Lennox WhisperHeat furnace banging/booming - electrical?


  #1  
Old 10-23-10, 08:02 AM
S
Member
Thread Starter
Join Date: Oct 2010
Location: canada
Posts: 2
Received 0 Votes on 0 Posts
Lennox WhisperHeat furnace banging/booming - electrical?

We moved into this house a month ago. It's furnace time now.. Inspector had no issues with the furnace. When we turn the furnace on (I usually have it set to about 65 during the day, and then evenings I bump it up to 69. when we go to bed we decrease it to about 65 again, and then first thing in the morning, bump it up to 69 again) at night or first thing in the morning, the furnace will power up and occasionally there will be some loud booms from the furnace. They are not duct sounds, they are definately the gas ignition sounds. Kind of like when you have the bbq starting and you've left the bbq gas running too long and upon ignition there's a big vwooom sound of the gas catching. It's loud enough to hear/feel upstairs. Sometimes it's onlyonce, sometimes it's several times in a row. It scares the heck out of me. I called in a hvac tech and he could find nothing wrong. He checked the gas levels, burners, cleaned the areas, etc and turned it on and off (at the furnace site) and no problems whatsoever repeatedly.

Here is where I think something is going on . When the tech came, it did it (small) once upon the first ignition...when he stopped it and reset it from the furnace switch downstairs, it never did it again. Over and over. He said to leave the temperature up higher so as to not have such a cold start on the furnace. So, it's been a few days...it still does it.

My husband has this 'trick' he does when it starts banging. He says it works every time. And it does. When it bangs, he switches the thermostat (upstairs) to OFF and then back to Auto in about a second or two to kind of reset it or something. Then, it doesn't do it anymore. If it does a few hours later (upon igniting when it's heating again) then we flick the auto switch to off, then wait a second, then back on to auto, and voila - it ignites properly without any booms and frightening things happening.

So here is my question - is this a thermostat problem, or something to do with the electrical or something completely different?

My thoughts are that resetting, turning off and on at the switch is somehow solving the problem. This definately isn't a permanent solution, but I thought it would be something to mention in the troubleshooting of this....

any thoughts? I've read on the internet, many many issues with this banging booming sound upon ignition (several times) and there seems to be no resolution.
 
  #2  
Old 10-23-10, 09:30 AM
K
Member
Join Date: Oct 2010
Location: United States
Posts: 66
Received 0 Votes on 0 Posts
The gas pressure could be too low at the outlet of the gas valve... Or their could just be a mechanical issue with the valve and it may be allowing a small amount of gas to seep through so it would be sort of collecting between cycles. Strange situation.
 
  #3  
Old 10-23-10, 11:42 AM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,499
Received 1 Vote on 1 Post
When a problem is marginal, happening infrequently, odd things may cause it to happen or not happen.


I recall one guy had a gas fireplace with glass doors on it. He found that if he "flapped" the glass doors the fireplace would turn on when otherwise it would not!


People find strange associations.


What you are describing is "delayed ignition," which is when the gas turns on but doesn't light promptly and reliably. The gas accumulates until it lights off with a whooosh or a boom.

Usually this is caused by burners that need to be cleaned, but other things can cause it.

If your repairman didn't remove, inspect and clean the burners, he didn't do the job he should have done.

Also, cycling the furnace 40-50 times to obeserve this condition happening is routine. He had the opportunity to observe it once, he should have observed where this defective ignition was occurring.

Observing this problem involves taking the front cover off the furnace and carefully observing how the burners light. It's not a good DIY projeect, because you can get a face full of flames when delayed ignition happens, and it may be difficult for the DIYer to understand what he is seeing.

:Leaving the temperature higher" is bogus advice. The guy wasn't able to identify the problem he had a chance to observe, and apparently didn't do the typical maintenance (cleaning the burners) that usually soloves the problem. He didn't do the job.


I'd call the service agency back and have them send someone out to do the job properly, carefully and thoroughly.
 
  #4  
Old 10-23-10, 04:27 PM
S
Member
Thread Starter
Join Date: Oct 2010
Location: canada
Posts: 2
Received 0 Votes on 0 Posts
Yes, I'm going to call again and ask for someone specializing in a Lennox.
Delayed ignition - even if it does the boom several times in a row?

Thank you for your help! This is definately NOT going to be a DIY thing. I'm not fiddling with gas stuff.
 
  #5  
Old 10-23-10, 04:44 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,499
Received 1 Vote on 1 Post
Multiple booms COULD be successive burners lighting off one after the other. I've never seen that happen though.

But your describing the noise as being similar to a barbeque burner lighting off suggests it a delayed ignition problem.

I wouldn't ask for someone specializing in a Lennox. You want the most experienced person available. That would be my bias, anyway.
 
  #6  
Old 11-02-10, 10:37 AM
geoimpala's Avatar
Member
Join Date: Jan 2008
Location: canada
Posts: 120
Received 0 Votes on 0 Posts
Hi see my booming "Lennox" thread as another possible cause...

My lennox furnace had a set of worn out electric motor bushings causing end play of over 1/4" allowing the squirrel cage air mover to Boom everytime it hit the frame. This type of unbalacned action was righted when the cage was knocked back into alingment after hitting the frame. Eventually the lose shaft will cause initerial destruction of the squirrel cage or a burn out of the motor. Good luck
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: