Have a friend with an old Rheem gas furnace and also central A/C... was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently the furnace has a
Honeywell S8910U ignition module and a Honeywell 47-22481-81 fan control
board. Neither of these appear to have been original to the furnace
which is a Rheem RGEB-06EC-FS which apparently originally came with a
Honeywell S-890G ignition module and I neglected to copy down the part
number of the original fan controller board (which was on the schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier which
I started to get working for him but never wired up because I meant to
bodge something together to interlock it properly and never got around
to it - the house did not really seem to need extra humidification even
over the winter. But it's there and the unit itself functions so he'd
like it to be working...) The description says "The ST9120U can replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should recommend to
my friend that he order the part that I suggest above rather than the
direct replacement? It's $50-100 cheaper depending on source and will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Sounds reasonable to me. I've not worked on this kind of thing, but it
sounds reasonable.

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

"Nate Nagel" wrote in message
...
Have a friend with an old Rheem gas furnace and also central A/C... was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently the furnace has a
Honeywell S8910U ignition module and a Honeywell 47-22481-81 fan control
board. Neither of these appear to have been original to the furnace
which is a Rheem RGEB-06EC-FS which apparently originally came with a
Honeywell S-890G ignition module and I neglected to copy down the part
number of the original fan controller board (which was on the schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier which
I started to get working for him but never wired up because I meant to
bodge something together to interlock it properly and never got around
to it - the house did not really seem to need extra humidification even
over the winter. But it's there and the unit itself functions so he'd
like it to be working...) The description says "The ST9120U can replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should recommend to
my friend that he order the part that I suggest above rather than the
direct replacement? It's $50-100 cheaper depending on source and will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On 05/05/2012 09:29 PM, Nate Nagel wrote:
Have a friend with an old Rheem gas furnace and also central A/C... was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently the furnace has a
Honeywell S8910U ignition module and a Honeywell 47-22481-81 fan control
board. Neither of these appear to have been original to the furnace
which is a Rheem RGEB-06EC-FS which apparently originally came with a
Honeywell S-890G ignition module and I neglected to copy down the part
number of the original fan controller board (which was on the schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier which
I started to get working for him but never wired up because I meant to
bodge something together to interlock it properly and never got around
to it - the house did not really seem to need extra humidification even
over the winter. But it's there and the unit itself functions so he'd
like it to be working...) The description says "The ST9120U can replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should recommend to
my friend that he order the part that I suggest above rather than the
direct replacement? It's $50-100 cheaper depending on source and will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate


FWIW the original fan controller board was Honeywell ST788C as best I
can figure. (original diagram is smudged, I guessed ST780C or ST788C.
ST780C yields no hits and ST788C was apparently discontinued and
replaced by the 47-22481-81 number that is in there now. That may be a
Rheem/Ruud part number not a Honeywell part number however.)

I did drop Honeywell a line as I couldn't get anywhere with their online
parts cross reference - they don't recognize 47-22481-81 and they say
there is "no replacement" for the ST788C?

Am wondering if I could just replace both the fan control and hot
surface ignitor module with this guy

http://customer.honeywell.com/honeyw...spx/S9200U1000

I don't see why it wouldn't work, but it's not directly listed, and with
something like a furnace that makes me a little nervous...

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

It does, but the instructions for the ST9120U do not specifically show
it being used with a hot surface ignitor control module, and Honeywell
doesn't specifically list it to replace either the original fan control
or the one that's in there now. I would really hate to have the furnace
cause some kind of issue (what that would be, I don't know) and not have
documentation to support my choice of replacement parts. My friend
seems less concerned about this, but then again he's the guy with the 30
year old furnace (outdoor A/C unit looks newer; A-coil is definitely
vintage) and he seemed surprised that I even suggested he have a pro
come do an annual service/checkout on it since I don't have a gauge set
or the ability to detect leaks...

I guess when it comes to stuff that I'm not super comfortable with, and
especially other people's stuff, I like to have my ducks in a row.

nate

On 05/05/2012 09:54 PM, Stormin Mormon wrote:
Sounds reasonable to me. I've not worked on this kind of thing, but it
sounds reasonable.

