How Does a Gas Furnace Thermocouple Work... How Does a Gas Furnace Thermocouple Work? The thermocouple responds to changes in temperature by producing an electrical current that causes the gas valve that supplies the pilot light to open when the temperature is high or to shut once there is no direct heat supply. In almost all cases, the thermocouples are welded into place, which creates a horrendous problem when maintenance is needed. That provided a means of proving the main burners would ignite when the main valve opened. Therefore, if the pilot light was not lit or the thermocouple was bad, the main valve could not open. A thermocouple is a heat sensor placed next to the pilot flame that indicates the gas valve to open when the flame is burning. If there is soot build up on your thermocouple, then the issue might be resolved by cleaning your thermocouple. [LEFT]At first the furnace was short cycling... running for a minute then s... Gas hot water heater turning off gas furnace. Several things can cause this, dirty boiler water or high pH level are the most common. The thermocouple is the copper rod the pilot flame directly hits. This Weil McLain boiler troubleshooting guide explores common problems and steps you can take to identify and possibly solve them. Take the thermocouple to a hardware store for a replacement which is the same size on each end and same length or longer. If the furnace still won’t work, the thermocouple is probably bad. Proceed cautiously with the diagnostic steps you take. I noticed it was cold and... Coleman Model 7975A856 Natural Gas Installed: 7-88 Pretty simple mobile hom... My furnace kicks on, sometimes it will fire and occasionally it won't. In fact, the problems that affect gas furnaces typically involve the furnace's thermocouple, the pilot light, or some component of the electrical system. You also want to make sure that you have the gas shut off, and the you set the gas valve to the off position. banging, whistling, gurgling) Low boiler pressure; Frozen condensate pipe; Radiators are cold; Boiler keeps switching itself off; Boiler is not responding to the thermostat Boiler malfunctions are a major inconvenience that can make a home an icebox until the problem is fixed. Check the furnace manufacturer and model and call the manufacturer for the right part number. That has a copper wire that goes from the probe to your gas valve. The tip of the thermocouple is positioned in the flame, keeping the tip heated at all times. Be sure to use your pilot lighting instructions on the side of the furnace while going through the following steps to insure an accurate inspection. It sounds like your boiler is "surging". Most furnaces run on standard measurement fittings, while others have their own specialized specs and dimensions. Tag : boiler thermocouple problems. You will need a screwdriver to loosen the screws and remove the thermocouple from the pilot assembly. Because of high pressure and temperatures in a boiler system, many malfunctions require the expertise of an HVAC professional. Therefore, inspecting and testing your thermocouple should be part of your furnace maintenance. The tube sits above the bracket, a nut holds the bracket and wires in place, and underneath the bracket, you will see the copper lead wires that connect to the gas valve on the furnace. Most hardware and home improvement stores carry replacement thermocouples. Once this is complete go ahead and remove the pilot cover which will reveal two upright posts, one is the gas line for the pilot and the other is your thermocouple. Honeywell CQ100A1005 36-Inch Replacement Thermocouple for Gas Furnaces, Boilers and Water Heaters 4.7 out of 5 stars 121. 1995-2018 MH Sub I, LLC dba Internet Brands. Malfunctioning thermostat : A faulty thermostat can lead to problems with the fan or comfort levels. I show how to bench test a thermocouple for a gas furnace using a multimeter. Fortunately, many boiler problems are common and can be simply repaired by a professional heating engineer or, in some cases, can even be resolved yourself. Because the thermocouple is such a vital part of your boiler system, it is highly recommended that a professional replace the thermocouple. A gas furnace thermocouple is a small electrical device that acts as a safety device on a furnace. You may freely link A thermocouple is the right hand man of the pilot light as it reads the pilots temperature on a rating, which tells it to keep the gas flowing. If you accidentally reverse the polarity of the … Then turn on the pilot again following the lighting instructions on your furnace and watch the pilot for failure to light. how to replace thermocouple and how to replace pilot assembly. When the thermocouple is clean, reattach it to the pilot assembly. It j... How to Find the Pilot Light on a Water Heater, Troubleshooting a Brick Outdoor Fireplace, How to Replace a Hot Water Heater Thermocouple. You then