# A2012-S118 solenoid/Aprilaire humidifier making horrible loud, quick clicks! Help plz



## ProGreen (Oct 2, 2014)

We have a 760 Aprilaire Humidifier, serviced with new parts. An A2012-S118, 24 volt Solenoid was put on in 2012 when old one died. Immediately we noticed when the AS AUD120OR9V5J two stage furnace came on or went off, the suddenness of begin or cease caused sucking in (slamming down) or out of the humidifier body against it's rigid supply duct which nastily reverberated throughout the house. I brought this up (even paid $115 after its installation for a check of it) as I thought the solenoid maybe wasn't interfacing right with the furnace but this raised no concern to the HVAC people. Last fall, I went and looked up the A2012-S118, and it is an Aprilaire compatible 40/40 24 volt unit. But still, the old solenoid did not cause this sudden nasty noise reverberation.

Two days ago, I turned on the humidifier for the first time, keeping it at 25% out of caution. Immediately, we noted the same slam effect when the furnace came on, which we tolerated. _Today all heck broke out, with extremely audible, fast clicking at the solenoid vs some electrical-mechanical fast AS-Aprilaire solonoid interfacing with fast clicking causing horrible reverberations through the duct work._ I went down to the furnace room this morning and the indescribable noise was emanating from the Aprilaire humidifier so I pulled the plug on the thing! It's 2015, service since 2012 involved 5 Aprilaire service visits, all of which included discussion of problem which now has taken a dead turn. 

What could be going on here?  Thanks for your input.


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## beenthere (Oct 11, 2008)

Sounds like something got wired up wrong to the furnace.


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## ProGreen (Oct 2, 2014)

Thanks beenthere. That's what we thought this morning too, in fact my husband thought it might be part electrical in nature so immediately, given even worse change from past, turned it off. Honestly, the new solenoid addition started us down this path years ago.

Here's the November readings on the A2012-5118 valve: 3/64 orifice; 
Ident: 32/12; 125 psi; 24/60 vac; 2.3 watt.

Hmm, 125 psi. That seems high to me; hate to have a leak (effluent water is directed into sump). Our water main pressure reducer is lower than that. 

Well, past time to seek out a new set up than this. Sad they didn't say the cost of new pieces for the 760 was equal to the cost of a completely new upgraded humidifier which I read online. Not wild about having this Aprilaire humidifier being on the supply duct either.


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## beenthere (Oct 11, 2008)

The 125 PSI is the max water pressure it can operate against. 

Can you post a video of it doing the noise.


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## raylo32 (Nov 25, 2006)

I converted my Aprilaire this year from a flexible water supply to a rigid copper line and the solenoid does transmit more noise into the water pipes than before. It makes a fairly loud bang on and off and is probably somewhat "normal".

But I don't have the cycling issue like you. Just speculating but if you have an outdor temp sensor maybe the control is hunting on and off around the point where it would turn the humidifier off due to the temp input. There really should be a control band to keep this from happening so maybe the humidistat control is the problem... or I suppose the ODT could be drifting but I think that is less likely since I think it is a simple resistor.


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## ProGreen (Oct 2, 2014)

Thanks raylur banging noise isn't in the water pipes feeding the humidstat but with the ventilation ducts to which it is attached at supply. Dang thing is nasty loud throughout the entire house, and even sets up some air flow jiggling noise back and forth due to pressure. We never had this before that specific model solenoid was put in. No outdoor temp sensor I'm aware of, unless it's related to the AC. Resistor problem sounds about right. 

Any new house humidifiers that would interface with our really excellently working, regularly maintained AS AUD120OR9V5J two stage furnace? I'd love to get that Aprilaire 760 off the supply vent.


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## raylo32 (Nov 25, 2006)

If you have easy access to the return plenum and space there you could install an Aprilaire 600 bypass type unit. Instead of a fan like in your 760 it works by using differential pressure between the return and supply to move air over the water panel. It has the same type of solenoid but for the 600 they generally recommend you install that part on the return plenum. The solenoid sound will still be transmitted into the plenum, but in this case the return plenum. Then a small flex duct brings warm air over from the supply plenum. The 600 also has the same type of humidistat control so if that is causing your current chattering problem the new one should fix it.


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## ProGreen (Oct 2, 2014)

Fascinating, (at least to me). But how would our current low voltage Broan Make Up Air low voltage system, which sits on our large return plenum, affect an Aprilaire 600 bypass? Can you have 2 low voltage systems near one another without transmission interference?

Also, regarding our supply plenum just off the AS AUD120OR9V5J two stage furnace: it is a rectangular box, not a circular or soft curved plenum. I've long thought much of the supply heat dispersion is wasted by it hitting the angles of the box, rather than being curved forward. I didn't catch that shape significance when the furnace was newly installed. Would this affect the small flex duct bringing supply (heated) air?


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## raylo32 (Nov 25, 2006)

I can't really help you that much with those questions. I am just a DIY guy (admittedly pretty heavy DIY!) and only have worked with standard setups. But the bottom line is the bypass type can work if you have access to mount the humidifier and access and space to run the bypass duct. That bypass duct will reduce your overall ventilation CFM by the nominal amount that goes through the humidifier.

BTW, I love my Aprilaire 700, that I installed myself years ago, other than the on/off clunks. I have a new solenoid I may install one of these days to see if that helps but it isn't a critical problem for me.


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## ProGreen (Oct 2, 2014)

beenthere said:


> The 125 PSI is the max water pressure it can operate against.
> 
> Can you post a video of it doing the noise.


I'm sorry beenthere. I didn't read your post until now. I might be able to post a video with my old phone in a day or two, but I don't know how to upload it. Good idea though.


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## raylo32 (Nov 25, 2006)

Upload the video to youtube or your favorite photo/video host site then use their link tools to cut and paste a link into a post there.



ProGreen said:


> I'm sorry beenthere. I didn't read your post until now. I might be able to post a video with my old phone in a day or two, but I don't know how to upload it. Good idea though.


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