I have a "Baseboard convective water" system sized to fully meet space loads (from a previous sizing run with no unmet hours) as primary on my Zone Equipment list and "PTAC Dx clg elec htg" second on my zone equipment list. the baseboards are hooked up to a hot water loop and boiler. They appear to be using energy as expected. After running this set up I had about ~5,000 heating hours unmet (building in zone 7) and no reduction in fan energy vs when I had the PTAC with hot water heating alone. I hard sized the PTAC w elec heat capacity to 0 with no effect, I set the supply airflow while heating to 0 with no effect. I also tried autosizing the baseboard and increasing the baseboard sizing well over what it should take with no effect.
1) any ideas on why annual fan energy didn't change by even 1 kWh per year vs just the PTAC with electric heat? I would think that the hot water baseboards would take the load and the PTAC would not run thereby saving fan energy.
2) why I am seeing ~5,000 unmet heating hours regardless of baseboard sizing?
Thank you!
