Lennox Pulse Furnace???

[Kirk]

Hi all,
Here's how a Pulse furnace burns gas. Sorry about the strange characters, I
copied this from a PDF file.

G21 and GSR21 units are condensing furnaces utilizing
the pulse combustion process. Initially, combustion
takes place in an enclosed chamber. Then, as combus

tion products pass through the heat exchanger system
into a coil, the latent heat of combustion is extracted and
water is condensed from the exhaust gas.
The unit uses a redundant gas valve to assure safety
shut
off as required by A.G.A. The units are manufac

tured for natural gas application. L.P. kits for A.G.A. /
C.G.A. units are available for field changeover.
An electronic direct spark ignition control initiates com

bustion. The ignition control serves four functions: pre

purge, ignition, flame sensing and post
purge. Controls
reset in the event of nuisance lockout. The control also
verifies loss of combustion during a cycle, closing the
gas valve. A differential pressure switch shuts down the
unit immediately if there are obstructions in the exhaust
outlet or air intake.
A purge blower clears the combustion chamber before and af

ter each heating cycle to ensure proper air mixture for start
up.

1 - Gas and air enter and mix in combustion
chamber
2 - To start the cycle a spark is used to ignite the
gas and air mixture (this is one "pulse").
3 - Positive pressure from combustion closes
flapper valves and forces exhaust gases down
the tailpipe.
4 - Exhaust gases leaving chamber create a
negative pressure. This opens the flapper valve
drawing in gas and air.
5 - At the same instant, part of the pulse is
reflected back from the tailpipe causing the
new gas and air mixture to ignite. No spark is
needed. (this is another
pulse").
6 - Steps 4 and 5 repeat 60 to 70 times per second
forming consecutive
pulses" of 1/4 to 1/2
Btuh each.
7 - Latent heat is removed from combustion
products and condensate (water) is formed in
the condensate coil.

Kirk, the occasional lurker

Turtle....you got no clue how a pulse works.
There is no mechanical device making the pulse.
Nothing is turning the gas on and off.
Maybe ya shoud buy a clue before opening yer mouth.
Okay, go ahead and call me names now.
Seems that is all this group is about now anyways.
About six people swearing and calling everyone else a hack.

This is Turtle.
Well Little Jamey Boy , Just explain to me how it works and what if any

was not true about what the statements I made. I know I'm

not the best on Pulse furnaces but please bring me up to date. I know you

know all about them so please explain to the poor little

Turtle how they work. Here is your time to shine.
TURTLE
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.639 / Virus Database: 408 - Release Date: 3/22/2004

[TURTLE]

Post by Kirk
Hi all,
Here's how a Pulse furnace burns gas. Sorry about the strange characters, I
copied this from a PDF file.
G21 and GSR21 units are condensing furnaces utilizing
the pulse combustion process. Initially, combustion
takes place in an enclosed chamber. Then, as combus

tion products pass through the heat exchanger system
into a coil, the latent heat of combustion is extracted and
water is condensed from the exhaust gas.
The unit uses a redundant gas valve to assure safety
shut
off as required by A.G.A. The units are manufac

tured for natural gas application. L.P. kits for A.G.A. /
C.G.A. units are available for field changeover.
An electronic direct spark ignition control initiates com

bustion. The ignition control serves four functions: pre

purge, ignition, flame sensing and post
purge. Controls
reset in the event of nuisance lockout. The control also
verifies loss of combustion during a cycle, closing the
gas valve. A differential pressure switch shuts down the
unit immediately if there are obstructions in the exhaust
outlet or air intake.
A purge blower clears the combustion chamber before and af

ter each heating cycle to ensure proper air mixture for start
up.
1 - Gas and air enter and mix in combustion
chamber
2 - To start the cycle a spark is used to ignite the
gas and air mixture (this is one "pulse").
3 - Positive pressure from combustion closes
flapper valves and forces exhaust gases down
the tailpipe.
4 - Exhaust gases leaving chamber create a
negative pressure. This opens the flapper valve
drawing in gas and air.
5 - At the same instant, part of the pulse is
reflected back from the tailpipe causing the
new gas and air mixture to ignite. No spark is
needed. (this is another
pulse").
6 - Steps 4 and 5 repeat 60 to 70 times per second
forming consecutive
pulses" of 1/4 to 1/2
Btuh each.
7 - Latent heat is removed from combustion
products and condensate (water) is formed in
the condensate coil.
Kirk, the occasional lurker

This is Turtle.

