Hitachi Shirokuma Air2Air HP
Good day everyone. I'm new here and have a few questions. I want to buy a Hitachi Shirokuma floor mounted model, but I'm not sure if it's a good option.
The distributors here in Bosnia are insisting that, for the proper operation of Shirokuma units (and other Hitachi equipment), a minimum of three meters of piping is required. They further claim that otherwise the warranty would be void.
As a mechanical engineer specializing in energy systems and HVAC, I find this explanation insufficient. In a regulated AC system equipped with an accumulator upstream of the compressor, prescribing a three-meter installation length seems unjustified (“so that all refrigerant could evaporate” – but then, where is the superheat? – my counter-question to which they have no reply).
I have written several times to Johnson Controls - Hitachi Air conditioning Company, UK, asking for instructions, but they have not responded. My questions are as follows:
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Is the three-meter piping requirement necessary for correct system operation, or is it related to vibration damping? 
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How should I proceed if the unit must be mounted on the same wall, only 35 cm thick, with both indoor and outdoor units back-to-back? 
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What should be done with any excess piping in that case? 
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Finally, would installing only one meter of piping invalidate the warranty? 
No answer...
Does this requirement imply that other manufacturers’ units, which do not mandate three meters, are superior to Hitachi?
Big dilemma... I'm asking anyone who can help me, suggest something else...
Regards, Edin
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