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## Line set lengths?

When manufactures state max line set lengths, how are they measured. Is the supply and return lines to the inside AH's added together to are they measured as a set. In other words if I have a distance of 50ft from the outside unit to the inside unit, is this considered a 50ft line set or is it 50ft (supply) + 50ft (return) for 100ft set.

2. It is the length of the set, so 50' in your example.
Also keep in mind that refrigerant pipe sizing calculations use the equivalent length(EL) of pipe and fittings, with corrections for lift, but refrigerant charge calculations use actual linear feet of pipe.
So depending on the fittings used, your 50' run of pipe could need to be sized based on a significantly longer EL, but the charge would still be calculated based on the 50' of actual pipe.

3. Originally Posted by mark beiser
It is the length of the set, so 50' in your example.
Also keep in mind that refrigerant pipe sizing calculations use the equivalent length(EL) of pipe and fittings, with corrections for lift, but refrigerant charge calculations use actual linear feet of pipe.
So depending on the fittings used, your 50' run of pipe could need to be sized based on a significantly longer EL, but the charge would still be calculated based on the 50' of actual pipe.
I thought this whole time you used the equivalent length for charging also.... Guess I learned something, like always!

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Originally Posted by mark beiser
It is the length of the set, so 50' in your example.
Also keep in mind that refrigerant pipe sizing calculations use the equivalent length(EL) of pipe and fittings, with corrections for lift, but refrigerant charge calculations use actual linear feet of pipe.
So depending on the fittings used, your 50' run of pipe could need to be sized based on a significantly longer EL, but the charge would still be calculated based on the 50' of actual pipe.
Where can I find information on these calculations, if I do this myself I want it to be correct. Also, would this only need to be considered if you are getting close to the max overall length stated for the HP.

5. "If I do this myself" is not a good idea, especially when talking about a heat pump.

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Originally Posted by 2old2rock
"If I do this myself" is not a good idea, especially when talking about a heat pump.
would you mind explaining why. I am a journeymen red seal instrumentation/controls tech with almost 20 years experience in oil and gas. Having said this I have never installed a HP before but alot of the time concepts are the same. Also, I have a good friend that is a refrigeration guy with experience with HP's as well. I am not just going to step into this blindly which is one of the reasons why I am on here. Also, I have access to vacuum pumps, brazing equipment, and all the other equipment that is required. I just need a little guidence from the knowledge on this forum....and I like doing stuff myself.

7. Originally Posted by ryan1088
I thought this whole time you used the equivalent length for charging also.... Guess I learned something, like always!
The EL of fittings doesn't change the internal volume of the pipe.
In longer lineset, and high lift applications, additional subcooling may be needed to prevent flash gas, so more refrigerant will be required once the system is started, but the initial charge is calculated based on the linear length of the lines.

8. Originally Posted by Newfiestang50
When manufactures state max line set lengths, how are they measured. Is the supply and return lines to the inside AH's added together to are they measured as a set. In other words if I have a distance of 50ft from the outside unit to the inside unit, is this considered a 50ft line set or is it 50ft (supply) + 50ft (return) for 100ft set.
Just apply for professional membership and avoid all of the diy comments. Your original question although quite elegant, is a little worrysome however.

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