Direct Vent Cap Clearance Distance FAQs

Distances vent under a building overhang
Direct vent onto to deck or lanai room
Other gas fireplace or direct vent Q&A

Direct Vent Cap Clearance to Overhead Overhang

Can we put both the direct vent cap from the gas insert fireplace
under a custom chimney top cap (decorative crown)?

We recently purchased a home that has a 68” x 25” chimney with four flues.

We wanted to cover the entire chimney and its flues with a custom made skirted chimney cap.

However, we also want to get a direct vent gas insert fireplace that will be vented out one of these flues. The flue tile is about 3.5" tall.

Would it be possible to have both the direct vent cap from the gas insert fireplace under the custom cap?

We were told by one installer that 3" clearance between the caps would be enough and another installer using a different insert told us their cap was only tested with 34" of clearance.

The custom cap is not cheap so we don't want to have it installed to remove it 1 year from now when we install the direct vent gas insert fireplace.

We are really confused by lack of information. Our first choice in fireplace brand would be Heat n Glo. Any advice would be greatly appreciated. On 2021-11-03 by Megan Mazz

Reply by Inspectapedia Com Moderator (mod) - Warning about plan to cover the entire chimney and its flues with a custom made skirted chimney cap

@Megan Mazz,

I'm confused by your question.

Usually a direct vent heating Appliance vents horizontally, straight out through a building side wall not up through at tall chimney flue.

Though indeed some "direct vent" fireplaces can also vent "up" through a roof.

You'd better check with the heater manufacturer

by Megan

@Inspectapedia Com Moderator,

These are definitely made to vent at the chimney as they are direct vent gas fireplace inserts. They are made to retrofit a wood burning fireplace.

by Inspectapedia Com Moderator (mod)

@Megan,

Let's identify the brand and model and look at the installation manual

by Megan - Heat n Glo with the Escape chimney requirements - HeatNGlow wouldn't answer our question

@Inspectapedia Com Moderator,

Thank you! We are looking at Heat n Glo with the Escape model. I included at link at the end.

We tried contacting Heat n Glo directly by phone and email but they directed us to the local rep.

The first rep we talked to never responded to our follow up email and the second rep responded with the 34" clearance which seems excessive.

Answer by Inspectapedia Com Moderator (mod) - warning about plan to cover the entire chimney and its flues with a custom made cap

@Megan,

If you don't have the installation manual for your fireplace you can download it from the manufacturer's link you provided, or here at

HEATnGLO ESCAPE FIREPLACE INSTALLATION MANUAL [PDF]

and

HEATnGLO ESCAPE FIREPLACE OWNERS MANUAL [PDF] original source: heatnglo.com/fireplaces/gas/inserts/escape-gas-fireplace-insert

In the Installation manual you'll see the venting instructions in considerable detail, including the skectch with clearance distances given in the excerpt we'll post with this note.

You will see that the manufacturer does not, in the instructions, anticipate venting into a masonry flue with a chimney cap, and you will see specific clearance distances that they require for safe operation of the appliance.

OPINION: You will probably find that no one concerned with both safety and accountability and against whom you might have recourse will be anxious to talk with you about any deviation from the installation manual; even if the scheme you plan for your home might work, there is no engineering analysis, no test data, no certification - is your proposed chimney cap even listed?

OPINION: you might find that someone else will promise you safety but may not really be accountable.

At our lead article on chimney caps, crowns, and shrouds, (you absolutely should read these articles)

CHIMNEY CAP & CROWN DEFINITIONS

we include this warning

Watch out: installing a decorative chimney pot or chimney crown on a factory-built chimney may be unsafe as well as a building code violation.

Unless the decorative chimney shroud or "crown" is listed and labeled for use with the specific factory-built chimney system where it is installed there is a risk that the added decorative covering can cause overheating, leading to a roof or chimney chase fire or other unsafe conditions such as inadequate draft.

We particularly empasize that warning for home-made or one-off or site-built chimney top shrouds or "caps" which might describe some of the concerns that apply to your special custom cap.

See details at

CHIMNEY SHROUDS.

Is it ok to vent a gas fireplace into a Lanai room?

(Or onto a Deck?)

I have a builder building a home for me with a direct vent fireplace in the great room.

He vented the fireplace outside to an area they call the lanai which is an area under the second floor of the home. ( Approx. 11'-0 from the outside of the building).

This seams like a very dangerous practice as the exhaust gases can and probably will gather under the roof and then seep into the area above the vent into the second floor of the house.

Also there is a door to the great room very close to the vent I believe gas fumes can also seep into the great room .

