Minimum Installation Clearances To Combustible Materials

kevin coppinger_4

It has paper on it...you need metal w/ an air space...kpc

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Patchogue Phil_29

Minimum Installation Clearances To Combustible Materials

For oil fired boilers, when refering to Minimum Installation Clearances To Combustible Materials, what material is NOT combustible for the purposes of this requirement?

To be more clear, what material can be used that will allow closer installation? Cement board (Durock type brand)? Sheet metal (what thickness)?

Is 5/8" drywall considered NON-combustible material for this installation requirement?

Patchogue Phil_29

More specific?

Can you be more specific? Like what kind/thickness of metal and how much of an airspace?

What about cement board?

Thanks for replying.

Edward A. (Ed) Carery

Clearances

Phil,

Combustible material is any material that will burn, regardless of its autoignition temperature.

The manufacturer’s I&O should state that a boiler or specific part thereof is labeled and listed to be installed with specific clearances. Install per those instructions. If possible, contact the manufacturer for that information.

If the manufacturer is not available, then refer to NFPA 31, 2006, Chapter 10, regarding clearance to combustibles and clearance reduction methods.

Ed Carey

Patchogue Phil_29

NFPA 31

refer to NFPA 31, 2006, Chapter 10, regarding clearance to combustibles and clearance reduction methods.

I do not have access to NFPA 31. That is why I am asking here. Was hoping someone could tell me about the reduction methods/materials.

Edward A. (Ed) Carery

NFPA Standards

Phil,

It is more than one or two sentences; it is the entire chapter in the book. The link below will take you to the NFPA site and specifically NFPA 31, so you can obtain the standards book from them.

Good luck,

Ed Carey



http://www.nfpa.org/catalog/product.asp?category_name=&amp;pid=3106&amp;target_pid=3106&amp;src_pid=&amp;link_type=search

Patchogue Phil_29

Ed

I had found the site prior, thanks for taking the time though to point it out for me.

However, I did not want to have to buy the whole book just to find out if cement board qualifies for non-combustible material. That is why I asked here, a learning website for asking questions.

LarryC

NFPA 31 free viewing

Here is a link where you can look at the NFPA 31 standard but no copying or printing.

http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=31&amp;cookie_test=1

Larry C

Weezbo

what you are asking is what are your options...

one is a heat shield on the vent with a 1 inch air gap that will enable you to place a heat shield on a sheetrocked wall and further reduce the clearances to 9"...

if you want you can use exterior insulated pipe and bring the boiler exhaust into it, maintaining man required clearences...the reason that is not done more often is it is a bit spendier for the pipe and fittings.

as to what is a non combustible surface it would likely have to have a proven listing in use in an assembly...

we generally consider concrete block or brick to be non combustible and still do what we can to maintain the clearances we would normally abide on a more easily combustible surface.

metal surfaces we generally maintain 1->2" seperation an example say would be an expansion (captive air) tank.

electrical enclosures are something that should be kept in mind also....

Patchogue Phil_29

free viewing

Thanks Larry.

Paul Fredricks_3

Besides NFPA 31, ask your local building official. I've seen different towns require different things.

Jed_2

MINERAL WOOL

2" thick, 16x48 sheets of "0" clearance, 2" thick mineral wool is used in my area to sastisfy this requirement. Passes every time, with proper application. Don't know what finish surface you're looking for, but this material sastifies the requirement.

Jed

Patchogue Phil_29

Jed

What area are you in?

Patchogue Phil_29

Weezbo

Thank you for your thoughts on this topic.

The insulated pipe is an idea I am looking into doing.

Thanks again.

Patchogue Phil_29

local inspectors

From what I understand, around here you need an appointment just to make an appointment!

Jed_2

Maine

Available through mechanical insulation distributors.

Jed

Bob Harper

NFPA 211 definition

Use that link to NFPA documents and look up Std. 211, page 12, section 3.3.110.2 for the definition of "non-combustible".
To paraphrase, any material that in the form used and conditions anticipated will not support combustion, ignition, release flammable vapors, open flame, smoke or most any other recognized form of burning, it would be considered non-comb.

The easy way is to find a material, such as Durock, that has passed ASTM E-136. This 750C vertical tube furnace (1382F) will utterly destroy most materials including type X drywall. Not only does the paper burn but the gypsum calcines and the material crumbles. It does no good if the material loses its strength and falls apart unburned.

A word of caution when asking code officials about non-comb. definitions: they don't know! I deal with them daily and very, very few understand the difference btw this definition for heating and venting equipment, which undergoes long term heat effects and pyrolysis while building officials are primarily concerned with piloted ignition one time fire hazards. Therefore, a B.O. might accept your type X "firecode" sheetrock as non-comb. because it has an ASTM E-84 flame spread of less than 50 (it comes in at 15). However, this means it burns 15% as fast as red oak in a 25 ft. Steiner Tunnel test. But it still burns! Flame spread ratings are useless around hot things such as furnaces and vents, hence these tougher definitions. Another misconception is when you find a building material rated for use in "fire walls", or ASTM E-119. Fire walls are "assemblies" meaning a collection of several materials. Thus, one layer of type X drywall on each side of a 2x4stud wall is rated as a 1 hr. fire wall. that means that wall should resist fire extension into the next compartment for one hr. BUT IT STILL BURNS! See where I'm going? You need to educate yourself about these materials because the construction, codes, HVAC, and testing industries have collectively done a miserable job of it. I think I've made this same speech over 100 times this yr alone whether when teaching classes, internet chat, meeting with code officials and builders or just explaining to a homeowner why they have to rip off a $5K wall surrounding a fireplace because there is plywood lapped over the black metal of the fireplace used to support stone veneer.

Off my soapbox now,

HTH

Paul Fredricks_3

A phone call is probably the way to go. If you call and talk to a secretary, she'll tell you the best time to call. Our local inspectors only take calls between 8 and 9. Leaving a message has never worked for me. I just keep trying til I get through.