Thread: Need Advice on Proper Venting Furnace and WH Closets

Hi,



Long time lurker, first time poster. Lots of great information on this site... I am from Chicago, IL.



I’ve got an HVAC question regarding my furnace closet and my hot water closet (separate with a shared wall).



Existing conditions:

·10 year old condo unit (w/ same age appliances)

Existing separate water heater in a small enclosed water heater closet

o Approx 3’x3’ area closet

o 50 gallon (40,000BTU)

o Solid door

o Flue pipe shared with furnace flue pipe, which enters through shared wall

o Shared wall with furnace closet

o Only other vent is a small 6”x10” grille in the shared wall with the furnace (approx. 6” from the ground)

Existing separate furnace in a small enclosed furnacecloset

o Approx 3’x4’ area closet

o (Rheem 100,000 BTU)

o Louvre door

o Flue pipe exits into shared wall, and into ceiling in the water furnace closet (shared flue pipe)

o As noted above, there is a small 8”x12” grille in the shared wall with the water heater (approx. 6” from the ground)

o The furnace return grille is actually outside the furnace closet – in the hallway

·General

o Both closets are centrally located in the unit, so no nearby walls for any new direct venting options

Unit is approximately 1200 SF total (or about 900SF minus the bedroom areas), so I should be able to pull combustion air from the unit (140,000 BTU / 1000 = 140 x 50cf = 7000 CF / 9ft height = 778 SF requirement)

Issue:

·I recently had my outdoor gas meter replaced,and the gas company technician performed a gas appliance compliance check during the new meter turn-on. He would not turn on the gas to the water heater section due to the following reasons:

1. “Not enough combustion and dilution air”(written on the work order)

2. He noted I did not have enough combustion air volume for the water heater (just a single small vent at the bottom of shared wall)

3. He noted if I have a plugged flue for any reason, or negative pressure backdraft, the CO2 will build up in the water heater closet and seep out through the bottom of door and small existing vent.

4. He also noted “Do not try to use a louvre door on water heater closet as it is too close (within 3’) of the furnace return” and CO2 could be filtered into the return through a louvered door.

5. His recommendation was that I cut a large hole between the furnace and water heater closet shared wall, large enough for the 2 rooms to have the ventilation of a single room – basically so the 2 ROOMS ACT AS A SINGLE ROOM. He acknowledged that this was not ideal, but would be better than the current condition.

- He noted that if I used grilles in the new opening, that would constitute an obstruction, and there should only be 1 obstruction for each passageway - so no grilles on this new opening.

- He indicated it would be optimal to have one opening high and one opening low between the 2 closets

- The existing louvre door would serve as combustion air source for both furnace and water heater

- Any CO2 would have more room for dissipation (I’m not sure if I heard that one correctly)


Question:

1 If I cut a hole into the shared wall, then aren’t I introducing a new way for any CO2 buildup to enter the furnace closet directly from the water heater closet? Or do I just assume that the furnace return plenum is air tight, and is only getting air from the hallway return grille?

2 Also, creating a larger single room might provide more volume for the CO2 to dissipate, however, it’s still going to reach the furnace return as soon as it exits the louvred door, no? Or do I assume CO2 will rise and hit the CO2 detector in the hallway ceiling?

3 Before I get out the drywall saw, I was hoping someone here might chime in if they have any strong feelings on the “new hole in the wall” recommendation, or if you have any other recommendations on a fix.



Please let me know if you think more information would be helpful - I tried to diagram out the situation in the attached photo...



Thanks in advance!

Tangent



- - - Updated - - -

Having some trouble adding photos... it keeps uploading and uploading, is there a cap to size? My jpgs are only about 400kb...


---I should also note that I'm not trying to avoid doing work, I just want to make sure I'm not making the situation worse before I get started...

Reduce the photo to about half or more and it should load.

Photos and a diagram attached...

Additionally, you stated you are from IL ... IL used a different code and parts of IL (Chicago and the vicinity) uses an even different code (the Chicago Building Code).

You really need to specify what part of IL, there are a few inspectors here from IL who could then answer your question better than the rest of us guessing at what IL (or Chicago) requires.

I see several errors in that gas company person's requests as they related to other codes, but IL codes are weird at times ... so I would not want to apply normal codes to those items.

Thanks Jerry, I'm located in Chicago, IL. Post will be updated to reflect the location...

Originally Posted by tangent

Hi,



Long time lurker, first time poster. Lots of great information on this site... I am from Chicago, IL.



I’ve got an HVAC question regarding my furnace closet and my hot water closet (separate with a shared wall).



Existing conditions:

·10 year old condo unit (w/ same age appliances)

Existing separate water heater in a small enclosed water heater closet

o Approx 3’x3’ area closet

o 50 gallon (40,000BTU)

o Solid door

o Flue pipe shared with furnace flue pipe, which enters through shared wall

o Shared wall with furnace closet

o Only other vent is a small 6”x10” grille in the shared wall with the furnace (approx. 6” from the ground)

Existing separate furnace in a small enclosed furnacecloset

o Approx 3’x4’ area closet

o (Rheem 100,000 BTU)

o Louvre door

o Flue pipe exits into shared wall, and into ceiling in the water furnace closet (shared flue pipe)

o As noted above, there is a small 8”x12” grille in the shared wall with the water heater (approx. 6” from the ground)

o The furnace return grille is actually outside the furnace closet – in the hallway

·General

o Both closets are centrally located in the unit, so no nearby walls for any new direct venting options

Unit is approximately 1200 SF total (or about 900SF minus the bedroom areas), so I should be able to pull combustion air from the unit (140,000 BTU / 1000 = 140 x 50cf = 7000 CF / 9ft height = 778 SF requirement)

Issue:

·I recently had my outdoor gas meter replaced,and the gas company technician performed a gas appliance compliance check during the new meter turn-on. He would not turn on the gas to the water heater section due to the following reasons:

1. “Not enough combustion and dilution air”(written on the work order)

2. He noted I did not have enough combustion air volume for the water heater (just a single small vent at the bottom of shared wall)

3. He noted if I have a plugged flue for any reason, or negative pressure backdraft, the CO2 will build up in the water heater closet and seep out through the bottom of door and small existing vent.

4. He also noted “Do not try to use a louvre door on water heater closet as it is too close (within 3’) of the furnace return” and CO2 could be filtered into the return through a louvered door.

5. His recommendation was that I cut a large hole between the furnace and water heater closet shared wall, large enough for the 2 rooms to have the ventilation of a single room – basically so the 2 ROOMS ACT AS A SINGLE ROOM. He acknowledged that this was not ideal, but would be better than the current condition.

- He noted that if I used grilles in the new opening, that would constitute an obstruction, and there should only be 1 obstruction for each passageway - so no grilles on this new opening.

- He indicated it would be optimal to have one opening high and one opening low between the 2 closets

- The existing louvre door would serve as combustion air source for both furnace and water heater

- Any CO2 would have more room for dissipation (I’m not sure if I heard that one correctly)


Question:

1 If I cut a hole into the shared wall, then aren’t I introducing a new way for any CO2 buildup to enter the furnace closet directly from the water heater closet? Or do I just assume that the furnace return plenum is air tight, and is only getting air from the hallway return grille?

2 Also, creating a larger single room might provide more volume for the CO2 to dissipate, however, it’s still going to reach the furnace return as soon as it exits the louvred door, no? Or do I assume CO2 will rise and hit the CO2 detector in the hallway ceiling?

3 Before I get out the drywall saw, I was hoping someone here might chime in if they have any strong feelings on the “new hole in the wall” recommendation, or if you have any other recommendations on a fix.



Please let me know if you think more information would be helpful - I tried to diagram out the situation in the attached photo...



Thanks in advance!

Tangent



- - - Updated - - -

Having some trouble adding photos... it keeps uploading and uploading, is there a cap to size? My jpgs are only about 400kb...


---I should also note that I'm not trying to avoid doing work, I just want to make sure I'm not making the situation worse before I get started...

