Flue pipe cut out and hardware cloth over the sides- oh my

seeker70

Hello all,
I perform a good deal of inspections that are not related to heating issues( that's not what I do) but over the last couple of decades I've seen a lot of crazy configurations. But this one is interesting. The client has a soot,drafting issue - so he was told by several oil companies.you will see the attempts made and appears to be against fire code or just common sense. Any thoughts?
- Thanks

JStar

Uhhh. Somebody doesn't understand draft.

icesailor

Sad.

Someone else who doesn't understand the peculiarities of a dual flue chimney in a tight modern house.

And it still didn't work any better than before.

SWEI

For those of us who aren't chimney geeks, would someone be so kind as to explain what we're looking at? To my untrained eye, it appears they have capped off the tops of the flues and vented them to the side, adding screening. Why?

Jamie Hall

You have got to be kidding. Where is this catastrophe?

SWEI -- looks to me as though that's exactly what they did do. I can't imagine why... I suppose the screening is to keep the squirrels out?

Gordy

SWEI said:

For those of us who aren't chimney geeks, would someone be so kind as to explain what we're looking at? To my untrained eye, it appears they have capped off the tops of the flues and vented them to the side, adding screening. Why?

The one they did cap off Kurt, the other one is not capped. Apparently who ever did this was counting on the wind blowing from a certain direction at all times.

I didn't know you can increase flue size by doing this method.

icesailor

FWIW, it probably goes something like this.

Its a fairly new house with the tiles extended above the chimney. The house is tight. The prevailing winds, usually out of the West or some quadrant from NW to SW, has the wind blowing across the two flue tiles. From the dark discoloration on the tiles, it would appear that the heating system is oil. On certain days, when the wind is right, the wind blows across the burner flue first, then the second fireplace flue next. The lesser and back drafting from the tight house lets make-up air get sucked down the fireplace flue where some of the gases from the burner get sucked into and down/out the fireplace. Causing an odor in the living space.

Because of the tight house and the poor draft, the fireplace doesn't work well and continuously puffs smoke back into the building. The owners called some chimney "expert" who half understood the problem but not a complete solution. But capping off one flue (probably the burner flue) at the top and leaving the fireplace flue open, he makes the flowing exhaust from the fireplace vent higher, and the burner flue below it. It doesn't work all that well because only on a windless day will smoke/exhaust rise straight up into the atmosphere. On a normal day, with normal wind, there is a lot of turbulence. On the Leeward side of a chimney, the exhaust/smoke swirls all around the chimney where the pressure is less until it gets back into the air stream.

Some Jurisdictions require "spark arrestors" on the top of chimney flues to stop sparks from leaving the chimney. Where they added the tile and cut a hole in it would require a piece of hardware cloth (Rat Wire) to act as a spark arrestor.

Really desperate for a solution.

Old 1820's and before New England houses often had 6 or more flue chimneys. They never had the problems because the houses were so leaky from air infiltration that it was never an issue. I've seen masons completely block off extra flues in houses because of make up air being sucked down chimneys. Blocked solid with wet concrete.

SWEI

Thanks, Chris -- that helps.

If you came across a similar multi-flue chimney, what would you propose?

R2.0

Outside combustion air for the boiler?

SWEI

What about the fireplace?

billtwocase

I'm with Jamie. I also don't see the major issue. Looks like a home made version of this, only a little crude, and has a screen to keep leaves and critters out

icesailor

Make up air.

I once went to a very expensive new home that had a fireplace that wouldn't draw. They had a large crawl space and partial cellar. They let me cut two closable HVAC floor registers in the floor on either side of the fireplace. It almost completely stopped the problem.

Flowing air has a lower pressure than static air. That's what makes draft work. The inside air is a higher pressure than the flowing outside. The two are trying to come to an equilibrium. With a gusty wind, the outside negative pressures are always going up and down. Often crossing the inside pressures. Like the water in a toilet bowl osculating on a windy day. In heavy wind storms, I've seen toilet bowls loose their trap seal.

Sometimes, opening a door to the cellar or a window on a lee side is all it takes. Or a "Fan In A Can" device.

Some of these 8,000 Sq. Ft "Summer Cottages" have residential kitchens that could qualify as commercial restaurant kitchens. They have fans in the hoods that are bigger than the average HVAC air handler. They need make up air from somewhere. Commercial Kitchen hoods now require positive make up air with the fans linked so both run.

Like I say. My iceboat went over 50 MPH in 10 to 15 MPH of wind. Over 25 MPH wind and you needed the little sail so you didn't go too fast and loose control. Between 55 and 60, the boat gets too "twitchy" and sensitive.

Gordy

A chimney top damper would have been the solution on the fireplace flue 30 min. done. And it looks a lot better. If the problem was boiler exhaust being sucked down the fireplace flue.

It would not solve fireplace smoke being sucked down the boiler flue unless the boiler had a automatic damper though. The above solution is not a fix 100%.

icesailor

I never was suggesting that the photos shown were any kind of a fix. It was my opinion of what happened and why.

As far as a chimney top damper, they aren't a positive solution either. I did a bunch of new "cottages where a certain mason was used regularly. He always used those chimney top dampers with the hanging chain to hold it shut. He was so bad at keeping the flue tiles tight that the whole entire chimney leaked back and forth between all the flues. There are very few multiple flue chimneys that are properly installed and tight between tiles. They leak where they are joined, they are installed with cracks and missing pieces, and wydths are often not tied in and sealed.

Then, they leak at the roof flashings and soak up water and leak into the structure.

