Line size on split question

[Tommy1010]

I have to change a compressor on a Carrier split system unit over in our other mill.

I ordered and recieve the replacement compressor and FD. The suction line is7/8.

Im coming from my other mill and would have to plan out and bring and couplings or pipe that i would need.

So i called the salesman to get the info for correct line size since I didnt order it myself, the director at the other plant did it. So i dont have the model # info.

So Carrier says it a 7/8 suction, but they changed the specs on it and it really needs a 1 1/8 line.

This throws a monkey wrench in my whole idea of a compressor change out. lol..Its the difference of an hour or 2, compared to a days work.

The lines go up 20' , through a concrete wall, straight about 10', and finally elbows about 3-4' into evap.

The old compressor ran for years with the 7/8 in there. The compressor failed mechanically. It runs, but just free spins inside. (If that helps what the possible failure could've been.)

What should I do?

a. Leave it as 7/8?

b. Do the 1 1/8 run?

c. Tell the plant manager what his options are, pros and cons (which im not even sure about besides the copper he has to buy) and ask what he opts for?

Its the same company I work for , just a different plant. So Im already on the clock so labor isnt needed to quote. Just a heck of alot of overtime.

[bunny]

Not a lot to go on here.

You might want to look at the system capacity and use a pipe sizing program to see what the suction line size ought to be, based on the equivalent length of pipe you've got in the system.

If the 7/8" turns out to be undersized compared to what the pipe sizing program recommends, then present the issue to the customer with the pros/cons of doing the job correctly. The only "con" is that it's going to cost him to do the job correctly.

If he declines to do the job correctly, make sure you get his signature that shows he knew what you were recommending, and declined.

[garya505]

I'm not a pro, but if I was, I'd be thinking about the minimum suction velocity in the 20' vertical section for proper oil return.

And ... if a pro said he would use 7/8 in the vertical and 1 1/8 in the horizontal I'd say that sounds pretty clever.

Just sayin' ...

[bunny]

The lines go up 20' , through a concrete wall, straight about 10', and finally elbows about 3-4' into evap.

If I read this correctly the evaporator is above the condensing unit.

Hence, there is no vertical suction riser. While maintaining that critical balance between minimum velocity and a minimal pressure drop in the suction piping is always recommended, oil return on a line that naturally drains downward 20' to the compressor shouldn't be an issue.

[garya505]

If I read this correctly the evaporator is above the condensing unit.

Hence, there is no vertical suction riser. While maintaining that critical balance between minimum velocity and a minimal pressure drop in the suction piping is always recommended, oil return on a line that naturally drains downward 20' to the compressor shouldn't be an issue.

Ah, I missed that.

[rundawg]

What should I do?

a. Leave it as 7/8?

b. Do the 1 1/8 run?

c. Tell the plant manager what his options are, pros and cons (which im not even sure about besides the copper he has to buy) and ask what he opts for?

I’m assuming this is a single stage, straight A/C, 410A system?

Carrier says that systems of 3 1/2 - 5 tons can use both 7/8” and 1 1/8” suction lines.

The 7/8” line can be used on the 3 1/2 and 4 tons units without any capacity loss as long as the TEL doesn’t exceed 80 feet.

If the 7/8” line is used on the 5 tons system, you would only have a 1% capacity loss on lengths up to 80 feet.

I would just use the 7/8” on your system seeing as it is only about 40 feet.

If you want to show the plant manager Carrier’s Long LineSet application that states what I said above, let me know, and I will email it to you.

[Tommy1010]

I’m assuming this is a single stage, straight A/C, 410A system?

Carrier says that systems of 3 1/2 - 5 tons can use both 7/8” and 1 1/8” suction lines.

The 7/8” line can be used on the 3 1/2 and 4 tons units without any capacity loss as long as the TEL doesn’t exceed 80 feet.

If the 7/8” line is used on the 5 tons system, you would only have a 1% capacity loss on lengths up to 80 feet.

I would just use the 7/8” on your system seeing as it is only about 40 feet.

If you want to show the plant manager Carrier’s Long LineSet application that states what I said above, let me know, and I will email it to you.

Is it recent? cause the rep I spoke wit said this today...but ofcourse he's probably a desk clerk.

Its 15 - 20' at most of a rise, through wall..20' to evap..

NO ITS A 22 system

Obviously im sayin it backwards as far as flow goes but from ground up regarding piping thats my case.

The salesman looked at a chart and verified that he agreed with carrier, it should be 1 1/8 though..

discharge is 1/2, and LL is 3/8.

CmON DAWG, lemme know.

[hvacrmedic]

Why did you post this in the open forum?

[Tommy1010]

Why did you post this in the open forum?

Honestly...cuz i dont know where to consider the PRO FORUM anymore!!!

People are all over since this change. Its also why I'm not on as much anymore.

I dont know WHERE TO GO LIKE I DID WHEN IT WAS ...LIKE IT WAS. "PRO....TECH" was on my desk top. So I feel lost with this big change man.

[dijit]

How big is the unit?

What is the design condensing temperature?

[rundawg]

NO ITS A 22 system

The capacity losses with R22 are different. It will be later today, but I will see if I can find that manual and email it to you.

[dandyme]

Tommy, check that aol account