Many many many issues -
1 . Return air intake within 10 feet of furnace combustion chamber . Hazard . Combustion fumes can enter return air duct.
2. Appears to be fan induced furnace draft sharing flue with water heater with open draft hood . Hazard. Fan induced draft fumes will spill out of open hood.
3. Combustion air is also an issue


Suggestion: attempt to get a duct to exterior for combustion air intake and seal louver doors.

Originally Posted by Jim Abram

Many many many issues -
1 . Return air intake within 10 feet of furnace combustion chamber . Hazard . Combustion fumes can enter return air duct.

You are making another presumption without explaining it - IF the door to that closet is sealed, there is no problem, however, IF the door to that closet is not sealed it could very well be a problem.

The information provided leaves open the possibility that the furnace door is too close to the return air - but it might not be.

2. Appears to be fan induced furnace draft sharing flue with water heater with open draft hood . Hazard. Fan induced draft fumes will spill out of open hood.

I must be missing something that leads you to think that it is fan induced, would you please point that out? Thanks.

3. Combustion air is also an issue

Yeppers, that is what the gas man said and why he is asking for information.

Suggestion: attempt to get a duct to exterior for combustion air intake and seal louver doors.

Might be needed, might not be needed.

Dan, Micheal, Markus - are you guys out there? Need someone who knows the Chicago codes.

Originally Posted by Jerry Peck

You are making another presumption without explaining it - IF the door to that closet is sealed, there is no problem, however, IF the door to that closet is not sealed it could very well be a problem.

The information provided leaves open the possibility that the furnace door is too close to the return air - but it might not be.



I must be missing something that leads you to think that it is fan induced, would you please point that out? Thanks.



Yeppers, that is what the gas man said and why he is asking for information.



Might be needed, might not be needed.

Jerry -1. No assumptions ,see picture 4 - pretty hard to seal louver door. See return adjacent in hall well within 10 feet.
2. See brand and model on front of furnace . Induced draft model.

Originally Posted by Jim Abram

Jerry -1. No assumptions ,see picture 4 - pretty hard to seal louver door. See return adjacent in hall well within 10 feet.

You've lost me there - I see that louvered door to the furnace, but there is no louvered door to the water heater, not that he stated (he stated the opposite) and not that is shown in the photo.

Where did you get the 'not within 10 feet' from? It looks to me like the return for the furnace goes to the hallway through a return air plenum to the furnace.

2. See brand and model on front of furnace . Induced draft model.

That I did not know - I looked the model up after your post and before replying ... sure enough, that has an inducer fan.

Now, another issue may be surfacing - does that inducing fan qualify as a positive pressure vent? If so, then it needs a vent type which is positive pressure (I wish I could see the photos while posting, but I can't go back and view them until done, so, relying on memory, that vent looked to be a Type B gas vent and Type B gas vents are for gravity vents, not positive pressure vents.

1. Water heater closet door is solid. Both the door and the water heater are within 3' of the furnace return grill in the hallway.

2. Furnace closet door is louvered from top to bottom. The furnace itself is just around the corner from its own return grille in the hallway. Just a few feet away technically since it's a louvred door, and for all intents, is an open passageway.

3. So I have 2 combustion operations happening within several feet of my furnace return grille. Both require combustion air, however, any openings I provide to feed the combustion, may also be the unwitting passage for CO2 to seep into my furnace return grille.

Fun...

Furnace and water heater are close to the return air grille, however, as they say "Close only counts in horseshoes.", to which has been added "and hand grenades" to which has been added "and atom bombs" ...

... All depends on how you define "close".

The code addresses "in the same room or space" and (whether some like it or not or agree or not) the return is not in the same room or space as the water heater and furnace are. You can count me in with the ones who do not like it, but I also recognize that it does not matter if I like it or not - that is how the codes address it (referring to the INC - which is why we need one or more of the guys in Chicago to help with this).

Originally Posted by Jerry Peck

You've lost me there -
Where did you get the 'not within 10 feet' from? It looks to me like the return for the furnace goes to the hallway through a return air plenum to the furnace.

