i have an old furnasman gas furnace.

It has AC

there is a honeywell transformer screwed on to the electrical connection
enclosure i suspect it was installed when the ac was installed.

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.

is there a relay i can install to do this or is there something else i
need to do.

mr. spam wrote:

i have an old furnasman gas furnace.

It has AC

there is a honeywell transformer screwed on to the electrical connection
enclosure i suspect it was installed when the ac was installed.

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.

is there a relay i can install to do this or is there something else i
need to do.


Hi,
You need extra single pole double throw relay with proper coil rating.
This relay has to be controlled by original fan control signal/power.
When idle relay will supply power to lo speed lead on the motor, when
fan is called for by heat, the relay will energize to supplu power to hi
speed lead.

mr. spam wrote:

i have an old furnasman gas furnace.

It has AC

there is a honeywell transformer screwed on to the electrical connection
enclosure i suspect it was installed when the ac was installed.

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.

is there a relay i can install to do this or is there something else i
need to do.


I think many (most? all?) furnace/AC combinations already incorporate
dual speed fans. Are you sure it doesn't already have the capability
you seek? You might just need an appropriate thermostat.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

On Mon, 18 Feb 2008 19:03:00 -0600, CJT wrote:

mr. spam wrote:

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.

I think many (most? all?) furnace/AC combinations already incorporate
dual speed fans. Are you sure it doesn't already have the capability
you seek? You might just need an appropriate thermostat.

I believe you are correct. The heat uses the low speed and the AC the high
one.

Don www.donwiss.com (e-mail link at home page bottom).

Don Wiss wrote:
On Mon, 18 Feb 2008 19:03:00 -0600, CJT wrote:


mr. spam wrote:


I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.


I think many (most? all?) furnace/AC combinations already incorporate
dual speed fans. Are you sure it doesn't already have the capability
you seek? You might just need an appropriate thermostat.


I believe you are correct. The heat uses the low speed and the AC the high
one.

Don www.donwiss.com (e-mail link at home page bottom).

Actually mine has several speeds, not sure how many. only three can be
controlled from the thermostat however. By moving wires around on the
circuit board you can change which speeds are used for which events. I
think the way it is set up now, if you command the fan "on" from the
thermostat, it runs at a low speed, in "heat" mode it runs at a
medium-high speed, and on A/C it runs at the highest speed.

I have on occasion found it useful to command the fan on even when the
furnace is not running, e.g. if someone is doing a lot of cooking in the
kitchen on a cold day it can be cold upstairs because the thermostat is
on the first floor, keeping the air circulating not only cools the
kitchen but tends to even out the temperature throughout the house.

I've also completely closed the supply dampers on the first floor, but
that's primarily because of the dramatic difference in insulating
properties between the first floor (block walls with brick facing) and
the second floor (sticks 'n' shingles) - I do plan to have the second
floor insulated but not until I'm done fixing all the wiring.

Anyway back to the topic at hand... it sounds like the OP does need a
new thermostat, and probably also needs to pull a new cable between the
thermostat and furnace to allow for more functions. (typical heat only
scenario would only require two wires, but heat/cool/fan only would
require at least four.)

nate

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

On Mon, 18 Feb 2008 19:03:00 -0600, CJT wrote:

mr. spam wrote:

i have an old furnasman gas furnace.

It has AC

there is a honeywell transformer screwed on to the electrical connection
enclosure i suspect it was installed when the ac was installed.

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.

is there a relay i can install to do this or is there something else i
need to do.


I think many (most? all?) furnace/AC combinations already incorporate
dual speed fans. Are you sure it doesn't already have the capability
you seek? You might just need an appropriate thermostat.

My furnace has a 2-speed fan, although it isn't switched the same way
as the OP wanted. Low speed for heat. High speed for A/C or manual.
--
Mark Lloyd
http://notstupid.laughingsquid.com

"How could you ask me to believe in God when there's
absolutely no evidence that I can see?" -- Jodie Foster

Nate Nagel wrote:
Don Wiss wrote:

On Mon, 18 Feb 2008 19:03:00 -0600, CJT wrote:


mr. spam wrote:



I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all
the time in slow speed. then when the burner or the ac comes on it
will change to high speed.



I think many (most? all?) furnace/AC combinations already incorporate
dual speed fans. Are you sure it doesn't already have the capability
you seek? You might just need an appropriate thermostat.



I believe you are correct. The heat uses the low speed and the AC the
high
one.

Don www.donwiss.com (e-mail link at home page bottom).


Actually mine has several speeds, not sure how many. only three can be
controlled from the thermostat however. By moving wires around on the
circuit board you can change which speeds are used for which events. I
think the way it is set up now, if you command the fan "on" from the
thermostat, it runs at a low speed, in "heat" mode it runs at a
medium-high speed, and on A/C it runs at the highest speed.

I have on occasion found it useful to command the fan on even when the
furnace is not running, e.g. if someone is doing a lot of cooking in the
kitchen on a cold day it can be cold upstairs because the thermostat is
on the first floor, keeping the air circulating not only cools the
kitchen but tends to even out the temperature throughout the house.

