Is Water Heater Exhaust Pipe Very Hot? Know reasons with Solutions

People ask the question, is the water heater exhaust pipe very hot? Yes. It is supposed to be hot, but sometimes it becomes scorching to touch. In this case, there can be problems with the water heater exhaust pipe, typical temperature problems on the exhaust pipe, and more.

Every water heater exhaust system utilizes an exhaust system to transport combustion gases away from the house. The linemight be made of metal or plastic, relying on a kind of vent system.

The exhaust pipe of a water heater can get very hot and cause a significant danger to anyone in its vicinity. We need to find the root cause of the problem and take action to fix it. Here, we will help you know why your water heater exhaust pipe is getting very hot and its solutions.

6 Reasons for Water Heater Exhaust Pipe Very Hot with Solutions

For a variety of causes, the water heater’s exhaust system may become excessively warm. We shall discuss a few of them here. The following table summarizes the causes and potential treatments for the water heater combustor becoming extremely hot.

Reasons For Exhaust Pipe Very HotPossible Solutions You Can Try
Venting problems with gas water heatersRepair the vent hood
Typical temperature problem on the exhaust pipehave six inches clearance from combustibles
Installed in a closed areaCheck the place of the water heater
Passing through an enclosed surfacedouble-walled exhaust pipes
Clogged Gas JetsClean out debris
Not enough air for combustionSupply air

Now, we will briefly discuss why the water heater exhaust pipe is scorching and its possible solutions.

Reason 1: Venting problems with gas water heaters

The gas hot water heater venting problems can cause the exhaust pipe of the heat exchanger to get extremely hot. So, follow the below procedure carefully.

Step 1: First, you need to check the vent hood. This is the portion where the exhaust pipe links to the water heater.

Step 2: With the water heater operating, light out a match nearby the hood.

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Step 3: If the smoke from the match gets absorbed into the exhaust pipe, it is possibly okay. If the smoke gets blown apart, there is either a block in the exhaust pipe or wrongly vented.

Step 4: If the latter occurs, you need to stop using the water heater instantly as this is a dangerous condition. It means the flue gases are roaming inside your home, emitting carbon monoxide and other toxic gases into the air.

In this situation, you have to repair the vent hood before using the water heater again.

Reason 2: Typical temperature problem on the exhaust pipe

There is some typical temperature problem on the exhaust pipe that turns the water heater vent pipe very hot. This is the reason why a single wall pipe needs to have six inches of clearance from combustibles.

A 90% furnace has a much lesser exhaust pipe temperature as further heat is put into the house. Sometimes rings go into the exhaust pipe to provide more surface area, hoping that additional heat will shift to the site. It is conceivable for a poppet valve with a long venting system to catch fire.

Advice: If faulty pipework emits fumes or pollutants, their heat usually is higher above 350°F, and then they will undoubtedly combust prior to contacting your vent’s ceiling hinge.

Reason 3: Installed in a closed area

Exhaust pipes can become exceedingly hot if positioned in a tight space. In this case, you need to provide a path to get fresh air like you can open a door. A water heater requires several square inches of fresh air for several British Thermal Units (BTUs). You need to check to see if the place the water heater is in doesn’t act like an exhaust pipe itself.

If you cannot provide a path to get fresh air, install the water heater again by following the below-outlined steps. There are:-

Step 1: At first, shut off both the electricity and water supply.

Step 2: Secondly, strip away the galvanized steel clamps to dismantle the exhaust pipes.

Step 3: Then, re-attach the water supply line.

Step 4: Afterwards, use any forming metal connectors and attach the hood’s exhaust duct.

Advice: Don’t ever employ a converter, regardless of how narrow the cover’s hole or gap is compared to the valve stem.

Step 5: Then, try to hook up the supply of gas.

Step 6: Next, keep the coolant pump in the closed area to prevent harming it.

Step 7: Afterwards, put the sprinkler’s arm further into a funnel with a hex wrench.

Step 8: End up making certain that the gas is appropriately assembled and tightened.

Step 9: Then, charge it up with fluid by opening the hose taps and, therefore, an adjacent spigot.

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Step 10: After step 9, allow fluid to pass out of the fixture by opening it up.

Step 11: And after that, turn off and inspect for breakage in the water supply lines.

Step 12: Now, you have to read the company’s directions for turning on the control valve and lighting the lights.

Step 13: Then, learn how to turn off all shutters. The vapor should indeed be pulled up and out of the room through the outlet. Otherwise, emissions can knock on your door.

However, if you cannot follow these steps yourself, switch off the gas and contact a licensed plumber.

Reason 4: Passing through an enclosed surface


If your water hot water heater exhaust pipe is hot and passes through a closed surface, they are probably not double-walled pipes. The exhaust pipes must be double-walled if they are passing through an enclosed shell. It would help if you were sure the exhaust pipes dismiss to the outdoors but are not near any windows or return air registers. Also, they must not be in contact with combustible materials.

Reason 5: Clogged gas Jets

Occasionally, contaminants and particles cause this to occur. You won’t have any other choice except to wipe it down. To fix it, take these steps:

Step 1: Firstly, insert a cotton swab through the entrance of the gas stove propeller.

Step 2: And then gently maneuver the brushes to remove any wreckage.

Step 3: Then, place the engine sideways in a garbage container to throw away its detritus.

Step 4: Next, return the nozzle to its original position in the combustion throttle outlet.

Step 5: You can finally return the turbine to its starting state by pressing it downwards.

The remedy provided here should resolve any issues you may be experiencing as a result of the above. If that doesn’t work, your last but not the least option is to hire a professional plumber.

Reason 6: Not enough air for combustion

There is only one method to resolve this problem and that is to increase the amount of air available for ignition.

A Helpful Tutorial You May Need!

Frequently Asked Questions (FAQs)

Is the water heater vent supposed to be hot?

It’s scorching hot, and that much is obvious. Exhaust from a hot water tank is perfectly typical, and you should not worry about it. Sometimes triple-walled pipelines will become extremely dangerously hot.

How hot does a heater vent get?

Usually, the vent temperature will be about 20 degrees greater than the water temperature for a brand new water heater. Many factors, including water quality and the unit’s functionality, will influence the vent’s heat. When a hot water tank can store freshwater at 140 degrees Fahrenheit to prevent Legionella bacteria from growing, the exhaust gases heating rate will be around 160 degrees Fahrenheit. As scale accumulates and furnace efficacy degrades, exhaust gas emissions can easily exceed 350 degrees Fahrenheit. Even if somebody had their water heater set at one hundred twenty degrees Fahrenheit, the flue gas temperatures can increase more than three hundred degrees Fahrenheit with scaling.

How do I know if your water heater is going to explode?

There are many signs of knowing your water heater is going to explode. For example, the lack of hot water and murky water are signs of a leaky storage tank, but so are the malfunctioning differential pressure release valve and audible popping and knocking noises.

Let’s Sum It Up


Although we rarely think about it, our water heater is indeed a considerable time bomb with the possibility of blowing up. It can cause severe injury and tear your home apart. When explosion accidents happen, they can cause substantial property damage, injuries, and even demise. So, when your water heater exhaust pipe very hot, you need to take it seriously and solve the problem.

Hopefully, after reading this, you have found out the reasons why your water heater exhaust pipe is getting very hot and the solutions to it. To keep the water heater vent functioning correctly, you need to clean your gas appliance and service it every year.

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