I have a large home that has a total of 4 HVAC units and I only notice room enough for 3 in Optimiser. I need to make sure I model all 4, as they have all been sealed and qualify for the duct seal rebate.
Once you have modeled the systems as described in that post, you can get a fourth duct sealing job to register by following these steps.
1. Go to one of the cooling systems interfaces
2. Setting the Shared control to Separate
3. Set the remainder of the Distribution controls identically system to which it was previously linked.