Not within 10 feet is a long time standard for return air ducts. Since the 1960's

Originally Posted by Jim Abram

Not within 10 feet is a long time standard for return air ducts. Since the 1960's

For fuel burning fireplaces, but we are not referencing a fireplace here - so I ask again "Where did you get the 'not within 10 feet' from? It looks to me like the return for the furnace goes to the hallway through a return air plenum to the furnace."

Originally Posted by Jerry Peck

For fuel burning fireplaces, but we are not referencing a fireplace here - so I ask again "Where did you get the 'not within 10 feet' from? It looks to me like the return for the furnace goes to the hallway through a return air plenum to the furnace."

Jerry - 2012 IRC


SECTION M1602 RETURN AIR

M1602.1 Return air.
Return air shall be taken from inside the dwelling. Dilution of return air with outdoor air shall be permitted.

M1602.2 Prohibited sources.
Outdoor and return air for a forced-air heating or cooling system shall not be taken from the following locations:

1. Closer than 10 feet (3048 mm) to an appliance vent outlet, a vent opening from a plumbing drainage system or the discharge outlet of an exhaust fan, unless the outlet is 3 feet (914 mm) above the outside air inlet.2. Where flammable vapors are present; or where located less than 10 feet (3048 mm) above the surface of any abutting public way or driveway; or where located at grade level by a sidewalk, street, alley or driveway.3. A room or space, the volume of which is less than 25 percent of the entire volume served by the system. Where connected by a permanent opening having an area sized in accordance with ACCA Manual D, adjoining rooms or spaces shall be considered as a single room or space for the purpose of determining the volume of the rooms or spaces.

Exception: The minimum volume requirement shall not apply where the amount of return air taken from a room or space is less than or equal to the amount of supply air delivered to the room or space.4. A closet, bathroom, toilet room, kitchen, garage, boiler room, furnace room, unconditioned attic or other dwelling unit.

Exception: Dedicated forced-air systems serving only a garage shall not be prohibited from obtaining return air from the garage.5. A room or space containing a fuel-burning appliance where such room or space serves as the sole source of return air.

Exceptions:1. The fuel-burning appliance is a direct-vent appliance or an appliance not requiring a vent in accordance with Section M1801.1 or Chapter 24.2. The room or space complies with the following requirements:2.1. The return air shall be taken from a room or space having a volume exceeding 1 cubic foot for each 10 Btu/h (9.6 L/W) of combined input rating of all fuel-burning appliances therein.2.2. The volume of supply air discharged back into the same space shall be approximately equal to the volume of return air taken from the space.2.3. Return-air inlets shall not be located within 10 feet (3048 mm) of a draft hood in the same room or space or the combustion chamber of any atmospheric-burner appliance in the same room or space.3. Rooms or spaces containing solid-fuel burning appliances, if return-air inlets are located not less than 10 feet (3048 mm) from the firebox of those appliances.6. An unconditioned crawl space by means of direct connection to the return side of a forced air system. Transfer openings in the crawl space enclosure shall not be prohibited.

Originally Posted by Jim Abram

Jerry - 2012 IRC


SECTION M1602 RETURN AIR

M1602.1 Return air.
Return air shall be taken from inside the dwelling. Dilution of return air with outdoor air shall be permitted.

M1602.2 Prohibited sources.
Outdoor and return air for a forced-air heating or cooling system shall not be taken from the following locations:

1. Closer than 10 feet (3048 mm) to an appliance vent outlet, a vent opening from a plumbing drainage system or the discharge outlet of an exhaust fan, unless the outlet is 3 feet (914 mm) above the outside air inlet.2. Where flammable vapors are present; or where located less than 10 feet (3048 mm) above the surface of any abutting public way or driveway; or where located at grade level by a sidewalk, street, alley or driveway.3. A room or space, the volume of which is less than 25 percent of the entire volume served by the system. Where connected by a permanent opening having an area sized in accordance with ACCA Manual D, adjoining rooms or spaces shall be considered as a single room or space for the purpose of determining the volume of the rooms or spaces.

