System sizing with ERV

Hello I wonder how OS (E+) size the system with ERV ? I made a 1 zone PTHP with ERV sized for ventilation . The PTHP capacity did not change after add ERV system. In pratice, we can use ERV to reduce PTHP size - we could do like this in OS E+ by autosizing, could not we ? Thanks

Did you turn the OA on the PTHP off when you added the ERV? The PTHP size will not change if it and the ERV are both supplying the zone with OA. Below is an image of turning the OA off in OpenStudio, the inputs should be the same in E+.

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