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

"Nate wrote in message
...
Have a friend with an old Rheem gas furnace and also central A/C... was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently the furnace has a
Honeywell S8910U ignition module and a Honeywell 47-22481-81 fan control
board. Neither of these appear to have been original to the furnace
which is a Rheem RGEB-06EC-FS which apparently originally came with a
Honeywell S-890G ignition module and I neglected to copy down the part
number of the original fan controller board (which was on the schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier which
I started to get working for him but never wired up because I meant to
bodge something together to interlock it properly and never got around
to it - the house did not really seem to need extra humidification even
over the winter. But it's there and the unit itself functions so he'd
like it to be working...) The description says "The ST9120U can replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should recommend to
my friend that he order the part that I suggest above rather than the
direct replacement? It's $50-100 cheaper depending on source and will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate



--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On May 5, 10:52*pm, Nate Nagel wrote:
On 05/05/2012 09:29 PM, Nate Nagel wrote:









Have a friend with an old Rheem gasfurnaceand also central A/C... was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently thefurnacehas a
HoneywellS8910U ignition module and aHoneywell47-22481-81 fan control
board. Neither of these appear to have been original to thefurnace
which is a Rheem RGEB-06EC-FS which apparently originally came with a
HoneywellS-890G ignition module and I neglected to copy down the part
number of the original fan controller board (which was on the schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier which
I started to get working for him but never wired up because I meant to
bodge something together to interlock it properly and never got around
to it - the house did not really seem to need extra humidification even
over the winter. But it's there and the unit itself functions so he'd
like it to be working...) The description says "The ST9120U can replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should recommend to
my friend that he order the part that I suggest above rather than the
direct replacement? It's $50-100 cheaper depending on source and will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate

FWIW the original fan controller board wasHoneywellST788C as best I
can figure. *(original diagram is smudged, I guessed ST780C or ST788C.
ST780C yields no hits and ST788C was apparently discontinued and
replaced by the 47-22481-81 number that is in there now. *That may be a
Rheem/Ruud part number not aHoneywellpart number however.)

I did dropHoneywella line as I couldn't get anywhere with their online
parts cross reference - they don't recognize 47-22481-81 and they say
there is "no replacement" for the ST788C?

Am wondering if I could just replace both the fan control and hot
surface ignitor module with this guy

http://customer.honeywell.com/honeyw...spx/S9200U1000

I don't see why it wouldn't work, but it's not directly listed, and with
something like afurnacethat makes me a little nervous...

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

Ugh... well after finally talking to honeywell tech support
(apparently they will actually talk to you if you say you are an
engineer) I still didn't get the warm fuzzies (the answer was
basically something like "eh, it should work") but the price diff was
so dramatic that I went ahead and ordered the universal board
anyway... showed up yesterday along with a new run cap, tore apart the
spaghetti in the old controls box in preparation to get this
working... now it appears that I have to also retrofit a flame sensor
to this POS because the old ignition control somehow used the ignitor
itself as a flame sensor and this new one doesn't... wish they'd have
told me that over the phone... even though they're both Honeywell
parts and I read off everything that I had to the guy.

....or is there something easy and obvious that I'm overlooking here?

nate

On Sat, 19 May 2012 08:27:25 -0700 (PDT), N8N
wrote:

On May 5, 10:52Â*pm, Nate Nagel wrote:
On 05/05/2012 09:29 PM, Nate Nagel wrote:









Have a friend with an old Rheem gasfurnaceand also central A/C... was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently thefurnacehas a
HoneywellS8910U ignition module and aHoneywell47-22481-81 fan control
board. Neither of these appear to have been original to thefurnace
which is a Rheem RGEB-06EC-FS which apparently originally came with a
HoneywellS-890G ignition module and I neglected to copy down the part
number of the original fan controller board (which was on the schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier which
I started to get working for him but never wired up because I meant to
bodge something together to interlock it properly and never got around
to it - the house did not really seem to need extra humidification even
over the winter. But it's there and the unit itself functions so he'd
like it to be working...) The description says "The ST9120U can replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should recommend to
my friend that he order the part that I suggest above rather than the
direct replacement? It's $50-100 cheaper depending on source and will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate

FWIW the original fan controller board wasHoneywellST788C as best I
can figure. Â*(original diagram is smudged, I guessed ST780C or ST788C.
ST780C yields no hits and ST788C was apparently discontinued and
replaced by the 47-22481-81 number that is in there now. Â*That may be a
Rheem/Ruud part number not aHoneywellpart number however.)

