Good Venting Guidelines For Gas
Water heating systems must be vented with ducts of appropriate size and height. Also, citizens should ensure that these pipes produce an adequate draft for the exhaust to fall out of the residence.
If the vents are not checked before installation, they may spill dangerous flammable and poisonous gases into the house itself. Lastly, the vent must be installed by a qualified person who knows all the tricks of the trade.
Some local codes also advise homeowners to install carbon monoxide detectors near their heaters. Sometimes, exhausts can rush into the building because of some error in the venting and rage havoc. It is better to have sensors that can sound the alarm for toxic gases like carbon monoxide.
All venting must be at least 6 inches away from surfaces in the house. Therefore, you will notice that most heaters have their vents a considerable distance away from walls. That is done to prevent the walls of the house from catching fire from the hot vent pipes.
Lastly, the code urges citizens not to merge vents between a gas-powered device and a power-vent appliance. All the above guidelines are a part of the National Fuel Gas Code for the USA. You can alternatively refer to the guidelines mentioned on product packaging.
Water Heater Vent Pipe Draft Hood
On top of natural draft gas water heater, in its center section, right above the water heater vent, you should have a draft hood installed. It sits on 3-4 short legs, sometimes secured to the water heater top plate with screws, or has its legs shaped like pins or hooks at the end, inserted into the holes in water heater top cover.
For the gas water heater vent pipe system to operate properly its Draft Hood Has to be Centered over the vent hole, and its legs must be straight any displaced or deformed draft hoods should be serviced / replaced if necessary. Water heater draft hoods serve a very important purpose and if not installed correctly, carbon monoxide gases may be expelled into the living space. Im pretty sure youre aware how dangerous Carbon Monoxide can be
Gas water heater draft hoods come in different sizes, and if you are replacing water heater, make sure, that the draft hood and the water heater vent pipe match each other.
If the draft hood that came with your water heater has a top opening diameter designed for 3 vent pipe, and you have 4 vent pipe installed, use an adapter / increaser to join both of them together.
-some 50 gallons might require 4
Ask A Question Or Search Inspectapedia
Try the search box just below, or if you prefer, post a question or comment in the box below and we will respond promptly.
Search the InspectApedia website
Note: appearance of your Comment below may be delayed:if your comment contains an image, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay. Our Comment Box is provided by Countable Web Productions countable.ca
Technical Reviewers & References
Don’t Miss: In Wall Heat And Ac Units
Gas Hot Water Heater Venting Problems
One problem you need to avoid is back-drafting. You see this most commonly with atmospheric configurations, and it means that your exhaust isn’t leaving the home. Back-drafting is usually the result of an inadequate vent design. Look for the signs:
- Corrosion at the top of the water heater
- Melted plastic at the top, near the draft hood
You can also run a manual test. Isolate the water heater by closing doors and windows, shutting off the furnace, and letting the water heater run solo. If you feel warm air near the draft hood, then your system is back-drafting.
Disconnect The Gas Vent And Water Lines
Disconnect the gas line at the union . Then disassemble the threaded tee and drip leg and remove the nipple from the water heater gas control valve. Dont throw them awayyoull need them for the new water heater. If your gas line is copper or a flexible supply line, just unscrew the nut.
To disassemble the vent piping, remove the sheet metal screws. Wear gloves the ends of the metal piping are sharp. You can reuse the vent pipes if theyre in good shape. But if you find even slight holes, cracks or corrosion, toss them into the trash. New pipe is inexpensive and leaks can allow deadly carbon monoxide to build up in your home.
Next, cut the copper water lines with a tubing cutter . If you have copper corrugated water lines, simply disconnect the nuts at the water heater. If you have galvanized steel pipes, disconnect unions just as we did with the gas union shown in Photo 2. Also unscrew the blow tube from the temperature and pressure valve. You may be able to reuse it on the new water heater.
At this point, the old heater should have drained enough so it can be moved off to the side . If the heater isnt draining fast enough, sediment may be clogging the valve. Allow it to drain as long as possible and then move the heater outside so you can remove the drain valve from the tank.
Don’t Miss: Coleman Mach Ac Reset Button
Proper Venting Prevents Backdrafting
The most common problem associated with water heater venting is a condition called backdrafting, in which exhaust gases from the water heater fail to exit the home via the vent and instead end up in the house. Backdrafting can have many causes, but it is most commonly due to poor vent design or installation and/or an imbalance of air volume in the home. The latter is often a result of ventilation fans, such as bathroom or kitchen vent fans, that pull air out of the house and create a vacuum effect that draws exhaust gas downward and into the home from the water heater vent.
Some water heater venting systems remove the possibility of backdrafting with fan-assisted ventilation or direct venting technology.
Types Of Water Heater Vents: Which One Is Right For You
Homeowners rarely think about the technology and equipment it takes to keep their home running until those components require maintenance, replacement, or repairs. Water heater vents definitely fall under that category of often-neglected or forgotten-about, but necessary, appliances.
Chances are that unless you work in the HVAC, plumbing, or home improvement industry that you probably didnt know there are different types of water heater vents that are only compatible with specific units that vent the same way.
If youre due for a new water heater, heres what you should know about the different types of water heater vents that are on the market.
Also Check: Ac Disconnect Pull Out Replacement
Rusted Anode Rod Port
Youll See: Water bubbling out of the anode rod port on top of the water heater.
If tightening pipe connections didnt stop the leak, inspect the pipes around your water heater for rust. There may be rust inside that you cant see, so calling a plumber is the best idea.
You should also inspect the steel wire you see screwed to the top of the water heater . This steel wire runs the entire length of the water heater tank on the inside.
The steel anode rod port is the water heater component involved in electrolysis. It acts almost like a lightning rod. Except instead of attracting lightning, it attracts corrosion.
The water in the tank corrodes this steel wire instead of corroding the inside of the tank. The anode rod port becomes rusted and no longer facilitates electrolysis.
As a result, the corrosion reaches the top of the anode rod and forces water to bubble up and out of the rod port. This could be the source of the leak youre seeing at the top of your water heater.
If thats the case, the water inside the tank will start corroding and rusting the inside of the tank. You should call a plumber immediately to replace your anode rod.
Without it, there is danger of the tank corroding and rusting even bursting if it isnt replaced. This can cause damage and even injury if left untreated.
Gas Fired Water Heating Venting Standards For Canada
See Chapter 7 beginning at page 152 and also see “Combustion Spillage” beginning on p. 160 in this example code: B149.1HB-00 Natural Gas and Propane Installation Code HandbookExcerpt:Gas appliances may be vented to either a chimney flue or a certified vent or factory-built chimney.
When vents are used, they must be certified to the applicable standard and bear a label that indicates that they have been so tested and approved.
It is important not to remove these labels in order to enable field inspection. In the case of Type B or Type L vents, each length extending above the roof line must be certified for exterior use and so identified. Excerpt:7.14.4 A chimney shall extend not less than 3 ft above the highest point where it passes through the roof of a building and not less than 2 ft higher than any portion of a building within a horizontal distance of 10 ft .
Nowhere in these standards is there an acceptance of a short-rise, horizontally-vented, dryer-vent flapper capped or painted-screen-capped water heater vent termination.
Side-wall vented appliances, without exception, make use of some form of power exhaust, never simply atmospheric exhaust. Such vent exits and terminations, if your water heaters were power-vented, cannot be obstructed and must use a listed termination cap or cover.
Check for proper exhaust venting of combustion products from your gas fired water heater.
Also Check: Gas Water Heater 40 Gal
What Is A Water Heater Vent Pipe
A water heater vent pipe is the affiliate drainage system for a heater. It acts as a pathway for exhaust gases to leave the system and enter the atmosphere.
Any heater, be it powered by gas or electricity, has to hold a venting system. That system is made out of a series of pipes that conduct the gases outside.
Every water heater system uses fuel of some kind to generate heat. Once this heat is generated, there is a systematic release of exhaust gases. Now, these gases need to be released out into the atmosphere as soon as possible.
The heater uses chimneys to facilitate the transfer of gases from inside the house to outside. Vents are essential because they prevent the building of additional pressure inside the storage tank. Such hyper pressurized containers can be risky and prone to explosions.
A vent pipe, also called a duct, is connected to the heater. It generally runs along the walls of your house. There are multiple types of water heater vents direct vents, power vents, and chimney flues are the most commonly seen.
A chimney can run along the walls of your house and dispense the gases through the roof. Similarly, a direct vent generally goes through the wall directly, whereas a power vent runs through the width of the wall horizontally.
Electricity-powered water heaters generally use power vents . These are vents placed horizontally across the wall. They also have a blower a fan set in the vent to propel hot exhaust gases through the horizontal duct.
In 2003 The International Residential Code Changed
Nearly All States Building Codes Match The International Residential Building Code
IRC Building Code No Longer Allows Combined Vents Serving Both A Gas Furnace & Water Heater Because All New Furnaces Are Mechanically-Vented.
The New IRC Code States:
4. Vent connectors serving equipmentvented by Natural draft Shall Not Be Connected Into Any Portion of Mechanical-Draft Systems .
https://telluride-co.civicweb.net/document/32311 Page: 360. Section: G2427.3.3
Recommended Reading: Pros And Cons Tankless Water Heater
Atmospheric Water Heater Vent
Atmospheric water heater vents are the most common and affordable of all of the types of water heater vents for residential structures mentioned here. This system relies on the natural movement of gases that rise out of the water heaters combustion chamber. These gases go through a flue that leads them upward and expels them into the air through the roof. The pipe thats connected to the ventilation system must be long enough to run all the way from the water heater to the roof without interruption.
Atmospheric-vented water heaters are extremely common due to their low upfront installation and operational costs. What they lack in versatility and flexibility, they make up for in efficiency and affordability.
Do you have a broken down or malfunctioning water heater vent system?
Natural Draft Gas Water Heater Vent Pipe Pitch
Gas water heater vent pipe connector must continuously run upward towards the chimney entrance, rising not less than 1/4 per linear foot, to provide proper draft. Some installation might be a significant challenge, or even become impossible, due to a water heater height and chimney flue connection level, in those cases, induced draft motor equipped water heater should be considered.
Don’t Miss: When Ac Is Not Cooling
Types Of Natural Gas Water Heaters
Storage Water Heaters
The most popular type of water heater for residential use is the storage water heater, which combines a gas burner with an insulated tank to store hot water. A storage water heater works by taking cold water from the home s water supply and moving it to the bottom of the tank where it s heated by a gas burner controlled by a thermostat. Since hot water is lighter than cold water, the heated water rises to the top of the tank where a delivery pipe sends it where it is needed. When the hot water leaves the tank and colder water replaces it in the bottom of the tank, the burner automatically comes on again to heat the new water. The storage water heater contains a relief valve to protect against temperature or pressure that is too high for the tank.
Storage tanks are normally made of steel, with insulated interiors lined with glass or another material to prevent corrosion. Some tanks also contain an anode rod, composed of one or more metals, which attracts corrosion away from the rest of the tank s components.
Combination Water/Space Heater
Combination water heating/space heating units are compact systems that require only one unit to heat both water and rooms. These units are ideal for townhouses, condominiums or other dwellings in which space is limited for a water heater and heating system.
Tankless or Instantaneous Water Heaters
Hydronic or Boiler Systems
Indirect Water Heater
Water Heaters For Mobile Homes
Water heaters in mobile homes are similar to those used in standard homes, but they must be designed for this application. Manufacturers often will not warrant a water heater installed in a mobile home unless it is specifically approved for that use. A standard atmospheric water heater hook up in a mobile home often requires an outside access panel. If a water heater is located inside of a mobile home without outside access, it is most likely a sealed-combustion unit with direct venting.
Also Check: How Much To Replace Furnace And Ac
Natural Draft Gas Water Heater Vent Pipe Material
For natural draft type just use galvanized steel pipe and dont experiment with aluminum pipes, food cans with removed both ends, stainless steel sections, blue stove pipes, high temperature plastic tubing, flexible pipes, etc.
Make the vent pipe section between the water heater and the chimney as short and as straight as possible. The common rule is that the horizontal part of the single wall vent pipe must be equal or shorter than 75% of its total developed height.
Release The Pressure From The Entire System
Open a hot water faucet to remove the pressure from the heater. Since the cold water inlet is closed, it should be a momentary flow.
Now, open the overflow at the bottom of the heater. Attach a garden hose that directs water out of the house or to your homes drainage. Leave the overflow open for one minute.
Recommended Reading: Power Vent Water Heater 50 Gallon
How To Vent A Water Heater To A Chimney
When venting a gas water heater to a chimney, be aware that holes in the chimney can prevent a good draw on the water heater, causing downdrafts and presenting the risk of carbon monoxide poisoning. To avert this problem, you can vent the water heater to the largest hole in the chimney and cap the remaining holes.
Be sure to check your gas water heater annually for cracks or leaks in the flue. Most building codes require 4-inch flue pipes on water heaters.
Here’s how to vent a water heater to a chimney:
Should The Water Heater Vent Pipe Turn Hot
Yes. Even a double-walled metal or PVC duct is susceptible to the heat of exhaust gases. A water heating system uses elements in the air to generate heat and then uses that ignition to warm the water in the storage tank.
The heat that the water heater generates is converted into residual gases like carbon monoxide, which have to be thrown out of the house. These gases are poisonous and cannot stay in the same small space as the heater. In transferring these hot gases outside, the vent pipe turns hot.
Also, venting is done on the scientific principle that hot air rises upwards. Therefore, the hot gases rise through the vents, casually heating them in the process. Moreover, most vent pipes are made of metals like steel, which is a good conductor of heat. Therefore, vent pipes are supposed to turn hot.
If you have your heaters thermostat set to 120 degrees F, your vent pipes can have a temperature of over 300 degrees F at the end of the day. Moreover, if your venting pipe is turning hot, it means that the pipe is conducting hot gases in the prescribed manner, therefore doing a good job. So, you do not need to worry if the vent pipe turns hot.
Read Also: Ac Unit Not Cooling House