need to let the furnace air out and cool down for a few minutes. It's a safety mechanism that shuts the gas off should the pilot go out. Attach one lead of the multimeter to the silvered end of the thermocouple wire (the part that made contact with the gas valve) and the other lead to the bare copper thermocouple wire. This heating can cause the dissimilar metals inside the thermocouple to break apart temporarily dropping the output voltage to zero. Natural gas and propane burn cleaner than fuel oil, and most gas furnaces present fewer operational difficulties than oil burners do. Our HVAC experts at PEACE OF MIND PLUMBING provide high quality furnace repairs that come with a 12 month no-hassle guarantee! Take your 3/8" wrench and turn the thermocouple nut (the copper one) to the left loosening the nut, this should cause the pilot to go out. Honeywell CQ100A1005 36-Inch Replacement Thermocouple for Gas Furnaces, Boilers and Water Heaters 4.7 out of 5 stars 121. DoItYourself.com®, founded in 1995, is the leading independent Thermocouple vs. Flame Sensor . Noisy Boiler or Noisy Central Heating. CDN$11.99. While some boiler problems are complex enough to warrant hiring Greenville heating and air experts, others can be resolved with a DIY approach. Plumbers and HVAC service companies are skilled and knowledgeable with standing pilot gas systems. This will help to insure you're getting the right size replacement for the thermocouple in your furnace. If this light keeps going out there could be a faulty thermocouple … What to Do if a Gas Furnace Pilot Light ... What to Do if a Gas Furnace Pilot Light Won't Stay Lit. A thermocouple is typically used on a gas furnace with a standing pilot, recognizable by its small, continuously burning flame that you can see if you remove the access cover on the furnace's burner chamber. Thermocouple and pilot tube burner in gas furnace Step 3 – Clean Dirty Thermocouple: If the thermocouple is NOT bent and is aligned correctly, you may have a clogged or dirty thermocouple. Thermocouples are essential for displaying the temperature especially in a residential environment. Attach one lead of the multimeter to the silvered end of the thermocouple wire (the part that made contact with the gas valve) and the other lead to the bare copper thermocouple wire. That is more of a catch-all time frame for thermocouples which may heat up (and thus generate current) more slowly. Thermocouples can last several years, but they don’t typically last as long as the furnace itself. There are three reasons why your thermocouple might be malfunctioning: It's Broken. If it does not light then you will then want to go ahead and unscrew the thermocouple with your wrench and remove it. If so, and the boiler or furnace isn't firing up, then you need a new gas valve. If the appliance has a thermocouple, the problem may be a faulty thermocouple. I suspected the thermocouple and replaced it, but this didn't fix the problem. This started occurring after I did some gas plumbing and had to relight the pilot. When a malfunctioning thermocouple provides improper readings, it can shut off the gas supply to the furnace even when the pilot light is working. The thermocouple was used to hold the pilot valve open. To be sure the problem is coming from the gas furnace thermocouple and not the pilot, clean the pilot valve out with a fine wire and be sure that the outlet is not clogged from residue or build-up. Then turn on the pilot again following the lighting instructions on your furnace and watch the pilot for failure to light. Physical damage to the connectors which can have an effect on the reliability of the test reading. Problems of Reference Junction Compensation : Thermocouples Diagnosing a Thermocouple Problem If your pilot light ignites but won’t stay lit, then the problem is most likely related to your thermocouple , a metal sensor (about the size and shape of a sharpened pencil) that heats up by direct contact with the pilot light’s flame, telling your gas valve that the pilot light is lit so it’s safe to open the valve to let gas flow. The Boiler or furnace Thermocouple, what it does why it fails and how to replace it. home improvement and repair website. If the thermocouple doesn’t produce a small electrical current when the … © 2001-2019 PEACE OF MIND PLUMBING Ltd. All rights reserved | Owned & Operated by Peace of Mind Plumbing Ltd. Relax…with us, you’ll know the full price BEFORE we start so there’s no guesswork or nasty surprises. There was a problem completing your request. Be sure you use the exact furnace details so you get the correct size and type for your thermocouple replacement. Like the other component parts in your furnace, the thermocouple can wear down over time, producing lower voltage than it should when heated. Asides from leaks, there are other problems that can cause a boiler to lock out including fault codes: 110 (overheating), to 160 (a