I'm installing an Aprilaire 600a on my antique [well- 1980 or so]
Sears? furnace.

So of course it doesn't have an 'eac' or 'hum' terminal. We don't
use it in 'fan only' mode anyway, so I thought it would be an easy
task to just hook the wires to the fan relay so the humidifier is
active when the fan is running.

I haven't hooked it up yet because I don't want to fry my electronics.
So I put my tester on what I thought would be a 24v fan circuit- but I
get no reading. . .

Operator error- or wrong assumption?
Here's a picture of the Honeywell R8184 relay
http://i289.photobucket.com/albums/l.../honeywell.jpg

I expected to find 24v on 'C' and 'G' - but get nothing. I tried the
AC scale, too just to see if I misunderstood the schematic. I get a
zero reading on that scale, too.

Can anyone tell me where I want to hook the humidifier to let it know
when the fan is on?

The humidifier 'installation instructions' show two wires hooked
either to "Hum" and common- or to 'W' and common.

Thanks,
Jim

On Wed, 29 Oct 2008 18:57:04 -0400, Jim Elbrecht
wrote:

I'm installing an Aprilaire 600a on my antique [well- 1980 or so]
Sears? furnace.

So of course it doesn't have an 'eac' or 'hum' terminal. We don't
use it in 'fan only' mode anyway, so I thought it would be an easy
task to just hook the wires to the fan relay so the humidifier is
active when the fan is running.

I haven't hooked it up yet because I don't want to fry my electronics.
So I put my tester on what I thought would be a 24v fan circuit- but I
get no reading. . .

Operator error- or wrong assumption?
Here's a picture of the Honeywell R8184 relay
http://i289.photobucket.com/albums/l.../honeywell.jpg

I expected to find 24v on 'C' and 'G' - but get nothing. I tried the
AC scale, too just to see if I misunderstood the schematic. I get a
zero reading on that scale, too.

Can anyone tell me where I want to hook the humidifier to let it know
when the fan is on?

The humidifier 'installation instructions' show two wires hooked
either to "Hum" and common- or to 'W' and common.

Thanks,
Jim

Yes, you should see ~24 VAC between G & C when the thermostat is
calling for heat. Was it when you did the test?

Paul F.

Paul Franklin wrote:

On Wed, 29 Oct 2008 18:57:04 -0400, Jim Elbrecht
wrote:
-snip-
Operator error- or wrong assumption?
Here's a picture of the Honeywell R8184 relay
http://i289.photobucket.com/albums/l.../honeywell.jpg

I expected to find 24v on 'C' and 'G' - but get nothing. I tried the
AC scale, too just to see if I misunderstood the schematic. I get a
zero reading on that scale, too.

-snip-
Yes, you should see ~24 VAC between G & C when the thermostat is
calling for heat. Was it when you did the test?

Yes- and I tried reversing my leads. I'll give it a go again
tomorrow. I just wanted to make sure I wasn't missing something
obvious.

Thanks,
Jim

Didn't they provide a little transformer? You really should get the power
from the blower circuit, so that the humidifier doesn't run during the warm
up period when the heat exchanger is coming up to temp. Though, in reality,
it won't make a lot of difference.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Jim Elbrecht" wrote in message
...
I'm installing an Aprilaire 600a on my antique [well- 1980 or so]
Sears? furnace.

So of course it doesn't have an 'eac' or 'hum' terminal. We don't
use it in 'fan only' mode anyway, so I thought it would be an easy
task to just hook the wires to the fan relay so the humidifier is
active when the fan is running.

I haven't hooked it up yet because I don't want to fry my electronics.
So I put my tester on what I thought would be a 24v fan circuit- but I
get no reading. . .

Operator error- or wrong assumption?
Here's a picture of the Honeywell R8184 relay
http://i289.photobucket.com/albums/l.../honeywell.jpg

I expected to find 24v on 'C' and 'G' - but get nothing. I tried the
AC scale, too just to see if I misunderstood the schematic. I get a
zero reading on that scale, too.

Can anyone tell me where I want to hook the humidifier to let it know
when the fan is on?

The humidifier 'installation instructions' show two wires hooked
either to "Hum" and common- or to 'W' and common.

Thanks,
Jim

Jim Elbrecht wrote:

I'm installing an Aprilaire 600a on my antique [well- 1980 or so]
Sears? furnace.

So of course it doesn't have an 'eac' or 'hum' terminal. We don't
use it in 'fan only' mode anyway, so I thought it would be an easy
task to just hook the wires to the fan relay so the humidifier is
active when the fan is running.

I haven't hooked it up yet because I don't want to fry my electronics.
So I put my tester on what I thought would be a 24v fan circuit- but I
get no reading. . .

Operator error- or wrong assumption?
Here's a picture of the Honeywell R8184 relay
http://i289.photobucket.com/albums/l.../honeywell.jpg

I expected to find 24v on 'C' and 'G' - but get nothing. I tried the
AC scale, too just to see if I misunderstood the schematic. I get a
zero reading on that scale, too.

Can anyone tell me where I want to hook the humidifier to let it know
when the fan is on?

The humidifier 'installation instructions' show two wires hooked
either to "Hum" and common- or to 'W' and common.

