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PLUMBING SYSTEM INSPECT DIAGNOSE REPAIR
BACKDRAFTING HEATING EQUIPMENT
DRAIN & SEWER PIPING
FLOODED HEATING EQUIPMENT REPAIR
FLOODED WATER HEATER REPAIR
GAS DETECTION INSTRUMENTS
GAS EXPOSURE EFFECTS, TOXIC
GAS EXPOSURE LIMITS & STANDARDS
GAS FIRED WATER HEATERS
GAS LP & NATURAL GAS SAFETY HAZARDS
GAS PRESSURES LP vs NATURAL GAS
GAS PIPING, VALVES, CONTROLS
GAS BTUH, CUBIC FEET & ENERGY
GAS CONVERSION LP-NATURAL GAS
GAS FLAME & NOISE DEFECTS
GAS IGNITER DEFECTS & REPAIRS
GAS LEAK DETECTION, LP / NG
GAS LIGHTING, PIPES, FIXTURES
GAS PIPING DEFECTS
GAS REGULATORS for APPLIANCES
GAS REGULATORS for LP TANKS
GAS REGLATORS, TWO STAGE
GAS SHUTOFF VALVES
LP / PROPANE GAS TANKS
GAS LP & NATURAL GAS SAFETY HAZARDS
LP & Natural Gas Pressures
METHANE GAS SOURCES
Natural Gas Combustion Products
SPILL SWITCH, FLUE GAS DETECTOR
TYPES OF FUEL GAS SOURCE
MANUALS & PARTS GUIDES - HVAC
METHANE GAS SOURCES
ODORS GASES SMELLS, DIAGNOSIS & CURE
ODORS, SEPTIC or SEWER
ODORS, SULPHUR SMELL SOURCES
OIL TANK PIPING & PIPING DEFECTS
PIPING IN buildings, Clogs Leaks Types
SEWER GAS ODORS
SHUTOFF VALVE LOCATION, USE
SULPHUR & SEWER GAS SMELL SOURCES
Gas igniter troubleshooting on heating equipment:
This article explains the cause, diagnosis, and cure of gas heater or gas appliance igniter problems that cause bangs, whooshes, noises, clicking, or failure to ignite properly.
Watch out: some of these conditions are dangerous. We also discuss both gas igniters and gas regulators on gas fired heating equipment and LP or Natural Gas Pressure Regulators used on building appliances such as gas fired furnaces, boilers, water heaters, and stoves.
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This article series provides descriptions and photographs of unsafe gas piping, regulators, or controls on heating systems, indications of unsafe or improperly operating gas appliances, gas meters, and other gas installation defects.
This document also provides free sample draft home inspection report language for reporting defects in oil and gas piping at residential properties.
[Click to enlarge any image]
Photo at left: the igniter module for a Jenn-Air countertop gas cooktop. We replaced this item as well as the wiring and individual igniters to cure chronic gas burner ignition problems: endless clicking. Details of that repair are found in the article below.
General safety warning: improper installation and even improper inspection and testing methods involving natural or "LP" gas can involve dangerous conditions and risk fire or explosion.
If you smell gas you should leave the building immediately and should do so without doing anything that could create a spark such as operating a light switch or telephone. From a safe location, call your gas company's emergency line and/or your fire department. The text provided here is a working draft and may be incomplete or inaccurate
Question: Noisy gas burner igniter worry: when the valve opens it sounds like a hammer hitting a metal pipe
Both times InspectAPedia has warned me about possible errors I avoided by reading your website on Furnace Inspection. You've heard it many times I'm sure, but thanks for the heads up. Many times I've learned the expensive way what not to do in DIY project.
May I ask your opinion on intermittent pilot valves for gas furnace? My furnace works perfectly. However, when the valve opens it sounds like a hammer hitting a metal pipe...Is it possible the electronic ignition is sending more than 24 volts to the valve solenoid and that's why it makes such a loud noise on opening?
There's a box that regulates and sends the 24 volt electronic signal to the pilotless ignition that I've thought about replacing.
About your pro bono advice, I'm 60 years old, no job, no pension and would appreciate any advice. - R.K., MI
Reply: Short answer: the gas burners may need cleaning, the system may be unsafe, you need a service call
First we ought to rule out a dangerous noise that can be heard when the gas furnace ignites.
Properly when the thermostat calls for heat the igniter lights a pilot that then ignites gas when it is released into the burners.
If burners are dirty or clogged, the gas flame may not be igniting across all of the burner tubes as quickly as it should. A result could be incomplete ignition and a banging sound when the accumulated gas finally ignites. You should be able to detect this problem by observing with care just what happens during a heater on-cycle.
