if so, does it pump down quickly? you would think a 2.5t system with 15ft of line would pump down in a jiffy. did you use rigid copper to tie the unit in? if you did, did you take the rubber plug out of the end of it? (stupid question but ive seen an experienced guy in a rush leave the plug in it and melt it as he welded the joints creating a MESS and restriction.) I havent seen it first hand but have heard of moisture freezing up near a txv partially clogging it. 500 micron is prefered, not 250. you may not have enough refrigerant in the system. "116in of refrigerant"? is that some kind of metric system im not aware of? do you mean 116oz? who knows, its hard to troubleshoot over the net. keep looking, youll find the problem. either that or call a different tech that CAN be there with you to offer a different perspective.

By fail, I meant stop cooling. The tech said the system stopped cooling because it froze. It had to be shut down for a day before they could add freon. You folks have made it a lot clearer for me why just a few pounds loss could be so significant. I still don't grasp how it works physically, but it's not necessary. I now know it will fail if the freon drops below some high level and when freon is added it's to a level below capacity. Sensitivity to 2-3 lbs loss makes sense knowing this. I was told 3 years ago the leak couldn't be soldered because of its location. The guys now are saying at 12 years whatever it requires isn't worth it, just get a new unit. They seem honest and knowledgeable. I'm in south Florida, so it's used a lot. I'm inclined to do it and avoid the hassle of more service and sales appointments. At least, that's the way I'm feeling tonight. I want to thank all of you for your help.