On Tuesday, November 25, 2014 9:25:35 AM UTC-5, wrote:
On Tuesday, November 25, 2014 7:58:57 AM UTC-5, trader_4 wrote:
On Monday, November 24, 2014 11:46:43 PM UTC-5, micky wrote:
On Mon, 24 Nov 2014 19:28:33 -0800 (PST), Hongyi Kang
wrote:


Thanks Edward, one of the websites Nate posted earlier:
http://home.fuse.net/clymer/water/rh.html=20

actually had the conversion between different temperature's RH. And I just=
finished the salt calibration of my hygrometer, it's actually measuring 70=
% instead of 75%, so I guess it is 5% off. The temperature of the air comi=
ng out of the hot register was between 95 and 102. Based on these, I think=
my humidifier is probably working fine, just not enough yet for my wife's =
problem. I'll ask the service tech and see if they could rewire the unit s=
o that it can run while the blower is on. Thanks!

That' a very good idea. I had a room AC when I lived in a very small
room and the AC was right next to my bed, and the fan ran all night even
if the air had cooled off and the compressor wasn't running. I hated
the noise.

I took off the cover, and just had to rearrange three slip-on
connectors. I didnt' have to cut or solder anything, and when the
compressor went off, the fan did too. Furnaces and humidifiers are
more spread out so it probably won't be that easy, but it can certainly
be done.

Actually you only need one wire with two ends.

There is probably a neutral wire from the humidifier to a common neutral
somewhere . You can leave that alone. All you need is a hot
wire that runs from the hot wire where the blower gets its power and
goes straight to the humidifier, where the hot wire from the furnace
control unit already connects to the humidifier. So the power
doesn't have to go through the furnace control unit.


Are you aware that he said he had a variable speed blower, which
today is likely ECM?

right.

and even with an old fashion multi speed blower there are complications. If you connect the humdifier directly to the blower motor, the humidifer will be fed with different voltages when the blower operates at different speeds.

The best way to deal with this is to add another relay to power the humidifer. A not so bad way to deal with it is to connect the humidifier to the HIGH speed tap. Then the humidifier will see full line voltage when the blower is on high and it will see LOWER line voltage when the blower is on low. This is not too bad usually. The worst thing you can do is connect the humidifer to a low speed tap. Then the voltage to the humdifier may get above 120 when the blower is on high speed, which can be very bad for the humidifer.

Bottom line, use a relay or be sure to connect to a the high speed tap and use a meter to check the voltage at the humidifer over all modes of operation.
Nothing is ever easy. :-)

Mark

Tony mentioned that those humidifiers should usually come with a little transformer which transforms 120V to 24V I suppose, and can be used to connect the blower power to the humidifier. I might be able to ask the contractor that?