Do North American chimney sweeps do smoke tests?

[chimneyballoon]

Last time I was in England an associate was telling me about how there are mandatory chimney smoke tests done in the UK in order to commission a wood burning unit.

If I understand correctly, basically the top of the chimney is sealed off. Then an ignited smoke pellet is dropped in the firebox. Then the base is immediately closed off with plastic in order to trap in the smoke. The tester then has to view the visible areas of the chimney structure to see if any of the smoke comes out around the mortar joints or any other location. I guess the intent is to create a smoke laden positive pressure inside the flue, so you can see the weak points in the chimney structure.

My question is...is this type of testing ever done in the US? I know some sweeps use smoke pellets to test chimney draft. But do they also close the top and bottom of the flue and positive pressure test the flue this way?

 

[bholler]

My question is...is this type of testing ever done in the US? I know some sweeps use smoke pellets to test chimney draft. But do they also close the top and bottom of the flue and positive pressure test the flue this way?

nope never heard of anyone here doing that

 

[Lake Girl]

Have to say it seems like a good way to troubleshoot chimney. Do they use liners much in the UK? or still just use masonry chimneys?

 

[Ashful]

Our oldest houses are considered "new" by UK standards, so not a surprise they have stringent requirements for commissioning a chimney, which may be mostly based on homeowners wanting to use old existing flues. Seems like good practice, to me, but I've not heard anyone report such a test here before.

 

[chimneyballoon]

The way I understand the market. They do liners pretty much all the time if something is being retrofitted into an existing flue. It is just too hard to get an old flue to pass the mandatory tests if you try to mix old chimney with new stove or insert. However, there is still a good bit of old coal burner "pocket fireplaces" that people try to maintain that are masonry.

 

[dlj]

I'd like to get the info on how they are doing it and the product used to create the smoke. Sounds like a great method to check a chimney...

dj

 

[chimneyballoon]

This is the best description that I can find on the 3 levels of smoke tests done in the UK. The "Chimney Integrity Test" is the one I am discussing. I guess they use Hardyboard or plywood at the bottom to close the fireplace or stove opening. The top covering can be trickier. If you have an assistant and the chimney top is accessible, you can just use any old flat board as a cover or a plastic bag. If you don't have an assistant or the chimney top is not easily accessible, you use a Chimney Cork that threads up the flue from the inside and inflates to plug the chimney near the top.

As far as the smoke pellets go...the most common one is a simple pyrotechnic smoke pellet that meets code requirements of BS5440-1. The UK is very specific about their tests and codes.

 

[bholler]

This is the best description that I can find on the 3 levels of smoke tests done in the UK. The "Chimney Integrity Test" is the one I am discussing. I guess they use Hardyboard or plywood at the bottom to close the fireplace or stove opening. The top covering can be trickier. If you have an assistant and the chimney top is accessible, you can just use any old flat board as a cover or a plastic bag. If you don't have an assistant or the chimney top is not easily accessible, you use a Chimney Cork that threads up the flue from the inside and inflates to plug the chimney near the top.

As far as the smoke pellets go...the most common one is a simple pyrotechnic smoke pellet that meets code requirements of BS5440-1. The UK is very specific about their tests and codes.

That test is fine but honestly in most cases it will not tell you if just the liner has failed which is a definite safety issue. In order to see smoke escape the chimney structure you would need the liner to be compromised as well as the chimney structure. I will stick with my camera inspection

 

[chimneyballoon]

My UK associate sent me a copy of the BFCMA manual on smoke testing. This is the official step by step from page 15:

1. If there is an appliance fitted at the base of the chimney, burn some newspaper in the grate for 2 to 3
minutes to establish a flue draw. A longer warming up time may be needed with wet or cold flues. If there
is no grate or fire box fitted use a blow lamp for at least 10 minutes to establish a flue draw. This will assist the
testing of the flue and not is intended to simulate real conditions.

2. Place at least two flue testing smoke pellets on a brick in the opening at the base of the flue or in the
appliance if it is fitted. Follow the pellet manufacturer’s safety instructions. The actual number of smoke
pellets required will be determined by circumstances and the size of the pellets used. Generally, the larger
the flue diameter the fewer pellets required. This is the result of the ratio of flue diameter compared to the
surface area of the flue.

3. Ignite the pellets and when they start smoking cover the opening with a board or plate sealed at the edges
or if an appliance is fitted, close all doors, ash pit cover and vents.

4. When smoke begins rising out of the top of the chimney, cap the top of the flue, terminal or pot using an
inflated football bladder or plastic bag sealed in position with tape. A hole with a minimum diameter of
50mm must be left in the capping or sealing device.

5. Examine the full length of the chimney for any leakage of smoke. If possible check for signs of smoke
leakage from wall cavities at the sides and back of the chimney, if it is built into a wall. Also check for
smoke leakage at openings around windows near to the chimney and the roof space area.

6. If any smoke is seen establish the point of leakage and carry out remedial work to correct any faults.

7. After completing the remedial work repeat the testing procedure until no major leakage or fault is apparent.
Remove the closures at the top and bottom of the chimney.

