My Aprilaire humidifier is leaking, please help!

Consumer question:

We have an Aprilaire 760 humidifier installed on the return side of our furnace, connected to the cold water line, and the units leak water from the front edge of the unit. The HVAC tech says it is condensation build up on the water panel dripping down. Thoughts?

Aprilaires’ response:

Thank you for contacting Aprilaire.

This does not sound like condensation. Actually, you should not have condensation in your humidifier.

Leaking is caused by a few different things… You will want to make sure that the water panel is not leaning forward, back, left or right. Also, make sure that the distribution tray at the top, (where the water is dropped into) make sure that there still is a gritty/sandy coating in there. If the tray is smooth where the water builds up before going into the ‘collar’ type holes, all the water will go into the first hole or two it comes to and will not be evenly distributed. When this happens, the water panel is not able to handle that amount of water and will go over the sides of the scale control insert and leak.

The last thing to check is if there is an orifice correctly in place. Then check to make sure that it has not been stretched out.

To check proper water flow through orifice, you would pull out the water feed tube, and have the water go into a 32 oz jar. That jar should fill in two and half minutes. If it fills way faster than that, you have too much water going in that it can not handle, and will leak out. The fix for that would be a new orifice.

You may check these things or give us a call Monday thru Friday from 7:00 am to 5:00 pm central time.

30 thoughts on “My Aprilaire humidifier is leaking, please help!

  1. terri

    My Aprilaire 700 is dripping from the bottom. I have change the pad, cleared the drain, removed mineral deposits from the top and bottom of the water panel tray and cut back the water at the souce valve and still a drip drip….there is water coming out of the condesate line

  2. Corey

    Thank you for your comment regarding our model 550 Aprilaire Humidifier.

    First, check to see if the Aprilaire humidifier is draining properly. If it is clogged or restricted the water can back up into the model 550. Next, check the drain connection. Is the hose old and no longer flexible. This could also lead to some leaking. You can also clean the plastic parts double checking for any cracks. After these steps, if you do not find a cause, it is time to get a hold of your HVAC Specialist.

  3. Brad

    Here are the things to check when troubleshooting a power humidifier, which is leaking. Some issues may require a contractor to correct.

