morning Warm-up issue with water source hybrid geo system
We have struggled with building warmup issues during the morning keeping the temperatures warm on cold days below 40 degrees outside.
The facility is heated and cooled with a vertical loop geothermal hybrid system. The building uses a centralized pumping system from the geothermal well field to the mechanical room and out to the buildings water source heat pump terminal units with a return loop using a cooling tower for supplemental cooling. Three (3) pump water throughout the buildings to zones of water source heat pump terminal units. One (1) of pumps is used for backup and is sized at smaller rate of 102 GPM. There are a total of seventy six (76) terminal units ranging from 2.3 to 45 GPM. The water is pump to and from the well field using two (2) pumps sized at 53 GPM. A cooling tower is used for supplemental cooling. Building flow is 330 gpm. This flow is based on the calculated cooling load requirement. Well field flow is 106 gpm. This is flow that is lower than the building flow is based on the calculated heat requirement of the building. The building pumps run when the building is occupied and whenever any heat pump is running to maintain night setback temperature. The building pumps shut down during night setback when no heat pumps are running. The geothermal pumps run whenever the building loop is below 60deg or above 80deg. The pumps start as soon as there is a call for a heat pump to run and there is a delay start on the heat pump itself to allow the water flow to be established. The owner would like a night setback to 55deg but it is now set at 65deg since the building would take too long to recover from the lower setback. All piping throughout the building using the geothermal system is insulated. The well field has 200 foot deep wells with 1 pipe and a reverse return loop. The well field is not sized for future additions.
Location: Central Kentucky
Area: 50,000 ft2
Any suggestions would be greatly appreciated