Unrelated? Brown Chimney Ooze and White Powder in Breeching?

Leo

We have a lot of Buderus boilers and they run with a very low stack temp causing condensation in the chimney. What is the gross and net stack temperature readings?

Leo

D107

Ooze came after heavy Thanksgiving rain

Oct Buderus G115 install. Chimney experts I've spoken to say it could be rainwater entering chimney wall from below ground. Should dig 18" down and examine, then repoint if required, cover with tar and build up earth 12" above ground at chimney sloping down to two feet out. See attached photos--I see a brown stain on one side of chimney. Ground is certainly got some sunken areas capable of ponding. The old cleanout door from which ooze is emerging is now sealed --well almost--and not used since liner was installed. Seems possible that for some reason water is streaming down side of chimney. (The closeup photo of chimney #4359 is from the opposite side of the stain, but it shows the setup at the top from as close as I could get.)

Photo 4358 shows inside the boiler breeching after I took the cap off. It appears much more powdery than the photo shows. After only 5 weeks of operation is this normal for an oil-fired boiler? Looking inside the breeching back to the T I see no sign of the brown ooze. Though on the floor in photo 4356 I do see whitish floor stains--but they might be from the boiler install. So I'd be concerned that somehow rainwater might somehow be splashing into the boiler from above though the wide distribution of the powder seems to indicate combustion by-product to me. Boiler's running great.

Thanks,

David

Any thoughts would be greatly appreciated.

D107

Last reading in early Nov

was 350 gross stack (two baffles out): 11.5% CO2, .021 draft, 0 smoke. This is a newly installed stainless steel 5" liner with thermix insulation in a 7 x 7 chimney space. Does the white powder indicate condensation to you? I did not see white powder looking back by the T, but perhaps it might tend to run down the house side of the stack.

Thanks,

David

D107

I remember installer was on phone with Joe at Buderus

and with a room temp of 70, they seemed to be more concerned with gross stack temp.

David

Unknown

Dave,,

I`ve seen this exact same thing before. Usually when (like yours), the chimney is exposed on 3 sides. Its like Leo says, there is so little heat going up the chimney, it`s condensing. The white powder you see in the smoke-pipe, is the by-product of the burned oil. Try taking a temp reading right at the base of the chimney in the smoke pipe.
Edit- 350* gross, with a room temp of 70*, that`s pretty low by the time it goes-up.

S Ebels

The chimney guys are barking up the wrong tree

I would highly suspect condensation in the chimney due to two things. The first being that the G-115 operates at very low stack temps which allow the flue gases to condense before exiting the chimney. The second is that even though the chimney appears to have a clay liner it may be oversized for the present input and at any rate, it's an exposed chimney. (cold chimney) I would wager that unless you install a stainless liner in the chimney it will be crumbling to dust in a matter of a couple years. The problem will get worse as the weather cools which of course drops the temperature of the chimney and raises the amount of flue gas available to condense. The liquid you see running from the cleanout is flue gas condensation which is dissovling the residue currently in the flue from the old boiler.

We installed the first few G-115's we did sans liner and were back within 2 years to drop one in. It's now SOP to install one whenever we use a high efficiency oil boiler like the G series from Buderus or the Vitola or Vitorond from Viessmann.

You can move or remove the flue baffles in the G series to attain higher flue temps but you will sacrifice some efficiency in doing so. More heat up the flue = less heat transfered to the water. High efficiency appliances come with their own set of design quirks and problems.

D107

Thanks Steve--we DO have a 5 inch stainless steel liner

supposedly insulated with Thermix throughout. (You may have missed my post on that.) Perhaps I should get someone to check to see if that insulation was done correctly or at all. In all fairness to the chimney people I spoke with, they were not aware of the white powder inside the liner which I discovered today. We associated the brown ooze at least with the heavy rains.

Trying to figure out if the flue was insulated or not might be tricky--trying to get a look inside. Maybe from the bottom cleanout.

They took the baffles out because they couldn't get a high enough stack temp with them in. Interestingly the G115/21 Riello comes set up for a G115/28 with a .65 nozzle. That was changed as per the G-115-21 instructions to a .5 nozzle; that's when they had to take out the baffles.

Unfortunately this is my mom's boiler and not mine so I'll have to find a way to solve this a bit long distance. I'm concerned about damage to this new boiler.

Thanks,

David

D107

If the liner was uninsulated then perhaps condensate

could flow on the outside the liner as well as the inside down into the old cleanout which would explain the brown ooze.

Leo

The 21 set as a 28

If the G 21 comes set as a G 28 it may be done for a reason. I once had one that the rep had me up fire to the next set of specs. This one was in the summer and just making hot water. It was condensing so bad a puddle was forming on the basement floor. Upfiring cleaned it up.

Leo

Mark Hunt

I think


that moisture is coming out of the "Thermix". It isn't coming out of the liner so it has to be outside the liner.

If the boiler was condensing, you would see the stains at the vent connections and clearly this is not happening.

As for rain, tough to get that much rain down a chimney with a cap.

My vote goes to the Thermix. It is still a conductor and will get warm when the boiler runs, but the mix near the exposed sides of the chimney is where I believe the condensation is coming from.

