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Category: Humidifier FAQs
Here we have humidifier FAQs with questions and answers.
Question: How often should I replace the 4004 water in-line strainer on my Aprilaire humidifier?
Answer: We have had this question asked several times before and this is my answer: If it was me, I would only replace the strainer and the restrictor orifice if I was having low water volume coming out of the humidifier supply tube. If water is coming out of the supply tube when the humidifier is on then I would leave it alone because you are asking for more problems when you start turning the saddle valve water valve off / ON and if you allow sediment in to stop up the 4040 solenoid valve. I copied the solenoid valve replacement instructions from our site below. I would recommend always flushing out the saddle valve and water line into a bucket if you ever turn the water off and back on at the saddle valve. Flushing the humidifier water line out makes sure that all the sediment goes into the bucket instead of getting caught in the humidifier’s strainer, orifice, or 4040 solenoid valve. Some contractors recommend replacing the 4004 strainer every 2 to 3 years, but I would only do it when you are experiencing low water volume out of the humidifier. I would try replacing the orifice first before the strainer. We sell the Aprilaire humidifier orifices on the following page: Please click here if you are interested in the Aprilaire humidifier orifices that we sell. We sell the Aprilaire 4004 strainers on the following page: Please click here if you are interested in the 4004 Aprilaire Strainers that we sell. Sometimes the strainers are very hard to get out because of all the sediment that has built up over the years. Some people end up messing the 4040 valves up if they can not remove the strainer properly. Many times the strainer gets stuck and is hard to remove. Please click here if you are interested in the Aprilaire 4040 solenoid valves that we sell. I also copied a picture below that shows what others recommend on replacing the strainer. If you have any questions please either comment below or email us anytime at firstname.lastname@example.org
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Solenoid Valve Replacement Instructions:
For power units unplug the electrical cord. For bypass, units turn off power to the furnace. Also, turn the humidistat off.
Shut off the water supply at the saddle valve
Disconnect inlet and outlet water compression nuts. Double wrench. Note, some water may drip on the floor. Remove the orifice (which controls the water flow) from the plastic or copper tube and make sure there is no obstruction. If blocked clean or replace.
Remove the wire nuts from the water solenoid valve wire connections. Set aside.
Remove screws that secure the valve to the unit.
Attach a new valve with screws. Do not over-torque screws into the plastic housing.
Reconnect wires with wire nuts.
For units with plastic feed, tubes inspect for brittleness, hairline cracks, nicks or abrasions, etc. Replace if necessary.
I would highly recommend completing this step while the humidifier water supply line is disconnected to clean out the supply line/saddle valve and make sure that you have a good flow of water coming out of the water supply line. Many times a new valve can become stopped up if this step is not completed. This can be accomplished by taking a bucket, setting the loose humidifier water supply line down into the bucket (two people are best), then turn on the saddle valve to get all loose sediment out of the saddle valve and the waterline. This can be accomplished by allowing the water to run into the bucket for 10 to 15 seconds. If you can not get adequate water flow out of your saddle valve then you will need to replace your saddle valve. We sell a really good Supco saddle valve on the following page: Please click here for the saddle valve we recommend.
Reconnect the water lines, double wrenching the compression nuts.
Turn the water back on and check the system for leaks. Tighten compression nuts as necessary.
Restore electrical service and activate the furnace by turning up the thermostat.
Turn up the humidistat to verify the operation of the humidifier.
Recheck for leaks. Turn down the humidistat to make sure the valve shuts off. Reset humidistat and thermostat to original levels.
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Below we have an Aprilaire humidifier 500 maintenance video made by HVAC.com. Many thanks to HVAC.com for making this informative video! This video shows you step by step how to perform the seasonal maintenance on your Aprilaire 500 Bypass Whole Home Humidifier. In the video it shows how to check the water feed tube, the strainer, the drain tube, the drain spud, the orifice, and the water panel. All of these are important parts that ensure your humidifiers performance and efficiency. Please click here if you would like to see the parts and supplies that we sell for the Aprilaire Model 500 series humidifiers. Please email us anytime if you have questions. Our email address is: email@example.com. We would love to help you out and have your business!
Question: What is the difference in a power humidifier, Aprilaire 700 and a by-pass humidifier such as the 550, 600, & 400?