That was very informitive on the Pulse action there. That was very good for I did nothing think it was that may pulses in a second
and was thinking it would be more temp. rise and fall between pulses. The problem of the fire chamber failures is still there by
what you said of the nevative and possitive of the time between pulses. This would be putting a Neg. and a pos. pressure on the
metal along with heating up of the metal or floating of the temperature in the chamber.

That was very good.

TURTLE


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.648 / Virus Database: 415 - Release Date: 3/31/2004

[brian]

Post by TURTLE
The problem of the fire chamber failures is still there by
what you said of the nevative and possitive of the time between pulses.

This would be putting a Neg. and a pos. pressure on the

Post by TURTLE
metal along with heating up of the metal or floating of the temperature in the chamber.

The failure in the Pulse was not a result of "pulses", pressure, etc. The
problem was the solder used in the secondary heat exchangers. This problem
was discovered in '87 or '88, and the correction made, but it was too late.
The damage had been done, both to the individual furnaces, and the line's
image. By then manufacturers were producing the more traditional furnace
with secondary heat exchangers. Pulses produced after 1990 are fine. And
they were able to reduce the sound output. We have one heating our office,
and standing 4' from the furnace all you hear is the blower. From inside
the office you hear nothing at all.

[TURTLE]

Post by TURTLE

Post by TURTLE
The problem of the fire chamber failures is still there by
what you said of the nevative and possitive of the time between pulses.

This would be putting a Neg. and a pos. pressure on the

Post by TURTLE
metal along with heating up of the metal or floating of the temperature in

the chamber.
The failure in the Pulse was not a result of "pulses", pressure, etc. The
problem was the solder used in the secondary heat exchangers. This problem
was discovered in '87 or '88, and the correction made, but it was too late.
The damage had been done, both to the individual furnaces, and the line's
image. By then manufacturers were producing the more traditional furnace
with secondary heat exchangers. Pulses produced after 1990 are fine. And
they were able to reduce the sound output. We have one heating our office,
and standing 4' from the furnace all you hear is the blower. From inside
the office you hear nothing at all.

This is Turtle.

You say the ones after 1990 are Ok ? This is new to me and I try to keep up with this. This sure sound like it.

TURTLE



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.648 / Virus Database: 415 - Release Date: 3/31/2004

[Joseph]

Post by TURTLE

Post by TURTLE
The problem of the fire chamber failures is still there by
what you said of the nevative and possitive of the time between pulses.

This would be putting a Neg. and a pos. pressure on the

Post by TURTLE
metal along with heating up of the metal or floating of the temperature in

the chamber.
The failure in the Pulse was not a result of "pulses", pressure, etc.

The

Post by TURTLE
problem was the solder used in the secondary heat exchangers. This problem
was discovered in '87 or '88, and the correction made, but it was too late.
The damage had been done, both to the individual furnaces, and the line's
image. By then manufacturers were producing the more traditional furnace
with secondary heat exchangers. Pulses produced after 1990 are fine.

And

Post by TURTLE
they were able to reduce the sound output. We have one heating our office,
and standing 4' from the furnace all you hear is the blower. From inside
the office you hear nothing at all.

This is Turtle.
You say the ones after 1990 are Ok ? This is new to me and I try to keep

up with this. This sure sound like it.

TURTLE

I do the pressure test on two schools here that have the pulse furnaces.
About 60 or so units and not one of them have failed the pressure tests to
date. The furnaces are going to be tested again next year, will see how it
goes then as the units are going to be 15+ years old. I agree that these
are very quiet running furnaces and have had minimal problems over the last
10 years.

