how long can it be?

My client stumped me today, not that it’s hard to do, since I’m not a wealth of knowledge when it comes to HVAC systems.

He asked the maximum length allowed on the refrigerant line. The one today went from basement, across house, then outside, probably a good 75 feet total. I told him I honestly don’t know, but have inspected 3 story 5000 sq ft homes with lines longer than this one.

Is there a maximum length? Would it need to be increased in diameter for a very long line?

Copper tubing comes in rolls of fifty feet when I was installing if the length exceeded the 50 feet we went to the next size copper on both the liquid line and the suction line. MFG have charts for lines sets distance I no longer have those charts. Standard 50 feet was always 3/8 liquid line and 3/4 suction line the next size would be 1/2 inch liquid and 7/8 suction and so forth. I have seen suction lines as big as 1 inch and 1-1/4 but that is mostly commercial

There is a max length, determine by manuf. had this problem in a commercial job and had to upsize ac components for additional piping length, think it was at 100 or 125 feet.

I’m pretty sure this was greater than 50 feet. The liquid line I think was 3/8 and suction was 3/4. The liquid line was not insulated, but I don’t think it needs to be?

Is there any reason to decrease the pipe for longer distance? I wouldn’t think so, since it’s a closed system, but am curious.

You’re on a roll, Charley, let me ask another. Today’s inspection when checking high efficiency gas furnace, the burners came on, popped, and shut off. Kept doing it. Like mini explosions inside the burner box. Each time, the pilot flame would lite, burners kick on, then blow out, with a pop.

Seller asked what was the problem. I just said I wasn’t sure, but wasn’t there to fix or diagnose, just to verify if it worked, which it didn’t. Cooling worked fine.

I guess the solenoid valve is opening, because the burners are lighting, but they are “blowing out”. Dirty burner tubes maybe? I think the furnace is 1990 model.

Hard to say from here could be a problem with the ignition valve opening before the glow coil heats properly and creates a roll out flame that kills the burner hard to see it thru my keyboard;-) I would just write it up as delayed ignition. Repair as necessary
As for reducing a refrigerant line it is not allowed. Both the liquid and the suction should never be smaller than the MFG has stubbed out from the unit. If the MFG stub out is 3/8 on the liquid line you can not use 1/4 inch

Slap me Charley. I meant to say** increase**, not decrease. :oops:

Thanks. I just wrote it up as furnace kept shutting down, and needs repair.

I have short arms I can not reach you from here so your safe!!!

When the size of the lines are increased due to distance its because of the pressure drop to the expansion valve the further the compressor has to pump you get a normal decrease in pressure so to allow for this pressure drop you increase the volume of refrigerant to compensate by increasing the line size. When a unit is first installed for example it comes with say 5 LBS of refrigerant within the condenser and that normally will suffice up to about 50 feet of refrigerant lines. When the line set is increased in distance extra refrigerant has to be added to the system upon initial start up

Makes perfect, logical sense.

Thanks, Charley. Not something a HI necessarily needs to know, but I have a curious mind. :slight_smile:

y’all cmiS ever hear of this newfangled thingy called google

refer line

heater issue

i’ll be starting a new biz real soon

happy 4th, y’all play nice ;~))