Thread: Direct Vent under opening window

I know this topic is on this site, and I saw the installation manual today while arguing with the Contractor's Site Superintendent about the location of this vent. The Superintendent showed me the Manufacturer's Installation Manual where it says 12" below a fixed window, 9" below an opening window. This vent is 4ft below the opening window in the upstairs bonus room. I could smell the gas coming in (with the window open) and it did not set the combo Smoke/CO Detector off which was 15 ft away in the opposite corner of the bonus room. The 2009 IRC says to follow Manufacturer's Installation Instructions. How can we argue with that even though it's a safety / health concern ? Better yet, why is the vent allowed to be closer to an opening window as opposed to a fixed one? Why is this allowed when garages have to be completely drywalled if living space is above, the door from the garage to the living space be installed with spring hinges, and, ventilators above a gas stove have to discharge outdoors?

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Here is the Continental Gas Fireplace Installation Manual. The External Vent Clearance Diagram is on page 14. . Your replies are appreciated.

What do you think this line means:

Δ The terminal shall not be located less than 6 feet under a window that opens on a horizontal plane in a structure with three walls and a roof.

I'm not sure what they mean by horizontal plane - i.e. awning window. Maybe try to contact the manufacturer and see what that line is referring to. The diagram certainly shows it as only 9" below a window that opens, which seems awfully close to me. I've been surprised before by DV fireplace clearances.

The Superintendent contacted an installer who said (I didn't actually hear the conversation) that that means if the vent is terminated in a covered area like a front porch that has an opening window located under the covered area.... Peoples interpretations are different, I didn't get that scenario from the manufacturer's description at all. If it isn't in writing, who knows what it means. In the manufacturer's diagram, it shows a double hung / vertically opening window, not one that opens on a horizontal plane.

Originally Posted by Jim Hintz

In the manufacturer's diagram, it shows a double hung / vertically opening window, not one that opens on a horizontal plane.

Yes it does.

A single or double hung window does open/s (opening/s) on a horizontal plane.

Descriptive geometry. I think you might want to look up what a horzontal plane is.

Originally Posted by H.G. Watson, Sr.

Yes it does.

A single or double hung window does open/s (opening/s) on a horizontal plane.

Descriptive geometry. I think you might want to look up what a horzontal plane is.

HG,
Are you able to make heads or tails of the comment in the manual that states:

Δ The terminal shall not be located less than 6 feet under a window that opens on a horizontal plane in a structure with three walls and a roof.

What is it they are referring to by saying 3 walls and a roof? Isn't the bonus room window "in a structure with 3 walls and a roof?"

I sent the manufacturer in Ontario Canada 2 emails today asking them to clarify their definitions for me, but no answer yet.

Poorly worded manual. They are addressing the common application of venting out into/ onto a covered balconey or porch. When you have a structure enclosed on three sides plus a ceiling, it cannot ventilate enough so it would trap gases and recirculate them back into the structure.

Originally Posted by Jim Hintz

...the door from the garage to the living space be installed with spring hinges, and, ventilators above a gas stove have to discharge outdoors?

Does the 2009 IRC say that?

Originally Posted by neal lewis

Does the 2009 IRC say that?

I was unable to locate anything specifically stating that gas stoves had to be vented outdoors in the IRC. I stand corrected Neal. But according to the WAC, Looks like ALL Kitchens have to have source specific ventilation to the outdoors, at least here in Washington.

M1507.1 General. Source specific exhaust ventilation is required in each kitchen, bathroom, water closet, laundry room, indoor swimming pool, spa, and other rooms where water vapor or cooking odor is produced.

M1507.3.1 Source Specific Exhaust Fans. Exhaust fans providing source specific ventilation shall have a minimum fan flow rating not less than 50 cfm at 0.25 inches water gauge for bathrooms, laundries, or similar rooms and 100 cfm at 0.25 inches water gauge for kitchens. Manufacturers' fan flow ratings shall be determined as per HVI 916 (April 1995) or AMCA 210.


