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Gas fireplace exhaust too close to AC/heat pump compressor/condenser unit (C) InspectApedia AJGas Fireplace Vent Cap Clearance Distance FAQs

  • POST a QUESTION or COMMENT about the installation or diagnosis of sidewall vent or direct vent chimney or flue exhaust systems for heating appliances: oil, gas, other fuels firing heating appliances & fireplaces

Q&A on clearance distances needed for direct vent chimneys or exhaust for gas fireplaces & gas fireplace inserts.

This article series gives typical clearance distance requirements between the termination cap of a gas fireplace or fireplace insert and other building or site features such as windows, doors, other mechanical system components, air intakes, exhausts.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Gas Fireplace or Gas Log Vent Distance FAQs

These questions and answers about the required clearance distances arount the vent termination cover for gas fireplaces or gas logs were posted originally at GAS FIREPLACE VENT CLEARANCE REQUIREMENTS - so you definitely want to review the gas fireplace vent distance tables given there.

[Click to enlarge any image]

On 2021-11-04 by Inspectapedia Com Moderator (mod) - warning about plan to cover the entire chimney and its flues with a custom made cap

@Anonymous,

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.

On 2021-11-03 by Anonymous

@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.

On 2021-11-03 by Inspectapedia Com Moderator (mod)

@Anonymous,

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

On 2021-11-03 by Anonymous

@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.

On 2021-11-03 by Inspectapedia Com Moderator (mod) - We want 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

On 2021-11-03 by Megan Mazz

Hello,

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 2021-10-08 by Doug Pirie

How close can a neighbour construct a fence to a neighbours natural gas fireplace vent

On 2020-10-28 by (mod)

Yes.

You asked this question and we posted a reply on another page earlier today. Perhaps you lost that link. We pointed out that at least some vent terminations are sold with the words hot embossed right into it.

On 2020-10-2 by John

How hot do the termination caps get on a side vent gas fireplace. Would it get hot enough to burn a child’s hand?

On 2020-10-28 by (mod) - side vent for a gas fireplace be installed over a shared driveway in Toronto

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

On 2020-10-28 by Jennifer

Can a side vent for a gas fireplace be installed over a shared driveway in Toronto Ontario.

On 2020-09-28 by danjoefriedman (mod)

See my amended comments and your annotated photo given here

Gas fireplace vent too close to soffit, has deflector (C) InspectApedia.com RebeccaYour fireplace vent appears to me to meet all of the clearance requirements listed.

(Your local building code compliance inspector or fire inspector is the final legal authority on these questions).

On 2020-09-28 by Rebecca

The vent is no where near the roof of our house. It is located at the first floor part of our house. I don’t know why the tech used the word soffit. The siding is vinyl.

On 2020-09-28 by (mod) - tech says gas fireplace vents too close to soffit

Your second photo, posted here, explains everything. Your gas fireplace is actually installed on the gable end of your home, on a pop-out that probably frames-in a factory-built fireplace.

And the little "soffit" that we saw in your first close-up photo [below] was not of the main roof but just over this little pop-out.

We still don't want moist gas exhaust entering that tiny roof space as it could still give us a mold problem, and under rather-unlikely circumstances could potentially leak dangerous carbon monoxide into the building.

While it's mere opinion and lacks any engineering analysis, a larger deflector that is somewhat wider than the whole gas vent assembly and that extends out past the lower edge of that little pop-out roof soffit and then bends "down" so as to avoid a water entry problem would be icing on the cake of improvement.

The most important safety steps you can take are the working smoke and CO detectors I cited earlier.

Your technician was technically "correct" in that the vent doesn't clear "A" "roof" "soffit" but this is a rather-limited exposure case as it's not an actual roof space.