I've also completely closed the supply dampers on the first floor, but
that's primarily because of the dramatic difference in insulating
properties between the first floor (block walls with brick facing) and
the second floor (sticks 'n' shingles) - I do plan to have the second
floor insulated but not until I'm done fixing all the wiring.

Anyway back to the topic at hand... it sounds like the OP does need a
new thermostat, and probably also needs to pull a new cable between the
thermostat and furnace to allow for more functions. (typical heat only
scenario would only require two wires, but heat/cool/fan only would
require at least four.)

nate

Hmmm,
My impression is OP has a OLD furnace which does not have multi-speed
fan and or elaborate electronics control board.

On Mon, 18 Feb 2008 21:05:47 -0500, Don Wiss
wrote:

On Mon, 18 Feb 2008 19:03:00 -0600, CJT wrote:

mr. spam wrote:

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.

I think many (most? all?) furnace/AC combinations already incorporate

Not mine, although it is quite old.

dual speed fans. Are you sure it doesn't already have the capability
you seek? You might just need an appropriate thermostat.

I believe you are correct. The heat uses the low speed and the AC the high
one.

Hmmm. That would mean that., if he has to change something in the
furnace (air handler?)** either he should make his change a little
more complicated, or he'll be using the high speed for heat as well as
AC. And I guess the designers don't think that is good. I'm not
assuming here that just because it's winter, his goal is to change the
heat and not the AC.

**And if he did half his testing in the summer and half in the winter,
he'd be especially likely to be wrong.

OP, do you plan to use this when the Fan switch on the thermostat is
in the ON position? Do you want High speed for the heat? I don't
know why they use high speed for the AC, but it seems to me that while
you would get more hot air with the fan on high in the winter, the hot
air wouldn't be as hot as if the fan were on low. So that part seems
like 6 of one, a half dozen of the other.


Don www.donwiss.com (e-mail link at home page bottom).

mm wrote:
On Mon, 18 Feb 2008 21:05:47 -0500, Don Wiss
wrote:


On Mon, 18 Feb 2008 19:03:00 -0600, CJT wrote:


mr. spam wrote:

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.

I think many (most? all?) furnace/AC combinations already incorporate


Not mine, although it is quite old.


dual speed fans. Are you sure it doesn't already have the capability
you seek? You might just need an appropriate thermostat.

I believe you are correct. The heat uses the low speed and the AC the high
one.


Hmmm. That would mean that., if he has to change something in the
furnace (air handler?)** either he should make his change a little
more complicated, or he'll be using the high speed for heat as well as
AC. And I guess the designers don't think that is good. I'm not
assuming here that just because it's winter, his goal is to change the
heat and not the AC.

**And if he did half his testing in the summer and half in the winter,
he'd be especially likely to be wrong.

OP, do you plan to use this when the Fan switch on the thermostat is
in the ON position? Do you want High speed for the heat? I don't
know why they use high speed for the AC, but it seems to me that while
you would get more hot air with the fan on high in the winter, the hot
air wouldn't be as hot as if the fan were on low. So that part seems
like 6 of one, a half dozen of the other.



Don www.donwiss.com (e-mail link at home page bottom).


Hi,
Law of physics. Heat input is fixed, output can't be increased by
increasing blower speed. Hot air is light, cold air is heavy. So
slow speed for heat, high speed for a/c.

On Mon, 18 Feb 2008 21:33:56 -0500, mm wrote:

On Mon, 18 Feb 2008 21:05:47 -0500, Don Wiss wrote:

I believe you are correct. The heat uses the low speed and the AC the high
one.

Hmmm. That would mean that., if he has to change something in the
furnace (air handler?)** either he should make his change a little
more complicated, or he'll be using the high speed for heat as well as
AC. And I guess the designers don't think that is good. I'm not
assuming here that just because it's winter, his goal is to change the
heat and not the AC.

As heat rises you don't need as much fan to push it up into the house. Cold
air is heavy, and more fan is needed.

The ideal for AC is a variable speed fan and variable speed compressor. It
would adjust itself to be always running and keeping the temperature at the
set point. Then maximum humidity is removed. The top of the line Carriers
now have this. But to install this AC you also have to replace the whole
furnace to get the variable speed fan.

Many (most?) new furnaces these days run at 80% efficiency. That Carrier
can get up to 90%, but only if you install special air intake and outtake
ducts. It needs outside air to get the efficiency up.

Don www.donwiss.com (e-mail link at home page bottom).

Tony Hwang wrote:
Nate Nagel wrote:
Don Wiss wrote:

On Mon, 18 Feb 2008 19:03:00 -0600, CJT
wrote:
mr. spam wrote:



I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all
the time in slow speed. then when the burner or the ac comes on
it will change to high speed.



I think many (most? all?) furnace/AC combinations already
incorporate dual speed fans. Are you sure it doesn't already have
the capability you seek? You might just need an appropriate
thermostat.