Exception: The minimum volume requirement shall not apply where the amount of return air taken from a room or space is less than or equal to the amount of supply air delivered to the room or space.4. A closet, bathroom, toilet room, kitchen, garage, boiler room, furnace room, unconditioned attic or other dwelling unit.

Exception: Dedicated forced-air systems serving only a garage shall not be prohibited from obtaining return air from the garage.5. A room or space containing a fuel-burning appliance where such room or space serves as the sole source of return air.

Exceptions:1. The fuel-burning appliance is a direct-vent appliance or an appliance not requiring a vent in accordance with Section M1801.1 or Chapter 24.2. The room or space complies with the following requirements:2.1. The return air shall be taken from a room or space having a volume exceeding 1 cubic foot for each 10 Btu/h (9.6 L/W) of combined input rating of all fuel-burning appliances therein.2.2. The volume of supply air discharged back into the same space shall be approximately equal to the volume of return air taken from the space.2.3. Return-air inlets shall not be located within 10 feet (3048 mm) of a draft hood in the same room or space or the combustion chamber of any atmospheric-burner appliance in the same room or space.3. Rooms or spaces containing solid-fuel burning appliances, if return-air inlets are located not less than 10 feet (3048 mm) from the firebox of those appliances.6. An unconditioned crawl space by means of direct connection to the return side of a forced air system. Transfer openings in the crawl space enclosure shall not be prohibited.

Jim,

Now you are part way there to getting it - all you have to do now is READ what you just posted.

Once you understand what it is saying (or even what you think it is saying) point out the part which requires the 10 feet you are referring to.

I am always open to learning more, I misread things too at times, so please point it out.

Originally Posted by Jerry Peck

Jim,

Now you are part way there to getting it - all you have to do now is READ what you just posted.

Once you understand what it is saying (or even what you think it is saying) point out the part which requires the 10 feet you are referring to.

I am always open to learning more, I misread things too at times, so please point it out.

Jerry - See: Exception 2.3 .

Basic design criteria , ( prior to code) , has always been that return air ducts are located at least 10 feet from any combustion source. The open grill on the furnace face is the combustion source.

Originally Posted by Jim Abram

Jerry - See: Exception 2.3.

Jim,

Did you happen to notice the wording I used in a previous post? I used that wording for you.

"in the same room or space"

Exception 2.3 does not apply - see my previous post.

Originally Posted by Jerry Peck

Jim,

Did you happen to notice the wording I used in a previous post? I used that wording for you.

"in the same room or space"

Exception 2.3 does not apply - see my previous post.

Jerry - What you have missed is the meaning of same room or space. A louvered door does not create a separation of spaces.The return air duct is still well within 10 feet of the combustion chamber. A door that is weatherstripped is a requirement to create a separate space.
You seem to lack even a minute amount of common sense.

(Bold is mine)
G2407.5 (304.5) Indoor combustion air.*
The required volume of indoor air shall be determined in accordance with*Section G2407.5.1*or*G2407.5.2, except that where the air infiltration rate is known to be less than 0.40 air changes per hour (ACH),*Section G2407.5.2*shall be used. The total required volume shall be the sum of the required volume calculated for all*appliances*located within the space. Rooms communicating directly with the space in which the*appliances*are installed through openings not furnished with doors, and through*combustion air*openings sized and located in accordance with*Section G2407.5.3, are considered to be part of the required volume.*



G2407.5.3.1 (304.5.3.1) Combining spaces on the same story.*
Each opening shall have a minimum free area of 1 square inch per 1,000*Btu/h (2,200 mm2/kW) of the total input rating of all*appliances*in the space, but not less than 100 square inches (0.06 m2). One opening shall commence within 12 inches (305 mm) of the top and one opening shall commence within 12 inches (305 mm) of the bottom of the enclosure. The minimum dimension of air openings shall be not less than 3 inches (76 mm).

Originally Posted by Jim Abram

Jerry - What you have missed is the meaning of same room or space. A louvered door does not create a separation of spaces.The return air duct is still well within 10 feet of the combustion chamber. A door that is weatherstripped is a requirement to create a separate space.
You seem to lack even a minute amount of common sense.

