I don't know the model numbers cross reference. I'm a customer, just like you. I'd suggest you measure the old one, ( the cover comes off typically with 1 thumbscrew) before you remove it and then measure the ones on the shelf in the store. They can be 'trimmed' if needed. Orientation is important, the replacement will indicate top end.
You need Honeywell HC18P for an Aprilaire 440
Yes, this is the same as hc26p.
This question is best directed to the manufacturer on the humidifier unit. They are probably specific to given a model.
This is just the pad. The plastic frame that your old pad is in comes off and the frame fits around the new pad. Are you measuring the size of the frame or the size of your old the pad? I recommend buying it, you can always return it if it doesn’t fit
No your windows will have condensation on them if your humidity is set to high. The colder it gets the lower humidity needs to be. In other words as the temperature drops the humidity that you request needs to drop to
My pad is also 1.5 x 10 x 13 inches, and this is the same part number I purchase at HD. My pad sits in a plastic carrier that snaps apart to replace the pad for model THUMD500.
For $13 for a new one, why would you bother? It dries up and hardens after one season of use and loses is ability to absorb the water from the feed tube.
Sorry. I can not answer your question. But if the applications on the box do not match your model. Give Honeywell or Aprilaire a call i am sure they have the answer.
I do not know the specifications of your particular unit...perhaps the manufacturers web page has detailed information. The HD web page says 14.5 x 11.5 x 1.5, however the spare one I have is 13 x 10 x 1.5. I'd suggest you open the humidifier and measure yours before you go to the store. Hope this helps - Mike