Joseph

[Tekkie]

TURTLE posted for all of us....

This is Turtle.
That was very informitive on the Pulse action there. That was very good for I did nothing think it was that may pulses in a second
and was thinking it would be more temp. rise and fall between pulses. The problem of the fire chamber failures is still there by
what you said of the nevative and possitive of the time between pulses. This would be putting a Neg. and a pos. pressure on the
metal along with heating up of the metal or floating of the temperature in the chamber.
That was very good.
TURTLE

This reminds me of having a good case of popcorn farts! Probably sounds &
smells the same. Wonder how many btu's I put out?

[TURTLE]

Post by Tekkie
TURTLE posted for all of us....

This is Turtle.
That was very informitive on the Pulse action there. That was very good for I did nothing think it was that may pulses in a

second

Post by Tekkie

and was thinking it would be more temp. rise and fall between pulses. The problem of the fire chamber failures is still there by
what you said of the nevative and possitive of the time between pulses. This would be putting a Neg. and a pos. pressure on the
metal along with heating up of the metal or floating of the temperature in the chamber.
That was very good.
TURTLE

This reminds me of having a good case of popcorn farts! Probably sounds &
smells the same. Wonder how many btu's I put out?
--
Tekkie

This is Turtle.

The BTU rating of a fart will be pretty high for Methan gas has a high btu rating. Don't stand near a flame when your enjoying
yourself.

TURTLE


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.648 / Virus Database: 415 - Release Date: 3/31/2004

[Noon-Air]

Post by Tekkie
TURTLE posted for all of us....

This is Turtle.
That was very informitive on the Pulse action there. That was very good

for I did nothing think it was that may pulses in a second

Post by Tekkie

and was thinking it would be more temp. rise and fall between pulses.

The problem of the fire chamber failures is still there by

Post by Tekkie

what you said of the nevative and possitive of the time between pulses.

This would be putting a Neg. and a pos. pressure on the

Post by Tekkie

metal along with heating up of the metal or floating of the temperature in the chamber.
That was very good.
TURTLE

This reminds me of having a good case of popcorn farts! Probably sounds &
smells the same. Wonder how many btu's I put out?

not much till you put a match to it

Post by Tekkie
Tekkie

[Stormin Mormon]

I think we can conclude that you're not fond of Lennox?
--
Christopher A. Young
Learn more about Jesus
www.lds.org
www.mormons.com


"Jake" <***@insightbb.com> wrote in message news:VWoac.145187$***@attbi_s52...
I, as a home-moaner, had a Lennox Pulse installed in our new house when it
was built in 1987. That thing did make a lot of noise... but on to more
important matters...

During the time we lived there, from '87 to '93, I had service calls on the
thing about once a year. Igniters, boards, relays, etc. It cost a fortune to
maintain. I had spec'd Trane when we built the place because I had done a
electrical job in their plant (I think it was in Tennessee but can't
remember anymore) and I always believe in helping out the people who help
you make a living.

Anyhow, flash to Christmas 2003... Me and the wife and 2 kids are back in
the old home town visiting Dad and my brother for the holidays and decide,
fondly, to drive by our old house (the first one we ever built).

There was a tarp over a roof portion of the garage and adjoining utility
room. No one lived there anymore.

Cautiously, I pulled into our old driveway. My wife said "We shouldn't be
messing around here" but I checked the door off the garage and it was
unlocked. I walked into a smoke-smelling, ash covered mess. I thought maybe
a car had caught fire in the garage.

Later, during Christmas dinner, I was telling this tale to my brother who's
a local cop in this small town. He said, "Oh, I meant to tell you about
that. Your old house burned up about a month ago and I was at the scene when
I heard the FD call on the radio... recognized the address. That monitored
fire & burglar alarm system I talked you into saved 4 people... the house's
furnace somehow exploded and a fireball went clear through the roof."

Enough said... everybody made it out alive... but only thanks (very luckily)
to a $2,500 security system.