faulty fan) or even 166 (air pressure switch fault). Because the thermocouple is such a vital part of your boiler system, it is highly recommended that a professional replace the thermocouple. A noisy boiler is often caused by “Kettling”, which is a build up of limescale in the heat exchanger. If your thermocouple is dirty, get some fine grain sandpaper and clean it off. A common culprit for this fault on Baxi boilers is a lack of pressure. Thermocouples fail, and must be replaced periodically. If there is soot build up on your thermocouple, then the issue might be resolved by cleaning your thermocouple. If the pilot in your boiler extinguishes on its own, your boiler probably has a faulty thermocouple. The water in Calgary originates in the Rockies. Working with electrical systems is dangerous and may cause damage to yourself and your home if handled incorrectly. Faulty Thermocouple. Weil McLain Boilers – Common Issues 1. View our Privacy Policy here. The thermocouple needs to detect the flame, otherwise it will shut the gas valve, and your furnace will not function correctly. Gas furnaces and heaters have control shutoffs to prevent gas leaks, but they are not fail-safe. Turn on the furnace and light the pilot light following the manufacturer’s manual. Be sure to inspect before you test, however, to ensure that there are no obvious problems … Once this is done you can remove the pilot cover which will reveal two upright posts, one of which is the gas line for the pilot and the other is your thermocouple. The furnace doesn’t heat at all : A furnace that doesn’t perform its main task may have problems with the thermostat setting, power, gas or the pilot light. This heating can cause the dissimilar metals inside the thermocouple to break apart temporarily dropping the output voltage to zero. The water in Calgary originates in the Rockies. To be sure the problem is coming from the gas furnace thermocouple and not the pilot, clean the pilot valve out with a fine wire and be sure that the outlet is not clogged from residue or build-up. Check the furnace manufacturer and model and call the manufacturer for the right part number. You must change a bad thermocouple as soon as possible. Once you have adjusted the gas furnace thermocouple, go ahead and turn on the gas using the instructions located on the side of your furnace. The thermocouple consists of up of a tube, a bracket, and wires. discoloration, cracks, or pinholes. You can find a gas furnace thermocouple replacement at any good hardware store, or even on some on-line stores. NOTE: It is the temperature difference between the cold and hot junction that creates the millivolts. I show how to bench test a thermocouple for a gas furnace using a multimeter. Problems Related to the Thermocouple Extension Wire. Sitemap A pilot flame that is overly large can cause thermocouple failure for two reasons, 1. overheating of the tip (hot junction), or 2. overheating of the base (cold junction) of the thermocouple. PRIVACY POLICY Signs of wear or corrosion of the wirings, e.g. Water can become discoloured by minerals like iron and copper, which cause the pipes to rust. But whenever a boiler failure occurs, it’s never ideal and always inconvenient. Partly to get the house warm again and partly to avoid problems like this g... Fraser Johnston furnace model #125 C 21 problems. Burnham burners and boilers are no different than any other manufacturer. If you get that pilot lit, let it run for a good minute or two then blow it out, if your pilot gas flow does not 'click' off within 30 seconds, then you could have a valve problem. Before attempting to check or clean the gas furnace thermocouple, you need to shut off the furnace’s power supply. Water can become discoloured by minerals like iron and copper, which cause the pipes to rust. Make sure the thermocouple and pilot light are properly aligned. Topping the system back up via the filling loop should resolve the problem. We welcome your comments and The pilot light going out is one of the most common reasons that a gas furnace fails to produce heat. Thermocouple vs. Flame Sensor . If you cannot detect any obvious problems then it may be time to call an HVAC contractor to check the functionality of your thermocouple. Pilot light doesn't stay lit on 25+ year old slant fin furnace. Insufficient water pressure will prevent the boiler from creating enough hot water to adequately... 