    1. Position Of Unit On Plenum-
    • Is the unit level (left to right)? Call a contractor to address this problem.
    • Is it plumb (front to back)? Call a contractor to address this problem.
    2. Feed Tube-
    • Is the Feed Tube tightened or is there a crack in the tube? Replace the tube.
    • Is the Nozzle snapped into position above the distribution tray? Is it pointing down so that water cannot “spray” to the front or back of the water panel assembly?
    • There is a test that can be done with a paper towel. Wrap the tube with the towel and run the humidifier for 1 minute. Look at the towel again and see if it has gotten wet, and if so, where? This should identify leaks in the tube.
    3. Position Of Scale control insert-
    • Is the base of the scale control insert sitting firmly in the drain spud at the base of the housing? If not, adjust the position of the scale control insert.
    • Does the bottom of the scale control insert have a taper to it to direct water to the drain spud?
    • Is the Scale control insert positioned correctly? The scale control insert has a front and a back. The back of the water distribution tray has an indentation in it to allow for clearance of the nozzle, which is attached to the top of the base. If reversed, and forced into place, the water distribution tray will break off the nozzle attached to the water feed tube and potentially the housing, causing water to leak
    4. Water Panel Assembly-
    • Are there aluminum strands hanging out of the scale control insert? Replace the water panel.
    • Is there a gap between the top of the water panel and the water distribution tray for air to go through? Shim the bottom corners of the water panel in the scale control insert to raise the panel closer to the distribution tray.
    • Is the colored dot on the water panel, up? Reposition the water panel with colored marker at the top.
    • Is there a consistent coating on the Water panel, or are there shinny spots or clumps of coating? Replace the water panel.
    5. Water Entrainment (Water Blowing out of the Humidifier)-
    • Are there signs of entrainment? Mineral build-up on fan blade, shroud, inside of cover?
    • Is the static pressure in the plenum over .4”w.c.? If so, entrainment and leaking could occur. Call a contractor to address this problem.
    • Are there supply vents in your home that have been closed or blocked? If so, this could increase the static pressure on the other ducts in your home, including the humidifier. Open any closed vents until the pressure drops sufficiently to stop the leaking humidifier.
    6. Missing Orifice-
    • If there is no orifice in the unit, the water entering the system could flood the panel. To check for proper water flow, a quart jar should fill at the fill line in about 2 ½ minutes for a red or blue orifice, 5 minutes for a white orifice.
    7. Drain line-
    • Is the drain line plugged? Flush or replace drain line.
    • Does it have a good downward slope? Correct the slope for continuous downward flow.
    • Is it “tee’d” with any other drain lines? Check the drain line for blockage and flush or replace those lines.
    • Is the drain tube held in place by a hose clamp? Hose clamps are not recommended as they can crush the plastic drain spud. The drain tube should have an inside diameter of ½” and fit snugly without the need for a clamp. If the end of the drain line has become rigid, brittle, or cracked, cut a few inches off of that end to use a more pliable part of the tube, or replace the tube entirely. If the drain spud has cracked on an almond or gray colored unit, the base of the humidifier will need to be replaced. If the drain spud has cracked on a black unit, replace the drain spud.
    • Does the drain line go into a condensate pump? Is the leak occurring at the pump? Troubleshoot the leaking pump with the pump’s manufacturer or call a contractor to address this problem.
    8. Water Distribution Tray-
    • Is the granular coating missing in places or entirely? Older trays had a ground pumice coating lining the inside to break up the surface tension of the water flowing into it. Newer trays use a synthetic fabric pad instead of the granular coating. If a tray has neither the coating nor the pad, replace the distribution tray.
    • Are there water stains on the underside of the tray between the holes and the edge? Clean the underside of the tray. Carefully remove the mineral deposits.
    • Is the plastic brittle or cracked in places? Replace the distribution tray.

  4. melissa

    My unit is leaking but is completely dry, have no idea what to do or where to go about it, we just seem to be cleaning a never ending source of water

  5. Ashok Vasavada

    The distribution tray in my Aprilaire Humiifier Model 760 is very brittle. Should I replace it? Where can I get one? Thanks.

  6. Tom Huppmann

    The Aprilaire Humiifier Model 760 leaks from the top right, where the beige housing meets the furnace. Removed the front of 760 unit, felt the foam-like material between the unit and furnace: material seems to have gaps, and is perhaps old (not sure if this is the problem).

    What can I do to resolve these leaks?

  7. Carol Prestowitz

    My Aprilaire humidifier continues to leak and I’ve had to replace carpeting twice in my basement. I have a regular servicing every 6 months by a heating company so it’s not due to negligence. I am thinking of switching to room humidifiers.

  8. dave

    my 440 leaks from bottom of base’ says in blog i need to replace almond color base’ how much does it cost to order one and shipping to 44147 ohio

  9. John Abercrombie

    My Aprilaire 760 is installed on the downstream side of my furnace. A lot of air escapes around the removable cover. Should there be a seal of some sort to prevent loss of air. I have duct tape to address problem, but that makes maintenance difficult,

  10. Jan

    Since installation my furnace has been leaking water and is covered in condensation. Never happened before Aprilaire was installed. Since it is summer I am assuming the hot air that comes in from the April aire mixes with the cold air from the Air conditioning unit and creates condensation. I am going to block the April aire holes until winter to see if this helps, My April aire unit it on top of the unit. One other contractor came and said you can never ,mount this unit on top of the Tempstar Air C unit. Is this a problem??

  11. John

    The tube going in the orifice is not a secure fit.
    I have pushed it in as far as possible, but there is backflow. The backflow continues down the feeder tube and then causes water to drip out.

    Is there some way to secure it?
    Glue / compression fitting / etc.

  12. Anil

    My external drain pipe that connects to the drain pad is broken, the pipe has a piece of drain pad with it. How can I get a replacement drain pad? Thanks.