EXCEPTION:Where a range hood or down draft exhaust fan is used to satisfy the source specific ventilation requirements for kitchens, the range hood or down draft exhaust shall not be less than 100 cfm at 0.10 inches water gauge.

M1507.3.3 Source Specific Ventilation Ducts. Source specific ventilation ducts shall terminate outside the building. Exhaust ducts shall be equipped with back-draft dampers.

Here's the response from the manufacturer concerning the location of the direct vent:

Hello again Jim,


As per your photo, the termination would have to be moved down an additional 2 feet. The clearance is 9” from any opening window on the top and side(in the U.S.), but must be a minimum of six feet below the bottom horizontal plane of the window. I hope this clarifies things a bit better.

Kind regards,

Tony L.
Technical Consultant, Customer Service

Wolf Steel Ltd.
24 Napoleon Road
Barrie / Ontario / Canada / L4M 0G8

Originally Posted by H.G. Watson, Sr.

Yes it does.

A single or double hung window does open/s (opening/s) on a horizontal plane.

Descriptive geometry. I think you might want to look up what a horzontal plane is.

How would you define horizontal plane? How do single/double hung windows open on that plane? Do casement windows also open on a horizontal plane?

I think I understand what they're getting at, but HG knows that everything in this forum is over my head, so perhaps he'll explain his remark.

Originally Posted by Kristi Silber

How would you define horizontal plane? How do single/double hung windows open on that plane? Do casement windows also open on a horizontal plane?

I think I understand what they're getting at, but HG knows that everything in this forum is over my head, so perhaps he'll explain his remark.

Kristi,
A good definition here could be A horizontal plane is a plane which is perpendicular to the plumb line." Or you could say "A horizontal plane is parallel to the horizon." As to what HC is saying......
Rich

Originally Posted by Jim Hintz

I could smell the gas coming in (with the window open) and it did not set the combo Smoke/CO Detector off which was 15 ft away in the opposite corner of the bonus room.

That 'Thar' is a better indication of a problem than what some manual says is OK. This is why Codes Change and Manuals get re-Written. Gas appliances when burning cleanly (properly) will not give off much (almost no) CO. This is why the CO detector did not go off, probably would not of, even if the CO detector was very close to where your nose was. A little dirt clogging an orifice or something partially blocking the combustion air (ten years from now)...and open window... could lead to an unsafe condition. If you can smell the odors (now) coming in the window it really makes no difference what code or the manual "states". if a kid dies-- IMO

Originally Posted by Rich Goeken

Kristi,
A good definition here could be A horizontal plane is a plane which is perpendicular to the plumb line." Or you could say "A horizontal plane is parallel to the horizon." As to what HC is saying......
Rich

Yep...I prefer the former, more exact. And the intent of the manual was to delineate a distance between the vent and the horizontal plane that is intersected by the bottom of the window opening, rather than a direct measurement between the window bottom and the vent. Poorly worded, though.

Originally Posted by Larry Morrison

That 'Thar' is a better indication of a problem than what some manual says is OK. This is why Codes Change and Manuals get re-Written. Gas appliances when burning cleanly (properly) will not give off much (almost no) CO. This is why the CO detector did not go off, probably would not of, even if the CO detector was very close to where your nose was. A little dirt clogging an orifice or something partially blocking the combustion air (ten years from now)...and open window... could lead to an unsafe condition. If you can smell the odors (now) coming in the window it really makes no difference what code or the manual "states". if a kid dies-- IMO

I couldn't agree more Larry..

If your client is a buyer, make very sure they understand that you can smell the exhaust coming into the home, and that is a dangerous condition. It does not matter what the manual and codes say in this case.

If your client is the builder, go to the Superintendent's boss and recommend that the company establish a cash reserve for the legal settlement after an occupant dies from CO poisoning. Make sure he understands that the cash reserve should be a big number since, because of your efforts, the company is making an informed decision to kill an occupant.

There is really not much more you can do.

A UL listed POS CO alarm located 15ft away is probably not going to ever go off from fumes from this window.

First of all, you are not smelling CO but aldehyes. If aldehydes are present then so is CO but not necessarily the opposite. At 69ppm, that listed piece of junk would not alert for 30 days; up to 4 hrs at 70ppm. These devices are not intended to alert you to the presence of CO but alert once you have at least 10% COHb just before you pass out and cannot escape. That's it. If you want to know if CO is entering the structure, you need to use a professional combustion analyzer that has been calibrated.

If this window is in the upper half of the house, fix the house and the fumes won't enter the structure. Upper level windows should be exhausting--not infiltrating.

Also, why are they burning a fireplace with a window open? Usually, the windows are closed during burn season.

I must say that I've looked at this venting diagram multiple times and, for the life of me, I don't see the 6' requirement applying UNLESS it is in a situation with 3 walls and a roof. If this is on the side of a house, as it appears, the "B" measurement should apply in reference to the clearance to windows or doors that open.

This does NOT take into consideration the clearance requirement to the fascia to the left (on the right in this perspective) of that termination assembly.

Bart Ogden
Wichita, KS

Originally Posted by Jim Hintz

Here's the response from the manufacturer concerning the location of the direct vent:

Hello again Jim,


As per your photo, the termination would have to be moved down an additional 2 feet. The clearance is 9” from any opening window on the top and side(in the U.S.), but must be a minimum of six feet below the bottom horizontal plane of the window. I hope this clarifies things a bit better.

Kind regards,

Tony L.
Technical Consultant, Customer Service

Wolf Steel Ltd.
24 Napoleon Road
Barrie / Ontario / Canada / L4M 0G8

Jim,

If I see what I think I'm seeing in this photo (looking out 2nd floor BR window down at DV), there's a LOT more wrong with this installation location than JUST the proximity to the window sill.

I've sketched up what I think I'm seeing...please advise where I'm right, and where I'm wrong.

Originally Posted by H.G. Watson, Sr.

Jim,

If I see what I think I'm seeing in this photo (looking out 2nd floor BR window down at DV), there's a LOT more wrong with this installation location than JUST the proximity to the window sill.

I've sketched up what I think I'm seeing...please advise where I'm right, and where I'm wrong.

Great Diagram HG, the only difference is the window wasn't a single/double hung, it was a bypass 3/0 - 5/0......

Darrel H, I did my best, everyone is aware.

Bob H, Everyone knows that the window is "usually" closed when a fireplace is being run, they just need to remember to shut the pilot light off in the summer months if the window is going to be open.

Bart - The vent is on the back of the residence, not the side. The soffit overhang is typical with bird vents. The manufacturer said it's wrong, gas odor enters when the window is open - what would you do differently?

Originally Posted by Jim Hintz

Great Diagram HG, the only difference is the window wasn't a single/double hung, it was a bypass 3/0 - 5/0......

Darrel H, I did my best, everyone is aware.

Bob H, Everyone knows that the window is "usually" closed when a fireplace is being run, they just need to remember to shut the pilot light off in the summer months if the window is going to be open.

Bart - The vent is on the back of the residence, not the side. The soffit overhang is typical with bird vents. The manufacturer said it's wrong, gas odor enters when the window is open - what would you do differently?

It wouldn't surprise me to have bonus room window open in the early evening, even partially, cooling off heat gain from the day, with downstairs running the fireplace for ambience, for more than half the year (fall & spring - on those "don't quite need or want heat on when sleeping" evenings)- in your area!

I'm one of those that prefer the room cooler when sleeping, like fresh air during same, and when cooler, use a blanket.

Tnx. Okay, lets apply the input, here's Revision 1 (HTH):

Originally Posted by Bob Harper

Upper level windows should be exhausting--not infiltrating. *

Also, why are they burning a fireplace with a window open? Usually, the windows are closed during burn season.

Bob,

* Huh?

Open windows on more than one side of the home without closed doors between - even with the entire downstairs closed up, will ventillate the upstairs; or one or more openings (opening even top & bottom of a dbl hung, or L & R sides of a bypass without fixed pane) in a single room with door closed - can ventillate a room; irrespective of which "floor" you're on!

Ventillation = air exchange. More so if you've got some wind-assist.