I did dropHoneywella line as I couldn't get anywhere with their online
parts cross reference - they don't recognize 47-22481-81 and they say
there is "no replacement" for the ST788C?

Am wondering if I could just replace both the fan control and hot
surface ignitor module with this guy

http://customer.honeywell.com/honeyw...spx/S9200U1000

I don't see why it wouldn't work, but it's not directly listed, and with
something like afurnacethat makes me a little nervous...

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

Ugh... well after finally talking to honeywell tech support
(apparently they will actually talk to you if you say you are an
engineer) I still didn't get the warm fuzzies (the answer was
basically something like "eh, it should work") but the price diff was
so dramatic that I went ahead and ordered the universal board
anyway... showed up yesterday along with a new run cap, tore apart the
spaghetti in the old controls box in preparation to get this
working... now it appears that I have to also retrofit a flame sensor
to this POS because the old ignition control somehow used the ignitor
itself as a flame sensor and this new one doesn't... wish they'd have
told me that over the phone... even though they're both Honeywell
parts and I read off everything that I had to the guy.

...or is there something easy and obvious that I'm overlooking here?

nate

Yeah. Calling in a HVAC repair pro.
I know this a DIY group.
But sometimes just using a pro is faster, safer, AND less expensive.
That's what I did when I got stumped on my furnace.
If you're really into it, stay on your path.
Just remember 2 engineers talking got you nowhere.
One "good" HVAC repair guy who's fixed that model furnace 30 times is
probably better than 30 engineers in this case - with one hand tied
behind his back. I saw that in action on my furnace.

--
Vic

On 05/19/2012 01:18 PM, Vic Smith wrote:
On Sat, 19 May 2012 08:27:25 -0700 (PDT),
wrote:

On May 5, 10:52 pm, Nate wrote:
On 05/05/2012 09:29 PM, Nate Nagel wrote:









Have a friend with an old Rheem gasfurnaceand also central A/C... was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently thefurnacehas a
HoneywellS8910U ignition module and aHoneywell47-22481-81 fan control
board. Neither of these appear to have been original to thefurnace
which is a Rheem RGEB-06EC-FS which apparently originally came with a
HoneywellS-890G ignition module and I neglected to copy down the part
number of the original fan controller board (which was on the schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier which
I started to get working for him but never wired up because I meant to
bodge something together to interlock it properly and never got around
to it - the house did not really seem to need extra humidification even
over the winter. But it's there and the unit itself functions so he'd
like it to be working...) The description says "The ST9120U can replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should recommend to
my friend that he order the part that I suggest above rather than the
direct replacement? It's $50-100 cheaper depending on source and will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate

FWIW the original fan controller board wasHoneywellST788C as best I
can figure. (original diagram is smudged, I guessed ST780C or ST788C.
ST780C yields no hits and ST788C was apparently discontinued and
replaced by the 47-22481-81 number that is in there now. That may be a
Rheem/Ruud part number not aHoneywellpart number however.)

I did dropHoneywella line as I couldn't get anywhere with their online
parts cross reference - they don't recognize 47-22481-81 and they say
there is "no replacement" for the ST788C?

Am wondering if I could just replace both the fan control and hot
surface ignitor module with this guy

http://customer.honeywell.com/honeyw...spx/S9200U1000

I don't see why it wouldn't work, but it's not directly listed, and with
something like afurnacethat makes me a little nervous...

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

Ugh... well after finally talking to honeywell tech support
(apparently they will actually talk to you if you say you are an
engineer) I still didn't get the warm fuzzies (the answer was
basically something like "eh, it should work") but the price diff was
so dramatic that I went ahead and ordered the universal board
anyway... showed up yesterday along with a new run cap, tore apart the
spaghetti in the old controls box in preparation to get this
working... now it appears that I have to also retrofit a flame sensor
to this POS because the old ignition control somehow used the ignitor
itself as a flame sensor and this new one doesn't... wish they'd have
told me that over the phone... even though they're both Honeywell
parts and I read off everything that I had to the guy.

...or is there something easy and obvious that I'm overlooking here?

nate

Yeah. Calling in a HVAC repair pro.
I know this a DIY group.
But sometimes just using a pro is faster, safer, AND less expensive.
That's what I did when I got stumped on my furnace.
If you're really into it, stay on your path.
Just remember 2 engineers talking got you nowhere.
One "good" HVAC repair guy who's fixed that model furnace 30 times is
probably better than 30 engineers in this case - with one hand tied
behind his back. I saw that in action on my furnace.


