Those of you with older homes might have an older model of Wait-Skuttle drum-style humidifier attached to your furnace. In my case, I’ve got the 45S model, which was very popular “in the old days”:


Cleaning these humidifiers is always an unpleasant task. Even more so if you have hard water – the evaporation that occurs leaves behind crusts and deposits of calcium that are difficult to remove. The evaporator pad is not worth cleaning – replacement pads are very easy to find at any hardware store, and they are very cheap, around 6 bucks:

humidifier_03If the float assembly is heavily encrusted, that’s pretty easy to deal with too – these are attached with a single screw, so you can just take the float off and give it a good soak in an acidic cleaner. Which brings me to my first tip – check out ZEP cleaners (sold at Home Depot) they are much more affordable than CLR and in my opinion, do an even better job:

humidifier_02Now if your float is in really bad shape, you can find very affordable replacements for that too. And changing out your humidifier float is pretty easy process.

But one thing that I have found very frustrating is the plastic water tray at the bottom of the humidifier. When calcium deposits on plastic, it tends to be very difficult to remove. After many sessions of scrubbing and acid treatments, the plastic tray in my humidifier was in really bad shape. Now you might be lucky enough to find a replacement plastic tray, but for me, it was very difficult to find the 9 inch square replacement for the 45S model humidifier. The other thing that bothered me was having another difficult-to-clean plastic tray… so I came up with an alternate solution.

I realized that metal cake pans are made 9 inch square – so I purchased a “no-stick” heavy-duty one. I found that the pan was the perfect height for the humidifier, but these cake pans do taper a bit upward, so that they are larger at the top (I suspect to make getting cake out easier!) So in order to make it fit perfectly into the humidifier, I had to place the pan vertically on my vise and pound each of the sides inward a bit with a hammer. When you are done, the cake pan will look something like this:


So once you have squared the top of the pan a bit, it will fit beautifully into the humidifier:

humidifier_05The huge advantage to a metal non-stick pan is that is SO much easier to remove calcium deposits. Generally, they can’t attach themselves to the non-stick surface, so it only takes a few minutes of simple rinsing to get a perfectly clean pan.

To finish, I’ll make one more recommendation – you can buy ammonium chloride packets that work well to keep calcium from building up rapidly in the humidifier water.

humidifier_06Due to nature of evaporation, even with the packets, you can’t hold off cleaning your humidifier forever, but if you use my cake-pan hack, your cleaning will be a lot easier!


  1. I like your non stick cake pan idea, never thought of that. What I’ve always done is to coat the pan and float with “Vasoline”. The deposits come off easily by scrapping with a putty knife. I have tried those drop in packets they do help a bit. I also have a water softener so I’m sure that helps too.

    1. I clean mine twice a year. You can get away with once a year, but expect it to be a yuckier job. Also, the longer you leave it, the more you risk deposits and dirt obstructing the water flow, potentially causing a leak.

      As I mention in the article, save yourself some misery and use a new evaporator pad when you clean. It’s just not worth the hassle cleaning the old one.

  2. what about a 9″ cake pan from the dollar store & just throw it out & replace it when needed . Also how important is it for the drum to turn to work properly . Mine is broke where the pad shaft sits on the right side . The pad seems to be wet anyways .

    1. Sure, as the article states, a 9″ pan will fit, but not without some bending. Unfortunately the opening of the 45 model humidifiers is just a bit too small for a standard 9″ cake pan (believe me, I have tried!), so you will need to bend the top of the pan inward to get it to fit.

      As for the drum not turning, as long as the pad is fresh it will wick/absorb moisture upward from the pan. However, if you want maximum humidification, a rotating pad is going to be much wetter and evaporate much more water into the air.

  3. NOW, I read this after spending hours cleaning all my components (Carrier 49WS model). I got it just about perfect, but not a job I look forward to. The plastic float was fairly easy to clean. Vaseline sitting in water that gets blown throughout your house? Any problems with that? I am looking for a liquid or tablet that not only helps to keep deposits off the parts, but also treats the water for potential bacteria, mold and other types of non-desirable things you don’t want blown in your home. Appreciate suggestions and experiences with ones you may have tried.

    1. I actually haven’t used anything except Wait’s humidifier conditioner: I notice on there are a few liquids to choose from. Did you end up trying any of them? BTW, I have switched the pan to one I found, in of all places, the dollar store… it’s dimensions were absolutely perfect! Has XMAS decorations on it, but who cares!

      1. I’m going back to a drum type after observing the water bills from an AprilAire flow-through.
        A bit of peroxide in the water will kill pathogens. It’s completely non-toxic, and does need repeating as the extra oxygen evaporates off.

  4. I have used WAIT humidifier conditioner packages for at least 40 years, and they work just fine. I add a new packet at the beginning of every month that the unit works (mainly winter: Nov-March in southern Canada). Sure, the clean up in April is a bit messy, but certainly not difficult. I just scrape off most of the calcium with a putty knife, then soak the pad and various parts in the tray, filled with vinegar. Rotate the pad every few hours. Cleans everything up within a day or two. Even the vinegar can be reused for several years. About as cheap a solution as you can desire.

  5. I have been using Wait’s humidifier conditioner for 30 years but cannot find it anywhere. Can I use ammonium chloride?

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.