Got a night reminder last night.........

[brian89gp]

Yes, and this is why they're required any time you have a zero-clearance issue between the masonry chimney and combustables, such as roof rafters or sheathing touching your masonry stack.

Is there any published documentation for clearances to combustables of an insulated metal flex liner in a masonry chimney?

 

[Ashful]

Is there any published documentation for clearances to combustables of an insulated metal flex liner in a masonry chimney?

Yep. Call DuraVent and ask to talk with Dale about this. He'll point you at the correct info.

 

[bag of hammers]

Both, and it does not seem to add that much expense. I've insulated half the flues on this old house, using both insulated (wood appliances) and un-insulated (oil appliances), but always being different lengths and conditions (thimbles, etc.), it's hard to compare price directly:

44' un-insulated 6" rigid tube with cap and collar, and thimble to basement oil furnace: $1300 in 2001
22' un-insulated 6" flex with cap and collar, and thimble to basement oil furnace: $1795 in 2011 (actually I paid less than this, that was the higher of the two quotes I received, can't remember the amount I actually paid)
23' insulated 6" smooth-wall flex with block-off plate for wood stove on 50' high, steep, standing-seam metal roof with enormous flag-stone chimney top in the way: $2400 in 2011
13' insulated 6" smooth-wall flex for woodstove, slid into existing 8" round clay tile, reusing existing block-off plate and cap, $1100 in 2011

The smooth-wall flex was a $200 - $250 mark-up above standard flex (installer quoted both ways), but I never asked the price difference to do the wood appliances with un-insulated. I knew I wanted insulation to help with my draft on the 13' flue, and to avoid creosote build-up in the 23' flue.

Joful thanks very much for the very detailed breakdown. Wow - 4 heaters (2 oil, 2 wood) - sounds like you live in a huge place. Must be a real good feeling to be able keep that space warm.

 

[bag of hammers]

Yes . . . one "trick" we have done for years . . . actually two "tricks" (maybe I should call them "techniques") is to drop pre-filled Ziplock baggies full of ABC dry chemical powder down the chimney if it is on fire . . . and since many of the homes that have chimney fires often do not have metal liners and are in masonry chimneys we sometimes can open up the clean out door and then sprinkle some water on to any hot creosote that has fallen down into the clean out area . . . water turns to steam, steam expands and rises on the draft and can put out the fire.

I should perhaps point out the obvious to folks . . . it is far better to not have a chimney fire. Burn well seasoned wood. Burn at the proper temps (not too cool and not too hot). Check and clean your chimney on a regular basis.

Using sand in a bag to throw in the stove is one of the tricks I read about here a while ago. The ABC in the bag approach is really interesting. Is this something a homeowner could do (could we get the chemical and make up a few bags)? If so, do you think it would work better than a bag of sand, if tossed right onto the fire from the stove door? Great ideas.....

 

[Sprinter]

Using sand in a bag to throw in the stove is one of the tricks I read about here a while ago. The ABC in the bag approach is really interesting. Is this something a homeowner could do (could we get the chemical and make up a few bags)? If so, do you think it would work better than a bag of sand, if tossed right onto the fire from the stove door? Great ideas.....

I think you'd be better off using an regular extinguisher which would distribute the product better and with more control.

And I wouldn't advise anyone to do the top-down approach at home. Jake's department does it professionally with all the proper equipment, protective gear and SCBA breathing apparatus.

 

[Sprinter]

We had a probie a few years ago (he was a truckie, sorry guys!) use a water can on a stove that took off, cracked the stove...But the wall was fairly warm also....

It would be so tempting for a homeowner to panic and dump water on a stove. It would also be tempting to pour a bucket of water in the stove for a chimney fire. Yes, it would probably extinguish the chimney fire, but also could cause damage and possibly expel burning material out.

Our usual protocol for a chimney fire was to pull a small booster line in with a special nozzle that sprayed only a thin spray of water up the chimney. It doesn't take much water to turn into enough steam to cool the fire and also displace the oxygen. Coincidentally, my installer was also a Captain in the paid department in town and their protocol is the same. At home I have a commercial grade garden sprayer charged up and ready along with my ABC's. It puts out more water than most sprayers and could also be useful in other small fires.

But if in doubt, the common ABC is probably the best overall approach for most situations.

 

[firefighterjake]

I think you'd be better off using an regular extinguisher which would distribute the product better and with more control.

And I wouldn't advise anyone to do the top-down approach at home. Jake's department does it professionally with all the proper equipment, protective gear and SCBA breathing apparatus.

Not to mention really nice ladders and ladder trucks . . .

To stop a fire in the stove cold . . . yeah . . . ABC extinguisher would probably be the ticket.

To stop a fire in the chimney . . . I'm not really sure how much of the extinguishing agent would get sucked up the chimney by the draft to be honest as it would have to curl around the baffle and then go up and out. I would think this would work better than tossing a bag of sand or a baggie of the ABC agent on a fire though as using an extinguisher would produce more of a fine powder.

In any case . . . probably should add that calling 911 is a very good idea . . . it's always better to have help on the way and then have to call back to cancel them if you are able to get the fire out rather than delay calling and think you can handle the situation only to have it go from bad to worse . . . and at that point know that no one has started responding yet.

 

[bag of hammers]

Would you folks who've dealt with this situation say that a metal chimney (e.g. Supervent) would typically need to be replaced after a chimney fire? I guess that question is a bit subjective, but in your experiences, have you seen enough damage to warrant replacement? Again hoping I don't have to go there, but I'm almost thinking I'd be too afraid after the fact to light another fire without new pipes...

 

[jharkin]

It would be so tempting for a homeowner to panic and dump water on a stove. It would also be tempting to pour a bucket of water in the stove for a chimney fire. Yes, it would probably extinguish the chimney fire, but also could cause damage and possibly expel burning material out.

It could also explosively shatter the cast iron and potentially kill them. This is why steam boilers have low water cutoffs... There have been cases of boilers dry firing, somebody notices, oh c$&*# and opens the water valve. Ice cold water hits red hot iron and BOOM.

Water and hot iron is a bad mix

 

[Sprinter]

Would you folks who've dealt with this situation say that a metal chimney (e.g. Supervent) would typically need to be replaced after a chimney fire? I guess that question is a bit subjective, but in your experiences, have you seen enough damage to warrant replacement? Again hoping I don't have to go there, but I'm almost thinking I'd be too afraid after the fact to light another fire without new pipes...

There are just too many variables to answer that question. As I recall, Class A chimney's are rated for three 10-minute burns at 1700°F. Some are 2100°F. So damage depends on temp and time and frequency. Temps can certainly exceed 2000, though.

If it were me, I'd have any chimney inspected for damage by a qualified sweep after a fire. I don't know what they look for in terms of damage, though.