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Thread: accurators
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20-07-2002, 09:45 AM #1
accurators
Ive noticed on some of the new split heat pumps, Pioneer, Carrier etc that they have now abandoned tx valves and check valves and are using 'accurators instead'.
Obviously there a form of expansion but how exactly do they work? Do they just keep a constant pressure drop across the evaporator? Are they bi flow or bypass?
Anyone out there?
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20-07-2002, 03:17 PM #2
Accurators, aka, short tube restrictors, are the norm with unitary residential a/c and heat pump systems. Units having 10 or 11 SEER ratings largely use restrictors. At 12 SEER, you will see a mix of restrictors and TEVs. Above 12 SEER, you will typically see TEVs.
Restrictors are quite simple. They are a precisely formed orifice which the refrigerant flows thru. They do not modulate refrigerant flow, as does the TEV. The flow rate thru the restrictor is a function of the pressure drop and the density of the refrigerent.
Most restrictors are designed with a bypass feature, so that the manufacturer can use the coil on either an a/c or heat pump system. It is possible to design a bi-flow restrictor, but it is not easy getting one size orifice to work correctly in both the cooling and heating modes. As a result, you don't see this too often.Prof Sporlan
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09-01-2003, 05:19 AM #3
Carriers' Biflow Accurator funtions as a restrictor when refrigerant flow enters the indoor coil from the outdoor unit (cooling mode)and as a bypass valve when the flow is reversed.