3. First take a wrench and slightly make a tightening adjustment at the base of the thermocouple. Sometimes the problem is simply that the thermocouple probe is too far from the flame. If you are wondering, Intermittent thermocouple problems can occur if the pilot flame heats the lower 1/3 of the thermocouple. If your system is set lower than 1.5 bar then it … If your thermocouple is dirty, get some fine grain sandpaper and clean it off. Thermocouples fail, and must be replaced periodically. A bad thermocouple itself can prevent a gas furnace or boiler from working - if you can light the flame at the pilot manually but then the flame goes out when you release the manual gas feed valve, the thermocouple is probably bad. The tip of the thermocouple is called the hot junction and is where the two dissimilar metals join. There was a problem completing your request. Be sure you use the exact furnace details so you get the correct size replacement for your furnace. Little or No Heat. Diagnosing a Thermocouple Problem If your pilot light ignites but won’t stay lit, then the problem is most likely related to your thermocouple , a metal sensor (about the size and shape of a sharpened pencil) that heats up by direct contact with the pilot light’s flame, telling your gas valve that the pilot light is lit so it’s safe to open the valve to let gas flow. If the pilot remains lit, but the main furnace doesn’t stay lit, it may be time to replace the thermocouple. A thermocouple is typically used on a gas furnace with a standing pilot, recognizable by its small, continuously burning flame that you can see if you remove the access cover on the furnace's burner chamber. Please try your search again later. Call 604-500-9876 now or fill out the quick form below and we will call you back in a few minutes to confirm your details. A common culprit for this fault on Baxi boilers is a lack of pressure. problems contact webmaster@doityourself.com. Use a piece of steel wool to gently remove the soot. The average HVAC tech will be clueless. If the appliance is a boiler or furnace, it'll use 24 VAC to operate the "main" valve. On old furnaces, the standing pilot light can go out due to a strong draft, a dirty orifice in the pilot burner, or dirt in the gas tube. You should get a reading of around 40 millivolts when the pilot flame is on. This … And the worst part is that you can have a bad thermocouple without even knowing. You are looking for the following: If you cannot detect any obvious problems then it may be time to call an HVAC contractor to check the functionality of your thermocouple. Tag : boiler thermocouple problems. It is installed so that its ends are in the pilot light of the furnace, and is considered the right hand man of the pilot light. Banging, gurgling, rumbling or whistling pipes can be caused by … Problems of Reference Junction Compensation : Thermocouples You can use a pencil eraser to clean between the threads of the screw that attaches the thermocouple. During your inspection of the gas furnace thermocouple, you will be turning the gas line on and off while making a number of slight adjustments and tests to determine if the source of your pilot problem. The thermocouple, which operates as a safety device, turns the gas supply off when the pilot light goes out. If you have removed the thermocouple nut from the gas valve and the pilot stays on, The gas valve is defective and must be replaced. If the pilot does not ignite, turn the gas switch off again, and wait the few minutes for gas dispersion. If you can’t find your furnace’s power switch, shut off the circuit breaker that supplies power to the furnace. Here’s a look at some boilers problems and ways to resolve them. You need to call a steam pro to check it out. If you are unsure about what’s going on with your furnace or how to inspect or replace your thermocouple, make sure you contact a professional HVAC contractor to do the job safely! Loose Connections; Your intermittent ignition system is electronic, and loose internal furnace connections can interrupt signals. It is high in calcium and magnesium, so limescale can create problems with plumbing and appliances. submitted to our "DoItYourself.com Community Forums". It should be about an inch high and mostly blue. They can troubleshoot the problems and replace the thermocouple if necessary. Sometimes it's referred to as the "flame sensor." Before checking the gas furnace thermocouple you want to make sure that you have the gas shut off by putting the pilot setting switch to off and waiting a few minutes. There are some boiler problems, though, that may be resolved by the homeowner. Be careful as the area could still be hot from the pilot touching it and a tight pair of leather gloves can help protect your fingers from getting scorched. It consists of a heat sensor connected to a solenoid; when the sensor is not heated by the pilot flame, the solenoid closes the gas supply line. Once you have located the thermocouple, do a visual inspection. This is due to your central heating system being inactive during the summer months. Check to see if you're getting 24 VAC at the terminals on the gas valve. Common Boiler Problems & Repair Costs Did you know your boiler is most likely to have a problem during the Autumn? How to Install a Gas Shut Off Valve in a... How to Install a Gas Shut Off Valve in a Gas Furnace. If the appliance has a thermocouple, the problem may be a faulty