Conditionally turn on solar thermal collectors pump based on storage tank temperature

asked 2019-04-20 17:56:22 -0500

mldichter gravatar image

updated 2019-04-21 08:27:51 -0500

I was using the SolarCollectorFlatPlateWater.idf EnergyPlus example file as a template, and I noticed that the pump circulating water through the solar collector panels and storage tank is on during the night. This has the effect of cooling the water in the storage tank since the water coming out of the solar thermal panels is colder than the water in the storage tank.

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There are some objects that are related to controlling plantloops based on temperature,
AvailabilityManager:DifferentialThermostat
AvailabilityManager:HighTemperatureTurnOff
AvailabilityManager:HighTemperatureTurnOn
AvailabilityManager:LowTemperatureTurnOff
AvailabilityManager:LowTemperatureTurnOn
but they are all based on a set temperature at a node. The closest one is the differential thermostat,

AvailabilityManager:DifferentialThermostat,
    Differential Thermostat Availability Manager,  !- Name
    Collector 1 Outlet Node, !- Hot Node Name
    Storage Tank Source Outlet Node,  !- Cold Node Name
    10.0,                    !- Temperature Difference On Limit {deltaC}
    2.0;                     !- Temperature Difference Off Limit {deltaC}

but if the thermal panels are 5C colder than the tank, this logic wouldn't turn off the pump.

Is there a nice, built-in object that will turn off the solar thermal panels pump if the solar thermal panels start outputting water that is colder than the storage tank?

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