Questions before Installing new Aprilaire 600

My wife and I have a new (less than 2 years old) house in Northeast Ohio, and we've determined that we need a humidifier. We're seeing the typical symptoms of dry air that are reported in the houses and in people.
Consumer reports did not put much effort at all into testing the furnace mounted models, only saying that "All should perform adequately.". Looking around on the web & talking to people at work, I find that Aprilaire is a decent brand, so I've ordered one.
Prior to ordering it, I've read the installation manuals I could find, located & marked the place on the duct where I'll install it & run the supply & drain lines.
There are a couple of questions that I have not found answers to as I STFW. I would appreciate any words of experience that the group can offer:
1. The installation diagrams I've looked at sometimes show the humidifier unit on the supply duct and sometimes on the return duct. Either way, warm air will flow from supply through the element to return. Therefore, it seems to me that the humidifier element should not care which direction the air flows through it, and it doesn't matter on which side (supply or return) the unit is mounted. Is this correct?
2. I specifically bought the Aprilaire 600 (instead of the Hamilton 12HF from Lowe's) because the Aprilaire's controller has an outside air temperature sensor. (Price was a wash, anyhow). I understand that the only purpose of this sensor is to decrease humidity when it's colder outside (and therefore colder on your windows & outside walls) to prevent condensation from occurring. Is this correct? Would anybody who is currently running one of these in automatic mode, maintaining humidity without adjusting the dial or seeing condensation please report their success? Or if not, then report failure?
Thanks for your assistance!
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The auto control works, you lower humidity just the point where there is no condensation anywhere. It will maintain humidity so condensation does not occur. Condensation leads to mold then rot of wood window frames. Keep outside thermometer higher than any snow will ever get, my instaler first put it at 6" I had him raise it way up to 5 feet in shade, N side. Keep snow from resting on sensor, mine is under my elec meter. I close airflow in summer with a damper and its mounted on the supply going back to the return. The unit you have is superior to non thermostat controled units by far. In fall clean the pad in CLR or similar acid solution.
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On Thu, 15 Dec 2005 06:56:26 -0600, snipped-for-privacy@webtv.net (m Ransley) wrote:

Dont mount the humidifier on the supply side. Your heating unit has many expensive electronic parts, none of which deal very well with leaking water. Dont clean the pad with CLR or anything else. They are less than $10. Sometimes you can use them more than one year but the manufacturer recommends that you toss it after 1 yr. Bubba
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Why not use CLR, lime away etc , it cleans them it is metal, and that is all you need. Its worked for years and is clear of any buildup. Leaks, mine if it did leak is far enough away from the furnace where water would not leak into it.
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On Thu, 15 Dec 2005 08:36:06 -0600, snipped-for-privacy@webtv.net (m Ransley) wrote:

Because they are not designed to be cleaned. Its not a serviceable part. It is meant to degrade. Thats why it starts turning into a crumbling mess. You'll notice the honeycomb shape of the pad. It is designed with and angled pattern to keep the water in the pad. Just for shits and giggle, install your pad upside down and turn the water on. Point being, they are easily prone to leaking, falling apart and making quite a mess. As an owner, technician, etc. I dont like callbacks and cleaning a pad would deifintely cause me many callbacks. Homeowners may choose to do this. Service companies wont.
Also, to the OP. Still dont believe it doesnt matter whether the humidifier is installed on the supply or retun duct? You are correct. It doesnt. Read the installation manual. It will tell you the same. Aprilaire nor any of the other humidifier manufacturers care if it leaks down into your furnace and causes damage. Wait till it leaks down into your Lennox or Carrier Variable speed unit. Especially under the furnace warranty. I hope you have lots and lots of money because that water shorted board will NOT be covered. Now are you catching on? Bubba
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Bubba wrote:

Excellent advice. Seems obvious, now that you mention it. Just the sort of thing you learn from experience!
Thank you
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snipped-for-privacy@hotmail.com wrote: ..

Yes, but Bubba comments make sense.
Make sure it is designed for either installation. Recheck the instructions to see if it indicates.

Yes, that is how it works and in my personal experience it works well.

--
Joseph Meehan

Dia duit
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"Would anybody who is currently running one of these in automatic mode, maintaining humidity without adjusting the dial or seeing condensation please report their success? Or if not, then report failure? "
I have the Aprilaire 760 with the outside temp sensor. I have a humidistat and can see that when it gets cold, the sensor does reduce the humidity by a small amount. I usually have it at about 58%. If it gets down into the low teens, it will lower to about 50 or so. Of course the problem is it doesn;t know the cold is coming. So if the temp drops quickly one day, you could still have some condensation because it will take a day or more for the humidity to adjust.
BTW, one reason I went with the fan powered 760 was the issue of moisture and the furnace. I'm not sure if a leak on one side of the furnace is any worse than a leak on the other side. But with the bypass type, you always have moist air going through the heat exchanger. Steel plus moisture is never a good combo. The 760 mounts only on the hot air plenum, so air from the humidifier never goest throught the furnace. On the other hand, I've never heard reports of pre-mature heat exchanger failure from a bypass humidifier, so whether it's a real problems remains unknown.
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On 15 Dec 2005 12:22:10 -0800, snipped-for-privacy@optonline.net wrote:

I can only lead you to the water. I cant make you drink it. Bubba
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My 760 is mounted on the return and works fine.
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snipped-for-privacy@optonline.net wrote:

If I read your answer correctly, even though you have the temp sensor installed, you mess with the setpoint. Did you actually observe condensation on your windows when you didn't do this?
If the outside temp sensor actually lets me use the humidifier without having to screw with the controls every few days, then I can mount the controls in the basement (where my wife doesn't have to look at it!).
However, if the outside temp sensor does a half-assed job of controlling humidity as advertised, the control is going in the living area, since we will be messing with it!
Thanks for sharing our experience.
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I set mine till there is no glass condensation, my humidity is well controled, My unit has to be mounted on a return, for me it is set and forget.
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I purchased and installed my 600 last year. I love the unit and easy to install. The duct is tapped into the supply and the water/pad is on the returned. Normally you would want this the other way around but my heater/air conditioning coils would not allow for that. I also check with the vendor and some mechanical engineering friends. This setup is not a major issue.
Be sure to hook the water solenoid to the heaters main (24v) supply so that the water comes on with the fan. They do make the inductor coils but I prefer the direct power source.
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On Fri, 16 Dec 2005 04:04:19 GMT, snipped-for-privacy@spam.invalid (mitchsklar) wrote:

<Normally you would want this the other way around>
WTF? Are you really that dumb? Think........."why would I not want to install the humidifier on the supply plenum where all the expensive electronics are directly below?" Why Oh Why Oh Why would I not want to do that? I'll give you a few moments on that one. (Hint: Think water and electricity) I'll continue to give you some time on that one. I dont want you to exert yourself too much. Bubba
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What is STFW? Shut the F'n Woman?
The ones I've installed have all gone on the return duct.
You'll need a bunch of tools that most home owners never need, such as red and green handled tin shears. Follow the directions in the package.
--

Christopher A. Young
Do good work.
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Stormin Mormon wrote:

STFW (Search the F... Web) is what you should do before you ask questions. Also, RTFM (Read the manual).
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