Watch out for sooty gas burners: If you see soot on or around gas burners such as shown in our photo (above) you should shut off the equipment (it is unsafe) and call a heating service technician promptly.
And if this is the problem, a service call that includes cleaning rust and debris off of the pilot and igniter, or rust and debris off of the burners and checking their adjustment might fix the trouble.
If the gas burner tubes include flame crossover slots, those are intended to assist the spread of flame from the first ignited gas burner tube over to the other tubes. Be sure those slots are cleaned as well. Be sure to also ask your service tech to check the proper operation of all of the heater safety controls while s/he is there.
Watch out: in boiler school our instructor came to class one night with his previously full-beard shaved off. His eyebrows looked odd too. He explained that he was kneeling by the burner, watching too closely when the flame was igniting. A flashback burned off half of his beard and one eyebrow. He had to finish the job himself with a razor. Don't get your face too close to the gas burners while inspecting for trouble during flame ignition.
There might be a different problem, a delay in igniting the pilot itself, though that is probably less common.
What Causes the Bang, Kaboom, or Loud Whoosh When the Gas Burners are Igniting?
A "bang" or "kaboom" (as some folks describe it) sounds very dangerous, if that's what you've got. It can signal that you are getting "delayed ignition" of the gas in your combustion chamber. If the gas valve opens and sends gas through the burners but actual ignition is delayed, gas accumulates, then ignites with an explosion when the spark finally occurs. The risk is a damaged, cracked heat exchanger leading to a costly furnace replacement, or worse, a dangerous heating system leaking potentially fatal carbon monoxide into the building.
A loud "whoosh" during burner flame ignition may be caused by the same burner clog and debris problem, especially if it's heard earlier in the development of this dirt and debris difficulty.
Watch out: for questionable advice we've come across when researching the noisy gas burner ignition worry: advice that focuses on adjusting the burner air shutter to improve the flame may be confusing a dirty burner problem (discussed just above) with the need for proper burner adjustment.
The two could be related: if there is a shortage of combustion air the burners could be producing a bit of soot that in turn clogs the burners and leads to a bang or whoosh sound when the gas furnace or boiler burner ignites.
But if the root problem was improper combustion air to the heater or improper air mix adjustment at the burner tubes themselves, that problem would have probably been present from day one of the heater's installation. If your heater has worked well for some time and now is developing noise, check the advice we gave at the start of this note.
Watch out: a heating appliance might have adequate combustion air only when the utility room door or some other nearby door is open. If the service tech adjusts and tests the system with the door open, the system may look just fine. But when s/he leaves and shuts the door to the utility room there might be inadequate combustion air.
Details about diagnosing and correcting gas or oil appliance combustion air problems are at Combustion Air Defects
Watch out: also for the presence of soot anywhere in, on, or around the gas burners. If the system is producing visible soot its operation is improper and very dangerous as production of potentially fatal carbon monoxide is probably going on. While natural gas and LP gas normally burn clean, a chimney or draft or combustion air problem can lead to very rapid system clogging, soot, and potentially fatal heating system troubles.
Sources of Heating System 24V Transformer Noise
Question: [continued] My first note should have mentioned that I narrowed the hammer on a pipe sound to the actual valve by shutting off the natural gas supply and reproducing the sound without an actual ignition. However, I would guess you answered my question on improper voltage going to the ignition because your note did not even mention that as a possible issue.
I did replace the valve last fall. New Honeywell equivalent valve. You guessed it same issue. Maybe even a little more noisy than the 20 year old original. I will look into a transformer replacement.
I have never seen a heating system coil develop a defect that led to high voltage coming out of a furnace or boiler 12V or 24 V transformer, so I didn't suspect that cause. According to our electrical expert Paul Galow (Galow Consulting), the transformer is very unlikely to be the root cause of the sound you describe, and a more likely cause, if you have indeed traced the sound to the valve itself, is a mechanical problem in the valve that means it needs replacement.
The output voltage of a transformer is determined by the input voltage and the number of wire turns in the transformer winding. To double the output voltage of the heating system 24V output transformer you'd need to have cut or shorted the transformer in a way that eliminated half of those turns. Such a defect would be not only unusual but it would more likely lead to burn-up of the device and it would stop working altogether. You could replace the 24V transformer as an experiment - they are quite inexpensive, but it doesn't sound as if the trouble lies there.
Transformers do make noise, but more likely they make a 60-cycle buzzing or humming sound. The transformer often has a core made up of laminated metal components. If the glue fails the core can vibrate, causing a hum.
So while we don't rule out some bizarre defect that causes the transformer to send an overcurrent to the gas valve mechanical solenoid that opens to actually send gas to the burners, it's not likely and more likley is wear or something breaking inside the mechanical parts of the solenoid itself.
