1995 Lennox Pulse 21 furnace. Ironically I did everything from welding
the heat exchanger to assembling it to installing it in my house. I am
not an HVAC tech or an engineer.
The other day I noticed my second problem. A couple of years ago the
blower motor failed. Had to replace it with an upgraded motor as the OEM
was unavailable at the factory. Very successful operation. I also
replaced the air flapper as the old one was caked with dirt.
Last week I noticed it was short cycling. The purge blower would run and
the for about 5 seconds it would try to fire. Then it would go silent,
then the purge blower would run. Then the cycle would repeat. Anyway, I
found that if I have the thermostat set at 75 deg instead of the 68 deg
I usually run it at, it fires and cycles just fine.
Weird.
Before I call a real tech, does anyone think the problem could lie in
the electronic thermostat?

Thanks.

On 2/25/2010 5:44 PM, zimpzampzormp wrote:
1995 Lennox Pulse 21 furnace. Ironically I did everything from welding
the heat exchanger to assembling it to installing it in my house. I am
not an HVAC tech or an engineer.
The other day I noticed my second problem. A couple of years ago the
blower motor failed. Had to replace it with an upgraded motor as the OEM
was unavailable at the factory. Very successful operation. I also
replaced the air flapper as the old one was caked with dirt.
Last week I noticed it was short cycling. The purge blower would run and
the for about 5 seconds it would try to fire. Then it would go silent,
then the purge blower would run. Then the cycle would repeat. Anyway, I
found that if I have the thermostat set at 75 deg instead of the 68 deg
I usually run it at, it fires and cycles just fine.
Weird.
Before I call a real tech, does anyone think the problem could lie in
the electronic thermostat?

Thanks.


And I inspect the heating coil return bends for leaks every year. Mine
is the model that had the improved brazing material.

By "purge blower" I presume you mean the blower
which blows air into the combustion chamber. What
happens when it "tries to fire"? Does the hot
surface ignitor glow, and the gas valve open?

So, you say that when you turn the thermostat up
hard and far, the furnace runs?

Of course, there are two fans. One to supply air
to the fire. And one to blow heat into the
building. Some of the more complicated furnace use
a timer, to turn on the blower fan that blows the
heat into the building. I can't comment on the
Lennox, never worked with that brand. Others use a
heat sensor, or other device to know when to turn
on the hot air blower.

A tech with Lennox experience would be more help.
Too much electronics.

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


"zimpzampzormp"
wrote in message
...
1995 Lennox Pulse 21 furnace. Ironically I did
everything from welding
the heat exchanger to assembling it to installing
it in my house. I am
not an HVAC tech or an engineer.
The other day I noticed my second problem. A
couple of years ago the
blower motor failed. Had to replace it with an
upgraded motor as the OEM
was unavailable at the factory. Very successful
operation. I also
replaced the air flapper as the old one was caked
with dirt.
Last week I noticed it was short cycling. The
purge blower would run and
the for about 5 seconds it would try to fire. Then
it would go silent,
then the purge blower would run. Then the cycle
would repeat. Anyway, I
found that if I have the thermostat set at 75 deg
instead of the 68 deg
I usually run it at, it fires and cycles just
fine.
Weird.
Before I call a real tech, does anyone think the
problem could lie in
the electronic thermostat?

Thanks.

zimpzampzormp wrote:
1995 Lennox Pulse 21 furnace. Ironically I did everything from welding
the heat exchanger to assembling it to installing it in my house. I am
not an HVAC tech or an engineer.
The other day I noticed my second problem. A couple of years ago the
blower motor failed. Had to replace it with an upgraded motor as the OEM
was unavailable at the factory. Very successful operation. I also
replaced the air flapper as the old one was caked with dirt.
Last week I noticed it was short cycling. The purge blower would run and
the for about 5 seconds it would try to fire. Then it would go silent,
then the purge blower would run. Then the cycle would repeat. Anyway, I
found that if I have the thermostat set at 75 deg instead of the 68 deg
I usually run it at, it fires and cycles just fine.
Weird.
Before I call a real tech, does anyone think the problem could lie in
the electronic thermostat?

Thanks.

