How to Properly Vent a Gas Hot Water Heater

[AdrianeS]

It's been pointed out to me that my current setup is not okay. I'd like to fix it but I'm not sure how best to do this. I just have a typical gas hot water heater that was installed in 2019, one year before I bought my house. I've added pictures to show what I have going on now. The vent goes from the top of the water heater, through a finished bathroom wall (drywall) in the basement, across the ceiling of the basement bathroom, and into a brick wall where it eventually goes up and out the house.

What do I need to get to make sure this is properly vented and up to code? Aside from the improper venting used, I would imagine there needs to be some kind of a spacer or protection where it runs through the drywall.

Also, I measured the pipe that's there now and it's 3.5" diameter. What size pipe do I buy? I don't see any 3.5" sizes at Home Depot.

Any help would be appreciated!

 

[Sparky617]

Is that a single wall or double wall pipe? Can you post a picture from the outside? That would help identify the type of pipe. What is the make and model number of the water heater? There are water heaters designed to be vented out a side wall with a double walled flue. The hot gases go through the inner pipe and fresh air is brought in in the outer pipe, keeping the hot pipe away from combustible materials. I'd have to say though, it doesn't look right to me, and I'd probably relocate the water heater so it was in the space the duct is going through, with a short, direct route to the outside of the house.

 

[AdrianeS]

Is that a single wall or double wall pipe? Can you post a picture from the outside? That would help identify the type of pipe. What is the make and model number of the water heater? There are water heaters designed to be vented out a side wall with a double walled flue. The hot gases go through the inner pipe and fresh air is brought in in the outer pipe, keeping the hot pipe away from combustible materials. I'd have to say though, it doesn't look right to me, and I'd probably relocate the water heater so it was in the space the duct is going through, with a short, direct route to the outside of the house.

Thanks for your reply!

The vent goes up inside the wall, through the chimney, and out the roof so I can't really post a picture of that, sorry.

The long pipe in the fourth picture is a double wall B pipe. This section appears okay to me, I just figured I'd include the whole setup for context. It is sloped correctly and the horizontal pipe is less than 75% of the total vertical height which code requires.

It's more the pipe that's coming off the draft hood that I'm concerned about, and where it runs straight through the wall, with no clearance. Definitely a fire hazard. I'm just not sure what type of pipe I'm supposed to use to connect to the draft hood, and how to safely run it through the drywall.

It is a Rheem XG40506EC34U0. Here's a link to it: Find product information, documents, videos, and installation assistance for the Rheem XG40S06EC34UO

 

[bud16415]

I’m not an expert on this and don’t know who gave you advice on this? Were they a professional?



To me it looks like the upward angle of the exhaust is ok and the only part that bothers me is where it passes thru the drywall wall. If it were mine I would open that drywall making a larger hole and getting the pipe away from anything combustible. If you don’t mind a larger hole in the wall then just secure the pipe in the hole with strapping. If the wall is important then you could buy or make a split sheet metal piece with a hole for the pipe, if you want to take the pipe apart then it could be a single piece with a hole cut in it. Screw the tin to the wall.



The sheet metal piece I made for mine I cut the hole about an inch smaller than the pipe and then made radial cuts out to the pipe size and bent the tabs up to 90 degrees. Doing that it holds the pipe better and the tabs allow for a screw or two.

 

[AdrianeS]

I’m not an expert on this and don’t know who gave you advice on this? Were they a professional?



To me it looks like the upward angle of the exhaust is ok and the only part that bothers me is where it passes thru the drywall wall. If it were mine I would open that drywall making a larger hole and getting the pipe away from anything combustible. If you don’t mind a larger hole in the wall then just secure the pipe in the hole with strapping. If the wall is important then you could buy or make a split sheet metal piece with a hole for the pipe, if you want to take the pipe apart then it could be a single piece with a hole cut in it. Screw the tin to the wall.



The sheet metal piece I made for mine I cut the hole about an inch smaller than the pipe and then made radial cuts out to the pipe size and bent the tabs up to 90 degrees. Doing that it holds the pipe better and the tabs allow for a screw or two.

Thanks for your reply! Sorry for my delay in responding. It was just pointed out to me by an HVAC guy that the pipe coming off the water heater is not made for a water heater. It's the wrong kind of pipe altogether. As for the rest of the advice, I just looked it up the code.

 

[bud16415]

Thanks for your reply! Sorry for my delay in responding. It was just pointed out to me by an HVAC guy that the pipe coming off the water heater is not made for a water heater. It's the wrong kind of pipe altogether. As for the rest of the advice, I just looked it up the code.

There is flex water heater connectors and from your photos I couldn’t tell if the one you have is correct or not. There are similar looking ones that are intended for venting other things like clothes dryers etc.



Here is a link to one.



https://www.lowes.com/pd/Selkirk-1-...b9fqXX-xjfs2fu-jzm4aAtn7EALw_wcB&gclsrc=aw.ds



I would normally do the whole job with snap together vent pipe, but sometimes where the water heater placement and where you need to get to would make for complicated routing something like this helps. When you get a ridged 90 fitting they are made in pieces and you can turn the joints in the 90 to make other angles and odd bends.



This link shows how they swivel.