Jim,

I have plenty of common sense, however, it appears as either you do not or cannot read - let know which you need help with.

(A bit difficult to post much using my phone, the two code sections were intended to be a the bottom instead of at the top. )

Originally Posted by Jerry Peck

(Bold is mine)
G2407.5 (304.5) Indoor combustion air.*
The required volume of indoor air shall be determined in accordance with*Section G2407.5.1*or*G2407.5.2, except that where the air infiltration rate is known to be less than 0.40 air changes per hour (ACH),*Section G2407.5.2*shall be used. The total required volume shall be the sum of the required volume calculated for all*appliances*located within the space. Rooms communicating directly with the space in which the*appliances*are installed through openings not furnished with doors, and through*combustion air*openings sized and located in accordance with*Section G2407.5.3, are considered to be part of the required volume.*



G2407.5.3.1 (304.5.3.1) Combining spaces on the same story.*
Each opening shall have a minimum free area of 1 square inch per 1,000*Btu/h (2,200 mm2/kW) of the total input rating of all*appliances*in the space, but not less than 100 square inches (0.06 m2). One opening shall commence within 12 inches (305 mm) of the top and one opening shall commence within 12 inches (305 mm) of the bottom of the enclosure. The minimum dimension of air openings shall be not less than 3 inches (76 mm).



Jim,

I have plenty of common sense, however, it appears as either you do not or cannot read - let know which you need help with.

(A bit difficult to post much using my phone, the two code sections were intended to be a the bottom instead of at the top. )

Jerry - We are not discussing combustion air . We are discussing return Air .
The need to separate the return from the combustion chamber is to prevent fumes from being drawn into the ducts . A louver door does nothing to separate these elements.

[QUOTE=tangent;238359]


- - - Updated - - -

Tangent - If I were you I would contact the AHJ that granted a permit for the initial installation.
He is the one with ultimate jurisdiction.
The gas company tech may be out of line.

If the building is 10 years old - There was a requirement at the time that 100% of the combustion air come from the exterior. IMC 701.2

The installation does have numerous issues and could use improvement.

Originally Posted by Jim Abram

Jerry - We are not discussing combustion air . We are discussing return Air .
The need to separate the return from the combustion chamber is to prevent fumes from being drawn into the ducts . A louver door does nothing to separate these elements.

Jim,

We are discussing the REQUIREMENTS of that separation and therefore must first establish whether or not they are already separated based on the requirements in and of the code.

You keep wanting to have things your way because you think they should be that way ... I can see the you have not yet grasped the idea and understanding that what you want does not mean squat - unless what you want happens to match what the code wants/allows/requires.

The code addresses what we are discussing, not as you want it to, but as to what is required and not required.

So ... back to square one - the code does not consider that return air grille as being in the same room or space as either the furnace or the water heater.

The code, therefore, has no 10 foot separation requirement.

I'm not saying that I like it either, but just as what you like or want does not matter, what I like or want does not matter - what matters is what the code requires/allows/prohibits ... and the code does not require 10 feet separation, nor does the code prohibit that return being there, the code does allow it.

I explain that very thing almost every day as it does not matter what the contractor wants either - what matters is what the code says.

We have pretty well established that you disagree with what the code requires as you think it does not require enough ... then submit code changes and change the code ... If you can get your code changes passed and accepted.

[QUOTE=Jerry Peck;238487]

Jerry -I disagree with your interpretation and would never approve this installation.

I can only work to help keep people safe. Having a return air register within ten feet of a combustion source is a known hazard. I will make it an issue every time .

Originally Posted by Jim Abram

Jerry -I disagree with your interpretation and would never approve this installation.

Apparently it is not my interpretation as that was installed that way and the gas company person had no problem with that aspect of it.

I can only work to help keep people safe. Having a return air register within ten feet of a combustion source is a known hazard. I will make it an issue every time .

As long as you don't say it is required/not allowed/etc then you can have any opinion you want.