Does this sound like a bad situation to you . The builder has installed these fireplaces in the same house at least 4 or 5 examples I have seen and ran a chimney up thru the house like I expected On 2019-01-16 by John Revtai

by (mod) - Questionable or downright unsafe to vent a gas fireplace into a Lanai room

John

(For other readers, a lanai room is an outdoor living space that has a roof over it but is open to the outdoors at its sides. The sides may be open to the outdoors through screening, or enclosed by glass. Lanai room is a term originating in Hawaii.)

The tables in the gas fireplace vent clearance requirments article GAS APPLIANCE / HEATER DIRECT VENT CLEARANCES give a summary of all of the direct-vent fireplace manufacturer's clearance distance specifications I've found.

There is a requirement to keep the exhaust termination of a direct vent at leaste 12 inches above a deck.

Your local code inspector, at the very least, might require the same for a lanai room floor but that doesn't address the issues of venting under a roof (where flue gases may accumulate) nor onto occupants of the lanai room.

The manufacturer can't anticipate every possible installation situation and I have not found any manufacturer who directly addresses the question of venting into a Lanai room, but

Watch out: My OPINION is that it's a bad idea and possibly dangerous. The concern is that you may be blowing flue gases right onto people sitting in the lanai room. A second concern is that we can't predict what someone may do to that space over the life of the home including creating immediate hazards such as

• Pushing furniture up against the vent, blocking it or creating a fire hazard
• Enclosing the lanai room sides with glass to cause you to vent gases into an enclosed space, risking fatal carbon monoxide poisoning.

For an authoritative answer to a question such as yours, which I consider perfectly reasonable, the best approach would be to ask your local building code compliance inspector for an opinion and to also review the IO manual for your fireplace.

1. identify the brand and model of your direct vent fireplace

2. find the installation and operation manual for that fireplace

Check GAS LOG FIREPLACE MANUALS

as we may have already provided that information.

3. Use the manufacturer's contact information to give their technical support line a call.

4. Let me know what you are told, and post a photo of your installation inside and outside, and we can comment further.

Blocked Direct Vent Gas Fireplace Safety

Is this gas fireplace vent normal?

Is this normal. New home to us.

by (mod) - minor corrosion on aluminum gas exhaust vent not an issue

If you refer to a bit of corrosion on an aluminum chimney sidewall vent, yes.

If there's another blockage or safety concern I can't see it in your photo.

by Kate - fireplace "lint" or fiberglass is blocking the vent outlet

No I’m referring to the fiberglass or lint it seems to be in the middle of the termination cap.

We’re trying to track after it and we’re also wondering if maybe it’s simply is the fresh air intake into the house I tried to add another image

by (mod) - Blocked gas fireplace vent: unsafe, do not use

a gas fireplace with clogged, blocked, or damaged exhaust vent

Watch out: NO that looks DANGEROUS

TURN OFF the heater immediately.

I'm sorry for the inconvenience but it looks to me as if your exhaust vent is blocked .

Watch out: The risk is more than improper heater operation: under these conditions the system could produce fatal carbon monoxide gas indoors - killing building occupants.

Please confirm you've taken this action and also called for repair.

Also be sure that you have working Carbon MOnoxide and smoke detectors properly installed and tested in your home.

And no, it's not a "fresh air intake" - first because the vent is labelled "HOT"

Furthermore even if there were a fresh air intake for a fireplace, blocking it makes the fireplace unsafe. Inadequate combustion air for any gas appliance makes the production of fatal carbon monoxide gas a serious risk.

by Kate: we are not using the fireplace with the blocked vent

We are not using that gas fireplace at all, we have multiple CO detectors.

We will get someone out here this week to check it out. I think there’s s large silver fresh air intake tube that my be going to it & the gas fireplace may be venting up the main chimney.

If so, weird the ceo they used. Do it yourselfer.

by (mod) -

That's good news on all accounts. Thank you for the update and the clarification of just what's being vented. As long as you're not using the fireplace and its fuel is shut off we an all sleep in peace on that account.

 

Is it ok to cover our gas fireplace vent with a wood cover for better looks?

We have a gas fireplace in our home being built. Outside, right behind the fireplace is the vent that says hot.

This is in a conspicuous place since we had planned to entertain outside and this vent is just there attached to the stucco wall about 7 feet above the ground.

Can a wood piece be fashioned around it with the top left open to give the illousion of an art piece, etc. Basically, we are trying to hide the vent and want something that is safe. On 2018-05-02 by C. Penderagraft -

Answer by (mod) - No: never block a gas fireplace vent

CP

Watch out: I would not cover a gas fireplace vent in any way that

- risks your cover material catching fire

- risks blocking the flow of exhaust gases at the vent: doing so risks killing the people in the building with carbon monoxide

Check the brand and model of your fireplace, then

check the clearance distances and installation instructions regarding the exhaust vent.