AmeriVent 3EAL Elbow, 3 in Connection

 

[Sparky617]

There is flex water heater connectors and from your photos I couldn’t tell if the one you have is correct or not. There are similar looking ones that are intended for venting other things like clothes dryers etc.



Here is a link to one.



https://www.lowes.com/pd/Selkirk-1-...b9fqXX-xjfs2fu-jzm4aAtn7EALw_wcB&gclsrc=aw.ds



I would normally do the whole job with snap together vent pipe, but sometimes where the water heater placement and where you need to get to would make for complicated routing something like this helps. When you get a ridged 90 fitting they are made in pieces and you can turn the joints in the 90 to make other angles and odd bends.



This link shows how they swivel.



AmeriVent 3EAL Elbow, 3 in Connection

My previous direct vent water heater had a double walled exhaust pipe that was flex pipe for both the exhaust and supply. Exhaust being in the middle of the supply. It looked like the dryer vent stuff as well. That's why I thought asuhayda's first post was of a direct vent model. The rigid stuff looks to me like it is aluminum, I thought exhaust ducts were supposed to be galvanized steel. Not positive, that what the 2nd floor furnance in my house has. It vents through the roof. The basement unit is a high efficiency unit that vents using PVC drain pipe.

​

 

[AdrianeS]

Thank you! I believe the vent pipe on there now is for a gas dryer, not the flexible pipe you linked to. I posted pictures of the pieces I think I need. I think the Wall Thimble is what I'm supposed to use to protect the drywall from the heat but I'm not certain. These are all Type B Vent Pipes. There are also less expensive vent pipes that are not Type B. Can I use those instead? Why choose one over the other? Thanks again for your help!

 

[Snoonyb]

You'd be well advised to use the products in your pictures, you see, to thine own self, be true, so, by your own fault, you are no longer here,...............?

From the PDF;
NOTICE: The National Fuel Gas Code (NFGC) mandates a manual gas shut-off valve: See (NFGC) for complete instructions.

Local codes or plumbing authority requirements may vary from the instructions or diagrams provided and take precedent over these instructions.

Draft hood Pitch up 1/4” per foot

Manual gas shut-off

Thermostatic gas valve

Jacket door

Temperature and pressure relief valve


Thermal expansion tank (if required)


Combustion Air Inlet Openings


Vent connector to chimney


Installing the water heater.


A new combination temperature and pressure relief valve, complying with the Standard for Relief Valves and Automatic Gas Shut-Off Devices for Hot Water Supply Systems, ANSI Z21.22, is supplied and must remain in the opening provided and marked for the purpose on the water heater. No valve of any type should be installed between the relief valve and the tank. Local codes shall govern the installation of relief valves.

Relief Valve


The pressure rating of the relief valve must not exceed 150 PSI, the maximum working pressure of the water heater as marked on the rating plate.


The Btuh rating of the relief valve must equal or exceed the Btuh input of the water heater as marked on its rating plate.


Position the outlet of the relief valve above a suitable open drain to eliminate potential water damage. Piping used should be of a type approved for hot water distribution.


The discharge line must be no smaller than the outlet of the valve and must pitch downward from the valve to allow complete drainage (by gravity) of the relief valve and discharge line.


The end of the discharge line should not be threaded or concealed and should be protected from freezing.

No valve of any type, restriction, or reducer coupling should be installed in the discharge line.


Open each hot water faucet slowly to allow the air to vent from the water heater and piping.

A steady flow of water from the hot water faucet(s) indicates a full water heater.


WARNING: The tank must be full of water before heater is turned on. The water heater warranty does not cover damage or failure resulting from operation with an empty or partially empty tank.

Condensation


Condensation can form on the tank when it is first filled with water. Condensation might also occur with a heavy water draw and very cold inlet water temperatures.

 

[AdrianeS]

Thank you, I have already read through the product info. But what I'm wondering is why would one use the Type B pipe over this type of pipe:

The Type B pipe costs a bit more. What is the difference between the two?

 

[Snoonyb]

What is pictured in post #10 is single wall material and not fire rated.

Type B is fire rated and required when incased wall cavities and when transitioning thru walls, because the second layer has an air space so does not transmit the combustion to the surface, where it could cause combustion of contacted materials

"The Type B designation is assigned to gas venting systems that meet the safety requirements of Underwriters Laboratories, Inc. The AmeriVent all-metal, double-wall gas vent is listed as Type B by Underwriters Laboratories, Inc. and is approved for such residential and commercial applications as Category 1 water heaters, boilers, furnaces, space heaters, or wall heaters. UL-approved Type B gas vent products form a continuous passageway from an approved gas appliance to the termination of the vent above the roof of the structure.

 

[AdrianeS]

Thank you!

 

[AdrianeS]

I'm getting ready to do this project and thought of another question. How does the vent pipe attach to the hood on the hot water tank on one end and then to another B vent pipe on the other end? Screws (what size and what kind?), tape, pipe clamps? Or does it just snap together on its own? Here's what i'm going to use:

 

[Snoonyb]

The vent hood on the heater has a ridge that the fitting collar fits over, so, if the flex product you, choose, to use, doesn't retain it's bent shape, you will need to use screws.

However, were you too, instead, use the products you listed in post #8, screws would not be necessary.

However, no matter how long you choose to increase your time spent, your labor, is free, so spend it wisely.