I hear that... but the owner of this mess is, um, frugal (he makes me
look extravagant) and at this point it's a personal challenge.

I've already ordered a flame sensor retrofit kit... to date the total
parts bill is less than $100 and I've already got the A/C back on and
working. I know the heat won't work until I get the flame sensor in and
I also still have to figure out the stopped drain valve wiring as it was
a bit odd in the original installation. But I seriously doubt heat will
be required any time in the next six months.

Also, I am curious about something... this is a Honeywell control wired
to a Honeywell thermostat, so you'd think that everything would work
swimmingly, but when I originally tore into this I found "C" not landed
on the thermostat and the thermostat running off batteries. I landed
"C" at the thermostat and found that the thermostat would still not
power off the 24V xfmr. only batteries (if you took the batteries out it
would power down.) Now I have the new control in, same thing. Only
thing I can think is some weird interaction with the A/C contactor? (am
online from there now and don't want to power down A/C at the moment it
is actively cooling the house back down to the temp it should be.)

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On 05/19/2012 02:31 PM, Nate Nagel wrote:
On 05/19/2012 01:18 PM, Vic Smith wrote:
On Sat, 19 May 2012 08:27:25 -0700 (PDT),
wrote:

On May 5, 10:52 pm, Nate wrote:
On 05/05/2012 09:29 PM, Nate Nagel wrote:









Have a friend with an old Rheem gasfurnaceand also central A/C... was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently thefurnacehas a
HoneywellS8910U ignition module and aHoneywell47-22481-81 fan control
board. Neither of these appear to have been original to thefurnace
which is a Rheem RGEB-06EC-FS which apparently originally came with a
HoneywellS-890G ignition module and I neglected to copy down the part
number of the original fan controller board (which was on the
schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling
for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier
which
I started to get working for him but never wired up because I meant to
bodge something together to interlock it properly and never got around
to it - the house did not really seem to need extra humidification
even
over the winter. But it's there and the unit itself functions so he'd
like it to be working...) The description says "The ST9120U can
replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should
recommend to
my friend that he order the part that I suggest above rather than the
direct replacement? It's $50-100 cheaper depending on source and will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate

FWIW the original fan controller board wasHoneywellST788C as best I
can figure. (original diagram is smudged, I guessed ST780C or ST788C.
ST780C yields no hits and ST788C was apparently discontinued and
replaced by the 47-22481-81 number that is in there now. That may be a
Rheem/Ruud part number not aHoneywellpart number however.)

I did dropHoneywella line as I couldn't get anywhere with their online
parts cross reference - they don't recognize 47-22481-81 and they say
there is "no replacement" for the ST788C?

Am wondering if I could just replace both the fan control and hot
surface ignitor module with this guy

http://customer.honeywell.com/honeyw...spx/S9200U1000

I don't see why it wouldn't work, but it's not directly listed, and
with
something like afurnacethat makes me a little nervous...

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

Ugh... well after finally talking to honeywell tech support
(apparently they will actually talk to you if you say you are an
engineer) I still didn't get the warm fuzzies (the answer was
basically something like "eh, it should work") but the price diff was
so dramatic that I went ahead and ordered the universal board
anyway... showed up yesterday along with a new run cap, tore apart the
spaghetti in the old controls box in preparation to get this
working... now it appears that I have to also retrofit a flame sensor
to this POS because the old ignition control somehow used the ignitor
itself as a flame sensor and this new one doesn't... wish they'd have
told me that over the phone... even though they're both Honeywell
parts and I read off everything that I had to the guy.

...or is there something easy and obvious that I'm overlooking here?

nate

Yeah. Calling in a HVAC repair pro.
I know this a DIY group.
But sometimes just using a pro is faster, safer, AND less expensive.
That's what I did when I got stumped on my furnace.
If you're really into it, stay on your path.
Just remember 2 engineers talking got you nowhere.
One "good" HVAC repair guy who's fixed that model furnace 30 times is
probably better than 30 engineers in this case - with one hand tied
behind his back. I saw that in action on my furnace.


I hear that... but the owner of this mess is, um, frugal (he makes me
look extravagant) and at this point it's a personal challenge.