Operable windows are for ventillating rooms (natural) and the upper floor as well.

I see no reason why one wouldn't enjoy the "ambience" of the DV sealed door gas fireplace, ANY TIME of the year, including when you've got the upstairs windows OPEN for fresh air ventillation, anytime other than when you've got the home's HEAT or AC running!

"Side" or "back" of the house is irrelevant.

I want to know WHY the manufacturer says it's wrong. Their manual does not say it's wrong.

The wording in the manual only calls for the 6' difference when the area the vent terminates has a roof and 3 walls. This vent does not terminate in an area which has a roof and 3 walls..

A, Meets clearance.
B. Meets clearance if it's 9".
C. Meets clearance if it's 12".
D. Meets clearance if it's 18" and if it's a ventilated soffit.
E. Meets clearance if it's 12" and if it's an unventilated soffit.
F. N/A
G: Meets clearance. It's obviously over 2"
H. N/A
I. N/A
J. N/A
K. N/A
L. Doesn't apply. It's not public property.
M. N/A
N. N/A, it's a horizontal vent.
O. Meets clearance if it's 24". Doesn't appear to.
P. N/A
Q. N/A
R. N/A
S. N/A

What would I do differently? Unknown until I find out exactly why the manufacturer's manual says it's OK and the manufacturer says it's NOT OK.

Regarding the pilot light - I don't see that the 1k pilot light would cause any issues compared to when the fireplace is running, even on low.

Bart Ogden
Wichita, KS

Originally Posted by Jim Hintz

Great Diagram HG, the only difference is the window wasn't a single/double hung, it was a bypass 3/0 - 5/0......

Darrel H, I did my best, everyone is aware.

Bob H, Everyone knows that the window is "usually" closed when a fireplace is being run, they just need to remember to shut the pilot light off in the summer months if the window is going to be open.

Bart - The vent is on the back of the residence, not the side. The soffit overhang is typical with bird vents. The manufacturer said it's wrong, gas odor enters when the window is open - what would you do differently?

Looking at the drawing, photo and manual it looks ok from a install as instructed by mfg point of view. The 6 ft is about part enclosed porches.

Having read hundreds of this type of manual (gas dv stoves and fireplaces) the clearances are similar for the termination at the btu output of this product. Clearances to a fixed closed window is about heat and condensation on the pane.

To be clear there are many installs with caps under windows, sure it smells but it is a tested and approved situation.

Back to the drawing, is this location the best re: performance with wind eddies and swirling wind in a corner no, safe? looking that way.

Pick a random DV gas fireplace manual, read clearances. For a 30K btu unit they will be much like this one.

S

Boy, Would love to see their testing on that to get 9" clearance.

I am betting this was a mistake that got to the manual office and no one caught it. Someone in QC is going to have a bad day ; )

Funny the notes say that for a fixed window the "12" clearance is to prevent condensation and thermal breakage."

And why would that not happen with a window that opens that is shut?

HG, in response to my point about infiltration vs. exfiltration let me pose it to you this way: If I open a window, does the cold outdoor air infiltrate or does the warm room air exfiltrate and how does it know which way to go? The answer is pressures. Due to stack effect, the lower part of any heated structure is generally under negative pressure while the upper part is under positive pressure. The cross-over point is referred to as the Neutral Pressure PLane or Neutral Pressure Zone. Now, since we have dynamics such as wind, ducted air, exhaust fans, etc., the location of this plane shifts with the changes. If you open a basement window, it drops; open the upstairs window, it rises--it follows the leaks. Now, add in wind effect, exhaust fans, forced air distribution and you can severely tilt the NPP to one side or the other.

Now, back to my comment: if an upper window is infiltrating then it is below the NPP which means you have a serious upper level leak problem and/ or no air infiltrating below.

Originally Posted by H.G. Watson, Sr.

Jim,

If I see what I think I'm seeing in this photo (looking out 2nd floor BR window down at DV), there's a LOT more wrong with this installation location than JUST the proximity to the window sill.

I've sketched up what I think I'm seeing...please advise where I'm right, and where I'm wrong.

Nice!