thermocouple.The thermocouple, which operates as a safety device, turns the gas supply off when the pilot light goes out. Asides from leaks, there are other problems that can cause a boiler to lock out including fault codes: 110 (overheating), to 160 (a faulty fan) or even 166 (air pressure switch fault). In fact, the problems that affect gas furnaces typically involve the furnace's thermocouple, the pilot light, or some component of the electrical system. All our plumbing repairs come with a 12 month no-hassle guarantee for ... See our Common Service Questions here and check out our helpful home resources centre. Older boilers may have a permanent pilot light which needs to stay lit in order to light the larger burner within your boiler. I've used this furnace for over 15 years without replacing the thermocouple. CDN$11.99. Any heating system can be a source of problems. Leave a Review, FIXED PRICE REPAIRS But, sometimes, thermocouples wear out, then you may need replacing. Call a pro if you suspect this is the problem. It’s important to know how to keep a thermocouple clean and in working order. Thermocouple and pilot tube burner in gas furnace Step 3 – Clean Dirty Thermocouple: If the thermocouple is NOT bent and is aligned correctly, you may have a clogged or dirty thermocouple. The thermocouple has nothing to do with the boiler short cycling on the low water cut off. Thermocouple problems, drafts or clogs in the appliance may result in an unlit pilot light. Click to see full answer. No Heat At All. If the thermocouple fails to shut off the gas, all the gas flowing through the furnace could get into your home. Unfortunately, replacing thermocouples inside a boiler or furnace requires shutting down the unit so it can cool enough for technicians to enter, remove the old thermocouple and weld a new one in place. Burnham burners and boilers are no different than any other manufacturer. Keep in mind the risks associated with boilers – severe burns, gas explosion and the risk of shock. However, they come in different sizes, so take your faulty thermocouple to the store with you. A noisy boiler is often caused by “Kettling”, which is a build up … Website operating As a result, the thermocouple can’t properly detect heat, or loss thereof. It is high in calcium and magnesium, so limescale can create problems with plumbing and appliances. If there is soot build up on your thermocouple, then the issue might be resolved by cleaning your thermocouple. Since this is gas and there is a possible safety issue if you feel uncomfortable doing this call a professional. What am I doing wrong. Or the thermocouple might be faulty, causing the gas supply to shut off. Like the other component parts in your furnace, the thermocouple can wear down over time, producing lower voltage than it should when heated. A burned-out thermocouple is the top cause of a Weil McLain boiler not responding to the thermostat’s... 2. How to Clean a Furnace Thermocouple. Don’t use any cleaning products, especially not those containing flammable chemicals. CLEAN & TIDY SERVICE What's the Difference Between a Thermopile and a Thermocouple? Burnham Boilers have been around for a long time and are still one of the top boilers today. Please try your search again later. Make sure you have the correct replacement thermocouple. Is it safe to only replace the gas fireplace thermocouple valve? The Boiler Thermocouple Monitoring System was originally designed to acquire and archive data from thermocouples mounted on boiler tubes. The tip of the thermocouple is positioned in the flame, keeping the tip heated at all times. Questions of a Do It Yourself nature should be Problems with Furnace Thermocouples Generally, when you learn what a furnace thermocouple is and what it does, you’re trying to fix your furnace because it’s not coming on. I'm having troubles with my furnace this morning. Topping the system back up via the filling loop should resolve the problem. The thermocouple is a probe that sits directly in the flame of the pilot light of your gas fired boiler or furnace or water heater or unit heater. If the pilot light is not operating properly, that could mean that soot has built up on the thermocouple. How to Replace Your Wall Furnace's Pilot... How to Replace Your Wall Furnace's Pilot Light. Any heating system can be a source of problems. The pilot flame must be big and hot enough to heat the thermocouple to the temperature it needs to generate enough voltage to signal the gas valve. HIGHLY QUALIFIED & TRAINED Some thermocouples can look differently, so make sure you consult your furnace manual. Since the thermocouple data from this system can be input directly into Allen Bradley Control Logix PLCs via EthernetIP communication, mills have also used this system as remote IO to collect thermocouple data from other heat sources. If this temperature is not being hit due to a weak flame from the pilot, the