[This comment was amended twice after seeing Rebecca's photos - shown here]

I would expect your building code inspector to opine that this gas fireplace vent meets all of the vent clearance requirements given below and as well, meets the requirement

The tech was exactly right and trying to keep you safe - the gas fireplace vent in your first photo (shown below) looks as if it's considerably closer to a roof soffit underside than the minimum allowable 15" clearance distance that I list below.

The fact that the soffit in that photo is not vented and that the soffit and siding look as if they're aluminum may reduce the risk of heat damage;

The bend in that white horizontal wall top trim just under the soffit and against the house might (speculating) have been done by someone thinking they were reducing dangerous flue gas leakage into the attic space. But the actual risk of such leakage depends on whether that horiontal strip is simply trim (usually the case) or if it's some sort of (ineffective and minimal) air intake into the attic.

Certainly you do not want a gas fireplace vent's exhaust to be able to enter the attic through soffit vents - a safety and a moisture and mold concern.

I wonder, if you look up at the soffit, if you see any damage or signs of overheating? In your photo I see a bit of sooting over the vent and what looks like drip marks that could be condensation from the gas fireplace exhaust.

In the attic are there any signs of moisture?

And I'm confused about how a fireplace vent could have been located close to a roof soffit or ovehang in the first place.

It's possible that this fireplace was not installed according to the manufacturer's instructions. Extend a thank-you to your tech for paying attention.

Perhaps you can post a photo or sketch showing more-distant views outside and an indoor view of the fireplace so that we understand the situation (one image per comment).

Gas fireplace vent too close to soffit, has deflector (C) InspectApedia.com RebeccaA gas fireplace vent needs to have

Watch out: at the very least, be sure you have properly installed, located, tested CO and smoke detectors in your home.

On 2020-09-28 by Rebecca

We have a heat ‘n glow gas fireplace that is 19 years old. It works great,(gets minimal usage) and we keep it maintained. We had a new company service it last week.

The technician told us that the vent on the outside of our house is too close to the soffit. [see photo above]

He recommended putting some type of vent deflector on top of the vent to redirect the flow of the hot air out away from the house. We are getting older and have no clue how to do this type of repair. Is there such a vent to redirect the flow and who would we get to do this type of work?
Thanks for your advice.

Not the soffit on the roof. I don’t know why he called it soffit. It’s a strip of siding capping. Looks minimal to me.

On 2019-01-16 by (mod) - venting a gas fireplace into the Lanai room?

John

The table in the gas firepalce vent clearance requirments article linked-to just above gives a summary of all of the direct-vent fireplace manufacturer's clearance distance specifications I've found.

The manufacturer can't anticipate every possible installation situation, so for a question such as yours, which I consider perfectly reasonable, the best approach would be to

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 https://inspectapedia.com/heat/Gas-Fireplace-Heater-Manuals.php

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.

On 2019-01-16 by John Revtai

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 2018-10-26 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.

On 2018-10-26 by Kate: re blocked gas fireplace 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.

On 2018-10-26 by (mod) - do not use gas fireplace with clogged, blocked, or damaged exhaust vent

Unsafe clogged gas fireplace exhaust vent (C) InspectApdia.com KateWatch 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 - 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.

On 2018-10-26 by Kate

No I’m referring to the fiberglass or lent 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

On 2018-10-25 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.

On 2018-10-25 by Kate - is this gas fireplace vent normal?

Is this normal. New home to us.

Unsafe clogged gas fireplace exhaust vent (C) InspectApdia.com Kate

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

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.

On 2018-06-26 by Alan

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

On 2018-05-02 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.

On 2018-05-02 by C. Penderagraft - ok to cover our gas fireplace vent with a wood cover for better looks?

I have a ?. 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 2017-11-28 by (mod) -

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

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

On 2017-11-28 by Bob

How far from pvc conduit does termination cap have to be?

On 2017-09-13 by (mod) - distance from gas fireplace vent to awning

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.

On 2017-09-13 by Richard McDaniel

What distance should i have between a gas fireplace outside vent and hanging a sunsetter awning?


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