HVAC equipment like furnaces would added to the same class that you have the building in - class 1, 3 or 6. All of those classes are subject to the half year rule.

Thank you very much for your prompt response.  I haven’t and am not planning to do CCA for the building portion of my rental property.  In this case, can I do CCA just for the furnace itself ?  Or  the CCA for the furnace can only be claimed together with the building ?

Yes, you can just take CCA on the furnace, but which class you put it in will still depend on the building (class 1, 3 or 6).

Thank you