A/C size and line set?

[Slidell]

Had new Goodman 14 seer 5 ton unit installed and makes a noise on the outside unit ONLY when it starts up, and the noise is longer and louder the longer the unit sits without running. Only last about 1-4 seconds.

A/C company says its the line set, has 3/4" now and with the more efficent unit and size it needs a larger line set? The old unit was also a Goodman 5 ton but 10 yrs old and did not make any noise at start up. Guy says because the new unit is 14 seer and makes a big difference with line sets?????

Am I being fed crap there from these guys???

[mattison]

Your lineset should be at least 3/8" Liquid X 7/8" Suction.

Why didn't they mention this before the installation??

[Slidell]

Sorry company that is the homewarranty companies "preferred" provider... so 3/4 " is wrong?

Does that sound like the problem making noise at start up only?

[Slidell]

They are supposed to come out next week and redo line set to 7/8". I think they just didn't want to do it right the 1st time and hoped it would work fine. NOT
Even Goodmans site says 7/8"line set.

Will have the wrong size lineset for this new unit hurt the Scroll compressor or anything else until it gets fixed? has been this way for a month now??
\
THanks

[Grady]

Short term I don't think any damage would be done. Watch them like a hawk. By now you should know how lines are supposed to be run.

[Slidell]

Question: Looked at surrounding neighbors A/C's and all of their large copper pipes coming out of the house into the outside unit are either straight or have a slight bend to connect to the unit.

Mine comes out of the house about 6 inchs then has a 90 degree bend on way towards the unit for about 4 inches then bends again another 90 degrees to go into the unit> basically the copper line makes a Z shape. Is this messing up the pressure in the line contributing to the noise at start up?

[mattison]

What kind of noise is it?? I really don't think your lines are causing the noise. How does it cool once it's up and running.

[Grady]

If they are short radius (plumbing) ells, they could be creating too much restriction. Long radius ells are better & the only kind which should be used in a refrigeration system. Better yet is just to sweep the line into the unit.

[Slidell]

matt,

cools fine, digital temp coming out of the farthest register is 58 degrees. The noise is a kinda rattling noise that sounds like the unit is going to explode for about 2-4 sec ONLY when the unit first starts, and it is worse the longer the unit sits without running between cycles. Has 3/4 line now Goodman website says 7/8 ?????

[mattison]

Where's the air handler? Is it high up in the attic? Sounds like it's slugging on start.

[Grady]

Are you thinking a liquid line solenoid might be in order?

[Slidell]

Have an a/c closet inside is the gas furnace/ ac coil and I assume the air handler above them??? The noise is coming from the unit part of a/c system.

[mattison]

So the "furnace" with the blower in it is on the same level as the outside unit? Still sounds like it's slugging from maybe refrigerant flooding back or overcharge or something of the sort. When is the installer coming back to replace the lineset?

[Antbet5]

You definately need to have the line size corrected. The contractor should have changed or made a the recommendation. We should always go with the manufacturers suggestion.

With the quick turns and the size of the lines, this could cause some additional noise.

However, the scroll compressor, especially in the 4-5 ton range will have normal amount of noise on start-up. It will sound like a hard growl for a couple of seconds.

Hope this helps

[GregH]

I'll ditto the comment that the sound of a scroll may take some getting used to,
especially the backspin when the unit shuts off.

[Slidell]

Yeah something somewhere is not right, they are suppose to be back out this week, its nice and quite when it shuts off. If the unit is running and you go out and pull the fuse thingy to shut it off and then replace it right back it will start up nice and quite.

[Slidell]

Guess is or is not normal but when you here the thermostat "click" a second later the outside unit makes its noise for about 2 secs then a second or two later the air actually kicks on and blows. I also hear noise in the wall where the pipes go through to the inside coil making a gas type flowing sound or hissing.

[Grady]

The hissing sound is perfetly normal the condenser has not yet had time to get all of the refrigerant to a liquid. The hissing should stop in less than a minute.

[Slidell]

OK Owner of A/C company called said he had talked with GOodman and described problem of the loud shaking grinding type noise the outside unit is making when it starts and they told him it should have a time delay thingy added because the pressure is not equallizing before the scroll compressor kicks on? Said thes new high efficent units with Scroll compressors should really have them? He said that Goodman said having a 3/4 lineset instead of a 7/8 lineset which is what the specs call for doesn't really make a difference? A/C tech is coming out Wed morning to put on this time delay thingy and see what happens from there...

Does this sound right????
thanks