Thread: Water pipe insulation clearance from draft diverter hood

Sure looks like the exhaust gases are melting the insulation to me....I'm thinking the cleance between the pipe insulation and draft hood should be six inches but I can't find that in the code anywhere.

Does anyone know?

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I have never seen the 6 inch rule applied to WH draft hoods although that would make perfect sense.

Check the manufacturer's instructions. It will probably say something about not obstructing the draft hood which would be the case here.

I saw some sort of manufacturer spec or something a couple years ago about insulation distance from the hood. I think it might of been on IN.
Doesn't really matter though. The picture makes it obvious there's a problem. Recommend they remove the insulation a foot or two up or more depending on which way the flue pipe runs. That little less insulation isn't going to make a real difference in pipe temp. The melting insulation probably won't catch fire or produce enough fumes to kill anyone either but it could.

The spec. for heat distance might be listed by the insulation company.
As far as how far it needs to be trimmed back, 6 inches would do it since
its only melted close to the hood.

I was just at a class and this very issue came up and the concensus was nothing combustible within 6" of the hood or pipe, if no info was available.

A couple guys said some manufactures also require nothing combustible within 12" of the top of the water heater. Basically, imagine a 12" tall, round (same dia. as water heater) box on top, this area would be free of any combustibles.

Being melted that bad makes me think that there might be some back drafting going on there.

Melted insulation or plastic at a draft hood are always signs of venting failure and should trigger a level II inspection of the chimney or vent and Worst Case Depressurization draft testing.

B-vent is allowed to be attached as shown but is a horrible practice. The screw tips will push the inner vent section inwards thus reducing flow, which could be the problem with this vent here. Always recommend the use of listed draft hood connectors.

The 1" clearance to combustibles on B-vent is off the insulated sections. You do not have this protection at this joint shown. Here it should be treated as single walled pipe with a 6" clearance to combustibles. I've see insulation disrupt the air flow into the hood. Aways remove insulation to meet a 6" clearance.

This draft hood appears to be working exactly as designed-to spill.

Originally Posted by Bob Harper

Melted insulation or plastic at a draft hood are always signs of venting failure and should trigger a level II inspection of the chimney or vent and Worst Case Depressurization draft testing.

Not true. And that is a pretty outlandish statement. Gas water heaters will off gas before they can get a proper draft that is why ANSI draft standards call for testing after 5 minutes of operation and so do the manufacturers.

This picture looks like the insulation is too close to the vent and draft hood. That's it.

Originally Posted by Mike Lamb

Not true. And that is a pretty outlandish statement. Gas water heaters will off gas before they can get a proper draft that is why ANSI draft standards call for testing after 5 minutes of operation and so do the manufacturers.

This picture looks like the insulation is too close to the vent and draft hood. That's it.

Mike, I can appreciate someone disagreeing on something like this but to call my remarks "outlandish" is, well, quite outlandish to me.

Have you ever been certified in CO and Combustion Analysis?

Have you ever worked as an investigator responding to reported CO exposures and injuries?

Do you have any clue about the ANSI Stds. you so lovingly refer to or what they mean?

Do you care about the combustion analysis of an appliance during your 5 minute grace period?

Do you live in a home with draft hoods?

Did you read my last comment about the draft hood performing as designed?

From a CPSC study
http://www.cpsc.gov/PageFiles/130036/furnace.pdf:
Conclusion on page 11 was that the current ANSI Stds. do NOT provide adequate protection from common appliance failure modes and conditions that allow CO leakage into the building. (paraphrased).

Originally Posted by Bob Harper

This draft hood appears to be working exactly as designed-to spill.

Exactly!

If the drafthood were functioning properly, room air should be going up it which won't melt grommets or pipe insulation. Granted high draft can also create issues but it changes the location of the flue gas spillage.

For enough heat to be generated to melt that insulation flue gas spillage is occurring. Spillage is unacceptable at any time interval regardless of what applicable standards or manufacturers may say.

Originally Posted by Bob Harper

Mike, I can appreciate someone disagreeing on something like this but to call my remarks "outlandish" is, well, quite outlandish to me.

Have you ever been certified in CO and Combustion Analysis?

Have you ever worked as an investigator responding to reported CO exposures and injuries?

Do you have any clue about the ANSI Stds. you so lovingly refer to or what they mean?

Do you care about the combustion analysis of an appliance during your 5 minute grace period?

Do you live in a home with draft hoods?

Did you read my last comment about the draft hood performing as designed?