Do not make any changes to the vent without agreement from the fireplace manufacturer.

Gas Fireplace Distance to Other Overhead Features

What's a safe distance from gas fireplace vent to an awning?

What distance should i have between a gas fireplace outside vent and hanging a Sunsetter awning? On 2017-09-13 by Richard McDaniel

Answer by (mod) -

Richard

There are two different concerns behind any answer to your question:

1. clearance from combustibles

or from materials that could be damaged by heat - for which there is no explicit guide in the standards we cite in the table above.

Safest would be to ask the manufacturer or your specific fireplace, or leave a large distance say 48".

Your code inspector might except a much smaller clearance such as the 12" from a window or door (that opens).

The actual fire clearances from sides of a vent pipe for a gas fireplace in some product literature can be as little as one inch.

2. clearance from an area where people may be spending time

standing, sitting, etc. Again there's no explicit standard but I'd figure that the clearance from a sidewalk is a good model: 84" - or what your local building code inspector recommends.

The two concerns are

2.1. We don't want to blow exhaust for people to inhale

2.2. We don't want hot components that someone might lean against or touch

The codes do indeed throw in the towel when faced with trying to specify a safe arrangement for every possible building situation; that's why we end up going back to the manufacturer or the building department.

What’s the minimum distance from the side wall fireplace vent to a patio cover above

What’s the minimum distance from the side wall fireplace vent to a patio cover above - On 2018-06-26 by Alan

Reply by (mod) -

Alan

The table of sidewall vent clearances for gas fireplaces

at GAS FIREPLACE VENT CLEARANCE REQUIREMENTS is compiled from various code sources and gas fireplace installation manuals.

The first precise authority you should consider, whether your patio roof is vinyl, an awning, wood-framed, or a simple aluminum cover, is the installation manual for the specific gas fireplace. That's because the manufacturer's vent clearance distances for the specific fireplace are the most-authoritative answer we could cite.

If you tell me the brand and model of your gas fireplace and if you don't already have the installation and operation manual for it, I'll help find one.

Also take a look at the table of fireplace sidewall vent clearances above - and look for the type of material or construction of your "patio cover" as I don't know to what you refer. For example see "vinyl" materials if you're talking about vinyl siding or trim.

If you're talking about an awning I'd be extra cautious.

Watch out: check with the manufacturer of your heater and venting system for specific venting instructions and clearances to combustibles or to other features as these distances may vary from one appliance and manufacturer to another.

For example the Travis Industries direct vent clearances include some distances that are different from the tables given above.

Keep in mind that while there is a "soffit clearance" given, there is no clearance given for venting what is expected to be an outdoor air vent location but is in fact under a roof.

Other Gas Fireplace Vent Clearances Q&A

Ok to put a side vent for a gas fireplace be installed over a shared driveway in Toronto?

Can a side vent for a gas fireplace be installed over a shared driveway in Toronto Ontario. On 2020-10-28 by Jennifer

by (mod) -

I don't see why not as long as you respect the clearances given in the main article of this series

Gas heater termination cap distance to PVC Conduit

How far from pvc conduit does termination cap have to be? On 2017-11-28 by Bob

by (mod) - 12" or more

I'd use the same clearance as from vinyl given in

the GAS FIREPLACE VENT CLEARANCE REQUIREMENTS table - 12" or more.

Want to run a gas vent up 24 feet in PVC

I am considering venting a tankless water heater through the sidewall from garage , what is the distance the opening needs to terminate from eaves , its on 1st story of 2 story house.

Also, what is BEST practice through the roof in which I would use about 24 feet of PVC or side of house using about 3 feet of PVC ? The Location of Tankless is in the Garage On 2020-10-27 by Anthony

Reply by (mod) -

Anthony

Thank you for the questions.

Gas heater vent clearances are given above on this page; and of course the IO manual for your specific tankless water heater brand and model will have specific clearances that the manufacturer has determined must be respected for that very heater - those may differ from what we show here.

There is no direct vent gas fired heater that I would vent up 24 feet. None of the vents discussed here run that distance.

Gas meter vent piped away from combustion air intake for gas heater

Matt said:

I have a natural draft tank its dying so I bought a power vent tank which I will install but I have a venting question I have very limited options for where the exhaust will have to go through the wall see pic

I planned on putting it either directly right of my furnace exhaust or to the left of my gas meter

Now my gas meter is vented about 12 feet down the wall so I am clear of the meter venting. I made green marks on the brick for approx location i want to run it On 2021-03-09 by Matt

by (mod) - g

@Matt
|
Check with your local plumbing inspector: it looks as if your vents in your photo may be a bit too close to that gas meter.

Really? Well maybe someone has already addressed this safety concern: notice that the gas regulator vent appears to have been piped away, though we can't see its destination.

