Gravity Furnace advice/Safety

Reply

  #1  
Old 12-22-07, 07:30 PM
Member
Thread Starter
Join Date: Dec 2007
Posts: 3
Received 0 Votes on 0 Posts
Gravity Furnace advice/Safety

We have a old 1942 Gravity Furnace in the basement garage.

We just noticed that it is making a louder "shooshooshing" sound. (the noise of a gas flame burning). I looked down at the front and noticed that a flame is actually burning just behind where the small air intake holes are before the gas enters the furnace body. See Photo links.

I am guessing here, but it seems that the gas is actually burning/lighting inside the "cast iron" intake/pipe, on it's way to the burner. The Main burner is still burning fine.

I think it's not supposed to work this way!
The gas is supposed to travel down the pipe into the furnace, and then ignite when it reaches the pilot light and the Main Burner.

Am I right to assume this is a VERY dangerous hazard??
I'm going to call a HVAC guy on Sunday, but want to know if I should SHUT it down completey so it does not turn on while we are asleep (in the COLD!!! arghh!!)

Could something be causing a back-up in the pipe??
I turned it off and ran a wire down the length to the burner, but not obstacle was hit???

Please see pictures ( you can see the blue flame in the darker picture)

Thanks,
Norbert





 
Sponsored Links
  #2  
Old 12-23-07, 12:18 AM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Received 0 Votes on 0 Posts
The burner you have is a bunson burner. There is a small jet in the gas pipe that allows a jet of gas to be directed into the burner, and the speed and volume of that jet sucks air through the air shutter which then mixes with the gas.

The gas will only burn so fast, and when the burner is operating properly, the flame burns on top of the burner as you describe. When the burner is dirty or improperly adjusted, the gas moves too slowly to burn on top, and flashes back to burn inside the burner as you are experiencing.

No surprise that this is called flashback.

So something is causing the gas velocity to be too slow. Quite a few things can cause this.

I'd start by taking out the burner and cleaning the burner ports, emptying out any accumulated rust and corrosion which tends to accumulate inside the burner, and blowing out any accumulated debris.

Is the burner shutting off completely? The "whoosh" noise is typical of flashback with a normal head of gas, but the picture you post looks like just a small jet of flame is present, which suggests the gas valve isn't shutting off completely.
 
  #3  
Old 12-23-07, 05:58 AM
Jay11J's Avatar
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 18,427
Received 0 Votes on 0 Posts
I agree with SP's post.

From the view of the photo, looks like it is due for a good cleaning there.. Also, the air shutters are closed down more than I think it should be open for.

I'd hate to say this, but you are wasting a lot gas on this type of furnace to heat your home, may want to start putting money away for a new one down the road.
 
  #4  
Old 12-23-07, 10:17 AM
Member
Thread Starter
Join Date: Dec 2007
Posts: 3
Received 0 Votes on 0 Posts
Thanks guys,

The tech is cleaning the furnace as I type.

He said that the part has probably failed and would be hard if not impossible to find a replacement.

He said he would clean it, but could not guarantee the problem going away.

Is it a Major Safety problem to run the furnace when this occurs?? Is there a chance of explosion or such?
 
  #5  
Old 12-23-07, 06:32 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Received 0 Votes on 0 Posts
What's "the part" the repairman is talking about? I presume it's the cast iron burner. They are pretty much bullet proof (almost literally) and can usually be cleaned pretty much forever as well.

If it's properly cleaned and adjusted, the flashback problem should go away, unless there is something else that is causing or contributing to it, such as an electric gas valve that isn't closing properly or completely.


While some flashback usually isn't an actual hazard, it could be. You don't want to operate a furnace with that kind of problem.




Originally Posted by norbertsf View Post
Thanks guys,

The tech is cleaning the furnace as I type.

He said that the part has probably failed and would be hard if not impossible to find a replacement.

He said he would clean it, but could not guarantee the problem going away.

Is it a Major Safety problem to run the furnace when this occurs?? Is there a chance of explosion or such?
 
  #6  
Old 12-25-07, 02:17 PM
Member
Thread Starter
Join Date: Dec 2007
Posts: 3
Received 0 Votes on 0 Posts
Burner was cleaned ($200) and everything is working OK again.

Yes....time to save up for a more efficient furnace.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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