Technical question about mini split heat pump line set maximum length


I'm installing a two-zone Mitsubishi mini split (in Pasadena, CA area, 1400 sf, single family detached, one-story home, if context is relevant). This is my first install, and I am trying to determine if extra refrigerant needs to be added based on the line set distance to each of the two indoor units. The outdoor unit is factory charged with R410A.

Outdoor Unit - MXZ-2C20NAHZ2

Indoor Unit 1 - PEAD-A12 (pipe length distance from outdoor unit: ~25 feet)

Indoor Unit 2 - MSZ-FH12NA (pipe length distance from outdoor unit: ~40 feet)

The manual (attached image) for the outdoor unit (MXZ-2C20NAHZ2) says "Max. pipe length per indoor unit for multi system" is 82 ft, and that refrigerant adjustment for longer lengths is 1.08 oz/5 ft. The manual for indoor unit 1 says maximum pipe length is 23 feet (before additional refrigerant is required). The manual for indoor unit 2 says maximum pipe length is 25 feet (before additional refrigerant is required). So...I'm trying to determine which number is applicable -- 82, 23, or 25? Does the system need additional charge?

I'll contact the manufacturer as well, but I thought I'd ask here in case anyone has installed one of these systems and already determined the answer to this question. Thanks for your help.

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Hi Chris!

  I just happened to come across your question after I posted my most recent blog - Mitsubishi Ductless happens to be my specialty (and full-time job)!

  That condenser is pre-charged for 98' of pipe.

  Each zone can be a max 82' from the condenser.

  Total pipe length would be 164' (82 x 2).

I think the confusion regarding the 23/25 comes in if you are installing these as single zone systems...always check the install manual for the condenser on :

Hope you have a successful install, and a Happy New Year!



A million thanks! This is very helpful; thank you for sharing your expertise. I can post an update once I'm further along. I am tempted to ask more questions but will not abuse your generosity. :) Happy New Year to you as well!



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