  13. Bill Irvin

    I had a new 700m unit installed recently, replacing an old 760 model. After noticing the indoor humidity was dropping, I saw the water flow draining from the unit was just a trickle, or much slower than it was on our old unit. Upon a closer look I noticed the saddle valve was just very slightly open. So I opened the saddle valve a little more, and in a few seconds water was leaking from the unit. I read the Owner’s manual and saw where it said water input should be controlled with the orifice and not the saddle valve. That was true with my old unit which had leaking problems until the orifice was properly sized. So I called the installers and they sent out a different technician. He said his experience was (assuming there were no water pressure problems) that it was much better to control the water input with the saddle valve versus the orifice for a number of reasons (mineral build-up was one). He checked out the balance of the unit with a level (not tipping one direction or another), checked out a few other things, and "eyeballed" the water discharge speed adjusting it with the saddle valve so water did not leak. He said it was operating correctly, and with any higher water flow it would leak. Meanwhile, several days later, the humidity level in the house has not improved. So I started reading this web page, and saw where 32 oz. of water should drain from the unit in 2-1/2 minutes. I tested it for five minutes (should be 64 oz.), and got only 20 oz. Isn’t this affecting the proper functioning of the unit?

  14. Brett

    Thank you for contacting us with regards to your model 700 Humidifier. You are correct that the water flow rate is low. Low water flow will affect the evaporation rate of the humidifier. You are also correct that the water flow rate should not be controlled by the saddle valve but by the orifice. If opening the saddle valve fully causes the humidifier to flood, verify that an orifice is installed in your humidifier. Remove the feed tube from the solenoid valve on the bottom of the humidifier and look into the end of it. There should be a small, blue plug with a pinhole through it. If it’s dislodged, reseat it. If it’s missing, it will need to be replaced.
    We appreciate the opportunity to be of assistance.

  15. Kevin

    Thank you for contacting us about your 550 humidifier. We would recommend replacing the feed tube (part #4226) and the nozzle (part #4184) and that should solve your problem. If the nozzle is coming off the distribution tray (part #4218) then you might need to replace that also. We appreciate the opportunity to be of assistance.

  16. Jack

    We have a 550 model that was leaking. It turned out to be a crack in the black rubber hose that connects to the solenoid. We are hoping that we can find the same type of hose at home depot!

  17. Phyllis

    Thank you for contacting Aprilaire.

    The correct part number for the black rubber feed tube that takes water from the solenoid and delivers into the humidifier is part #4226. ( for the model 550 humidifier)

    This may be obtained by contacting your local HVAC company. We do not sell our Aprilaire products at Home Depot or Lowes or any retail store.

    You may also order a replacement directly from us.

  18. Bill

    Is there a maximum inlet pressure from the water line so the Aprileaire 700 humidifier does not overfeed and leak?

    1. David

      We have a service contract for our heating system (which runs on gas), but since the contract does not cover the humidifer (Aprilaire 760), the technicians do not know how to fix it.

      Within the past three weeks or so, three technicians have tried to determine the reason for leaking water.

      The first one flushed the line.

      The second one replaced the humidifier pad.

      The third one cleaned the plastic frame in which the pad sits and wherever else he found grime,

      But none solved the problem.

      Can you please email me guidelines for the technicians on what to check?

      Please do not suggest that they watch the video. I know they won’t do it. I have to HAND them something to make clear that NOW, with the written guidelines, they have no excuse for not checking where they should.

      Thank you for your attention to this matter.

      1. aprilaireadmin

        Thank you for contacting us with regards to your Aprilaire Model 760 Humidifier. Please review the troubleshooting guide for this issue, that was emailed to you. We appreciate the opportunity to be of assistance.

  19. Will Sonderberg

    Thank you for your email regarding the Aprilaire model 700; The maximum water pressure should not exceed 125 psi, If there is no orifice or defective orifice at the solenoid, the water entering the 700 could flood the evaporative panel. To check for proper water flow for the 700, a quart jar should completely fill in about 2 ½ minutes.