If I'm right then yes, an expert also considered this an unsafe installation and addressed it by relocating the termination of the gas meter/regulator vent

I don't see any green marks.

 

Is a 35 foot tall masonry chimney too tall to use to vent a direct-vent gas fireplace?

I want to convert my wood fireplace to a direct vent gas unit running the vent pipes up my existing chimney. The chimney is 35’ tall (3 story home). Is that too tall to do this? On 2020-12-01 by Rick

by (mod) - probably yes

Most likely yes. You will see in the installation manual for a typical direct vent gas fireplace that the vent like this quite short and run horizontally out through a wall.

There are some models that will allow vertical venting option however. So what we need to do is select a model that you like and look at the specifications and the installation manual.

Exactly where to Measure Gas Vent Distance to a mechanical (systems) air supply inlet

The NFGC Recommended Clearance Distance Table for a Direct Vent Gas Appliance shows a requirement K for "Distance to a mechanical (systems) air supply inlet as 6 feet and 3 feet above if within 10 feet horizontally"

My outside air supply inlet has a hard plastic cover which only allows fresh air in thru a horizontal entry port below the main house inlet vent.

This horizontal plastic entry port is 5" deep covering the main house inlet vent. Am I able to include this 5" with 31" for the total vertical separation of 3 feet to the bottom edge of the direct vent heater port?

The NFGC Recommended Clearance Distance Table from a Direct Vent Gas Appliance shows a requirement K for "Distance to a mechanical (systems) air supply inlet as: 6 feet and 3 feet above if within 10 feet horizontally."

Does this apply to an inside the house mechanical (systems) air supply exhaust inlet which is part of an Energy Recovery Ventilator System ERV ?

This ERV inside the house air supply exhaust inlet draws inside air into a heat exchanger and expels the air to the outside of the house.

Fresh air is brought into the heat exchanger from an outside air inlet and passes thru the heat exchanger and is forced out vents inside the house.

I would believe that the answer is that this inside the house exhaust air supply is not addressed by the above rule.. On 2020-11-05 by Joe Poland

by (mod) -

Joe

Thanks that's an interesting question;

In my mere opinion, as the concern is total distance from point of exit of the building to the air inlet, and as the purpose is safety, I'd measure from the closest point on the vent termination cover to the closest point on the air inlet.

The final authority is your local building inspector;

OK to route a direct vent exhaust through a closet ?

Can a direct vented fireplace be vented through a closet through a bulkhead to an outside wall? On 2021-07-09 by Jeff

by (mod) - Wall Firestop may be required

@Jeff,

Possibly:

1. Your vent must follow the manufacturer's instructions including for fire clearance distances from combustibles and maximum vent length, number of bends and elbows, and outside clearance distances as well.

2. In a typical direct vent installation manual you may find text such as the following

Wall Firestop may be required by the appliance manufacturer as additional thermal protection for the wall.

If the wall being penetrated is constructed of noncombustible material only, i.e. masonry block, brick, or concrete only, a hole with zero clearance to the vent pipe is permissible if allowed by the appliance manufacturer.

Can I route a 3-inch direct vent gas line up through an existing 4-inch chimney liner?

I am installing a direct vent gas insert with 3” intake and exhaust ports, replacing an older style gas insert which had a single 4” exhaust only.

Can I use the existing 4” liner to vent the exhaust to the roof cap and connect the intake to a wall vent which would be easier to install. On 2021-07-01 by Paul

by inspectapedia.com.moderator (mod) - Can I use the existing 4” liner to vent the exhaust

@Paul,

I saw this question last night and didn't know how to to answer it then, nor now. Because there is no "one size fits all correct answer"

Start with the installation instruction manual for your specific heater (whatever it is: water heater, boiler, furnace or ?) - as the BTU rates, clearances, and venting requirements vary.

Continue with the IO manual for the specific direct vent device if it's separate from the heater that it's venting.

Watch out: part of the confusion of this question is venting out through a wall rather than a roof, and also what vent material is permitted. Vent materials range from PVC piping for condensing heating equipment that runs at low temperature and vents out through a side-wall, through gas venting through a B-vent chimney to oil-fired equipment that requires an insulated flue if you're using a metal chimney.

So you can see there's no safe "right" answer to the question as phrases. Perhaps with more specifics we can narrow down the answer.

Can the gas vent outlet be under an eave?

On a side wall vent, can the outtake vent be under an eave and if so how far up or down from the eave? Thanks On 2021-05-25 by Manny

by (mod) - can the vent outlet be under an eave

@Manny,

In the gas vent clearance drawing and table above on this page see dimensions D and E for what the code suggests.

See details at DIRECT VENT CLEARANCES to SOFFITS - US & Canada