On Jan 3, 7:29*am, Mikepier wrote:
On Jan 2, 8:21*pm, Mikepier wrote:

I have an Aprilaire hooked up to my furnace also, but it only comes on
when heat calls, not when the fan is running by itself. I just checked
the wiring on my furnace and the humidifier is hooked up to the W and
C terminals on the circuit board, so you can check if thats correct on
your furnace. You might have your humidifier wired up wrong and thats
why it comes on even if you only have the fan running.

My partucular model has no blower, it's mounted outside the return
plenum and it's only the 24VAC that opertes it.
I was not aware there are 120VAC models with blowers, so I have a
totally different animal than you.

That leaves me confused because previously you said the humidifier was
plugged into a 120V outlet on the furnace. The Aprilaire's I'm
familiar with that require 120V use powered fans and mount on the hot
side. The bypass models do not use 120V and mount on the return.

I have an Aprilaire powered unit that is connected the way you want.
When I installed it, I found 2 convenient 24V terminals that come on
when the gas burner is on. You should be able to do the same thing.

But, on another note, I'm wondering how energy efficient your whole
situation is. I would think constantly running the blower to even
out temp differences presents two problems:

1 - The blower constantly running uses a considerable amount of
electricity.

2 - Constantly moving room temp air through ducts has to result in
some additional heat loss, which I would think could be
considerable. For example, in my house the ducts run through the
basement, some up outside walls, where due to the ducts vs wall size,
mean those ducts have no insulation around them inside the walls,
etc. Also, most duct systems are far from perfect with some air
leakage, etc. The more air moved through there, the more loss.

I would suggest looking at:

balancing the system better by closing off some of the downstairs
registers, particularly those that are on a duct run that also serves
upstairs

consider getting booster fans, either the kind that sit at the
registers and come on automatically with the heat, or the kind that
you can insert into ducts and wire to the furnace blower or other AC

consider some small electric heaters upstairs to supplement the
existing heat