Lining an old chimney or alternate options

OnTheHill

It's a pretty old house, chimney runs through the middle of the house (not outside) so not sure about any need for insulating it, but we definitely want to either line it, pull it out and ? or consider some sort of power vent or other option. 

Building is down to the studs so the walls are all open and access is very easy right now. 

Boiler is an oil steam system, not too old. 

Suggestions on what to use for lining the boiler, or alternatives. Or - Would it make sense just to tear the chimney out and do something different? 

Jamie Hall

If it were mine, I'd get a good chimney sweep in there to make sure it's sound (it looks it, but I'm not there) and then use the slip casting technique to line it. That bend in the attic -- not unusual -- makes rigid stainless not a good option, and I've never been keen on flexible...

random12345

Are you planning on keeping the boiler? I agree with the chimney sweep idea. Important to see what it looks like inside the flue. Is that condensation or some kind of leak on the 4th picture?

heathead

No one can tell without testing but some of the insulation looks like asbestos. Don't disturb it until you know. Don't want you to panic your are fine until it gets disturbed. In one of the pictures it looks like a bath fan is tied into the chimney, if in the same flue that is a no.

bburd

A chimney of some sort is much simpler than a power venter, with little to go wrong until it wears out (no moving parts). People I know who have had power venters on oil burners have not been happy with fumes in the yard nearby, marks on the siding, failures on a cold day… several ended up installing metal chimneys instead, which don’t look very nice on the side of most homes.

EBEBRATT-Ed

the chimney looks in decent shape hopefully the offset is as well. I would have it inspected and keep it if it is sound and line it

Bob Harper

Not sure we're all looking at the same chimney. This thing is full of holes, failed mortar, missing mortar, efflorescence, condensate stains, unsealed thimbles, exhaust fan common vented, zero clearance to combustibles, improper/ unstable corbelling in attic, corbel strapped due to instability, attic offset parged to glue chimney together and hide defects, exterior chimney rebuilt due to failure, lack of cleanout, improper breeching, undersized chimney connector, barometric damper incorrect position, lack of firestopping, improper crown, exterior chimney improper mortar joints, chimney connector improperly supported. That's just the quick blush from the pics provided.
You can perform a level II inspection to determine the suitability of use, but it will fail miserably. Since the offset is unstable, relining is not an appropriate repair. Not sure why flex is a problem if properly size and installed. In this case, it might be best to replace the masonry chimney with a UL listed Class A factory-built chimney installed with 2" clearance to combustibles, listed firestops, vertical fireblocking, elbows, roof support, pitched roof flashing, storm collar, rain cap and extended roof support. At base, it would have a tee support with the base extended for a cleanout. The connector should be replaced with stainless steel rigid chimney liner material for a permanent installation. Curious why such a monstrous boiler is required. Huge building?

random12345

@Bob Harper Is that yellow dripping on the chimney condensate in picture 4? The efflorescence you're referring to is in picture 2 on the outside? Why would this be happening on an internal chimney with an oil boiler? I thought this kind of thing usually only happened with external chimneys...

Bob Harper

Yes, condensate dripping. Efflorescence is soluble salts. The acid from the flue gases react with the alkaline mortar: acid + base > salt + water. The mortar is converted into sand and salt, which means it has lost its bond and compressive strength. It is weak and crumbling. Once the mortar has converted to salt, it cannot be reconstituted. The signs you see on the exterior faces of this chimney are a harbinger for the destruction internally. Since there is no cleanout, the falling debris will pile up blocking the flow of flue gases.

Jamie Hall

I think we are looking at the same chimney, @Bob Harper -- but drawing very different conclusions. Since I am not on site, I can't, obviously, be certain of the condition. I have, however, dealt with a number of chimneys which looked a good deal worse than that -- and they were fine. Yes, the extra flue connectors need to be properly filled. Yes the mortar needs pointing. Slip casting will do the interior.

I have to be admit to being slightly amused by your panic about the offset -- that is a very common situation in New England, and most are treated in exactly the way that one is treated. It is not unstable.

Steamhead

I'll second making whatever repairs are needed and then installing a stainless-steel liner. When finished, the chimney will likely last another 100 years. And with no moving parts, you won't have trouble with it.

I do not like power-venters in any application. They invariably break down in the middle of winter.

pecmsg

Jamie Hall said:

I think we are looking at the same chimney, @Bob Harper -- but drawing very different conclusions. Since I am not on site, I can't, obviously, be certain of the condition. I have, however, dealt with a number of chimneys which looked a good deal worse than that -- and they were fine. Yes, the extra flue connectors need to be properly filled. Yes the mortar needs pointing. Slip casting will do the interior. I have to be admit to being slightly amused by your panic about the offset -- that is a very common situation in New England, and most are treated in exactly the way that one is treated. It is not unstable.

@Jamie Hall
having looked at 100’s of houses on the East End what is the reason for the off set?

