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Ben Grunow
07-17-2006, 8:36 PM
I just installed a new Carrier air handler in my attic and I am suprised at the amount of compressor noise that comes from the line set. It is a 3 1/2 ton unit with 3/4 line set, insulated and about 40' long. It runs through the rim joist at the first floor level and up in an exterior wall through 2 more layers of 2x4 plates to the attic. There are 2 90 degree fiitings in the 3/4 line and the 3/8 line was bent with a tubing bender so there are no kinks. I have not over strapped the line set so that is not the problem (vibration transfer to the house structure). The lines are fire caulked at the wall plates. There is a filter/dryer with the arrow poiting toward the air handler in the attic (16" away).

Anyone have any ideas? Is there such a thing as an expansion tank like gizmo to reduce the compressor noise?

Randy Denby
07-17-2006, 10:43 PM
Ben, Compressors have internal isolator springs to dampen noise. (Imagine a motor suspended inside the compressor shell with springs all around ). If the unit was dropped in freight hard, then those springs could have dislodged , enabling the internal compressor motor/pump to vibrate against the shell. Usually this will be quite evident standing next to the condensor, unless the compressor is wrapped with a noise insulator. Another thing that could cause this is if the unit is running high head pressure due to a number of variables....unlikely if its new, exception; if they didnt do a good job of evacuating the unit and left noncondensables in the system.
They do make mufflers for condensors. It looks like an oversize filter/drier and is put in the system just after the compressor and before the condensor coils in the discharge line. Due to location, the sytem will need to have refrigerant reclaimed before it can be installed...but can be re-used as long as its filtered when recharging .
Randy
Air-Tech Service

edit; I just reread and realize you said air-handler replaced. Did they not replace the condensor? If they only replaced the air-handler and evaporator coil, then double check to make sure its not fan vibration resonating down the line set by just turning fan to on and leaving the condensor off. If it only vibrated with the condensor on and you didnt replace the condensor, then I'd suspect the metering device. Carrier sometimes uses a drilled brass orifice to meter the refrigerant. It is backed by a spring or teflon bushing....could of been left out , installed backwards, or the wrong size.If the metering device is an expansion valve, then make sure they have the superheat set to factory specifications.
If it is fan vibration then make sure their isnt any paper or trash lodged inside the blower wheel. Make sure the fan wheel is not out of balance .
As you can see, there is a number of possiblities, without being there its hard to trouble shoot something of this nature. But I hope this helps you find the problem. Good luck, and let me know what they find!

Ben Grunow
07-18-2006, 8:56 PM
Thanks Randy- I installed this system of all new equipment (not replacement- system is Carrier 3 1/2 ton 13 seer puron condensing unit and variable speed air handler) and a friend of mine had his service guys charge it and turn it on for me (wire zone dampers and thermostats, charge refrigerant turn on). I installed all of the ductwork (made in his shop), mounted the air handler, piped the hot water lines from the boiler and sweated the line set from the condensing unit to the air handler. I must assume that they charged it right but they are coming back to check on Tuesday. I have cold air but the fan speed seems low (variable speed unit with fan set on lowest setting I think, they are going to set it higher on Tues as well).

After reading your reply I remembered seeing a small plastic bag with a piston and piston ring marked 073 sitting on top of the unit after the service crew charged the system. Is this the metering device you are referring to and if so where is it supposed to be installed? It came with directions that said it goes before the indoor coil (I think) so that must mean that I was supposed to put in the air handler (pic in directions shows piston being installed inside what looks like a compression type fitting). I hope this is the problem because it seems like an easy fix. Any chance of damaging the condensing unit by running the system?

Wow this is way off topic but I got carried away. It's great to have access to so many skilled people like this. Thanks a ton. Ben

Randy Denby
07-19-2006, 11:28 PM
Ben, sorry its taken me so long to reply. This 104-106 temp has got me running.
Puron is a very high pressure refrigerant. It normally runs from 350 to 400 psi on the high side. It also soaks up any moisture readily. Therefore, the lineset and coils should always be triple evacuated and purged with nitrogen between evacuations and then charged. Did you braze the copper with 15%silfos or "sweat" with silver solder? Sweating with solder (350 deg) only applies to low pressure water lines, etc.Brazing (1200deg+) is the method for A/C, otherwise you'll have leaks pronto.
It sounds as tho you might have left out the metering orifice, if its laying there on top of the unit:) . Altho, sometimes the evap. coils will have one inside the entrance to the coil, and the condensor will have the one they want to be used taped in a baggy on it....this is for those that are just replacing the condensor and need to match it to the existing evap coil. So...it could be in there (evap flare fitting) ...hopefully. If its the right size, dunno. It should be double checked if its in fact in there and if it meets specs. There is an engraved no. or letter on them.
Also noticed you stated 3/4" on the suction line. This is an area of confusion between plumbers and a/c guys. We go off outside diameter (OD) they go off inside diameter (ID). The suction line should in fact be 7/8 " od type L or thicker copper. as should the 3/8" liquid line. Thinwalled water copper wont work.
I am bouncing all of this criteria off you to see if any thing might be amiss that will ring a bell for you.
I'd have the guys put there gauges on a see what the pressures are running. If you left out the metering orifice or its the wrong size, they'll be able to tell by the pressures.
Hope this helps, gotta go take a shower as I think my deodorant failed me about 2pm.:eek:
Randy