I've already ordered a flame sensor retrofit kit... to date the total
parts bill is less than $100 and I've already got the A/C back on and
working. I know the heat won't work until I get the flame sensor in and
I also still have to figure out the stopped drain valve wiring as it was
a bit odd in the original installation. But I seriously doubt heat will
be required any time in the next six months.

Also, I am curious about something... this is a Honeywell control wired
to a Honeywell thermostat, so you'd think that everything would work
swimmingly, but when I originally tore into this I found "C" not landed
on the thermostat and the thermostat running off batteries. I landed "C"
at the thermostat and found that the thermostat would still not power
off the 24V xfmr. only batteries (if you took the batteries out it would
power down.) Now I have the new control in, same thing. Only thing I can
think is some weird interaction with the A/C contactor? (am online from
there now and don't want to power down A/C at the moment it is actively
cooling the house back down to the temp it should be.)

nate


Never mind the latter... I found the point where the thermostat and
contactor wires were spliced together (not inside the furnace) and the
blue wire going up to the thermo was never connected to the common of
the fan control/contactor. One problem solved (hopefully) I went ahead
and powered down to make that connection... waiting for A/C compressor
timeout to see if it kicks back on OK. Guess whoever wired it up
originally didn't land that wire because house originally had one of
those round thermostats, and whoever installed the new thermostat didn't
put much time into troubleshooting it.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On 05/19/2012 02:58 PM, Nate Nagel wrote:
On 05/19/2012 02:31 PM, Nate Nagel wrote:
On 05/19/2012 01:18 PM, Vic Smith wrote:
On Sat, 19 May 2012 08:27:25 -0700 (PDT),
wrote:

On May 5, 10:52 pm, Nate wrote:
On 05/05/2012 09:29 PM, Nate Nagel wrote:









Have a friend with an old Rheem gasfurnaceand also central A/C... was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently thefurnacehas a
HoneywellS8910U ignition module and aHoneywell47-22481-81 fan control
board. Neither of these appear to have been original to thefurnace
which is a Rheem RGEB-06EC-FS which apparently originally came with a
HoneywellS-890G ignition module and I neglected to copy down the part
number of the original fan controller board (which was on the
schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling
for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than
directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier
which
I started to get working for him but never wired up because I
meant to
bodge something together to interlock it properly and never got
around
to it - the house did not really seem to need extra humidification
even
over the winter. But it's there and the unit itself functions so he'd
like it to be working...) The description says "The ST9120U can
replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but
I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should
recommend to
my friend that he order the part that I suggest above rather than the
direct replacement? It's $50-100 cheaper depending on source and will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate

FWIW the original fan controller board wasHoneywellST788C as best I
can figure. (original diagram is smudged, I guessed ST780C or ST788C.
ST780C yields no hits and ST788C was apparently discontinued and
replaced by the 47-22481-81 number that is in there now. That may be a
Rheem/Ruud part number not aHoneywellpart number however.)

I did dropHoneywella line as I couldn't get anywhere with their online
parts cross reference - they don't recognize 47-22481-81 and they say
there is "no replacement" for the ST788C?

Am wondering if I could just replace both the fan control and hot
surface ignitor module with this guy

http://customer.honeywell.com/honeyw...spx/S9200U1000

I don't see why it wouldn't work, but it's not directly listed, and
with
something like afurnacethat makes me a little nervous...

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

Ugh... well after finally talking to honeywell tech support
(apparently they will actually talk to you if you say you are an
engineer) I still didn't get the warm fuzzies (the answer was
basically something like "eh, it should work") but the price diff was
so dramatic that I went ahead and ordered the universal board
anyway... showed up yesterday along with a new run cap, tore apart the
spaghetti in the old controls box in preparation to get this
working... now it appears that I have to also retrofit a flame sensor
to this POS because the old ignition control somehow used the ignitor
itself as a flame sensor and this new one doesn't... wish they'd have
told me that over the phone... even though they're both Honeywell
parts and I read off everything that I had to the guy.

...or is there something easy and obvious that I'm overlooking here?

nate

Yeah. Calling in a HVAC repair pro.
I know this a DIY group.
But sometimes just using a pro is faster, safer, AND less expensive.
That's what I did when I got stumped on my furnace.
If you're really into it, stay on your path.
Just remember 2 engineers talking got you nowhere.
One "good" HVAC repair guy who's fixed that model furnace 30 times is
probably better than 30 engineers in this case - with one hand tied
behind his back. I saw that in action on my furnace.