Now to the Gas Solenoid Valve Itself
With all those safety warnings and dirty burners out of the way, if you do not see any burner troubles and you can trace the clicking hammering noise really right to the gas solenoid valve, it probably needs replacement.
As you have made clear that you are hearing a loud hammer-click that seems to come right from the gas solenoid valve itself, it sounds as if there lies a mechanical defect.
We [DF] fixed a humming transformer by whacking it once with a hammer. Not very elegant and certainly not recommended by a repairman, but the humming quit for another year or so. About replacing the solenoid valve, given that your previous replacement didn't last: It's a bit subtle but
Watch out for Batches of Bad HVAC Replacement Parts
Watch out: I [DF] have bought and replaced heating and air conditioning system replacement parts (and for that matter car parts) only to find the new parts were defective. Worse still is to go back to the same store, buy another new part, only to find it's defective too.
Keep in mind that often all of the replacement parts of a given part number that are stocked at a local supplier often arrived in the same box, on the same day, and came from the same production run. So if one of them is bad, sometimes all of them are. Try buying the part somewhere else when you replace it, or check the lot numbers on the package to see if you can get a part from another production run.
See GAS REGULATORS for APPLIANCES for details on how to inspect and test LP or natural gas regulators and controls.
When a gas-fired heating appliance stops working the problem may be with the igniter, not other gas valve components.
Our photo (left) shows an LP gas stove top burner igniter sparking away.
Watch out: we disassembled the stove top burner to make this photo. But don't turn on your gas stove with burner parts missing - the flame won't ignite properly and you could cause a dangerous gas explosion.
Start by checking the wire connected to the igniter itself. If the connection is loose or damaged that could be the problem.
If the ceramic igniter is cracked or damaged it may be shorting to ground and unable to ignite the gas flame.
We have seen recurrent problems with some stove-top gas igniters whose wires ran across the interior pan of the stovetop where they rested in water or cleaners used to clean that appliance.
The result was a shorted igniter wire and constant clicking that drove the homeowners crazy.
Details about how we diagnosed & repaired this problem are at GAS COOKTOP IGNITER REPAIR .
The gas igniter control module may itself fail and need replacement. This is a more costly part, and in our experience is less often the problem than the items above.
Continue reading at GAS COOKTOP IGNITER REPAIR where we discuss the diagnosis & repair of gas igniters on cooktops & gas ranges or select a topic from the More Reading links shown below.
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Frequently Asked Questions (FAQs)
Question: gas system does not light
(Aug 22, 2011) wilson m. said:
every year the heating system goes out the repair man comes out. the system comes on but the system do not light. I have an elecita and gas system
Wilson from your question I'm not sure what kind of heat you have - gas or electric.
If you mean it's gas fuel (LP or natural gas) but an electric igniter, than you may have a bad igniter, igniter wiring, igniter control box or board, or a bad flame sensor that is not sensing that ignition was successful, OR a bad safety control that is shutting down the system.
You might give the service manager a call at the heating company you use, let her or him know that this has been a recurrent problem and ask that they send an experienced technician to find and fix the problem.
(Dec 30, 2011) ann said:
how can a wire in a gas stove catch fire top burner
Ann I'm not sure I understand the question but you may be referring to a wire that carries a small voltage to an igniter that in turn makes a spark at the burner when the gas burner's valve is opened.
(Feb 14, 2014) Paul said:
If i turn on my gas stove while a burner is already on there is what i would call a small explosion inside the stove. What causes this?
Sounds VERY DANGEROUS _ as you probably have either a gas leak or an igniter that is so slow to ignite that a volume of explosive gas accumulates before ignition.
It's common to hear a soft "whoosh" sound when ligting a pilotless gas oven, for example, using a match or manual igniter, as enough gas has to accumulate to pass back up the ignition tube where you are holding a match.
But on an electric ignition gas burner stovetop you should not be hearing an explosion. Your appliance needs repair.
(Apr 30, 2014) Rick said:
My stove propane stove top burners light fine, but the igniters keep firing after the burner or burners are lit. What causes this?
Often when the igniters won't stop sparking (which can drive me crazy), it's because of
- damaged, leaky wiring to the igniters
you want to take a look at the companion article
6/14/14 Andre Matthew said:
facing a lot of problems regarding gas leakage in my stove but still can’t found the dimage place, how can i find it???? tristaterepairs
Typically experts use gas leak detection instrument such as the TIF 8800 combustible gas detector,
to check for gas leaks - this is a VERY sensitive device.
OR plumbers and installers use a simple soap solution to check pipe joints, control seams, etc.
Don't forget checking the supply piping and valves.