Jamie Hall

Generally people tried to get the chimney as close to the peak of the roof as possible -- though only in very old houses will it go through the peak -- to get as good and reliable draught as they could without having to build too much chimney outside, subject to wind loading. Not stupid.

If you were to peel the mortar off the outside of the offset, you'd usually find that it was made by offsetting each course of brick perhaps a quarter width as you go up. The inside should have been made smooth with mortar as they went up (and usually was). Outside was then smoothed when they were done.

Sometimes the offset was to clear a window... or in some types of construction, major roof purlins (again, that's older -- the use of small dimension rafters came in pretty early). Whatever worked...

Bob Harper

I'm not here to be some prima donna chimney fanatic. I'm simply applying THE national standard for chimneys: https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=211
You can mock it, laugh it off, disagree with it all you want but it does not go away. It is what is referenced in the IRC, NFGC, IFGC, NFPA 31, and most appliance installation instructions. It has been held up in court all over the country.

The standard exists to dispel armchair quarterbacking and keyboard commandos. I'm really impressed that you can tell ignore visible conditions of the chimney, signs of failure, signs of various repairs and yet, without an internal video inspection pronounce it suitable for continued use if only it has a liner. Well, this is a big appliance requiring a big flue liner. Is there clearance to even get one that size down? Are all those head and bed mortar joints intact to at least 75% of their thickness to ensure an absolute minimum of 4" nominal wythe wall? If that improper offset, as defined in 211 is so stable and not a problem, why did someone feel the need to wrap a steel band around it and fasten the band to the combustible roof?

"Slip casting" or otherwise known as "cast in place" liners have many limitations. It is almost impossible to do them properly through slight offsets but certainly not through one like this. All those gaps of missing mortar would lead to major blowouts with liquid refractory pouring out like a sieve. You need a minimum 3/4" of material on one system, 1" on several and 1.5" on the German vibrating bell through zero slump systems around the flue. If the flue cannot be round due to aspect/ ratio, it is very difficult to do on vertical chimneys and almost impossible to do well through offsets. The listings on these systems are for straight vertical chimneys only to my knowledge and not through offsets. Maybe I'm wrong but educate me.

I fail to understand the bravado here of people expressing opinions without sufficient basis. Are you willing to stand by your findings to a reasonable degree of engineering certainty? I am. A chimney fails unless you can prove to the contrary. I never met a chimney professional who ever found a single code compliant chimney. They don't exist. Liners are not The Wizard's Cure-All. They are tested and listed to a narrow scope of conditions. If those conditions, such as a nominal 4" wythe wall cannot be met then don't attempt to reline. A chimney must be supported by its own foundation. Strapping it to a house, which can wobble like a bowl of Jell-O in winds will force joints to flex that are not designed or intended for movement. The result is gradual failure of joints, which means inherent instability.

You guys have an amazing knowledge of boilers and heating but on the issue of chimneys I'm afraid some of you are stuck in that old school bravado of knowing it all without knowing nearly as much as they think they do. Get F.I.R.E. Certified in chimney inspection then tell me how your position is still valid. Tell NFPA and the ICC how they got it wrong and should re-write their codes and stds. I have a bunch of references right out of the ICC codes that would call for this chimney to be torn down and rebuilt or replaced with listed venting. That is the only leg to stand on. All else is just smoke and sooted mirrors.
Shalom.

Jamie Hall

It's so nice to have an absolute expert, @Bob Harper , to correct and school us armchair quaterbacks and keyboard commandos, and I'm sure you have done and inspected thousands of chimneys. It's also reassuring to know that your opinions are backed up by reams of Code language and even court judgements.

captainco

Jamie, Bob is one of the smartest and most experienced persons when it comes to chimneys and flues. Often I need to go on Wikipedia or get out a dictionary to interpret all that he writes, but it is not opinion, it is facts. Okay there are some of us that get emotional when a potential danger exists and we start guessing instead of getting someone to start testing and measuring and inspecting. Bob means no harm and Jamie you have great contributions to this site. Plus, it is football season and everyone wants to be a quarterback.

Bob doesn't always agree with me when I say bigger is better but only testing can prove when it is and when it isn't.

Jamie Hall

May I simply point out that my recommendation was -- and remains -- to get the chimney inspected by a reliable chimney sweep? I can neither determine whether it can be repaired -- not whether it needs to be taken down and rebuilt -- without being there.

Intplm.

Jamie Hall said:

May I simply point out that my recommendation was -- and remains -- to get the chimney inspected by a reliable chimney sweep? I can neither determine whether it can be repaired -- not whether it needs to be taken down and rebuilt -- without being there.

Agree with the ^^^^ @Jamie Hall write here.

But @OnTheHill You are renovating as the house is down to the studs?

I would get the thing inspected. It is hard to see what's what from a picture. There are some visible issues that need some attention. ( Cracks on the brick asbestos? at the bend in the attic. etc.)
Knowing whether to repair, line, demolish, or leave it alone?

Getting it looked at is the best thing to do and then, way the cost to use information.