VRF question help needed

[frosty74]

there are 2 ypes of vrf system which are 2 pipe and 3 pipe systems.
2 pipe is where indoor units can either cool or heat only
3 pipe systems can cool and heat at the same time as i understand the is known as a heat recovery system please correct me if i am incorrect.

what i want to know is what is the function of the third pipe is it that the third pipe always feeds the units which are on heat mode via the branch boxes.
thanks for your time and help

regards

mark

[Argus]

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Various manufacturers aproach this differently, but in broad terms the three pipes are Liquid, Suction and the third is Hot Gas to provide the heat.

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[The Viking]

Or if you look at Mitsubishi (Electric), then they manage heat recovery (simultaneous heat/cool) with only 2 pipes.

[Argus]

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Yes indeed........ Various manufacturers aproach this differently..............

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[techguy]

Hi Frosty,

The guys above are right with any 3 pipe system there is a decitated suction, discharge, and liquid line.

With the Mitsu system there are only 2 pipes on their heat recovery system they oversize the liquid line and under condense so they send gas in two phases down the liquidline. Its seperated at their BC box.

Mitsu say theres is best we 3 pipe guys say ours is best.
Not interested in getting to an argument over it they both work if there installed correctly.

T