I have two American Standard central AC units. The Trane Evap coils (Type 4NCX and Type 4TXF) are located in the garage attic and drain to grade outside the garage, not to a sewer system. The Trane manual for these units says to install a loop in the condensate system, providing detailed dimensions for construction of the loop. The original installer installed a loop on one unit (not meeting the Trane dimensions) and no loop on the second unit. I often have issues with both drain installations so am trying to clean up the mess the original installer did. Since my system doesn't drain to a sewer system, is the drain loop still required or recommended? If so, in my case what is the purpose of the loop? Is it to prevent water and other contaminants from sucking back into the evaporator (which runs at negative pressure relative to drain line discharge) coil section? I see differing opinions about this on the internet. What is the real requirement (code and practically) and reason for it? If not needed in my case, I would like to eliminate this loop as it another place in the drain line where particulate accumulates and plugs the line. My current plan is to install All-Access AA1 units in both drain lines to make cleaning them easier.

Hello all. Quick question that perhaps someone can help me with. Im looking to put 3 indoor units on one side of my house. 15k btu downstairs, 7k and 9k btu units in two bedrooms upstairs. I understand that mini splits modulate. The thing I dont understand is minimum output of the condenser. The condenser I was looking at is rated 24k btu. I know that if all these units are on full blast it wont be the best performance. I see a minimum btu output of the condenser is 10k as per manufacturer specs. What happens if I turn off the 15k and 9k unit? Will the 7k run by itself off that large condenser or will it cause an issue?