Was anyone playing with the thermostat and changed the "heat
anticipator" setting? For that matter, is the t-stat mechanical or
electronic?

On Feb 25, 5:44*pm, zimpzampzormp
wrote:
1995 Lennox Pulse 21 furnace. Ironically I did everything from welding
the heat exchanger to assembling it to installing it in my house. I am
not an HVAC tech or an engineer.
The other day I noticed my second problem. A couple of years ago the
blower motor failed. Had to replace it with an upgraded motor as the OEM
was unavailable at the factory. Very successful operation. I also
replaced the air flapper as the old one was caked with dirt.
Last week I noticed it was short cycling. The purge blower would run and
the for about 5 seconds it would try to fire. Then it would go silent,
then the purge blower would run. Then the cycle would repeat. Anyway, I
found that if I have the thermostat set at 75 deg instead of the 68 deg
I usually run it at, it fires and cycles just fine.
Weird.
Before I call a real tech, does anyone think the problem could lie in
the electronic thermostat?

Thanks.

If it works fine and cycles fine set at 75 but not 68, replace the
thermostat

On Feb 25, 10:00*pm, ransley wrote:
On Feb 25, 5:44*pm, zimpzampzormp
wrote:





1995 Lennox Pulse 21 furnace. Ironically I did everything from welding
the heat exchanger to assembling it to installing it in my house. I am
not an HVAC tech or an engineer.
The other day I noticed my second problem. A couple of years ago the
blower motor failed. Had to replace it with an upgraded motor as the OEM
was unavailable at the factory. Very successful operation. I also
replaced the air flapper as the old one was caked with dirt.
Last week I noticed it was short cycling. The purge blower would run and
the for about 5 seconds it would try to fire. Then it would go silent,
then the purge blower would run. Then the cycle would repeat. Anyway, I
found that if I have the thermostat set at 75 deg instead of the 68 deg
I usually run it at, it fires and cycles just fine.
Weird.
Before I call a real tech, does anyone think the problem could lie in
the electronic thermostat?

Thanks.

If it works fine and cycles fine set at 75 but not 68, replace the
thermostat- Hide quoted text -

- Show quoted text -

If it is a pulse type, trash it. My neighbor's only lasted about 3
years before he had to replace it.

I still have an old 1965 gas-fired furnace where the flame is ignited
by a pilot light and burns inside a great big can. It may be old, but
I have never had any problems other than oiling the blower motor and
changing the filter. I also filled in the gas nozzle and then drilled
it out with a smaller size drill so the gas flow is about half of what
it used to be, so it doesn't burn as hot and I put less heat up the
chimney. I have the blower temperature sensors set low so the blower
comes on at a low temperature and runs until the air is down to about
80F. That extracts most of the possible heat available. I have
provided a 6-inch diameter air inlet directly from the outside to feed
into the combustion area so it doesn't use heated household air, and I
have a carbon monixde detector close to the furnace as well as a
couple near the bedrooms in case the big can ever develops a leak. My
gas bill is way down from what is was when we first owned the house.
So newer is not always better.......

On 2/25/2010 10:37 PM, hr(bob) wrote:
On Feb 25, 10:00 pm, wrote:
On Feb 25, 5:44 pm,
wrote:





1995 Lennox Pulse 21 furnace. Ironically I did everything from welding
the heat exchanger to assembling it to installing it in my house. I am
not an HVAC tech or an engineer.
The other day I noticed my second problem. A couple of years ago the
blower motor failed. Had to replace it with an upgraded motor as the OEM
was unavailable at the factory. Very successful operation. I also
replaced the air flapper as the old one was caked with dirt.
Last week I noticed it was short cycling. The purge blower would run and
the for about 5 seconds it would try to fire. Then it would go silent,
then the purge blower would run. Then the cycle would repeat. Anyway, I
found that if I have the thermostat set at 75 deg instead of the 68 deg
I usually run it at, it fires and cycles just fine.
Weird.
Before I call a real tech, does anyone think the problem could lie in
the electronic thermostat?

Thanks.

If it works fine and cycles fine set at 75 but not 68, replace the
thermostat- Hide quoted text -

- Show quoted text -

If it is a pulse type, trash it. My neighbor's only lasted about 3
years before he had to replace it.