Answer: Depending on the square footage of your home, and cost would determine which humidifier you choose. If your home is over 2,000 square feet I would definitely go with the 700. If you have a smaller home under 2,000 square feet I would probably go with the 550, 600 or 400 humidifiers. My own personal opinion is that I like the power humidifier (700) over the by-pass humidifiers because with the bypass humidifier you are running humidified air across your filter, blower, heat exchanger and up through your furnace. The thought of having the moist air running up through your furnace just doesn’t make sense to me, but people having be using them for years with excellent humidification results. Also, make sure you have enough room for the humidifier. You should have at least 16″ between the furnace and a wall or obstruction to be able to install and service the humidifier. 16″ is the minimum. 24″ would be more preferable. The hole that you cut in the furnace duct work for the 700 is approximately 15″ square. If you do not understand the concepts of high and low voltage electrical wiring, some sheet metal work and plumbing work, then I would probably leave it to a professional. The humidifiers with the computerized humidistat (700,600, 400) require 6 low voltage wiring connections and one high voltage 110 volt connection. If you have a friend that understands wiring and how to read a diagram then maybe they could help? The Aprilaire humidifiers can turn off and on by using an A50 current sensing relay. If you have a newer furnace, with hook ups on the control board for humidifiers or electronic air cleaners, then you will not need the A50 relay. You can wire you humidifier to turn off and on using your furnace’s control board. You can tell whether or not you need the relay by looking at the board or looking and reading the furnace’s wiring schematic. The Aprilaire 700 humidifier has a transformer built in, to control the power fan relay and on off relay in the 700. The 550, 600, and 400 humidifiers come with a transformer that you can wire up. I always use the furnace’s existing transformer to power the humidistat. I run wires up to the humidistat off the “R” and “C” terminals on the furnace’s control board. If you decide to install the humidifier yourself, and you do not understand the wiring you can possibly burn the humidifier, humidistat, and your furnace controls up. This would void the humidifier’s warranty. I would recommend hiring someone if you are not familiar with the wiring. I believe you will really like the humidifier once it is installed and working for a few days. No more dryness and static electricity. You will wake up feeling better!
Question: My humidifier runs all the time, even when the furnace is off. What could be the problem?
Answer: Being able to interface the Aprilaire humidifiers to turn off and on with the furnace blower or gas would depend on whether you have “HUM” (humidifier) hookups on your furnace’s control board. Sometimes the “HUM” hookups are high voltage (110 volts) and sometimes they are low voltage. (24 volts). Please see the pictures of furnace control boards below. Sometimes if you have an older furnace you probably will not have any “HUM” hookup at all. If you do not have a “HUM” hookup you would need to purchase an A50 current sensing relay to make the humidifier cut off and on in conjunction with the furnace blower. The A50 acts like a light switch. When the furnace blower is on it senses the current and closes the connection between its two wires. When the blower goes off the A50 opens the circuit and turns your humidifier off. You can purchase an A50 on the following page for $27.00 plus shipping. We sell the A50 current sensing relay on the following page: Please click here if you are interested in seeing the A50 current sensing relay we sell. The A50 relay would be wired up in series with one brown wire that comes out of the bottom of the 700 humidifier. On the Aprilaire 600 & 400 humidifiers the A50 current sensing relay would make and break the circuit in the “H H” terminals of the 56 humidistat. If you are installing an Aprilaire 700, and if you have a high voltage hook up on your furnace’s control board, then you can use the high voltage hookup on the furnace’s control board, wire up a receptacle (plug) attached to the side of your furnace so the Aprilaire 700 can plug in. I mount the 110 volt receptacle using self tapping sheet metal screws to the side of the furnace. If you have a low voltage hookup on your control board…you can run this up to the “R & C” terminals of the Aprilaire 56 humidistat. It would be wired, Low voltage “HUM” on your control board up to “R” on the 56 humidistat. Low Voltage “C” (Com) on your control board up to “C” on the Aprilaire 56 humidistat. Polarity must be observed or it will burn up the humidistat and void the warranty. Also make sure these are low voltage, not 110 volts are it will burn the humidistat up. Please look at your furnace’s wiring schematic or test with a meter. The low voltage hook up wires for the humidifier are usually located on the same row as your thermostat’s low voltage wires. Once you get the humidifier wired using the A50 current sensing relay or through using your furnace’s control board then you humidifier should turn off and on with your furnace’s blower or gas valve. We sell many humidifier parts and supplies on the following page: https://www.arnoldservice.com/parts-humidifier-parts-supplies/
Below is a picture of a Carrier Bryant board with a low voltage “HUM” connection on the board. You can tell this is a low voltage connection because the “HUM” hookup is on the same row as the low voltage thermostat wire hookups.
The board pictured below has a “HUM” hookup near the low voltage wires, but not on the same row. I would test the “HUM” terminal with a Volt meter to see if it is a 24 or 110 volt hookup.
Below is the wiring diagram for the Aprilaire 550:
Question: Is it normal for quiet a bit of water to be running out of my 550, 600, 700 Aprilaire humidifier?
Answer: Yes, It is normal for a small stream of water to run out of the bottom, through the drain tube in the humidifier. This water flow should stop shortly after the humidifier goes off. If the water continues to run more than 5 minutes, you have a not wired the humidifier properly or you have a bad 4040 solenoid valve. Turn the furnace power off with the switch on the side. If the water stops flowing the humidifier is not wired properly. Recheck the wiring diagram and wire properly.
Question: What tools and supplies might I need to install a humidifier?
1. Sheet Metal tools to cut out the metal.
2. Electrical wire strippers, Needle nose pliers, a real small screw driver to attach the wires on the humidistat, regular screw drivers, pliers, open end wrenches for the water saddle valve installation.
3. Small wire nuts for the 18 gauge wire. Most of the time I use the orange wire nuts.
4. 3/4″ PVC pipe with some elbows and a Tee possibly for your drain line. PVC cement. Saw or cutter to cut PVC pipe. You might not need the PVC pipe, depending on how your drain is set up. Most people Tee into the existing air conditioning drain line.
5. If you have a by-pass humidifier like the 400, 550 or 600 then you would need a couple of 6″ Tin Vent elbows and 2′ to 4′ of 6″ straight tin vent piping for the by-pass part of the installation.
6. Sheet metal screws to screw the tin vent, by-pass pipe together.
7. 1/4″ copper tubing for the water line to the humidifier.
8. Pipe dope or Teflon tape to place around the threads on the saddle valve so it does not leak.
9. You might need an electrical outlet (metal) junction box and cover, depending on how you want to wire up the supplied transformer.
10. For the 700 humidifier you might need to mount a 110 volt outlet box on the outside of your furnace for the 700 to plug in. You would need an outlet box, receptacle, receptacle cover and some 14-2 romex wire to run from your furnace’s control board to the receptacle.
Most service people already have most of these supplies on their truck.
Question: It looks like I need to mount the Aprilaire 700 unit on my cooling coil. How difficult is this and how do I know if I am going to cut into the coil since I can’t see inside?
Answer: I mount many of the humidifiers on the side of the cooling coil all the time when I was doing installs. You want to make sure that you are on the sides of the coil and not on the ends. If you install the humidifier on the ends of the coil then it will restrict air flow to the humidifier. I always traced around the template making sure the template is level. You want to make sure your template is positioned high enough where you aren’t cutting into the drain pain of the coil. Many times I take one end of the cased coil off, or move the coil cover back away enough so I can see inside the coil. I have seen so many coils that I know pretty much where to cut and not to cut. I would suggest starting as high as possible on where you drew the cut out with the template. Since the coils are pointed away near the top it is unlikely you would hit the coil if you start drilling near the top. I drill a hole large, sometimes with a metal cutting hole saw or large drill bit (do not drill deep just enough to go through the metal) big enough to get my sheet metal shears started then cut a small opening so I can see inside the cased coil, so you can see where the coil is positioned. You can always move the template up if you are not in a good position for cutting. Best of luck!
If you can disconnect the wires from the humidistat that go to the humidifier (wires that go to the two brown wires that come out of the bottom of the humidifier) then plug the humidifier into a 110 volt outlet. Tie the two brown wires together that come out of the bottom of the humidifier together. The humidifier should come on and the water should flow. If it does come on then you probably have a 56 humidistat problem or outdoor sensor problem. If the humidifier doesn’t come on then you probably have a humidifier control board problem. Please make sure you are getting 24 volts to the humidistat on the R & C terminals by checking with a meter. We have a real good humidifier troubleshooting video below produced by ntsupply showing how to troubleshoot a solenoid valve. We sell the solenoid valves on the following page: Please click here if you are interested in the Aprilaire 4040 solenoid valve that we sell. We sell humidifier parts and supplies on the following page: Please click here if you are interested in seeing the humidifier parts and supplies that we sell. If you have any questions please feel free to email us at: firstname.lastname@example.org. We would love to have your business!
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