I hear that... but the owner of this mess is, um, frugal (he makes me
look extravagant) and at this point it's a personal challenge.

I've already ordered a flame sensor retrofit kit... to date the total
parts bill is less than $100 and I've already got the A/C back on and
working. I know the heat won't work until I get the flame sensor in and
I also still have to figure out the stopped drain valve wiring as it was
a bit odd in the original installation. But I seriously doubt heat will
be required any time in the next six months.

Also, I am curious about something... this is a Honeywell control wired
to a Honeywell thermostat, so you'd think that everything would work
swimmingly, but when I originally tore into this I found "C" not landed
on the thermostat and the thermostat running off batteries. I landed "C"
at the thermostat and found that the thermostat would still not power
off the 24V xfmr. only batteries (if you took the batteries out it would
power down.) Now I have the new control in, same thing. Only thing I can
think is some weird interaction with the A/C contactor? (am online from
there now and don't want to power down A/C at the moment it is actively
cooling the house back down to the temp it should be.)

nate


Never mind the latter... I found the point where the thermostat and
contactor wires were spliced together (not inside the furnace) and the
blue wire going up to the thermo was never connected to the common of
the fan control/contactor. One problem solved (hopefully) I went ahead
and powered down to make that connection... waiting for A/C compressor
timeout to see if it kicks back on OK. Guess whoever wired it up
originally didn't land that wire because house originally had one of
those round thermostats, and whoever installed the new thermostat didn't
put much time into troubleshooting it.

nate


Should have mentioned I was using the Fluke meter and not the Simpson up
at the thermostat and I found the voltage between red and blue to vary
but not to be zero... bet if I'd used the Simpson I would have suspected
an open in the first place. C'est la vie. So used to low voltage that
I work on being DC that I forgot that this was AC. Lessons...

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On 05/19/2012 03:14 PM, Nate Nagel wrote:
On 05/19/2012 02:58 PM, Nate Nagel wrote:
On 05/19/2012 02:31 PM, Nate Nagel wrote:
On 05/19/2012 01:18 PM, Vic Smith wrote:
On Sat, 19 May 2012 08:27:25 -0700 (PDT),
wrote:

On May 5, 10:52 pm, Nate wrote:
On 05/05/2012 09:29 PM, Nate Nagel wrote:









Have a friend with an old Rheem gasfurnaceand also central A/C...
was
messing with it today because his air handler wasn't running on a
cooling call and therefore his A/C was all iced up and the house was
nice and warm. Thermostat checks out OK, currently thefurnacehas a
HoneywellS8910U ignition module and aHoneywell47-22481-81 fan
control
board. Neither of these appear to have been original to thefurnace
which is a Rheem RGEB-06EC-FS which apparently originally came
with a
HoneywellS-890G ignition module and I neglected to copy down the
part
number of the original fan controller board (which was on the
schematic
on the box cover) but I believe that the one that is in there is
actually the recommended service replacement.

Here's my question. I believe that the fault is in the fan
controller
board; I am getting control voltage on "G" when the fan is manually
turned on at the thermostat and also when the thermostat is calling
for
cooling but the fan does not run. I made a kludgy little harness to
force the fan to run 24/7 so he can have cooling. Rather than
directly
replacing the fan controller, I found this online:

http://customer.honeywell.com/honeyw...px/ST9120U1011

Looks like a universal replacement for the same function, and has
the
benefit of providing "HUM" and "EAC" terminals as well which is nice
(the old control does not have that, and he does have a humidifier
which
I started to get working for him but never wired up because I
meant to
bodge something together to interlock it properly and never got
around
to it - the house did not really seem to need extra humidification
even
over the winter. But it's there and the unit itself functions so
he'd
like it to be working...) The description says "The ST9120U can
replace
any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below" but
I'll
be damned if I can find Table 3.

Could someone more HVAC literate than I tell me if I should
recommend to
my friend that he order the part that I suggest above rather than
the
direct replacement? It's $50-100 cheaper depending on source and
will
make getting the humidifier working again a hell of a lot easier.

thanks,

Nate

FWIW the original fan controller board wasHoneywellST788C as best I
can figure. (original diagram is smudged, I guessed ST780C or ST788C.
ST780C yields no hits and ST788C was apparently discontinued and
replaced by the 47-22481-81 number that is in there now. That may
be a
Rheem/Ruud part number not aHoneywellpart number however.)

I did dropHoneywella line as I couldn't get anywhere with their
online
parts cross reference - they don't recognize 47-22481-81 and they say
there is "no replacement" for the ST788C?

Am wondering if I could just replace both the fan control and hot
surface ignitor module with this guy

http://customer.honeywell.com/honeyw...spx/S9200U1000

I don't see why it wouldn't work, but it's not directly listed, and
with
something like afurnacethat makes me a little nervous...

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

Ugh... well after finally talking to honeywell tech support
(apparently they will actually talk to you if you say you are an
engineer) I still didn't get the warm fuzzies (the answer was
basically something like "eh, it should work") but the price diff was
so dramatic that I went ahead and ordered the universal board
anyway... showed up yesterday along with a new run cap, tore apart the
spaghetti in the old controls box in preparation to get this
working... now it appears that I have to also retrofit a flame sensor
to this POS because the old ignition control somehow used the ignitor
itself as a flame sensor and this new one doesn't... wish they'd have
told me that over the phone... even though they're both Honeywell
parts and I read off everything that I had to the guy.

...or is there something easy and obvious that I'm overlooking here?

nate

Yeah. Calling in a HVAC repair pro.
I know this a DIY group.
But sometimes just using a pro is faster, safer, AND less expensive.
That's what I did when I got stumped on my furnace.
If you're really into it, stay on your path.
Just remember 2 engineers talking got you nowhere.
One "good" HVAC repair guy who's fixed that model furnace 30 times is
probably better than 30 engineers in this case - with one hand tied
behind his back. I saw that in action on my furnace.


I hear that... but the owner of this mess is, um, frugal (he makes me
look extravagant) and at this point it's a personal challenge.

I've already ordered a flame sensor retrofit kit... to date the total
parts bill is less than $100 and I've already got the A/C back on and
working. I know the heat won't work until I get the flame sensor in and
I also still have to figure out the stopped drain valve wiring as it was
a bit odd in the original installation. But I seriously doubt heat will
be required any time in the next six months.

Also, I am curious about something... this is a Honeywell control wired
to a Honeywell thermostat, so you'd think that everything would work
swimmingly, but when I originally tore into this I found "C" not landed
on the thermostat and the thermostat running off batteries. I landed "C"
at the thermostat and found that the thermostat would still not power
off the 24V xfmr. only batteries (if you took the batteries out it would
power down.) Now I have the new control in, same thing. Only thing I can
think is some weird interaction with the A/C contactor? (am online from
there now and don't want to power down A/C at the moment it is actively
cooling the house back down to the temp it should be.)

nate


Never mind the latter... I found the point where the thermostat and
contactor wires were spliced together (not inside the furnace) and the
blue wire going up to the thermo was never connected to the common of
the fan control/contactor. One problem solved (hopefully) I went ahead
and powered down to make that connection... waiting for A/C compressor
timeout to see if it kicks back on OK. Guess whoever wired it up
originally didn't land that wire because house originally had one of
those round thermostats, and whoever installed the new thermostat didn't
put much time into troubleshooting it.

nate


Should have mentioned I was using the Fluke meter and not the Simpson up
at the thermostat and I found the voltage between red and blue to vary
but not to be zero... bet if I'd used the Simpson I would have suspected
an open in the first place. C'est la vie. So used to low voltage that I
work on being DC that I forgot that this was AC. Lessons...

nate


....aaand in the same place as the splice previously mentioned, the
yellow from thermostat was never connected to fan control, so when A/C
was commanded, only the green wire was turning the fan on, so in A/C
mode the fan was running in heat speed... waiting for it to cycle back
on to see if there's a noticeable improvement (I hope so, I was actually
thinking that the fan didn't seem noticeably faster in A/C, guess I was
right!)

I can't imagine that that was good for the A-coil, but it's ancient and
still kickin'

nate


--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On Sat, 19 May 2012 15:31:33 -0400, Nate Nagel
wrote:



...aaand in the same place as the splice previously mentioned, the
yellow from thermostat was never connected to fan control, so when A/C
was commanded, only the green wire was turning the fan on, so in A/C
mode the fan was running in heat speed... waiting for it to cycle back
on to see if there's a noticeable improvement (I hope so, I was actually
thinking that the fan didn't seem noticeably faster in A/C, guess I was
right!)