 

[bholler]

Is this test typically aimed at unlined flues? It seems to me they would normally be the only ones that this test would give you and good results for. And if I am looking at an unlined flue it has already failed my inspection. And if it is lined I can inspect the liner with a camera faster and with no risk of putting smoke into the customers house.

 

[chimneyballoon]

The way I understand it, it is a mandatory test for lined or unlined. It is kind of their standard flue integrity test. Can you think of any reason this smoke testing would work better than a camera inspection? Or does it seem antiquated compared to a level 2 chimney inspection with camera?

 

[bholler]

Can you think of any reason this smoke testing would work better than a camera inspection?

No I cant think of any really. The oly time it may be useful would be in an unlined chimney which I would never ok to use anyway.

 

[dlj]

A camera inspection may not show you if there is a gap that has an overlap you can't see through, but smoke can get through.

dj

 

[bholler]

A camera inspection may not show you if there is a gap that has an overlap you can't see through, but smoke can get through.

Yes the camera will show the gap and that gap is enough to say that that liner is compromised. But if the smoke gets through that gap in the liner will it show up out side the chimney? Probably not but if it does it will be nowhere near where the breach in the liner is. And it is almost unheard of that there would be a gap in a lined chimney that you could see out of the chimney through. It just does not happen. With the camera we inspect every joint in the clay tiles for missing mortar and inspect every tile for gaps. So yes we would see if there was somewhere for the smoke to escape.

 

[begreen]

I think the smoke test can be a good idea. A camera inspection has to look at every joint and all of the tiles, 360º all the way down. It's very possible and human nature that something might be missed in a tall chimney system. The smoke test is another verification method to cover possible oversight.

 

[Ashful]

I think a lot of people are missing the point bholler is making. If the liner is compromised, the smoke leaking out will still be trapped between the liner and chimney chase. If that smoke does somehow then find its way out of the structure, it will almost certainly be at another location, no where near the failure in the liner.


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[begreen]

Understood. It still has the value of showing there is a leak and need for a re-inspection. This is similar to pressure testing roof drains for 24 hrs.. If there's a leak it may show up at the bottom of the pipe at the cleanout as it trickles down the pipe, but that's still valuable info for indicating there is a leak somewhere. One would expect that the smoke pellet test has produced results for it to become SOP in the UK.

 

[Blowndiffuser]

The way I understand it, it is a mandatory test for lined or unlined. It is kind of their standard flue integrity test. Can you think of any reason this smoke testing would work better than a camera inspection? Or does it seem antiquated compared to a level 2 chimney inspection with camera?

I live in the UK and I never had this sort of test. I've got two burners both lined that were installed by a HEATAS engineer. The only smoke test that was performed was to ensure that their was draw and that the smoke was released from the chimney.

But I have seem the document before and it is only guidance and the smoke test is only recommend if the chimney has not been used for a long time to test the integrity of it.

 

[dlj]

Yes the camera will show the gap and that gap is enough to say that that liner is compromised. But if the smoke gets through that gap in the liner will it show up out side the chimney? Probably not but if it does it will be nowhere near where the breach in the liner is. And it is almost unheard of that there would be a gap in a lined chimney that you could see out of the chimney through. It just does not happen. With the camera we inspect every joint in the clay tiles for missing mortar and inspect every tile for gaps. So yes we would see if there was somewhere for the smoke to escape.

I've done a lot of boroscope work in many areas. You cannot always see defects no matter how well you perform your inspection. All techniques have their limitations. The smoke test I'm sure also has it's limitations. Is one technique better than the other? Likely, I don't know which, and each may be better in some way and less so in another.

I do know it would be easier to do a smoke test compared to having to get the equipment to have to visually inspect the inside of my chimney.

dj

 

[bholler]

I've done a lot of boroscope work in many areas. You cannot always see defects no matter how well you perform your inspection. All techniques have their limitations. The smoke test I'm sure also has it's limitations. Is one technique better than the other? Likely, I don't know which, and each may be better in some way and less so in another.

I do know it would be easier to do a smoke test compared to having to get the equipment to have to visually inspect the inside of my chimney.

dj

Yes it would be easier but just because you pass the smoke test does not mean you chimney is safe to use. It only means that you don't have a failure in the liner and in the masonry structure that connect. There can be failures in both parts multiple places that would still not let the smoke out of the structure. And I have used a boroscope also and it is absolutely nothing like my chimscan. I have 2 cameras on it one faces forward the other to the side and with the push of a button I can rotate that side facing camera. The smoke test would be useful for evaluating an old unlined chimney because with it would be hard to tell what was a breach with a camera. But simply the fact that it is unlined would make me fail it so no further testing would be needed.

 

[stoveguy2esw]

why not just put pressure in the sealed chimney and read it? if the flue is compromised you could tell with a manometer.

 

[begreen]

Not sure the smoke test was called the final word. It sounds like the smoke test is just another verification method to compliment other forms of inspection.

One benefit of this type of test might be in a new liner installation that has a flaw in the liner or a tear due to unforeseen issues in the chimney.