Jake

[Jake]

It's not that I dislike the brand... I don't know enough about the whole
company to comment on that. I was just glad as hell my kids and my (dear
(-: ) wifey were not in the house when the thing went up. I guess I also
feel a little guilty about not checking things out a little more when we
built the place.

This brings me to my real point... it seems too many times that residential
stuff is under-engineered for safety. I work with industrial environments,
where most everything is heavy-duty and built to run safely and economically
for the long haul. I look at some of the crappy electrical panels people
buy at Home-Cheapo and others and just shake my head. It's really a poor
reflection of the consumers in this country that they aren't willing to pay
for quality anymore. Yeah, I've had engineers try and talk me into doing
things to cut corners, but they almost always understand the downside when
it's explained to them. Consumers don't see a down-side to saving a buck...
no matter what.

As I've said before, I work in the electrical trade and not specifically in
HVAC, but we're all in the same boat here. People think they can outsmart a
technical professional and never consider the risks of doing so... it
probably happens 1,000 times a day in this country.

Enough of this tirade... I'm just so tired of folks discounting the notion
of "doing things right" versus just doing them. Our country became
prosperous on the premise of being the best, but now every Tom, Dick and
Harry is happier going to Wal-Mart and buying 20 Awg. extension cords
instead of having properly installed outlets in their homes. I'll stay in
industry until we don't have it anymore (probably coming soon!!!).

I hope they have good insurance...

Jake

Post by Stormin Mormon
I think we can conclude that you're not fond of Lennox?
--
Christopher A. Young
Learn more about Jesus
www.lds.org
www.mormons.com
I, as a home-moaner, had a Lennox Pulse installed in our new house when it
was built in 1987. That thing did make a lot of noise... but on to more
important matters...
During the time we lived there, from '87 to '93, I had service calls on the
thing about once a year. Igniters, boards, relays, etc. It cost a fortune to
maintain. I had spec'd Trane when we built the place because I had done a
electrical job in their plant (I think it was in Tennessee but can't
remember anymore) and I always believe in helping out the people who help
you make a living.
Anyhow, flash to Christmas 2003... Me and the wife and 2 kids are back in
the old home town visiting Dad and my brother for the holidays and decide,
fondly, to drive by our old house (the first one we ever built).
There was a tarp over a roof portion of the garage and adjoining utility
room. No one lived there anymore.
Cautiously, I pulled into our old driveway. My wife said "We shouldn't be
messing around here" but I checked the door off the garage and it was
unlocked. I walked into a smoke-smelling, ash covered mess. I thought maybe
a car had caught fire in the garage.
Later, during Christmas dinner, I was telling this tale to my brother who's
a local cop in this small town. He said, "Oh, I meant to tell you about
that. Your old house burned up about a month ago and I was at the scene when
I heard the FD call on the radio... recognized the address. That monitored
fire & burglar alarm system I talked you into saved 4 people... the house's
furnace somehow exploded and a fireball went clear through the roof."
Enough said... everybody made it out alive... but only thanks (very luckily)
to a $2,500 security system.
Jake

[MechAcc]

This is Turtle.
the Pulse is a over engineered piece of equipment for just a simple job or

a high tech operation applied to a low tech operation. I

have only worked on one for we don't have a Lennox dealer near here for we

was the last Lennox dealer the left them in 1979.
Other than the cracked solder joint problem (which was a BIG problem no
doubt), we have had many Pulse furnaces run 10+ years with no maintenance,
and no breakdowns. Does that sound complicated? Honeywell fan relay to
turn the fan on in heat. A 24v relay to turn the fan on for cool. An
inducer motor that runs only at start up and shut down, which means it last
a very long time. It's actually a very simple machine. It's human nature
that anything we don't understand seems overly complicated. Remember when
the 58GP first came out with that new fangled circuit board?
The solder problem was fixed around '89. If you have an '87 furnace it will
more than likely fail the pressure test- either now or in the future.
Lennox will honor the replacement warranty even if it hasn't failed yet. It
had a limited lifetime warranty with the original purchaser, 20 years for a
buyer. That means it's out in 3 years. Lennox will supply a brand new 90%
furnace (of a much more common design) for no cost, and the homeowner pays
just the labor.
Go ahead and replace it.
Brian

The solder joints are not the only sections that will leak go to the
following link of a photo I took of a leak at the resonator.
Loading Image...