Where you get into trouble and look foolish is by saying something is required/not allowed/etc and not compliant with the code and then end up showing that you have no idea of what you are referring to ... of course, if you want to do that too ... no problemo from this end as I'm only trying to help you not look like you don't know what you are talking about (that's your job).

Originally Posted by Jerry Peck

Where you get into trouble and look foolish is by saying something is required/not allowed/etc and not compliant with the code and then end up showing that you have no idea of what you are referring to ...

Jerry - Often the Code or those that interpret the Code does not properly address issues.

It is not about being Code compliant - It is about being safe. You appear to have been blinded by the Almighty Code. The Code is not infallible.

Combustion fumes , ( and CO),being drawn into return ducts is a possible hazard. However you want to address it is up to you , but a longtime rule of thumb is 10 foot separation between combustion sources and return air ducts. BTW - A louver door is not a separation.

Originally Posted by Jim Abram

Jerry - Often the Code or those that interpret the Code does not properly address issues.

It is not about being Code compliant - It is about being safe. You appear to have been blinded by the Almighty Code. The Code is not infallible.

Jim,

You appear to be blinded by being unable to continue with one discussion without trying to change it to mean something else.

The discussion has been about you stating what is required, I have been answering about what is required ... HOWEVER ... if you would like to start a NEW discussion on what is not required, we can do that too.

The code is what is REQUIRED. The does not address what IS NOT required.

There are MANY THINGS which ARE MUCH BETTER when done ABOVE WHAT IS REQUIRED by the code.

Venting and combustion air is one of those, just as Bob Harper to explain that to you as he is much more qualified than you are to address those issues, and, in fact, Bob has addressed those issues here before ... going into what 'should' (versus 'shall') be done and why.

Nonetheless, I am not " ... blinded by the Almighty Code.", and I also know that "The Code is not infallible.", regardless ... the CODE addresses what is REQUIRED as a MINIMUM ... oh, wait, gosh darn it ... code is minimum? Oh, yeah, I've said that many times before, and I can tell that, even for just yourself, I will have to say it many more times in the future - CODE IS MINIMUM ... CODE IS THE MOST UNSAFE ONE IS LEGALLY ALLOWED TO DO SOMETHING (I've said that before too).

You seem to think, or at least have implied in the past, that if something 'should' (versus 'shall') be done, then it should be in the code - that is not how the code works ... the code establishes a minimum starting point (I've said that before too).

... but a longtime rule of thumb is 10 foot separation between combustion sources and return air ducts.

Again, I ask, provide back up for that as the longtime rule of thumb (and it has been code too) has been the 10 foot separation between a fireplace opening and return air.

Oh, by the way ... "between combustion sources and return air ducts" - huh? Now the duct need to be 10 feet from the combustion air? I think I know what you mean, but you keep changing what you are saying so much that I want to verify what you actually meant to say.

BTW - A louver door is not a separation.

A louver door does not "combine spaces" either.

I guess that means that the spaces are "separate spaces" and the door does not affect that separation? Jim, you are trying to defend your indefensible statements and are digging your hole deeper ... I have a new shovel here you can borrow anytime you wear that one out.

Again ... it all gets back to this: CODE IS MINIMUM ... CODE IS THE MOST UNSAFE ONE IS LEGALLY ALLOWED TO DO SOMETHING ... oh, wait, I just said that above, didn't I? Yeppers, I did.

@Jerry Peck - "The discussion has been about you stating what is required, I have been answering about what is required ... HOWEVER ... if you would like to start a NEW discussion on what is not required, we can do that too."

Jerry - You seem to have lost your way in your blind defense of the "CODE" My posts were about possible hazards not about what is required. Often the "CODE" overlooks serious issues.
I am just adding some insight as to where safety might be improved.

maybe it's optical illusion from the photo to me , but the horizontal leg of the flue doesn't appear to be sloped upward properly...

Originally Posted by brianmiller

maybe it's optical illusion from the photo to me , but the horizontal leg of the flue doesn't appear to be sloped upward properly...

I think that it may be an illusion.
A far bigger issue is the flue servicing a induced draft furnace ,and a hot water heater with an open draft hood.