I only use a specific for microfiber soap, never used anything else..
Like to wash them warm or hot water temp., depending on what I just used them for.
Like to occasionally run Distilled White Vinegar ( Gallon Jug at Walmart), in the Rinse Cycle, sometimes, I might add a little to the Wash Cycle with the microfiber soap..
Run all microfibers in a Clean Dryer on Low Temps, monitor that load to insure they don`t get too hot, take them out and fold them while warm..
Never, Ever, use any of those Downy Coating Liquids for laundry in the Wash Cycle,
Never, Ever, use those Coating Sheets for laundry in the Dryer...
These things
coat your laundry ! Every time I visited my Parents when they were alive, and used their towels, I was amazed how terrible they absorbed water.. Yes, my Dear Mother, was a fan of those blue laundry sheet things AND Downy in the Wash, forever..
Since I was alive before those horrid blue, etc., colored things were
invented and towels were hung on lines outside, I can tell you, there IS a difference..
Perhaps, it would be good, to occasionally run a big
Affresh Pill in the Washer to help clean it all out and perhaps make the wash more efficient for cleaning instead of sloshing all that extra Downy water in there already, on your towels again???
Or perhaps a load of Distilled White Vinegar through the machine before you wash your microfibers??
I`ve read this whole post and even my old microfibers from 15+years ago still work great.. No issues with absorption..
Regarding Tankless water heaters- I have never seen one I can say I liked.. Perhaps it is a bigger math equation than I can do, but I will never understand how water that is running by some hot elements, (that is definitely jacking up your electric bill, right?), is ever going to be better than the old 50-gal tank, already full of hot water that is usually run by way less expensive natural gas..

Dan F