On 17.04.2015, at 10:31, "pedromarques.be@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
Hello guys,
I'm having a tough time with EnergyPlus and I'd like to ask you all guys because I'm sure I'm not the only one who has had this issue. Attached there is a file named "crazy hr.png", in which you see the normal behavior of the heat recovery, that works as follows:- if the outdoor temperature is below the ahu (or the HR recovery) setpoint temperature, then the HR modulates its bypass damper to regulate the supply air temperature (correct operation)
- if the outdoor temperature rises above our setpoint temperature, then the bypass damper of the HR closes and all the air passes through the HR, leading to a overheating of the air.
I am aware of the fact that one could use the economizer to bypass the HR, however there are many problems with that manoeuver:
1 - controlling the AHU operation solely on the outdoor air temperature is sometimes not possible (e.g. when we're using a "warmest" setpoint to acclimatize a room, so using schedules will always limit my control;
2 - not all AHU have economizer operation (aka recirculation). In Europe, most of the AHU operate with 100% outside air, meaning that if I am adding an economizer to control my HR I'm adultering my HVAC simulation.
My question is then why there is no way to control the heating battery and the HR simultaneously from one AHU. This problem becomes serious when no cooling battery is available: the indoor conditions become unbearable with overheating during the wintertime. Briefly, one should be able to have the HR totally bypassed when the outdoor temperature is above the setpoint temperature. Then, there is still the HR for cooling mode but that's very easy to control: on if the outdoor air temperature is higher than the exhaust air. The only option I see is to add a profile to the HR that turns it on and off depending on the outdoor air temperature but, again, then I'm limited in my supply air temperature control.
Has any of us ever had this problem before? Any suggestion on how to fix? Could anyone also explain me the reasoning behind the actual HR control?
Thanks,
Pedro
<CRAZY HR.png>
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Posted by: "jeannieboef@xxxxxxxxx" <jeannieboef@xxxxxxxxx>
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