WATCH OUT: do not leave the stove gas supply turned ON until you've found and fixed the leak. You risk a fire or explosion.
Question: Caloric range oven made a loud POP now oven won't light
(June 21, 2014) tamnic656 said:
Sounds as if an electronic control failed. I'd be worried about an electrical short and unsafe range/oven and would turn off power to the unit pending inspection and repair.
Question: Wolf brand gas cooktop troubleshooting
(July 30, 2014) Joe Cato said:
Joe, It's an excellent question and beyond my expertise.
Typically the igniters expect to see 120V power routed through the appliance control board. I would give Wolf a call, talk to their technicians, and if necessary (since they may not know how to answer you) get the name and contact information for the manufacturer of the igniters used in Wolf gas cooktops, then take this question to them.
I'm assuming you've already checked voltage levels.
If you are in the U.S. call Wolf Customer Service at (800) 222-7820 - there is no other information on the company's Contact page - it's as if their actual location is secret.
Question: buzzing from heater
(Sept 20, 2014) Mike said:
I do intend to call a professional but this problem has plagued me for years. I've tried calling someone to fix it twice before and the technician said it might've been a bad thermalcouple so he recommended replacing it. But the buzzing continued. Is a thermalcouple the same thing as a transformer or relay? I'm hoping to canvas whether you've heard of this problem before so that at least I can feel like the tech isn't just guessing.
NO a thermocouple is not a transformer. The thermocouple is a temperature sensor. A transformer is an electrical device that produces low voltage, typically 24V, to operate HVAC controls. - DF
Question: hissing sound from bathroom gas heater
(Sept 25, 2014) Crystal said:
If you smell gas you should leave the building and call for emergency assistance as there could be a dangerous gas leak.
If the hissing sound is not a gas leak I'm uncertain what it might be -there could be moving parts (such as a blower fan) making noise, or something else.
TO be safe, turn off both power and gas to the heater immediately if you can do safely. Then call a heating service company for inspection and repair.
Question: furnbace makes sound like a washing machine
(Oct 29, 2014) Sharon said:
No I don't think so Sharon.
I infer that you really mean a boiler (furnaces are hot air heaters); it sounds as if there is a problem with a motor, circulator pump, or air in the piping.
Question: gas hob burners keep cutting out
(Nov 5, 2014) Anonymous said:
Anon the question makes me worry about a potential fatal gas poisoning or gas explosion. I'd turn off gas to the appliance until it can be inspected and repaired by a trained gas appliance service technician. That person may find dirty burner orifices, clogged gas piping, or a bad regulator or something else.
For other non- U.K. readers, a gas hob is a British term that refers to the top part of a cooker that accepts pots and pans. In older buildings the hob was a shelf projecting from the back side of a fireplace also used for cooking or for keeping food or pots and pans and dishes warm.
Question: exploding sound when gas heater ignites
(Nov 13, 2014) Anonymous said:
(Dec 8, 2014) Jim M said:
Watch out: what you describe sounds dangerous - as if there is too much UN-ignited gas and a delayed ignition. I would ask for help from a trained gas appliance or gas heater service tech. I suspect misaligned igniters or a gas leak when I hear this symptom.
The problem may be a gas leak or an improperly-operating control or igniter.
If you have to bang on the boiler's gas valve something is wrong, and maybe unsafe, and certainly not practical - I'd ask for help from a service tech.
Question: gas furnace has trouble igniting
(Nov 17, 2014) Louisa said:
No Louisa. That's not normal and it may be unsafe. I'd ask for help from a trained heating service tech.
(Jan 1, 2015) Anonymous said:
Question: did I pay too much for replacement of an igniter on my boiler?
29 January 2015 Bob said:
Just had an igniter replaced on my boiler. Bill came with a charge of $159.00 for the part. Should I complain about this cost, since it is advertized on line for $29.69 from various suppliers?
Having embarrassed myself on occasion by getting too irate too quickly, I'd suggest a calm, polite inquiry in conversation with the service manager at your heating service company. Provided that labor is being charged separately, still you'd figure that the company has to put a mark-up on the part price.
You're paying them for having the item stocked on and carried around in the truck in sufficient variety to have the particular part you needed.
On the other hand, a more than 500% mark-up sounds a bit steep. Make sure FIRST that you are checking the proper price for the part. "igniter" might refer to a small assembly or an entire gas valve and igniter assembly as a unit.
The take a look at the total service call bill break-down: parts, labor, other charges. If the labor and other charges are paying the service company fairly for the service call then you might ask them to reconsider the part price. On the other hand, some service companies tack on a minimum travel time charge while others don't. So as Mark Cramer says ... it depends.
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