I believe you are correct. The heat uses the low speed and the AC
the high
one.

Don www.donwiss.com (e-mail link at home page bottom).


Actually mine has several speeds, not sure how many. only three can
be controlled from the thermostat however. By moving wires around
on the circuit board you can change which speeds are used for which
events. I think the way it is set up now, if you command the fan
"on" from the thermostat, it runs at a low speed, in "heat" mode it
runs at a medium-high speed, and on A/C it runs at the highest speed.

I have on occasion found it useful to command the fan on even when
the furnace is not running, e.g. if someone is doing a lot of
cooking in the kitchen on a cold day it can be cold upstairs because
the thermostat is on the first floor, keeping the air circulating
not only cools the kitchen but tends to even out the temperature
throughout the house. I've also completely closed the supply dampers on
the first floor,
but that's primarily because of the dramatic difference in insulating
properties between the first floor (block walls with brick facing)
and the second floor (sticks 'n' shingles) - I do plan to have the
second floor insulated but not until I'm done fixing all the wiring.

Anyway back to the topic at hand... it sounds like the OP does need a
new thermostat, and probably also needs to pull a new cable between
the thermostat and furnace to allow for more functions. (typical
heat only scenario would only require two wires, but heat/cool/fan
only would require at least four.)

nate

Hmmm,
My impression is OP has a OLD furnace which does not have multi-speed
fan and or elaborate electronics control board.

LOL

--
Zyp

Don Wiss wrote:
On Mon, 18 Feb 2008 19:03:00 -0600, CJT wrote:

mr. spam wrote:

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.

I think many (most? all?) furnace/AC combinations already incorporate
dual speed fans. Are you sure it doesn't already have the capability
you seek? You might just need an appropriate thermostat.

I believe you are correct. The heat uses the low speed and the AC the high
one.

Don www.donwiss.com (e-mail link at home page bottom).
guys its made in 1966 there was no 2 speed fans then

mr. spam wrote:
i have an old furnasman gas furnace.

It has AC

there is a honeywell transformer screwed on to the electrical connection
enclosure i suspect it was installed when the ac was installed.

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all the
time in slow speed. then when the burner or the ac comes on it will
change to high speed.

is there a relay i can install to do this or is there something else i
need to do.


ok this thing is vintage 1966

one speed fan motor

for both ac and heat

first guy was right i need a relay

i want to change motor to 2 speed so the fan runs continuously in low
speed and speeds up when the furnace calls for the fan to be on.

I know it needs a relay

i was looking for a part number / manufacturer of said relay

any ideas?

On Wed, 20 Feb 2008 02:27:24 GMT, "mr. spam" wrote:

ok this thing is vintage 1966

It must be horribly inefficient. Run of the mill new ones are 80%. I've
just learned that the Carrier Infinity with the outside air duct runs at
96.6%. Efficiency can be measured with a sniffing device that measures the
outtake air. I think it's time for you to upgrade.

Don www.donwiss.com (e-mail link at home page bottom).

mr. spam wrote:
Don Wiss wrote:

On Mon, 18 Feb 2008 19:03:00 -0600, CJT wrote:

mr. spam wrote:


I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all
the time in slow speed. then when the burner or the ac comes on it
will change to high speed.


I think many (most? all?) furnace/AC combinations already incorporate
dual speed fans. Are you sure it doesn't already have the capability
you seek? You might just need an appropriate thermostat.


I believe you are correct. The heat uses the low speed and the AC the
high
one.

Don www.donwiss.com (e-mail link at home page bottom).

guys its made in 1966 there was no 2 speed fans then

There also wasn't much central A/C. You sure the motor's that old?

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

mr. spam wrote:
Don Wiss wrote:
On Mon, 18 Feb 2008 19:03:00 -0600, CJT wrote:

mr. spam wrote:

I want to replace the fan motor with a 2 speed one

i want to add a switch to the furnace so i can have the fan on all
the time in slow speed. then when the burner or the ac comes on
it will change to high speed.

I think many (most? all?) furnace/AC combinations already
incorporate dual speed fans. Are you sure it doesn't already have
the capability you seek? You might just need an appropriate
thermostat.

I believe you are correct. The heat uses the low speed and the AC
the high one.

Don www.donwiss.com (e-mail link at home page bottom).
guys its made in 1966 there was no 2 speed fans then

"there was no?" great!

--
Zyp

Don Wiss wrote:
On Wed, 20 Feb 2008 02:27:24 GMT, "mr. spam" wrote:

ok this thing is vintage 1966

It must be horribly inefficient. Run of the mill new ones are 80%.
I've just learned that the Carrier Infinity with the outside air duct
runs at
96.6%. Efficiency can be measured with a sniffing device that
measures the outtake air. I think it's time for you to upgrade.

Don www.donwiss.com (e-mail link at home page bottom).

efficiency can be measured with a "sniffing device?" that measures the
outtake air? LOL

--
Zyp