Re: [EnergyPlus_Support] Problem with removing reheat coils in VAV

[Vinay Devanathan <vinay.devanathan@xxxxxxxxx>]

The main heating coils setpoint temperature will be set such that it only heats air to a certain temp, (say around 15 - 16 C), so that the reheat coils can be sized for proper capacity to meet the load. When you remove the reheat coils, your supply air will obviously be under-heated as the main heating coil is not sized for that high capacity and will end up providing supply air at the setpoint temperature. You can look at what the heating coils design leaving air temperature by viewing the expidf file under Sizing:System object.

On Mon, Jul 11, 2011 at 1:02 PM, n_junk@xxxxxxxxxxxxxx <n_junk@xxxxxxxxxxxxxx> wrote:

 

Hi!

I'm trying to simulate an existing HVAC system which is similar to a VAV, only with heating, without cooling coil or reheat coils. I'm using the HVAC Template VAV Packaged.
The rooms' temperatures stay above 20ºC, like I configured in the Thermostat, until I remove the reheat coils. When I do that the temperature drops under 20ºC and only reaches it if there are internal loads.

I have almost everything in autosize, except the maximum flow of the input air (but autosize never reaches it, so I think the problem is not from there).

To see my problem just open this example file that comes with EnergyPlus: HVACTemplate-5ZonePackagedVAV.idf. Then run a simulation and consult the evolution of Zone Air Temperature for any of the conditioned zones and see that it stays inside the temperatures of the Thermostat. After that go to the file, remove the reheat coils of every zone (and deactivate the system cooling coil), run the simulation again and compare the temperatures. You'll see that now the temperatures stay under the Thermostat limit and only reach it when the internal loads harm the room enough.

I'm looking in the expidf file for days and I still don't know what is wrong with it. Since I really have to remove the reheat coils, what can I do to correct this problem?

Thanks in advance!

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