Thanks,
Jim
I just installed an AprilAire 700 earlier today on one of my my systems,
a Thermopride. I suspect it is wired in a similar fashion to yours.
Your photo is of what Honeywell refers to as an Oil Burner Control. It
has a relay inside but it is not the relay you want to hook the
AprilAire to. If you look you should find a Control Center (Honeywell
R8285...the suffix will probably be A or B). Since you aren't using the
fan (G) lead, the best way is to get a model 50 Current Sensing Relay
from either AprilAire or GeneralAire and use that to control the 24 volt
signal to the humidifier. As I recall I paid about $18 for the one I
bought.

All voltages coming from your thermostat will be ac. Measure using C as
your reference and from C to R should measure 24 vac, +/- (this is the
source.) C to W only when calling for heat will also be 24 vac. When
your thermostat's Fan switch is in the manual position then C to G will
measure 24 vac. Your blower is probably being turned on using 120 vac by
the Fan and Limit Control, Honeywell L4064, which is most likely
connected through the Control Center relay to the blower.

Boden

Jim Elbrecht wrote:
I'm installing an Aprilaire 600a on my antique [well- 1980 or so]
Sears? furnace.

So of course it doesn't have an 'eac' or 'hum' terminal. We don't
use it in 'fan only' mode anyway, so I thought it would be an easy
task to just hook the wires to the fan relay so the humidifier is
active when the fan is running.

I haven't hooked it up yet because I don't want to fry my electronics.
So I put my tester on what I thought would be a 24v fan circuit- but I
get no reading. . .

Operator error- or wrong assumption?
Here's a picture of the Honeywell R8184 relay
http://i289.photobucket.com/albums/l.../honeywell.jpg

I expected to find 24v on 'C' and 'G' - but get nothing. I tried the
AC scale, too just to see if I misunderstood the schematic. I get a
zero reading on that scale, too.

Can anyone tell me where I want to hook the humidifier to let it know
when the fan is on?

The humidifier 'installation instructions' show two wires hooked
either to "Hum" and common- or to 'W' and common.

Thanks,
Jim
HI,
Dom't try to tap 24V AC from the 'stat circuit. Use provided 24V
transformer connected to blower power leads. I installed 700a about a
month ago replacing old Lennox spray type humidifier. BTW, AC current is
not polarized. Reversing meter leads is meaningless!

On Wed, 29 Oct 2008 21:08:35 -0400, "Stormin Mormon"
wrote:

Didn't they provide a little transformer?

Yes- The transformer goes to a couple other terminals that need power
24/7. There are 8 terminals in all.

You really should get the power
from the blower circuit, so that the humidifier doesn't run during the warm
up period when the heat exchanger is coming up to temp. Though, in reality,
it won't make a lot of difference.


I think I've got it now- thanks,
Jim

Tony Hwang wrote:
-snip-

HI,
Dom't try to tap 24V AC from the 'stat circuit. Use provided 24V
transformer connected to blower power leads.

I think this is the way I'm going to go- but I'll need a new
transformer. The provided one needs to provide constant power & is
wired to a different circuit.

-snip-
BTW, AC current is
not polarized. Reversing meter leads is meaningless!

Smacks self in head Until I read that I was *expecting* the 24v to
be DC, but was checking for AC & DC on the terminals.

Thanks,
Jim

Boden wrote:

-snip-
Operator error- or wrong assumption?
Here's a picture of the Honeywell R8184 relay
http://i289.photobucket.com/albums/l.../honeywell.jpg

-snip-
I just installed an AprilAire 700 earlier today on one of my my systems,
a Thermopride. I suspect it is wired in a similar fashion to yours.
Your photo is of what Honeywell refers to as an Oil Burner Control. It
has a relay inside but it is not the relay you want to hook the
AprilAire to. If you look you should find a Control Center (Honeywell
R8285...

Aha- I found that one. I'm guessing the fan terminals on the one I
photographed sends a pulse to the other relay which switches the power
to the fan.

suffix will probably be A or B). Since you aren't using the
fan (G) lead, the best way is to get a model 50 Current Sensing Relay
from either AprilAire or GeneralAire and use that to control the 24 volt
signal to the humidifier. As I recall I paid about $18 for the one I
bought.

Looks like a transformer will be about the same. and I'll still be
able to use the 'change your water panel' idiot light. Tony
recommended hooking it right to the blower power leads.

All voltages coming from your thermostat will be ac. Measure using C as
your reference and from C to R should measure 24 vac, +/- (this is the
source.) C to W only when calling for heat will also be 24 vac.

I just noticed that the schematic has 3 wires to the t-stat. I have
2- W & R. I get 24v on c-r constantly. [also R & a few others, but
I've forgotten the details already]

I replaced that part 6 yrs ago- but copied the wiring that had been
existing for 15 yrs previous.

When
your thermostat's Fan switch is in the manual position then C to G will
measure 24 vac. Your blower is probably being turned on using 120 vac by
the Fan and Limit Control, Honeywell L4064, which is most likely
connected through the Control Center relay to the blower.

Looks likely- that's probably where I'll tap into the blower power
when I get the other transformer..

Thanks for your thoughts-
Jim

Boden wrote:
-snip-
measure 24 vac. Your blower is probably being turned on using 120 vac by
the Fan and Limit Control, Honeywell L4064, which is most likely
connected through the Control Center relay to the blower.


That's where I ended up going. Had a handy utility box already
mounted to tap into it. Bought a transformer at Lowes for $15. Wired
it up and all is well.

Thanks all-
Jim