Gordy

That would be a job for Golden Flue or Thermocrete.

SWEI

Had to go look those up. Interesting stuff, though some of their info is a bit dated. Maximizing flue area is not something most of us shoot for, though I can see the potential benefits with a large fireplace. This one also stood out, "Golden Flue is ideal for use with modern high-efficiency oil and gas furnaces and boilers."

Gordy

Actually HeatSheild is another one more dedicated to fixing clay flue tiles in place. Such as Chris's example above.

icesailor

billtwocase said:

I'm with Jamie. I also don't see the major issue. Looks like a home made version of this, only a little crude, and has a screen to keep leaves and critters out

The major issue was improper draft. That is a "P" poor excuse for a solution. You never saw anything like that in a 200 YO house that leaked air like a sand screen. Why do you need make-up air assistance in new, modern tight energy efficient houses.

200 YO centrally heated houses with multi-flue chimneys on multiple floors had working fireplaces because the outside air flowed through them like wind through a forest.

billtwocase

I am thinking they were having some down draft issues Ice. Not too uncommon here, as you may well know. These houses are too damn tight for sure. You gotta love the "ghosting" calls. Definitely needs a good mason, but his problem, and someone's makeshift remedy is nothing new

billtwocase

You also see this kind of homeowner remedy when they get tired of paying countless contractors, etc for lip service when they need some mindful direction and repairs. See that all too often

Gordy

icesailor said:

I never was suggesting that the photos shown were any kind of a fix. It was my opinion of what happened and why.

As far as a chimney top damper, they aren't a positive solution either. I did a bunch of new "cottages where a certain mason was used regularly. He always used those chimney top dampers with the hanging chain to hold it shut. He was so bad at keeping the flue tiles tight that the whole entire chimney leaked back and forth between all the flues. There are very few multiple flue chimneys that are properly installed and tight between tiles. They leak where they are joined, they are installed with cracks and missing pieces, and wydths are often not tied in and sealed.

Then, they leak at the roof flashings and soak up water and leak into the structure.

Most times something happens through out the chimney's life that has unintended consequences.

Example being the simple act of pouring a new chimney cap incorrectly. That being not having expansion material between the flue perimeter, and the poured concrete which later is caulked with high temp silicone. This allows the stack of flue tiles to expand, and contract when heated to stay together as a unit. When the cap is done incorrectly the tiles expand throwing them out of alignment because they have no where to go but sideways, and when they cool gaps form as motar ends up in the fire box.

The stack of tiles has incredible expansion characteristics through out its elevation. The bottom tiles expanding the most, and decreasing in expansion as you go up the elevation of the chase where they are cooler. During fires, and in between fires there is a lot of movement in those instances. If the chimney is built incorrectly to begin with as in your example all bets are off. One is left with the first interpretation smoke is sucked down the adjacent flue when in fact there is cross contamination due to both flues having leak paths with in the chase.

You will figure that out as I did with my own chimney when I installed flue top dampers on both flues, and still had the odor, no smoke just the odor. So cross contamination was taking place.

icesailor

@Gordy:

For over 50 years ( I say that because 50+ years ago, I was a mason's helper), all codes required fire clay fire bricks inside fireboxes set in fire clay mortar. And flue tiles were supposed to be set in fireclay with an expansion space between the brick and tile. That no fire clay mortar was supposed to squeeze out of bottom joints and be left in contact with the masonry. In 50 years, I have never seen a bag of fireclay mortar on a job where I ever worked. "No one uses that ****". Fire bricks are now used inside fireboxes. No fireclay. At least where I worked.

My understanding of Cross Contamination was well understood when I discovered the fact that Beckett AFG's do NOT like to fire against positive pressure. I did a brand new Cape Cod Ranch (no second floor) house with a nice fireplace on the outside with the base going to the cellar floor. Where a Weil-McLain P468 was installed by me. (The only "P" I ever installed. I bought "A" blocks to get the extra return on the back) The thing was always going out in high winds. Nothing wrong. Finally, one windy day, I went there and found that there was more draft in the cellar space through the fireplace ash dump than in the actual oil burner flue. I stuck my draft probe between the sill and a foundation block under the fireplace hearth base and had higher draft readings in the block web hole than I did at the boiler.

I switched the AFG to a Carlin EZ-1 and never had another problem. EZ-1's and adjustable head burners don't mind a little positive pressure draft. Riello's too.

SWEI

I'm continually fascinated by the dead mens' achievements. 1930's and 1940's chimneys here are mostly dry-stacked firebrick inside, with mortared CMU or brick surrounding that. I don't know what's inside the pre-WWI chimneys here, but the low-fired brick in our pre-1900 buildings here is slowly dissolving.

icesailor

@SWEI:

Older chimney flues (before tiles) were usually "parged" with mortar and then brushed with a wet water brush. I've seen old unlined but parged chimneys that looked like the side of a Florida Stucco house. They were smooth and tight. The really old Colonial Chimneys were made with quicklime and sand. Some mortars you just can't figure out what was used. At some point, they started adding Portland Cement to the Lime and screened sand. Then, you can't get it off the old bricks.

Then, acids from condensation and combustion dissolve the lime and the sand all falls to the bottom of the old chimney.

You can often tell when driving by and notice black staining on the vertical end joints where the flue gasses are escaping the chimney and not making it out of the top.

Gordy

To the dead masons. These are two seperate fireplace/barbecues one indoor one outdoor sharing the same flue.

SWEI

Damn, that is some nice stone block work.

Gordy

For some reason you can't add more pics when editing a post so here's a couple more.