I need help here please we have had r/c installed now for a few months & my 19yo cat has been sick all the time... well a few hundred dollars later the Vet said it's all due to the heating as it's ducted so I need to buy a really good humidifier one that is long lasting.

Where do you live that you need a Humidifier this time of year? In most of the US, we are running Dehumidifiers!