    If you have any further questions regarding this or any of our products, please feel free to contact our customer service department at your earliest convenience.

    Will Sonderberg | Technical Support
    Aprilaire, Division of Research Products Corporation
    1015 East Washington Avenue | Madison, Wisconsin 53703
    Direct: 800-334-6011 | Fax: 608-257-4357|

  20. David Melberg

    Where can I buy Aprilaire Model 700 parts in the Minneapolis area? Specifically I think I need an orifice and/or a distribution tray.

    David Melberg

    1. aprilaireadmin

      Dear Mr. Melberg,

      Thank you for your inquiry regarding where you can buy Aprilaire Model 700 parts in the Minneapolis area. The orifice is our part number 4232 and the distribution tray is our part number 4246. Listed below are a couple HVAC installers in the Minneapolis area you may contact for these parts.

      Standard Heating & Air Conditioning Co
      130 Plymouth Ave North, Minneapolis, MN 55411
      Phone: (612)824-2656

      Freedom Heating & Air Conditioning, Inc.
      2500 Highway 88 Suite#107, Minneapolis , MN 55418
      Phone: (612)306-6400

  21. John

    I had the same problem – the blower was pushing the water back and it was leaking.
    The reason was, the hole I cut in the metal wasn’t big enough and the plastic ‘bent’ when I stuffed it in.

    I took the unit out and cut the hole bigger. After that, no leakage at all.

  22. john demott

    I have an AprilAire 600 humidifier. It recently began leaking a considerable amount of water from the dependent portion of the plastic housing, with no water going down the drain tube. I thought perhaps the drain opening in to the tube was plugged so plumbed it and water began going down the tube as it should. I put towels and a basin in place just in case, but despite these, it leaked overnight all over the floor and down to the ceiling in the room below, ruining it. Turned off the humidifier and water supply and called service and the tech came today and said that the plastic housing was warped and therefore the water emerging from the evaporator pad was not going to the drain opening but was being directed away from the drain opening into the dependent portion of the housing and then leaking out the crack where the cover meets the housing. I don’t see this explanation mentioned anywhere at your website or on-line and wonder if he’s right. He’s recommending a new unit.

    1. aprilaireadmin

      Dear Mr. Demott,
      Thank you for contacting us with regards to your model 600 Humidifier. The plastics in our humidifiers are UL listed and capable of withstanding up to 180° temperatures from your furnace. If the plastic warped, that would mean the temperatures in your furnace reached that level. He may be right. You can confirm with a tape measure. The top edge of the humidifier should be parallel to the bottom edge. Inconsistencies in the distance separating the two edges would confirm that the plastic has softened and sagged. If that has happened, replacing the plastic of the humidifier would not be sufficient to correct the issue with your furnace, and that may be something your installer will want to diagnose first.
      We appreciate the opportunity to be of assistance.

  23. Steve

    Hi there,

    I have an Aprilair 500 humidifier and there has been a leak coming out of the drain line. The previous homeowner taped a plastic tube to the drain line to properly drain the water but it has come undone as it’s not properly fitted for the drain line. Two questions…

    1) Should there be water dripping down and out of the drain line?, and
    2) Is there a specially fitted hose to connect to the drain line (or should I just put a bucket underneath the unit, which doesn’t seem right)?

    Thanks for your help

    1. aprilaireadmin

      Dear Steve,
      Thank you for contacting us with regards to your model 500 Humidifier. This humidifier should drain continuously while in operation. The drain line connected to the drain fitting should be rubber or vinyl tubing ½” ID. It should fit snugly onto the drain fitting, called a drain spud. Do not use any compression accessories to hold the tubing to the drain spud, i.e. don’t use a hose clamp or similar device. If the tubing does not hold itself in place, you can often find this size tubing at your local hardware store.
      Please let us know if we can be of further assistance.

      Technical Support
      Aprilaire, Division of Research Products Corporation
      1015 East Washington Avenue | Madison, Wisconsin 53703
      1-800-334-6011 | Fax: 608-257-4357
      Call Center Hours – M-F, 7:00 am to 5:00 pm CT


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