APPLICATIONS
GEOTHERMAL SIMULTANEOUS HEATING & COOLING
This system maximizes the distribution of energy in a four pipe hydronic based Geothermal system. Energy recovered from the cooling function is made directly available for any simultaneous heating requirements.
GEOTHERMAL SIMULTANEOUS HEATING & COOLING SCHEMATIC DIAGRAM
Heating Dominant Mode
Heating fluid supply temperature sensor, TH, will control the heat loop temperature based on a schedule. Should TH be below set point, the controller will start the first Compax unit. Each Compax is equipped with circulation pumps that are started along with the Compax compressor. Additional units will be staged on until a balance is reached.
During a heating dominant period, heat will first be removed from the chilled water circuit which will have its temperature maintained by valve VC. Temperature sensor TD shall monitor the cold side temperature and if it drops below the chilled water set point TC, valve VA will be opened to the ground loop and pump PG shall be operated. The flow rate of the pump PG will be regulated based on the number of Compax units on line.
Cooling Dominant Mode
If temperature at TG is above TC, close valve VA to ground loop. On a call for cooling from TC, valve VC will open to Compax loop and the first Compax will be started. Additional units will be staged on until a balance is reached. Units will be cycled to maintain set point.
Valve VB is modulated by TR in order to maintain the heating set point. Operation of pump PG will be initiated and its speed modulated to be in accordance with the position of valve VB.
  • Pump PH is available at any time to provide warm water to satisfy any heating requirements.
    It is normally provided with a VFD for variable flow systems.
  • Pump PC is available at any time to provide chilled water to satisfy any heating requirements.
    It is normally provided with a VFD for variable flow systems.
  • Pump PC is available at any time the system is functioning to provide ground loop water to satisfy any requirements for heat rejection or heat sourcing. It is operated whenever either valve VA or valve VB is called to open to the ground loop. It is normally provided with a VFD and its capacity is governed by the opening position of valve VA or VB.
Sequence of operation:
Normal
  • Pumps PC and/or PH are run continuously during the demand period.
  • Pump PP is operated simultaneously with PH or PC. (PP is a small ground loop circulation pump that keeps the loop uniform and allows for accurate temperature sensing on TG.)
  • For maximum efficiency, pumps PC and PH should be provided with VFDs and the appropriate controls.
  • Temperature sensors TC and TH monitor the supply fluid system temperatures.
  • Ground temperature is monitored by TG.
Cooling Dominant Mode
  • Supply fluid temperature is per schedule and controlled via TC.
  • On a call for cooling, pump PG is operated and if TG is below TC set point, valve VA is opened
  • to ground loop and valve VC is modulated to maintain set point.
  • VFD on pumps PC and PG is modulated to the same percentage.
  • If TG is above TC set point, close VA to ground loop, initiate operation of first Compax unit, and start appropriate pumps.
  • Add more Compax units to satisfy cooling load (if there are more than one).
  • Operate valve VB to maintain heating loop set point, operate pump PG to reject excess heat.
  • Pump PH will make heat available as needed.
Heating Dominant Mode
  • Heating fluid temperature is per schedule and controlled via TH.
  • Valve VB is closed to the ground loop.
  • Valve VA is modulated open to the ground loop whenever TD drops below TG.
  • On a heating demand, the operation of a Compax unit and its pumps is initiated.
  • Add more Compax units to satisfy the demand (if there are more than one).
  • Heating fluid temperature is per schedule and controlled via TH.
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Single Compressor Units
Compax 1 - Sizes 045, 060, 070, 075, 085
Compax 2 - Sizes 110, 135, 150, 175
Dual Compressor Units
Compax 3 - Sizes 210, 230, 260, 300, 350, 400, 450
Compax 4 - Sizes 600, 700, 900
Copyright ©2011 CGC Group Inc.        150 Britannia Rd. East, Unit 1, Mississauga, Ontario, Canada, L4Z 2A4, Tel: 905.568.1661, Fax: 905.568.2839