Lennox Pulse 21 Gas Furnace Repair/Replacement

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Old 03-25-05, 06:48 PM
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Lennox Pulse 21 Gas Furnace Repair/Replacement

I have several questions concerning our Lennox Pulse 21 Gas Furnace. I will provide some initial background and then include my questions with some additional detail.

The unit we have is an 80,000 BTU Lennox Pulse 21 Model. It was installed in 1992. In 1995 the control module was replaced. We recently were having difficulties (every few days would need to reset power for the unit to run) and the controller was diagnosed as needing replacement. The contoller on the unit is made by Johnson Controls.

My first question is that since this control unit appears to be just "plug and play" can I source the part and self-install for less than the $500.00 I was quoted for the repair.

It appears that these modules seem to burn out relatively quickly because they are mounted on the wall of the heat chamber which over time probably overstresses the componentry and causes the unit to fail so my second question is can the unit be mounted elsewhere as long as it is properly connected and grounded?

Now it gets interesting. The repair technician said that Pulse 21 Furnace has not been "officially recalled" but that there is a Lennox repair bulletin that says the heat exchangers are failing and they should be checked and the unit condemned there is evidence of the failure condition. The third question is has anyone heard this?

The technician recommended that the unit be replaced with a Lennox G51 90,000 BTU unit and that if we went this route the company could likely get us a credit of about $1K from Lennox towards the new installation. It would then cost us about $2,600 for the new unit. My final questions are does this sound plausible and is the price for the new unit reasonable? Also if you were going to replace an 80,000 BTU gas unit and could chose any manufacturer and model what would you recommend and why?

In essence I am trying to assess how big a concern, if any, is this heat exchanger situation. Should it be a concern in which case it makes sense to replace the whole furnace rather than the control or is it a minor situation that is being positioned in a way to sell a new furnace when one is not really needed.

Thanks for the help!
David
 
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  #2  
Old 03-25-05, 08:06 PM
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Yes Lennox has had some problems wih their pulse heat exchangers. I would encourage you to have it checked out. Apparently it was associated with cracks and carbon monoxide. Also it is difficult to buy some of the lennox parts at a good price. Even dealers must go thru lennox for a lot of parts.
 
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Old 03-25-05, 09:18 PM
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Get a pressure test done on your heat exchanger. Lennox warranties these exchangers for 20 years and will give you a new, non-pulse furnace rather than supplying a pulse heat exchanger. You will be far better off not having that noisey annoying POS in your house...
 
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Old 02-25-08, 02:53 PM
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pressure testing lennox pulse 21's

It costs from 200 to 300 depending on who does it. My carbon monoxide was not the usual 20 PPM but 7000 PPM, they said I "HAD" to get it done (they needed the money), even though the air intake 'filter' was plugged or they would have my gas turned off, during the winter till i bought a new furnace, they would have been wrong at my expense ... If you have no monoxide in the house, its this air intake filter, if you DO have monoxide, its the combustion chamber or heat exchanger ! Which then means you replace the furnace. Here in Canada I would have spent 7 grand to do that !

Pulse 21, Model 2103060-1 (60,000BTU), high efficiency furnaces, may be cheaper on natural gas and squeeze more heat out of the exhaust, but you spend allot more on hydro, in the end, keeping that 1/2 HP fan motor runing all day. There is very little savings overall.

TRUST NO ONE !!!

AS for the recall, it was issued AFTER the recall expiry date, and because the original contractor was not a lennox dealer, they would not honor it !!!
 

Last edited by pdp8e; 02-25-08 at 02:57 PM. Reason: adding details
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Old 02-25-08, 04:39 PM
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We just replaced a 60K BTU Pulse 21 that we had installed in '92 also. Never found out if we had the CO issue - the test here (upstate NY) was $400. We had the same issues as you with the system shutting down often. One Lennox service tech replaced a transformer, an internal relay, and re wired the 24V system to no avail. When he went out the door he thought it might have been the limit switche(s). I'll never know. $4500 dollars later we have an 80K two stage and have never been happier. The house is comfortable. The house actually responds to the thermostat. Our pulse was more like a heat pump in its performance. 3-4 hours to come up from a 6 degree setback. If you qualify, Lennox won't give you a new furnace, they told me that I'd get credit of the HE cost towards an 80% efficient furnace. If you like your Lennox dealer then try the rebate. We wouldn't touch Lennox again.
 
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Old 03-01-08, 10:20 PM
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Here is the scoop. Your control is failing because of vibration, over a period of time the diodes loosen up on the board. Yes, you can mount it away from the furnace, but there is no kit that I know of to do it.
Yes, if you can find a dealer to sell you the part over the counter(good luck) you can install it yourself. The recall program was for G14's the
1st family of pulse furnaces, from 1982-1989. They had problems with the weld joints on the secondary heat exchanger. They didn't hold up to the vibration of the furnace. Lennox changed the brazing material in 1987, but extended the recall to the manufacter date 1989.
Lennox recommends all Pulse furnaces have the heat exchanger pressure tested every 4 yrs.
The rebate on bad heat exchangers is 4 hundred dollars toward a new Lennox furnace of your choice. If you are the homeowner that had the G21 installed you have a lifetime wnty on the heat exchanger and are eligible for the rebate. If you you did not have the furnace installed the wnty reverts to 20 yrs.
The recall program was in 1998-99. Lennox was replacing the heat exchanger for a minimal price that was pro-rated depending on the age of the furnace. In Jan. 99, they did start giving away a G26 furnace and you had to pay for the install, but the program has been expired for awhile don't remember when.