I still have an old 1965 gas-fired furnace where the flame is ignited
by a pilot light and burns inside a great big can. It may be old, but
I have never had any problems other than oiling the blower motor and
changing the filter. I also filled in the gas nozzle and then drilled
it out with a smaller size drill so the gas flow is about half of what
it used to be, so it doesn't burn as hot and I put less heat up the
chimney. I have the blower temperature sensors set low so the blower
comes on at a low temperature and runs until the air is down to about
80F. That extracts most of the possible heat available. I have
provided a 6-inch diameter air inlet directly from the outside to feed
into the combustion area so it doesn't use heated household air, and I
have a carbon monixde detector close to the furnace as well as a
couple near the bedrooms in case the big can ever develops a leak. My
gas bill is way down from what is was when we first owned the house.
So newer is not always better.......



I hate to be one of those guys but I need to disagree with you. I've had
this for 15 years now and very little trouble. When I installed it my
gas bill was cut in half. Mine is very efficient, quiet (relatively),
and reliable. I also like the feel of the heat. Not too dry. It is also
the first furnace to use coil technology for higher efficiency. You
might say it was a pioneering furnace for high efficiency.
I do keep a carbon monoxide detector though.

On Feb 25, 10:54*pm, zimpzampzormp
wrote:
On 2/25/2010 10:37 PM, hr(bob) wrote:





On Feb 25, 10:00 pm, *wrote:
On Feb 25, 5:44 pm,
wrote:

1995 Lennox Pulse 21 furnace. Ironically I did everything from welding
the heat exchanger to assembling it to installing it in my house. I am
not an HVAC tech or an engineer.
The other day I noticed my second problem. A couple of years ago the
blower motor failed. Had to replace it with an upgraded motor as the OEM
was unavailable at the factory. Very successful operation. I also
replaced the air flapper as the old one was caked with dirt.
Last week I noticed it was short cycling. The purge blower would run and
the for about 5 seconds it would try to fire. Then it would go silent,
then the purge blower would run. Then the cycle would repeat. Anyway, I
found that if I have the thermostat set at 75 deg instead of the 68 deg
I usually run it at, it fires and cycles just fine.
Weird.
Before I call a real tech, does anyone think the problem could lie in
the electronic thermostat?

Thanks.

If it works fine and cycles fine set at 75 but not 68, replace the
thermostat- Hide quoted text -

- Show quoted text -

If it is a pulse type, trash it. *My neighbor's only lasted about 3
years before he had to replace it.

I still have an old 1965 gas-fired furnace where the flame is ignited
by a pilot light and burns inside a great big can. *It may be old, but
I have never had any problems other than oiling the blower motor and
changing the filter. *I also filled in the gas nozzle and then drilled
it out with a smaller size drill so the gas flow is about half of what
it used to be, so it doesn't burn as hot and I put less heat up the
chimney. *I have the blower temperature sensors set low so the blower
comes on at a low temperature and runs until the air is down to about
80F. *That extracts most of the possible heat available. *I have
provided a 6-inch diameter air inlet directly from the outside to feed
into the combustion area so it doesn't use heated household air, and I
have a carbon monixde detector close to the furnace as well as a
couple near the bedrooms in case the big can ever develops a leak. *My
gas bill is way down from what is was when we first owned the house.
So newer is not always better.......

I hate to be one of those guys but I need to disagree with you. I've had
this for 15 years now and very little trouble. When I installed it my
gas bill was cut in half. Mine is very efficient, quiet (relatively),
and reliable. I also like the feel of the heat. Not too dry. It is also
the first furnace to use coil technology for higher efficiency. You
might say it was a pioneering furnace for high efficiency.
I do keep a carbon monoxide detector though.- Hide quoted text -

- Show quoted text -

If you take a certain amount of air and its water content and heat it
by blowing the air over my can or over your coils, that does not
change the moisture content unless the air is exposed to some open
flame, so how can the tyoe of furnace make a difference in how the
heated air "feels"? Maybe the blower/air speed changes how the heated
air feels, but the type of heating does not change things at all.