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