[QUOTE]The technician recommended that the unit be replaced with a Lennox G51 90,000 BTU unit and that if we went this route the company could likely get us a credit of about $1K from Lennox towards the new installation. It would then cost us about $2,600 for the new unit. My final questions are does this sound plausible and is the price for the new unit reasonable? Also if you were going to replace an 80,000 BTU gas unit and could chose any manufacturer and model what would you recommend and why?
In essence I am trying to assess how big a concern, if any, is this heat exchanger situation. Should it be a concern in which case it makes sense to replace the whole furnace rather than the control or is it a minor situation that is being positioned in a way to sell a new furnace when one is not really needed.[/
QUOTE]

Sorry for the long diatribe, I've been dealing with the Pulse for years as a tech. and think the Pulse is a great furnace outside of being a little noisey. To answer your real concern about the heat exchanger, have it pressure checked. If it fails (it should have some air pressure in after 10min.) then take the rebate if you qualify and install something a little quieter. Now days, there are 2 stage gas valves and ECM moters to consider so you can get up to 95% effiency. By the way as long as the air flapper is clean and been replaced every 5 yrs or so the Pulse produces very little CO. $2600 is not a bad price, but think you should consider the 2 stage gas valves as mentioned previously.

Hope this helps in your decision.
 
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Old 03-01-08, 10:56 PM
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The heat exchanger situation is serious. Todays furnaces have enough safeties in them to avoid tragedy but if the safeties fail you are at the mercy of luck and God. I wish I had taken more pictures of the furnaces I have taken out. It scares me to even think of what could have happened in some of those situations. Lennox will stand behind their furnace if the exchanger is bad but not totally. I would take a look at Amana. You can compare all brands here:
http://www.furnacecompare.com/manufacturers/amana.html
 
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Old 03-02-08, 11:20 AM
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Even without the consideration of heat exchanger questions on your brand, it is VERY advisable to install one or more CO alarms in your house. CO is called the silent killer. Why take a chance? Massachusetts requires CO alarms in all dwellings which have fuel burning appliances. Other states will probably follow this trend. They are not expensive, and install easily just like a smoke alarm. You can get hard wires models, battery operated ones, and combo CO/smoke units.
 
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Old 03-03-08, 09:49 PM
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Lenox Resolution

I originally posted my question in October of 2004 and have fortunately resolved it consistent with has been said in the very recent posts.

We were able to find a competent and trustworthy technician who examined our furnace. He was familiar with the entire Lenox line and the heat exchanger issue. He did not perform a pressure check but appeared to do a through inspection of all the chambers and did take CO readings throughout. He was confident that the furnace was fine but did recommend we install CO detectors in each level of the house just for piece of mind. We have since done that.

He also replaced the controller (the blue box) and the system has been running fine for the past three seasons. This is the second time the controller has been replaced on this unit.

Thanks for all the follow-up.

David
 
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Old 12-01-10, 07:50 AM
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The diodes on the control module DO fail but it's not because of vibration.

What happens is, when it gets cold, the cold air drains down the intake and exhaust and causes the metal connection on the spark plug to warp, loosing contact with the spark plug. This causes arcing or no spark, when the little capicitor that produces the spark doesn't release, the energy builds up and ruins your diodes and circuits.

I've had this happen twice, both on really cold days, so I knew it was somehow related to the cold.

the first time it ruined my control module.

The solution is to bend the cap on the spark plug a little, so it fits the spark plug snugly, and put some conductive grease on it.
 

Last edited by MikeInIndiana; 12-01-10 at 09:32 AM.
  #11  
Old 12-03-10, 08:41 PM
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Lennox PulseG14 replaced with new G51 for $575 by Lennox Dec. 2010

Today our Lennox dealer installed a new furnace, replacing the G14 that had been installed in 1985. During a pressure test performed by a Lennox tech the heat exchanger did not pass and we qualified for the Lennox upgrade program, which is still open. We upgraded from the G51 to a G61 which qualifies for the tax rebate that ends 12/31/10. We had to pay the difference between the G51 and G61, and the installation. We love the new furnace.
We reached Lennox customer support at 800-9-Lennox, (or 800-953-6669.) They said the program is open until Lennox pulse furnaces, that qualify, are pressure tested and the issues resolved.
 
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Old 01-10-11, 12:46 PM
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lifetime warranty on heat exchangers

Our lennox pulse(GSR14) furnace's heat exchanger also failed.
I called the lennox 800 number and they to advised that they will allow the $575 towards the purchase of a new furnace. I have to pay the installation fee. The problem is, the furnace has been diagnosed by the technician that there is a hole in the heat exchanger, but lennox requires a pressure test to be done.
The dealer says it cost's $300 for this to be done.WHAT!!!!!
You can see the hole(with a mirror) in the heat exchanger and now the dealer wants to charge me $300 to have it pressure tested, cause that is what lennox requires??
What a rip off....and the $575 is not the purchase price of a furnace + installation, it is a $575 credit towards a new one.
Here's the local lennox dealers bid for new furnace & installation:
Lennox G61mpv-36B-071 gas(insalled and old one removed)
$4600-$575(warranty towards defective heat exchanbger)=$4025

OUCH!!!!!! you got to be kidding me. The local dealer is making all this money up on the installation.
I found out the g61mpv costs approx $2000. and this dealer wants to remove and replace for $2000.
BYE BYE Lennox....
 
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