direct vent furnace

[briang]

As a code official the 2003 IRC says to follow the manufacture's installation instructions for direct vent appliances. The instructions say nothing about how far from the property line or neighboring building for termination. The neighbors are complaining about the gas coming out but it is to code. How do you answer them when they are concerned about the health affects of the gas. The furnace is 95.1 AFUE.

[Jerry Peck - Codeman]

First a question: How far from the neighbors house is the exhaust vent located?

As you are using the 2003 IRC, refer to Appendix C at the back of the code, and first apply those clearances in an "any direction" dimension as the drawing is depicting those clearances as they are applicable to that same structure.

Then I would also go to G2427.3.3.6. (see code reference below) and apply that to 'property other than the property generating the discharge' and treat the other property the same as 'where located adjacent to public walkways' as 'the public', i.e., persons other than the occupants of the structure generating the discharge are being considered as 'the public', and their property is their 'walkway'.

Does that fit the wording of the code? No, but a follow up question needs to be asked: Does that fit the intent of the code? Yes, to that question.

From the 2003 IRC as referenced above:
- G2427.3.3
- - 6. The exit terminals of mechanical draft systems shall be not less than 7 feet (2134 mm) above grade where located adjacent to public walkways and shall be located as specified in Section G2427.8, Items 1 and 2.

Which now refers us to G2427.8, Items 1 and 2: (underlining and bold are mine)
- G2427.8 (503.8) Venting system termination location. The location of venting system terminations shall comply with the following (see Appendix C):
- - 1. A mechanical draft venting system shall terminate at least 3 feet (914 mm) above any forced-air inlet located within 10 feet (3048 mm).
- - - Exceptions:
- - - - 1. This provision shall not apply to the combustion air intake of a direct-vent appliance.
- - - - 2. This provision shall not apply to the separation of the integral outdoor air inlet and flue gas discharge of listed outdoor appliances.
- - 2. A mechanical draft venting system, excluding direct-vent appliances, shall terminate at least 4 feet (1219 mm) below, 4 feet (1219 mm) horizontally from, or 1 foot (305 mm) above any door, operable window, or gravity air inlet into any building. The bottom of the vent terminal shall be located at least 12 inches (305 mm) above grade.

The above is simply trying to provide explanation and other code sections as supporting documentation for application of code sections which do not cover each and every conceivable construction mess up option, to try to do so is simply impossible. As a code official I am sure that you have seen contractors do things which no other person would have deemed any one even considering doing - where you stand back and shake your head back and forth, wondering what they were thinking, then wondering IF they were thinking.

[briang]

Thanks for your help.

To answer some of your questions the homes are about 13.75 feet apart with a private driveway between the homes. Mechanical venting is treated differently than direct vent terminations in the codes. The neighbors only care about what is coming out of the vent and that it may get in to their home when they open their door which is over 15 feet away from the vent.

[Jerry Peck - Codeman]

Brian,

Mechanical venting is treated differently than direct vent terminations in the codes.

Which is why I highlighted that wording with bold in the code section I posted. I posted that section to show that the code addresses the exhaust from a venting system for clearances to openings, and, while excluding direct-vent appliance vents from the code requirements as they are addressed within their listing and labeling, the intent of the code is to not vent to areas where the venting gases will be a problem.

Nonetheless, though, the distance between the houses in your question exceeds the minimum requirements in the code for even mechanical venting systems.

The neighbors only care about what is coming out of the vent and that it may get in to their home when they open their door which is over 15 feet away from the vent.

If I knew the manufacturer of the direct-vent appliance I could contact them and ask them what the recommended horizontal distance is to openings in any structure, the same structure or other structures, and have them provide documentation that the gases being vented are not harmful at the distance they specify. Do you know, or can you get, the manufacturer's name of the appliance in question? If so, that would be helpful.

[briang]

The direct vent furnace in question is a Maytag 95.1 AFUE. I contacted them and could not get any data on the exhaust. They say as long as it is installed per manufactures instructions and the National Fuel Gas Code "there is no evidence supporting the possibility that any harm could stem from the exhaust of the furnace towards the adjacent home".

[Jerry Peck - Codeman]

Hi Brian,

I sent off a request for the complete installation instructions and other pertinent installation and use information. Hopefully I will get it within the next day or two.

[briang]

Jerry
Thank you again for all your help and insite.

Brian

[Jerry Peck - Codeman]

Hi Brian,

This is on page 14 of the installation instructions: (underlining is mine, bold is theirs)

- CIRCULATING AIR REQUIREMENTS
- - WARNING:
- - - Do not allow combustion products to enter the circulating air supply. Failure to prevent the circulation of combustion products into the living space can create potentially hazardous conditions including carbon monoxide poisoning that could result in personal injury or death.
- - - All return ductwork must be secured to the furnace with sheet metal screws. For installations in confined spaces, all return ductwork must be adequately sealed. When return air is provided through the bottom of the furnace, the joint between the furnace and the return air plenum must be air tight.
- - - The surface that the furnace is mounted on must provide sound physical support of the furnace with no gaps, cracks or sagging between the furnace and the floor or platform.
- - - Return air and circulating air ductwork must not be connected to any other heat producing device such as a fireplace insert, stove, etc. This may result in fire, explosion, carbon monoxide poisoning, personal injury, or property damage.


The underlined part specifically prohibits allowing the combustion products from entering or circulating through the living space, and this living space would include any and all living spaces.

The underlined part further specifically states that allowing the combustion products to enter or circulate through a living space "can create potentially hazardous conditions including carbon monoxide poisoning that could result in personal injury or death", which is warning of dire consequences from the combustion products in the exhaust.

I am also sending off an e-mail asking about further clarification for clearances not shown in the installation instructions.

[Jerry Peck - Codeman]

Hi Brian,

Below is my e-mail to the manufacturer followed by their response. Other than addressing it as I did above, there is nothing specifically addressing a horizontal distance, only the reference in the installation instructions to not allow the combustion products to circulate into and through living space.

My e-mail to them:

From: Jerry Peck [mailto:codeman@AskCodeMan.com]
Sent: Thursday,February,04,2010 6:56 PM
To: Bob Marx
Subject: RE: Maytag 95.1 AFUE unit installation instructions

Thank you for the installation instructions, they were very helpful in allowing me to answer (for the most part) the questions, however, some of the answers to the questions were not shown in the installation instructions, so I am asking if you have any additional information on this.

In addition to the clearances shown, some clearances are not shown, specifically clearances from an adjacent structure (as in Zero Lot Line developments) or another part of the same structure (as in Town Homes, apartments, condos, etc.). This clearance would be a horizontal clearance from the direct vent exhaust in the direction the direct vent exhaust is discharging, whereas the other clearances shown are from openings located on the same plane as the direct vent exhaust outlet.

For example, let’s presume (as is typical of Zero Lot Line developments) that the direct vent exhaust is located in the exterior wall of a house on the right of a house on the left, and that there is only 5 feet to 10 feet between the structures, and that the direct vent exhaust was discharging horizontally toward the adjacent structure only 5 feet to 10 feet away, and that the OTHER structure has a door or window located where the combustion products are discharging, Of course, this house on the left would have a similar discharge problem to the house on its left, etc., for the row of houses.

What is considered an appropriate minimum distance from the horizontal discharge to ANY (such in another structure) opening which leads to living space and where the combustion products are discharge directed toward those openings?

Thank you for whatever information you may have on this type of installation and these conditions.

Thank you,

Jerry Peck

Their response back:

From: Bob Marx [mailto:marxb@Nordyne.com]
Sent: Friday, February 05, 2010 2:39 PM
To: 'codeman@AskCodeMan.com'
Subject: RE: Maytag 95.1 AFUE unit installation instructions

We do not have figures for the scenario you have described. If the installation meets the criteria in the installation instructions and is in compliance with the Fuel Gas Code, we could add nothing further.

BM marxb@nordyne.com

[briang]

We may just not let them to face the outlet pipe to the neighbors.

thanks

Brian