The Holyoake HDC series provides full variable volume control in both the hot deck and cold deck of a dual duct system. The airflow rate can be varied between a regulated pre-set minimum and a regulated pre-set maximum.
HDC
Dual Duct VAV Terminal
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At any system static pressure above the minimum required for signalling the controller, the flow rate anywhere in the operating range is pressure independent.
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The HDC controls will hold the flow rate called for by the thermostat regardless of any fluctuations in system pressure between the minimum and 500 Pa.
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In addition to pressure independent variable volume, the HDC controls provide numerous combinations of settings for hot-cold air mixture proportions.
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The HDC control functions are the same as those described for the HCV single duct assembly on preceding pages. Standard construction includes a mixer-attenuator.
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Basic units without the mixer-attenuator are available.Flow averaging ∆P velocity sensors are standard.
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Single point sensing as required by some control types can be substituted where necessary.
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Standard units are furnished right handed as shown. Opposite handing can be furnished at no extra cost if order is detailed accordingly. Handing is determined by location of the cold deck.
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Available with square inlets.
