I've added a manufacturer parameter to the appliances menus since the number of part numbers is going to be so large I think it only makes sense to break these drop down boxes up a bit by "type" and "manufacturer". There will also be a "generic" option for those parts/appliances that do not have a manufacturer's logo affixed.

Modeling these various HVAC appliances is a bit tedious since I first have to find somewhat detailed literature or documentation so I can at least get them mostly dimensionally accurate. Some of the features modeled are my best guesses based on images found online since not everything is dimensioned within the manufacturer's documentation.
I also try to keep the models fairly low poly but typically there is not more than one or two of these appliances within a given model (for residential projects), so I am not as concerned as I am with HVAC fittings.

Modeling these various HVAC appliances is a bit tedious since I first have to find somewhat detailed literature or documentation so I can at least get them mostly dimensionally accurate. Some of the features modeled are my best guesses based on images found online since not everything is dimensioned within the manufacturer's documentation.
I also try to keep the models fairly low poly but typically there is not more than one or two of these appliances within a given model (for residential projects), so I am not as concerned as I am with HVAC fittings.