how many K superheat for vrv/split

[SkyWalker]

anyone know what sort of superheat VRV and day to day splits are trying to achieve, i read in a lg book larger than 0.5K, 0.5K seems low? a bit "touching cloth" as some of the smaller systems have no suction accumulators

i presume they are preset to aim for "x" amount of superheat, but between "y" and "Z" is considered o.k

anyone know these figures?

[nike123]

Differentiate between "day to day" split system without inverter compressor and electronic expansion valve and "day to day" inverter split systems or VRF systems with electronic expansion valves and inverters.

[SkyWalker]

to be honest nike we all work on all the systems you have mentioned so any info would be great.

inverters split systems, non inverter, capillary systems, and EEV systems, then of course 2 pipe and 3 pipe VRV,

i thought they would probably be all trying to achieve the same amount of superheat to be honest?

[nike123]

to be honest nike we all work on all the systems you have mentioned so any info would be great.

inverters split systems, non inverter, capillary systems, and EEV systems, then of course 2 pipe and 3 pipe VRV,

i thought they would probably be all trying to achieve the same amount of superheat to be honest?

On capillary systems with fixed sped compressor superheat varies as duty varies.

On systems with TXV superheat is fixed with setting at superheat adjustment stem within certain range of capacity and operating conditions.

On systems with electronic expansion valves superheat is adjustable by control logic even tho it is target to achieve same superheat in all conditions and varying refrigerant flows thru valve.

[SkyWalker]

this may be a stupid "easy to answer" :D question, but how do split systems measure what superheat they are achieving at any one moment? does it use the suction pressure at say l.p switch, then use evap outlet coil sensor?

i completely understand how we can measure superheat but just thinking how the system itself does it.

[nike123]

this may be a stupid "easy to answer" :D question, but how do split systems measure what superheat they are achieving at any one moment? does it use the suction pressure at say l.p switch, then use evap outlet coil sensor?

i completely understand how we can measure superheat but just thinking how the system itself does it.


Most of them don't use pressure measurements at all.
They measure temperature of pipes and heat exchangers at various places and with complicated algorithm and fuzzy logic adjust valves.

[SkyWalker]

i see, cheers nike

[mekaniko5]

Scroll compressors usually require 20F evap. superheat. I'm not sure if this answers your question though.