Furnace Delayed Ignition


Old 01-22-03, 06:39 PM
Visiting Guest
Posts: n/a
Unhappy gas furnace / water heater

Hello, this is my first time posting..

My husband and I bought a condo 4 months ago and it is supplied with gas furnace / water heater.

When we turned the heat on in November I noticed "banging" noises once in awhile but since this is our first house I've tried to be open minded to strange noises.

But lately it's been REALLY disconcerting. We had someone look at it who immediately turned off the furnace and said we couldn't use it until the gas company had inspected it. ugh! it's very cold here..anyway since then another repairman has come and spent some time with it and gave us the go ahead to use it. BUT...the banging noise continues.

It's only 4 years old at the most. I don't want to overreact but we are talking "gas" here.

Any ideas? and what is the worst that can happen should we just accept it as life with a gas furnace?

Sorry for the wordy message..

Sponsored Links
Old 01-23-03, 06:20 PM
Sharp Advice's Avatar
Admin Emeritus
Join Date: Feb 1998
Location: The Shake and Bake State USA
Posts: 10,440
Received 5 Votes on 4 Posts
Hello dilly. Welcome to my Gas Appliances topic & the Do-It-Yourself Web Site.

Noises are for you very difficult to explain and equally as difficult for me to diagnose without being there first hand. Since that's not possible, I will need to know what type of noise and an overall better description.

What I first need to know is exactly when the noise happens. At furnace startup or constantly during it's operation? Is the noise a rumble, squeal or an explosion sound?

Keeping in mind that I may not be able to exactly disgnose the source of the noise nor provide a correction for it. I have to rely on a licensed service persons judgement.

You mentioned quote "someone" looked at it and truned it off. You mentioned a repairman gave you the okay to use it. All very common in the industry. No two persons often agree unless the problem is very obvious. Who where these people????

Need far more specific information and I still would not be able to accurately diagnose a noise problem most likely.

Retail heating parts dealers, heating agents and part supplers can also help determine what the possible problem may be. Bring the make, model and serial numbers. Dealers are listed in the phone book.

Regards & Good Luck, Web Host & Multiple Topic Moderator.
TCB4U2B2B Company Enterprises. Energy Conservation Consultant & Gas Appliance Diagnostics Technician.
Old 01-23-03, 07:03 PM
Visiting Guest
Posts: n/a
Smile gas furnace / water heater


Thank you for your response.
Ok details...

It's a gas water heater / furnace unit.. I'm a little unsure how that works out but basically when I turn the heat on the "water heater" turns on.

After being turned on for about 20mins there's a bang that sounds like a car backfiring. Sometimes it happens twice close together.

A service technician from the gas company (actually a couple over the week) have all looked at it. one person from the gas company made what he said was an adjustment. And we've had it tuned up. The first reciept we were given says "Delayed ignition requires adjustment" which apparently has been made.

It didn't do anything to help the backfiring bang which keeps happening.

Thank you for the response.
Old 01-23-03, 09:44 PM
Sharp Advice's Avatar
Admin Emeritus
Join Date: Feb 1998
Location: The Shake and Bake State USA
Posts: 10,440
Received 5 Votes on 4 Posts
Hire A Professional

Hello: Dilly

Much better description. Problem is Delayed ignition. Causes for this condition can be both easy to correct and difficult.

Most common problem is a restricted pilot flame. Restricted meaning too small in physical size when compared to the size it should be. Clearing the pilot assembly usually resolves this problem.

Another possible problem is restricted burner ports {holes or slots} in the burner head. The ignition ports closest to the pilot flame or ignition source are most likely restircted and or plugged.

Clean the burner and the ignition ports usually resolves this problem, if the problem source is caused from the burner. Burner removal is required for most water heater appliances.

Since it's a water heater and supplies hot water to heat, the appliance is most likely a hydronic heating system, based upon the description you supplied.

Since the problem happens when the unit is already in operation, it's possible the burner is cycling back on to maintain temp. Which means the burner assembly is now hot and not cold or cool like it would be on first startup.

At this time the burner assembly is hot and the parts are expanded from the heat. This changes the entire dynamics and may be why the service person missed catching the problem. He/she did not wait and watch long enough or did not listen to your problem description.

Clearly the problem is still present if your still hearing the explosion {Bang} sound. A problem which needs to be identified and corrected by a skilled and qualified service person. Not a doityourself problem correction.

There are yet several other possible and more serious conditions which can and do cause this type of problem. Over gassed burners, higher than normal gas pressure, venting problems and firebox deterioration conditions are a few.

Takes a skilled and highly qualified service person to reconize the problem and correct it. Thus far not any you have have yet. Only solution is to call back those that have already been there and demand the problem be determined and corrected asap.

Any gas apliance that has a delayed ignition problem is serious. Continued usage causes further damage and high risks of personal injuries and property damage. Have the unit serviced.

Good Luck. Web Site Host & Gas Appliances Forum Moderator. Tom_Bart......Company Enterprises.....TCB4U2B2B
Energy Conservation Consultant & Natural Gas Appliance Diagnostics Technician.

Personal Assessment:
Amazing. Gas company services persons unable to make the required adjustments? If any simple or common adjustment would solve the problem??? HUMMMM!!!?????

PS Notes:
Most gas companies do not repair gas appliances.
They do make minor adjustments to correct minor problems or conditions.
They do issues notices for conditions which are or may be unsafe. They often make generic referrals on written forms describing the potental or suspected condition and recommend to have the appliance professionally serviced.
Gas company service persons do have the option to leave any appliance with a potential or known problem or condition turned off for safety.
Leaving a heating appliance off for safety does mean being cold.
However, it is always better to be cold and alive than cold & dead.

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
Ask a Question
Question Title:
Your question will be posted in: