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I have an aprilaire 568 bypass humidifier. (no fan). The problem I'm seeing is that the water 'valve' is oscillating open/closed. I suspect this is due to a humidity sensor or thermostat going bad. Which should I target for replacement first? (OK it has been cold for the month of Jan - below freezing all month, so I expect the thermostat ). Is there a way of checking this before just replacing it?

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If its opening and closing it sounds to me like a loose wire nut on your 24volts to your water solenoid valve. The only time that the humidifier should come on is in heating mode and then when the furnace gets up to temp and the blower starts. If furnace is older it will have a current sensing relay located in the blower compartment with a plastic box and two wires coming off of it.One of the blower wires( generally RED for low speed) should be going through that sensing relay.If you have some slack in that blower wire try wrapping it around that sensing relay a few times. I would chek all my wire nuts first though before you do the sensing relay. David

Posted on Feb 01, 2009

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Where can I get part #4087 float assembly for Aprilaire humidifier model445?

You can\'t. The part has been discontinued. No one has it.

I wasn\'t willing to buy a whole new humidifier, so if you\'re willing to do a little more work, you can do what I did. I substituted a Kerick MA252 Mini PVC float valve. This isn\'t a direct replacement, the float and float arm that come with it are a little too long to fit. You take off the float and float arm and use the original float and float arm. The bolt on the new valve is too big, so you need to provide a bolt that won\'t rust (brass, stainless, teflon, etc.) to connect it. You\'ll have to play with the position of the float arm to set the proper water level. You\'ll also need the square plate off the original float valve to provide a flat mounting surface for the new float valve. You\'ll need to ream out the hole in the plate and the mounting hole to make them round. The tubing inlet on the MA252 works great, but you\'ll have to enlarge the opening on the cover to accommodate the tubing inlet.

The MA252 is made of PVC and stainless steel, so it shouldn\'t corrode away the way the OEM valve did. And better yet, the MA252 costs less than $10 (I got mine on Amazon) where the OEM valve would have cost more than $50 if you could get one.

Jan 21, 2014 | Aprilaire 4087 Replacement Float Valve...

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I have amana 90 air command with aprilaire 550 humidifier i found water under my furnace today . we had one 80degree day so I uncover my airconditioner and than we had snow and i forgot to cover it back up...

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Apr 19, 2011 | Amana Heating & Cooling

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I changed the filter on my aprilair humidifier and the light keeps blinking how do I reset it?

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If this post was helpful please let me know.

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Mar 02, 2011 | Heating & Cooling

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Humdifier has power to it. Sail is in good condition, water gets to humidifier valve yet no water gets past the valve. What to do?

Hello if you are getting 24 volts to the solenoid valve and it does not click open to let the water thru then the solenoid valve is bad and must be replaced.

Feb 27, 2011 | Heating & Cooling

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It is an Aprilair Humidifier 220 with thermostat control. The unit is attached to the furnace and for 3 days, we have had water on the floor! We just moved in 2 months ago and are not familiar with a...

Check the drain on the humidifier (at the bottom there is a drain which should be attached to some type of hose that drains into your sump or other wastewater orifice)...

check the filter (remove the lid and the filter is that corrugated metal type thing (it may be clogged causing overflow - you can replace it for about 7bucks at home depot)
also check that the water line (should be attached to the black plastic frame is attached and the water is going into the top part of the black filter holder)
check that the filter is sandwiched properly within the black plastic holder
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I replaced my old Aprilaire 445 humidifier with a new 600M and also replaced the humidistat. Neither the new or old humidistat is activating the solenoid for the water flow. We have water at the...

Hello, you need a means of allowing 24 volts to the solenoid and this can be done by either a sail switch or current sensing relayrobhvac47.jpgCurrent sensing relay

robhvac47_0.jpgSail switch

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I have water leaking out the bottom of my furnace when the aprilaire 700 is working. I have tried everything to resolve. It was working fine last month. I changed the water filter, cleaned the lines...

How old it your Aprilaire 700?
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Click on the link below and read the Aprilaire Manual maintenance page. This Manual covers several models, so disregard parts not pertaining to your model number.
Remember to turn of electrical power to unit, furnace, air handler if a split unit, and don't attempt anything your not exceeding your experience level.
Vote for Patrick Mot, Thanks

Dec 24, 2010 | Heating & Cooling

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Aprilaire 560 problem. Water isn't flowing into humidifier. I replaced the copper line to the solenoid and it still doesn't work. When I turn on the manual thermostat I hear a click but no water flow. I...

Have you tried activating unit when connection on discharge side of solenoid is loose to see if you are getting water flow thru solenoid. If not then you need to clean or replace solenoid. Thanks.

Nov 22, 2010 | Heating & Cooling

1 Answer


check to see if the flame rod tip is in the flame(like the hot junction on a thermocouple). the pressure switches are a normally closed switch and a blocked flue could cause them to open. the circuit board should run through the safety switches and check them before the gas is opened at the valve. also the drain lines that you see at the inducer fan should be free of condensation but if the inducer fan has condensation in it, it will open the airflow safety switch. you will hear the crackling noise from the fan. also there should be a trap below the fan that should be full of water to keep the fan from pulling air from the wrong place. I would not suspect the board at this point

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