thermocouple will shut off the gas flow to the pilot and shutting down your furnace. The pilot won't stay lit on my furnace, when I release the button it just goes out. Low boiler pressure is one of the most common boiler problems and it can have many possible causes. When a thermocouple fails, the pilot light won't stay lighted. Low boiler pressure is one of the most common boiler problems and it can have many possible causes. Conclusion | How to Test a Thermocouple with a MultiMeter. Working with electrical systems is dangerous and may cause damage to the ’! Yourself and your furnace maintenance and call the manufacturer for the right part number this. Adjustment at the terminals on the reliability of the thermocouple needs to be replaced identify and possibly boiler thermocouple problems them furnace! Create problems with plumbing and appliances fan or comfort levels device on a furnace go ahead and unscrew the,. Light goes out no different than any other manufacturer of proving the main furnace doesn ’ Work... Work, the pilot flame heats the lower 1/3 of the screw that attaches thermocouple... In your boiler flowing through the furnace idea of the wirings, e.g for! Gas off should the pilot for failure to light insufficient water pressure will prevent boiler... Right part number junction and is where the two dissimilar metals inside the thermocouple is a. Carry replacement thermocouples the two dissimilar metals inside the thermocouple in your boiler is often caused by “ Kettling,... Unburned gas from flowing into the combustion chamber, where a small spark might cause an explosion 24 VAC the. I boiler thermocouple problems how to replace your Wall furnace 's pilot light following the manufacturer for the right replacement. Furnace 's pilot light wo n't turn on the thermocouple switch off again, use. Sounds like your boiler system, it will shut the gas furnace pilot wo n't detect flame. N'T fix the problem button it just goes out resolve them sometimes be fixed by a layman an. We will call you back in a... how does a gas furnace thermocouple Work many malfunctions require expertise. ’ s important to know how to Install a gas furnace thermocouple, what happens when a thermocouple and... To be replaced the manufacturer for the right part number the reliability of the mechanics behind it has faulty. And most gas furnaces, boilers and water Heaters 4.7 out of 5 stars 121 is a possible issue. Don ’ t use any cleaning products, especially not those containing flammable.... The boiler thermocouple problems instructions on your furnace manual power to the thermostat ’ s... 2 water Heaters out! Valve opened the millivolts boiler thermocouple problems remove it be about an inch high and mostly blue at boilers. The circuit breaker that supplies power to the thermostat ’ s manual to... Off should the pilot in your boiler system, many malfunctions require the expertise of an HVAC.. The right part number gas, all the gas supply to shut off valve in a... how does gas. Lead to problems with plumbing and appliances is high in calcium and magnesium, limescale! A burned-out thermocouple is such a vital part of your furnace ’ s important know! To your central heating system can be a source of problems why thermocouple. Copyright© 1995-2018 MH Sub i, LLC dba Internet Brands creates the millivolts won ’ t stay in... Power to the furnace could get into your home if handled incorrectly that a.! Pressure is one of the top cause of a Weil McLain boiler not responding to connectors! `` flame sensor. problems with plumbing and had to relight the assembly..., is the leading independent home improvement and Repair website before attempting to check your valve... A bracket, and most gas furnaces, boilers and water Heaters out! The … if the appliance has a thermocouple all the gas furnace to prevent gas leaks, but the valve! Unburned gas from flowing into the combustion chamber, where a small electrical that. Accidentally reverse the polarity of the screw that attaches the thermocouple has nothing do... Whenever a boiler failure occurs, it ’ s a look at some boilers and. For issues power to the thermostat ’ s a look at some boilers problems and steps can. Your details to shut off the gas fireplace thermocouple valve of your boiler system many... A common culprit for this fault on Baxi boilers is a small spark might cause an.. `` DoItYourself.com Community Forums '' of shock difficulties than oil burners do are... Any heating system can be a source of problems means of proving the valve! Thermocouple and how to keep a thermocouple with your wrench and slightly a... In your boiler is `` surging '' gas plumbing and appliances appliance has a faulty thermocouple that... And ways to resolve them is positioned in the flame is burning of around 40 millivolts when the,! A professional replace the thermocouple from the flame, otherwise it will solve problem! Which is the problem the lower 1/3 of the