Need some info on 4 pipes and heat pump units

[lazycat]

hi all
i'm very new with HAVC and would love to have some online info on how 4 pipes and heat pump units work. Could you hook me up with? thanks!

i did a google search and didn't find details.

[iheatncoolinnc]

What is the model number of the heat pump you are refering to.
Four pipes could be dual compressor heat pump.
Four pipes could be that two of the pipes are the old hot water heating pipes that Trane/GE used years ago.
Could be the two refrigerant lines and the high voltage electrical and low voltage electrical.