[Oscar_Lives]

I'm not interested in the house anyway. The foundation has been cracked all
to hell, and it looks like a hack tried to pier the foundation and really
did a crappy job.

I am considering making an offer on a house and I would like some advice.
It has a 1987 Lennox Pulse furnace in it. The furnace looks like new from
all that I can see, but the condenser unit looks like a crappy weathered
1987 Lennox builder's model.
Would I expect to have problems with a Lennox Pulse?
Weren't there some recalls, free service, etc. for them?
Anything else I need to know?
Thanks

[TURTLE]

Post by Oscar_Lives
I'm not interested in the house anyway. The foundation has been cracked all
to hell, and it looks like a hack tried to pier the foundation and really
did a crappy job.

This is Turtle.

When the Concrete foundations have problem. They don't go away but will return later when you least expect it. I know a fellow who
has had his slab pumped back up into place 3 times in the last 15 years.

Passing is not a bad ideal.

TURTLE


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.648 / Virus Database: 415 - Release Date: 3/31/2004

[r***@yahoo.com]

I'm not a pro when it comes to furnaces, but I was looking to run a gas line to a fireplace coming off of the furnace supply line and was curious of the requirements for a lenox pulse furnace when I ran into this group. I read through all of the posts and was amused by Brian and Turtle's exchange. So I thought I'd chime in and say the I have a Lenox pulse furnace installed in 1990 and it's still going strong (knock on wood). I live in Utah and we use it six months out of the year. No problems with the firebox although I have rebuilt the fan assembly where the side fatigued and cracked allowing the motor to flop around. If you guys are still alive thanks for 30 minutes of entertainment!

[PaxPerPoten]

Post by r***@yahoo.com
I'm not a pro when it comes to furnaces, but I was looking to run a gas line to a fireplace coming off of the furnace supply line and was curious of the requirements for a lenox pulse furnace when I ran into this group. I read through all of the posts and was amused by Brian and Turtle's exchange. So I thought I'd chime in and say the I have a Lenox pulse furnace installed in 1990 and it's still going strong (knock on wood). I live in Utah and we use it six months out of the year. No problems with the firebox although I have rebuilt the fan assembly where the side fatigued and cracked allowing the motor to flop around. If you guys are still alive thanks for 30 minutes of entertainment!

I suggest that you get you hands on a Gas/Fuel manual and make sure
those gas lines and pressures are of a size to properly service both.
You Gas Company might or might not help out. There is no free lunch.
The "International Mechanical Code Book" Has this Data" also.

http://tinyurl.com/y84bvjjr

http://tinyurl.com/y77jkl85

[Arthur Parker]

I had a Pulse furnace installed in March 1983 that is still running fine. It has had the new improved combustion chamber installed under the recall a year or so after it was installed. When it was newer it would sometimes fail to start making pop-pop sounds like a backfire. It would then run the purge fan for another cycle and fire up ok. Now it's been years and I have not noticed any miss-fire starts. I have replaced the flapper gas valve twice and I inspected it a third time, it still looked new so I put it back in. The ones I replaced had obvious signs of wearing out. I did have to remove the purge fan and clean and lube it. I found a dead cockroach in it that prevented the fan from running, must have come in from the fresh combustion air intake. I did replace the blower motor because the bearings wore out making a grinding noise. Note I run the blower fan 24-7 because on the return air duct I have a small fresh air intake from outside to provide a slight positive air pressure inside the house. I also have MERV 11 intake air filter on the furnace to help with relief from my hay fever. Having the fan always running may have been the reason the bearings wore out.

Art