From a CPSC study
http://www.cpsc.gov/PageFiles/130036/furnace.pdf:
Conclusion on page 11 was that the current ANSI Stds. do NOT provide adequate protection from common appliance failure modes and conditions that allow CO leakage into the building. (paraphrased).

Bob, my remarks were all about your comment. You said, “Melted insulation or plastic at a draft hood are always signs of venting failure and should trigger a level II inspection of the chimney or vent and Worst Case Depressurization draft testing.”

Outlandish? Maybe that is too strong. Silly and irresponsible is probably more appropriate.

Your comment comes nowhere near supporting what this picture shows. You see melted plastic? Neither of the plastic rings at the water heater inlet and outlet pipes shows any signs of overheating. Why is that? The picture looks like the insulation is too close to the vent and draft hood. That's it.

You should be recommending a simple draft test yet you recommend an NFPA level II inspection? Yes, that is outlandish.

Certifications and investigative CO reporting in no way supports bad advice. Use real credible references to support your statement and save me the blah, blah, blah.

I couldn’t open your CPSC link. Please provide me verse where it supports an NFPA level II inspection in this instance?

I only cited the ANSI testing standard (and American Water Heater and Rheem instructions) because proper draft cannot be immediately established on startup. Off gassing is common.

If I were concerned about the draft I would do a draft test with a match or a mirror.

The following are some references regarding testing for draft. Can you tell me again why you recommend a level II inspection? Recommending a draft test would be more prudent. Bolds are my own.

http://www.americanwaterheater.com/s...ls/res-gas.pdf

From American Water Heater
CHECKING THE DRAFT
After successfully lighting the water heater, allow the unit to operate for 15 minutes and check the draft hood relief opening for proper draft. Pass a match flame around the relief opening of the draft hood . A steady flame drawn into the opening indicates proper draft. If the flame flutters or is blown out, combustion products are escaping from the relief opening. If this occurs, do not
operate the water heater until proper adjustments or repairs are made to the vent pipe system.


http://www.testo.com/online/embedded...stionGuide.pdf

From Testco, Inc. (maker of CO detectors)
All appliances requiring draft are required to have and maintain draft during operation.
An appliance has 5 minutes under the ANSI standards to prove draft. During steady state
operating conditions, the draft should be stable. The draft will increase as the flue warms
until it reaches maximum flue temperature and stabilizes. The analyzer will record and
store the draft reading for the flue gas measurement screen and printout.
Note: If the appliance and chimney are cold it can take up to ten (10) minutes to
establish draft.

From NFPA 11.6* Checking the Draft. Vent-connected gas utilization equipment appliances shall be operated for several minutes and checked to see that the combustion products are going up the chimney or gas vent properly by passing a lighted match or taper around the edge of the relief opening of the draft hood.

http://www.rheem.com/documents/fury-...use-and-manual

From Rheem:
Test for spillage at the draft hood relief opening after 5 minutes of main burner operation. Use a flame or a match or candle or smoke. The flame or smoke should be pulled into the draft hood’s relief opening(s).

Originally Posted by DavidR

Spillage is unacceptable at any time interval regardless of what applicable standards or manufacturers may say.

Unacceptable? Hardly. It is common. What is your reference for this statement?

Why do CO detector instructions tell you not to put CO detectors in furnace rooms or within 5 ' of any fuel burning appliance? I'll wait for your answer.

Look Mike. I don't know who the heck you are or what horse you rode in on but I'd appreciate it if you cooled the arrogance and learned to be a little more professional and respectful in your posts. Remember, you are the one who came after me.

Where to begin? By your comments, the insulation is "too close". I stated it was too close within the 6" clearance to combustibles but due to the pattern of melting, I felt in my professional opinion it was a trigger for a level II. More on that in a moment. I'm a little puzzled by your repeated references to conducting a "draft test" when you also use a reference such a test is no good unless you fire the appliance for 15 minutes. In the first place, I don't know of hardly any residential appliances that fire for 15 minutes routinely in a normal duty cycle under normal operating conditions. More to that point, when the burner cycles off before your 15 minute allowance for establishment of an acceptable draft, then by your definition all residential appliances can be ventfree because they may never draw before cycling off. You apparently don't have a problem leaving people in such buildings under these conditions. I do.

Ok big boy, let's talk about a Level II inspection. Per NFPA 211-2013 edition, Chapter 14:
14.7.1 Chimneys, vents, and fireplaces shall be inspected, cleaned and repaired if there is any evidence of damage to the chimney, fireplace, or vent or to the surroundings.
14.7.2 Inspections required by 14.7.1 shall comply with the requirements for a Level II inspection in accordance with section 15.4
14.8 Operating Malfunction. When inspection or an operating malfunction shows that an existing chimney, fireplace, or vent is damaged, unsuitable or improperly sized, it shall be repaired, rebuilt, or resized to the construction and functional requirements of this standard.

Level II inspections
15.4.1 Circumstances. A level II inspection shall be conducted under the following circumstances:
1-Upon addition or removal of one or more connected appliances or upon replacement of an appliances with on or more of dissimilar type, input rating, or efficiency, unless the last connected appliance is removed and the chimney use will be discontinued.
2-Prior to relining of a flue or replacement of flue lining in accordance with 7.1.10
3-Upon sale or transfer of the property
4-After a building or chimney fire, weather or seismic event, or other incident likely to have caused damage to the chimney
5 At other times as indicated in 15.3. (Level I inspections).

Now, I see several triggers in those sections, do you?

As to your methods of testing draft, might I offer a comment? Worthless. I don't care what those mfrs. put in their manuals, the use of a mirror, match or smoke at a draft hood does not prove draft--it only proves flow of dilution air into the vent connector. In the first place, the industry standard for "testing" draft is to measure it. That means using a manometer that measures in inches of water column. That requires drilling holes in pipes if not already provided. Done improperly, it can result in grossly inaccurate data. That includes waiting 15 minutes while breathing the exhaust fumes. BTW, you can cause CO from too much or too little draft. How does your mirror or smoke measure that?

I don't have the patience to spar with you and your whiney schoolyard attitude Mike. I suggest you read a LOT more and take a certification course. The most highly respected CO cert. course is that offered by the National Comfort Institute. You know, the one taught by DavidR, whom you were not exactly warm to either. FYI, they teach methods that do ensure proper venting right from startup and how to measure it with a combustion analyzer so you're not relying on smoke and mirrors literally but a professional electronic instrument and a very precise draft gauge.

If you would come down off your high horse, open your mind and listen, you might learn a little. BTW, I do this for a living so it's not like I fell off the turnip truck yesterday.

Have a good day.

Originally Posted by Mike Lamb

Unacceptable? Hardly. It is common. What is your reference for this statement?

Why do CO detector instructions tell you not to put CO detectors in furnace rooms or within 5 ' of any fuel burning appliance? I'll wait for your answer.

The fact that this is common Mike should really throw up some red flags and raise concern. My reference for the statement is based on over a decade of testing thousands of different pieces of equipment. Just because an appliance is installed according to code and manufacturer instructions doesn't ensure it is operating safely.

Any appliance that allows its operation to continue when it can potentially harm the occupants of a building is unacceptable. A drafthood equipped appliance does just that.

So, why do the CO detector instructions tell you not to put them in the furnace room or within 5' of any appliance? Because they don't want them to alarm, the same reason they allow them to be subjected to insanely high levels of ambient CO before alarming. This makes as much sense as installing a burglar alarm system that doesn't monitor the windows and the doors.

In the furnace room and within 5' of the appliance is where you would want a CO detector if the appliance is malfunctioning. Wouldn't you want a CO detector to alert you flue gas spillage is occurring as quickly as possible?

Just a side note, store bought CO detectors really suck at performing their stated job like they should.

Do you guys recommend any certain CO detectors for homeowners?

Originally Posted by Mike Kleisch

Do you guys recommend any certain CO detectors for homeowners?

Yes: unlisted low level CO monitors. There are two I'm aware of:
The CO Experts available from George Kerr on the web or the NSI 3000 available installed only by NCI Certified Pros. The cost usually ends up about the same but you cannot buy and install the NSI yourself.

Anything listed to UL 2034 for single station alarms or 2075 for multiple station hardwired alarms suffer from the same ridiculous alert levels and poor reliability. When a listed alarm alerts, that means by definition, your carboxyhemoglobin level is at least 10%. In other words, these alarms are not intended to protect against CO poisoning but CO death. In the two CPSC studies I referenced, there were numerous cases where even though listed alarms alerted, people still died and all (as expected) has COHb levels >10%. Gee thanks. Those studies also illustrated the failings of the reporting mechanisms in this country or rather the lack thereof. The figures you see on CO deaths are based solely on cases where CO poisoning was documented. It totally skips all those cases of "natural death" and 99.99% of all CO poisoning cases. What I'm saying is the problem is MUCH worse than the public has been lead to believe. Relying on stds. written half a century ago for equipment technology and homes that pre-date Ozzy and Harriet is simply not representative of today's conditions. Back in the day, who cared about a little flue gas spillage as long as the pilot wasn't snuffed out? Homes leaked like a sieve BY DESIGN. Since then, we have weatherized homes while the efficiencies have risen to where its getting impossible to have atmospherically vented appliances in homes. Those stds. that allow spillage do not quantify how much spillage is allowed but rather a time lapse. Back in the day, it as ASSumed much of the flue gases would begin to draft up the chimney so the total actual spillage into the home was negligible. Now we have to rely in draft inducer fans to "prime" the combustion chamber since there is no natural draft at standby. We still allow these appliances to vent into cold wet high thermal mass chimneys that take that 15 minutes to dry and "prime", by which time the unit has cycled off. Low mass liners and venting are better but not a cure or guarantee and those must be sized properly.

We allow an 80% furnace to be common vented with a draft hood equipped water heater. If the chimney gets blocked, the furnace will happily vent out the draft hood without tripping any of the three primary safety controls on the furnace. Meanwhile, a WH is not required to have any primary safety controls unless FVIR and those only have a high limit at the base but no spill switch or pressure switch. That's because with draft hoods, the appliance is not connected to the chimney but deliberately de-coupled. They are held in proximity to each other hoping the smart smoke will figure out which way to go...................after 15 minutes....

Originally Posted by Bob Harper

Look Mike. I don't know who the heck you are or what horse you rode in on but I'd appreciate it if you cooled the arrogance and learned to be a little more professional and respectful in your posts. Remember, you are the one who came after me.

Where to begin? By your comments, the insulation is "too close". I stated it was too close within the 6" clearance to combustibles but due to the pattern of melting, I felt in my professional opinion it was a trigger for a level II. More on that in a moment. I'm a little puzzled by your repeated references to conducting a "draft test" when you also use a reference such a test is no good unless you fire the appliance for 15 minutes. In the first place, I don't know of hardly any residential appliances that fire for 15 minutes routinely in a normal duty cycle under normal operating conditions. More to that point, when the burner cycles off before your 15 minute allowance for establishment of an acceptable draft, then by your definition all residential appliances can be ventfree because they may never draw before cycling off. You apparently don't have a problem leaving people in such buildings under these conditions. I do.

Ok big boy, let's talk about a Level II inspection. Per NFPA 211-2013 edition, Chapter 14:
14.7.1 Chimneys, vents, and fireplaces shall be inspected, cleaned and repaired if there is any evidence of damage to the chimney, fireplace, or vent or to the surroundings.
14.7.2 Inspections required by 14.7.1 shall comply with the requirements for a Level II inspection in accordance with section 15.4
14.8 Operating Malfunction. When inspection or an operating malfunction shows that an existing chimney, fireplace, or vent is damaged, unsuitable or improperly sized, it shall be repaired, rebuilt, or resized to the construction and functional requirements of this standard.

Level II inspections
15.4.1 Circumstances. A level II inspection shall be conducted under the following circumstances:
1-Upon addition or removal of one or more connected appliances or upon replacement of an appliances with on or more of dissimilar type, input rating, or efficiency, unless the last connected appliance is removed and the chimney use will be discontinued.
2-Prior to relining of a flue or replacement of flue lining in accordance with 7.1.10
3-Upon sale or transfer of the property
4-After a building or chimney fire, weather or seismic event, or other incident likely to have caused damage to the chimney
5 At other times as indicated in 15.3. (Level I inspections).

Now, I see several triggers in those sections, do you?

As to your methods of testing draft, might I offer a comment? Worthless. I don't care what those mfrs. put in their manuals, the use of a mirror, match or smoke at a draft hood does not prove draft--it only proves flow of dilution air into the vent connector. In the first place, the industry standard for "testing" draft is to measure it. That means using a manometer that measures in inches of water column. That requires drilling holes in pipes if not already provided. Done improperly, it can result in grossly inaccurate data. That includes waiting 15 minutes while breathing the exhaust fumes. BTW, you can cause CO from too much or too little draft. How does your mirror or smoke measure that?

I don't have the patience to spar with you and your whiney schoolyard attitude Mike. I suggest you read a LOT more and take a certification course. The most highly respected CO cert. course is that offered by the National Comfort Institute. You know, the one taught by DavidR, whom you were not exactly warm to either. FYI, they teach methods that do ensure proper venting right from startup and how to measure it with a combustion analyzer so you're not relying on smoke and mirrors literally but a professional electronic instrument and a very precise draft gauge.

If you would come down off your high horse, open your mind and listen, you might learn a little. BTW, I do this for a living so it's not like I fell off the turnip truck yesterday.

Have a good day.

First of all, I am sorry for all my snarkiness. It was uncalled for and I apologize to you and David R.

For those who may not be familiar with what a NFPA level II inspection is, among other things it would include providing a video scan of the interior of the entire vent unless it can somehow be looked at by other means. Bolds are my own.

15.4.2.3 The inspection shall include examination of accessible areas of all chimney flues and the internal surfaces of all flue liners incorporated within the chimney with video scanning equipment or other means used as necessary to observe those areas.

You said, “As to your methods of testing draft, might I offer a comment? Worthless.”

It is not my method. I was citing instructions from water heater manufacturers, a company that makes carbon monoxide detectors, and the NFPA.

As I stated earlier, this is from NFPA 54.11.6: Checking the Draft. Vent-connected gas utilization equipment appliances shall be operated for several minutes and checked to see that the combustion products are going up the chimney or gas vent properly by passing a lighted match or taper around the edge of the relief opening of the draft hood.

You cite the NFPA and then trash their method for checking the draft as worthless. I think you lose credibility there. Are you really recommending drilling a hole through the vent in question and using a manometer to check the draft?

I still believe your recommendation for a level II inspection from what we have seen from one photograph is over the top.

Again, I apologize for the rude tone in my earlier posts.

Respectfully yours.

Thanks Mike, apology accepted.

I ask that you think for a minute about what and who drive these codes and stds. Mfrs. They want to sell products. As a member of the NFPA 211 Technical Cmte. and the UL Standards Technical Panel 103 for venting products, I can assure you money talks. They are interested in the minimum that they feel gets by. Take CO alarms. We have the technology to protect occupants down to a few ppm within 60 seconds of exposure. Yet the UL stds. are based upon people having to get CO poisoning (10% COHb) before they alert. Why is this? Because the lobbies of the Fire Marshals and Fire Depts. who are the primary responders to alerts not having the budgets or manpower to respond to more frequent lower level alerts. The decision was made to dummy down alarms after the 22 Dec., 1994 Chicago temperature inversion incident where 1,800 first generation CO alarms alerted resulting in only one hospitalization. The UL 2034 std, was dummied down in '96 as sensor technology was rapidly improving in accuracy and reliability. Meanwhile, we continue to weatherize homes so we retain spilled gases longer. There is no mechanism to study or report these effects. None. Then you have the mfrs. who can sell more units for more profit at the cost of UL listed units than the more reliable low level monitors. So, the big boys push their UL listed junk. FYI, they have a law in Congress to outlaw unlisted CO alarm manufacture, sale or distribution because they fear the competition. They certainly are not into saving lives or preventing illness.

As for Level IIs, I use just a digital camera along with my flashlight, mirror and tape rule.

When you take the NCI course, your eyes will be opened. For instance, you will learn of a phenomenon where an appliance can continue to fire and vent out the base of the unit while a high draft condition draws air into the draft hood giving a false sense of "good draft". Yes, I drill a hole in a CAT I vent because it is under negative vent pressure so room air will be entrained in. I snap a metallic button over the hole.

There are many variations of methods for testing the function of combustion appliances and nobody can agree with the other guy but very few are based upon actual field experience of what works. The NCI methods are. For instance, we can show you how providing code approved makeup air vents can lead to CO exposure. A mirror is not quantitative but merely demonstrates moisture from flue gases condensing on the mirror if it is held in the right place. These tests don't mention the need to hold that mirror 360 degrees around the draft hood because there's no telling to which side it may spill under what conditions. Same for an open flame or smoke. I've seen dilution air being entrained right under a hood while flue gases were spilling right under that blanket of dilution air. If the spillage is to certain sides, it may not melt the plastic rings around the water pipes.

I realize you're quoting from what seem to be reputable sources but what David and I are saying is those methods do not work, are not reliable and can give a false sense of security.

I acknowledge your opinion about triggering a level II based upon that one photo. If I was standing there and saw some other signs such as discoloration of the top of the WH or a soot trail at the TPR valve port, I would have a stronger case but I ain't there. What I can see is an improperly installed B-vent connector that I know from experience most probably has resulted in the inner aluminum liner pinching inwards like daisy petals thanks to those screws. You can inspect that can call it part of a Level I inspection but I know from experience a level II would be appropriate. Besides, if this is for a real estate sale or transfer, it should get a level II anyway. A quick peek at the rest of the vent connector would probably reveal more defects that together would more certainly justify the level II.

Relying on a UL listed CO alarm to protect you is about like relying on a Jiffy Pop popcorn container to alert me when my building is on fire. Too little too late.

Take care,