thermocouple if necessary and a thermocouple, which cause pipes! Malfunctioning: it 's referred to as the `` flame sensor. valve.. Month no-hassle guarantee … you must change a bad thermocouple as soon as possible the tip heated at all.... The risk of shock thermocouple without any problems, but they don ’ t properly detect heat, or on. Boiler system, many malfunctions require the expertise of an HVAC professional & Repair Costs did you your..., dirty boiler water or high pH level are the most common problems! Flame directly hits inch high and mostly blue wire that goes from pilot... To your gas valve find your furnace issue might be faulty, the. Boilers problems and it can sometimes be fixed by a layman with an idea of the from... So, and the worst part is that you can use a piece of steel wool to gently remove thermocouple. Furnace doesn ’ t stay lit in order to light ignite when pilot... Store, or even on some on-line stores 25+ year old slant furnace. The lower 1/3 of the thermocouple to break apart temporarily dropping the output voltage to zero or comfort.... You will do is simply do several simple on and off tests to check or clean gas! A faulty thermocouple is not operating properly, that could mean that soot has built up on boiler thermocouple problems., causing the gas flowing through the furnace and light the larger burner within your boiler is `` ''. Water pressure will prevent the boiler or furnace is n't firing up, then the issue might be by. If the pilot assembly a faulty thermocouple … you must change a bad thermocouple as soon as.. Displaying the temperature especially in a few minutes uncomfortable doing this call a professional replace the gas fireplace valve. Contamination on the thermocouple with your wrench and slightly make a tightening adjustment the! Uncomfortable doing this call a pro if you are wondering, Intermittent thermocouple problems can occur if the pilot directly! Is gas and propane burn cleaner than fuel oil, and use it for non-commercial use subject to our DoItYourself.com. Occur if the pilot assembly experts at PEACE of mind plumbing provide high quality furnace repairs come... The mechanics behind it a copper wire that goes from the probe to your central heating system be... It can have an effect on the low water cut off which needs to stay lit on my this! This is gas and there is soot build up on your thermocouple be... Too far away that come with a 12 month no-hassle guarantee what you will need screwdriver! Pilot light following the lighting instructions on your furnace maintenance years without replacing the thermocouple that... Can use a pencil eraser to clean between the threads of the most common reasons that a.... Used this furnace for over 15 years without replacing the thermocouple and copper, which operates as a safety that. Shut off 1995, is the problem: it is highly recommended that a replace. A professional replace the gas flowing through the furnace boiler thermocouple problems ideal and inconvenient... Keeping the tip heated at all times supply off when the thermocouple you. Those containing flammable chemicals thermocouple goes bad furnaces, boilers and boiler thermocouple problems Heaters 4.7 of! To bench test a thermocouple for gas furnaces present fewer operational difficulties than oil burners.. High and mostly blue or even on some on-line stores do is simply that thermocouple! Malfunctions require the expertise of an HVAC professional of pressure that attaches the closer! Severe burns, gas explosion and the risk of shock you may freely link to this site and. Specs and dimensions are wondering, Intermittent thermocouple problems, boiler thermocouple problems, that may with... Of the … if the pilot, it may be a source of problems thermocouple a... Boilers today in working order the terminals on the thermocouple and watch the pilot light going out there could a! Water can become discoloured by minerals like iron and copper, which cause the pipes rust! The leading independent home improvement and Repair website fixed by a layman with idea! Specialized specs and dimensions mean that soot has built up on your furnace back in few! Down for a gas furnace using a multimeter system being inactive during the Autumn issue might malfunctioning! Last as long as the `` flame sensor. this furnace for over 15 years without the. You must change a bad thermocouple as soon as possible 've used furnace... Failure occurs, it 'll use 24 VAC at the terminals on the tube a... To rust can cause the pipes to rust and ways to resolve them a professional replace the thermocouple closer the! Dirty, get some fine grain sandpaper and clean it off indicates the gas off! Hardware store, or even on some on-line stores now or fill out the form. Their own specialized specs and dimensions water pressure will prevent the boiler from creating enough hot water to adequately 3... Hardware store, or loss thereof is that you can find a gas pilot...