I can't imagine that that was good for the A-coil, but it's ancient and
still kickin'


Sounds like you're having fun. Wasn't for me.
The fan only worked on slow speed. No question all wiring was good.
I did the tapping on the MB relays with a screwdriver handle to no
effect.
The guy I called in - $75 for the call, deducted if he did more work -
had it running right in about 20 seconds.
He just powered it off, stuck his hands in there, turned it back on,
and it worked.
I told him you're a f**king genius, what did you do?
He said he twisted the MB, and that freed the relay.
I had him replace the MB, since it could happen again at a bad time.
Cost $450 total, board was $320. MB came with new flame sensor.
As a bonus, I haven't had to clean the flame sensor or touch the unit
since then, about 4 years..
Either the original flame sensor or the MB was flaky. At least twice
a year it would get cold in the house, starting the year I had it put
in. Drove my wife crazy, and she worked that on me.
Usually cleaning the flame sensor would fix it, but I also replaced
the purge valve, which is part of the start cycle.
Cheap, but I spent a lot of time horsing around with the thing.
Good luck on getting the new flame sensor configuration working.
Those IC's can be tricky.
Hope it's not a case where a good HVAC guy would say "Won't work."

--
Vic

On 05/19/2012 05:07 PM, Vic Smith wrote:
On Sat, 19 May 2012 15:31:33 -0400, Nate
wrote:



...aaand in the same place as the splice previously mentioned, the
yellow from thermostat was never connected to fan control, so when A/C
was commanded, only the green wire was turning the fan on, so in A/C
mode the fan was running in heat speed... waiting for it to cycle back
on to see if there's a noticeable improvement (I hope so, I was actually
thinking that the fan didn't seem noticeably faster in A/C, guess I was
right!)

I can't imagine that that was good for the A-coil, but it's ancient and
still kickin'


Sounds like you're having fun. Wasn't for me.
The fan only worked on slow speed. No question all wiring was good.
I did the tapping on the MB relays with a screwdriver handle to no
effect.
The guy I called in - $75 for the call, deducted if he did more work -
had it running right in about 20 seconds.
He just powered it off, stuck his hands in there, turned it back on,
and it worked.
I told him you're a f**king genius, what did you do?
He said he twisted the MB, and that freed the relay.
I had him replace the MB, since it could happen again at a bad time.
Cost $450 total, board was $320. MB came with new flame sensor.
As a bonus, I haven't had to clean the flame sensor or touch the unit
since then, about 4 years..
Either the original flame sensor or the MB was flaky. At least twice
a year it would get cold in the house, starting the year I had it put
in. Drove my wife crazy, and she worked that on me.
Usually cleaning the flame sensor would fix it, but I also replaced
the purge valve, which is part of the start cycle.
Cheap, but I spent a lot of time horsing around with the thing.
Good luck on getting the new flame sensor configuration working.
Those IC's can be tricky.
Hope it's not a case where a good HVAC guy would say "Won't work."


A good HVAC guy would run screaming from this setup. Furnace passed its
"best before" date about 15 years ago, although it is a "90 plus" unit
so as long as the heat exchanger holds together it's not costing him a
lot of money in fuel vs. a new unit. A-coil doesn't look much newer;
may even pre-date furnace. Outside A/C unit actually looks fairly good
and quasi-recent. I cleaned everything and went over it with a fin
rake, and of course blew out all the drains so the electronics don't
take a crap again. I hope to get this stuff working 100% without
spending any more $ and have already advised owner to start socking
money away for eventual replacement next time something breaks. I
suspect next failure will either be heat exchanger, air handler fan, or
a-coil, and in my mind at least failure of any would prompt replacement
of the entire containing unit of the affected component as everything
is, um, antique.

Owner also wants humidifier to work correctly which it hasn't in ages (I
found it valved off) I'll get that working although honestly I doubt it
will ever kick in. I put some little humidor hygrometers around the
place over the winter and the Rh never dropped below 50%.0 (that's what
I did at the last place that I owned; used them to dial in the
humidifier on the furnace and the dehumidifier that sat next to it that
was required in the summertime. I had that place tuned so that if you
set the thermostat on "auto" you could be comfortable 24/7 without ever
having to touch anything.) But it'll look nice if he ever goes to sell
the joint.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel