Discharge line bypass device utility ?

[kefah]

Hi
I checked a floor standing 4 ton LG split air conditioner unit
there was a bypass valve connecting between the compressor discharge line
and suction line
the tube connect the valve from discharge line is larger than the capillary which connect the bypass valve to the compressor suction line

these word are on the valve name plate
SP 280 psi


http://im33.gulfup.com/I2ASv.png
what its utility

[passandscore]

Sounds like it is used for capacity control. It's either regulating or opening at 280psi.
See Link: http://www.heatcraftrpd.com/res/pdfs/faqs/Capacity_Control.pdf (Page 8-9, Fig 2a)

Another reason for piping a line to the suction would be for over pressure protection. Its not recommended here in Canada but still seen frequently.

[kefah]

I took a photo for the valve from another unit
bcoz the tag on the valve of the first unit was removed


http://im31.gulfup.com/hGD4x.jpg

[bigor_2]

it's heat pump unit or not?

[kefah]

its heat pump unit
48000 btu

[bigor_2]

I had seen a similar circuit design in MHI units.
Tomorrow I can upload mhi documents.

[kefah]

I had seen a similar circuit design in MHI units.
Tomorrow I can upload mhi documents.

:cool: im waiting

[RusBuka]

I think its like pre-error of HP. If compressor don't stop by currency/overheating with discharge->suction bypass, so let him work)))

[bigor_2]

kefah
I'm sorry for my long silence.
MHI's documents do not provide description of the work this valve.
In some circuits he is called DPR
11146
In other circuits he is called High Pressure regulator valve
11147
Look at it
11148

11149

In both cases it is safety valve

[RusBuka]

First foto - Liquid injection and HP bypass ( after condenser to the suction)
Second foto - HP drop, bypass capillary tubes.

See that valve in old ME blocks r22