Assign mechanical ventilation with HR + PTAC system

Dear Ladybug community,

I would like to have in my building a conventional gas boiler combined with Mechanical ventilation with HR 70%.
I tried to do as follow but get a warning: “1. Solution exception:HVAC system must have an air loop to assign sensible_heat_recovery.

The message makes sense but I wonder how to add an air loop to such a already defined system? Are there components I can add to the workflow to do so?
Thank you

from my point of view, sensible heat ratio + latenet heat ratio should be equal to 1. Try to seperate them

As far as I’m aware, packaged terminal air conditioners work with the zone air, heating/cooling and recirculating it, while mixing it with outside air:

Baseboard heaters work with radiant and convective heat transfer, with the zone air and the surroundings - no air loops attached either.

The error message I think refers to this, that your template has zone inlet and exhaust nodes, but no return node applied (that would be connected to a central system), as your chosen template is not using any object that would use an air handling unit, which would have heat recovery in it.

You can try building your HVAC definition in OpenStudio or Ironbug, but I would just use another template having air loops defined in them.

Thanks for the replies!
I have tried to use another template that include an air loop.
However, I have noticed that when playing with the HR rate or _dcv (false to true) it did not change the final heating demand.
Is it possible that the defined system gets overwritten? Or is it a bug?

Can you post your GH definition with your input geometry internalised?

Thanks for the prompt reply.
Please find attached the graph and screenshots of unchanged outputs with different HR rates and _dcv

As you can see:

When _dcv is true and HR is 0.9
heating demand at 28.9 kWh/m2

When _dcv is false and HR is 0.6
heating demand remain the same… (265.1 KB)

I still couldn’t figure out if it has something to do with my own laptop or if it’s a bug in honeybee