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gas coil not turning on

asked 2015-01-26 10:39:21 -0500

MattStewart's avatar

updated 2015-07-11 13:07:05 -0500

Hello, This is an Open Studio Question.
I would like to run a model with electric DX cooling coils and gas heat. The feature under AirLoopHVAC:Unitary Sytem allows one to add Unitary - Single Speed DX cooling - Gas heat - Cycling - Elec reheat. to an empty air loop.
Adding fans, setpoint manager and zones and the model will run but you get no gas consumption.

This is a simple split system with no reheat and fans do not run all the time. " A real world system I see all the time". Is Open Studio just not set-up for these smaller systems types (no economizer, no outdoor air, no fan - on always)? Thank you, Matt

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answered 2015-01-26 12:58:52 -0500

I'm thinking that the reheat coil may be picking up all of the load. Or perhaps there is no heating load for another reason. Like the heating thermostat setpoint is exceptionally low, there are high loads and/or warm climate, or the gas coil has no capacity. It is true, that the HVAC library does not include an instance of the AirLoopHVACUnitarySystem with DX cooling, gas heating, and no reheat, but try setting the reheat coil's availability schedule to an "always off" schedule. You may then see unmet hours, but at least you'll be closer to diagnosing your system with the reheat coil disabled.

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It will be helpful if you report back here with your findings. We can adjust the HVAC library to avoid setting the availability schedule if necessary.

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Asked: 2015-01-26 10:39:21 -0500

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Last updated: Jan 26 '15