This may just go away eventually.(How long?? Who knows??)

I see no reason to worry about the boiler though. It is not the source of the brown ooze.

Mark H



To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Constantin

Hi David!

As long as all that sauce is running out of the chimney cleanout and not the smoke pipe, the boiler might be OK. However, if this water is coming down the chimney liner, then the sulfur and other condensation products might attack the liner, which is not a good long term condition for it to be in.

Our Vitola runs at a even lower gross stack temp ~250-275°F and I have yet to pop the cleanout door. During the summer, I did notice some minute signs of condensation in the flue pipe that leads to the chimney. Consequently, I ordered some KAOWool from McMaster Carr, wrapped the KAOWool around the flue pipe, and then held the KAOWool in place with some cheaper fiberglass wraps for water pipes.

I figure that the KAOWool is very heat resistant (over 1000°F) and fairly good at insulating the smoke pipe. As a result of my insulation work, I now have a 6' light yellow burrito in my utility room, but the condensation problem seems to be licked - at least in the utility room. My chimney base may look a lot like your mothers, however!

I wonder if a change in the control strategy could work to make the chimney warmer - if there is some way to run the boiler on larger ΔT's such that its firing time can be maximized, then the flue will have a longer time to get hotter and hopefully drive off the condensation.

Another thing to verify is how well the chimney cap and the rest of the system up there are sealed. High-temp silicone and the right hardware can keep the joints between the masonary and the smoke-pipe well-waterproofed. Given the color of the ooze, I wonder if there isn't a gap up there between the Thermix and the pipe... even a small gap can allow a surprising amount of water into the chimney system.

Our smoke pipe sticks out of the chimney a 6" and hence I had the guys insulate that little bit up there too - with cold a wind, that piece would be condenser city inside the pipe. I also had them seal the masonary/pipe interface because our chimney has the same kind of insulation schedule as yours (though thicker).

I would have the heating guys come back and take another look at the liner to determine the origin of that ooze. There may be something to what the chmney people are saying, but I'd have the heating guys go in first to inspect the liner to see if the sauce is coming down the liner or out of the chimney base around the liner. For all you know, the old chimney ran so hot that the endemic water leak was covered up for all these years.

Given that the appearance of the ooze coincided with a rainstorm makes me believe that the cause may be more related to a water issue in the chimney than condensation per se. I look forward to the solution to this mystery.

D107

True, Riello set for 28 but

then the special one sheet instruction page that comes with the package specifically gives the correct settings, which is the .50 nozzle etc. Perhaps Buderus just sells more 28s and uses that setting as the template. I recall that Buderus boilers can be upfired as much as 10% without other alterations. The .50 nozzle I believe fires at .60gal/hr which gives the 84Kbtu firing rate that's specified. Not sure what a .65 nozzle would fire at. Whether you remove baffles or use a larger nozzle, probably lose efficiency either way. I'm not so concerned about a few percentage points; as you suggest we should check this out. Here's the different settings as listed on the spec sheet:

Nozzle Delavan: G-115/21: .50 x 80deg B; 28: .65 x 60 degB
Air gate setting: 21: 2.25; 28: 3.50
Turbulator setting: 21: 0.0; 28: 2.0

Pump pressure is same for both (145) and insertion depth same (6.0" plus or minus 0.06")

Thanks,

David

D107

Thanks Mark; re: boiler only white powder concerns me

FYI the chimney consultant --not the liner installer--who's top notch by the way but of course is working off limited info-- says:

From photo "It looks like rainwater, the top of the liner should have a top plate (can't see from the picture if it has one) a storm collar and a round cap. Right now it has only a 8x8 cap. I would recommend changing out the top hardware. Pictured below are the components for lining systems."

I appreciate all the puzzle solving responses--I am open to the idea that there are two unrelated thing going on here. I first will get some suggestions from Joe at Buderus, get a tech to look at boiler, and then get a chimney company to inspect and augment what was done if necessary. (Certainly seems possible that rainwater could pond in sunken ground around a 50 yr old chimney and seepage could happen underground--in addition to the other problems you mentioned.)

Thanks again,

David

D107

PS idea: perhaps cold basement causes condensing in breeching?

just another possibility. The two large basement rads probably haven't been on in years. With new better insulated boiler basement seems a little cooler. With 63deg night temp (70 deg day) and no rads, basement could get very cold especially on a night where it didn't get cold enough to activate night heat--and therefore heat those basement supply and return pipes which in effect heat the basement. Just guessing......

Thanks,

David

Mark Hunt

Well


this never happened BEFORE the liner went in right? Why now all of a sudden?(WRT rain water)

The Thermix is applied wet. THAT is where the water came from. As I said, it may just stop once the thermix is completely dry.

The white powder you see is probably some of the galvanizing leeching out of the new flue piping. Keep an eye on it though.

Mark H

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Dmitri_2

Great

Nice!

Brad White_9

Of brown stains, Elvis and the Madonna...

Chiming in if I may- My old house (1873) has a central chimney once used for coal, oil, eventually gas and possibly wood at one time. It is interior to the house except for the top four feet. There is no cap on top but one may argue there should have been. Still, for 130 plus years it has witheld.

About 20 years ago I had the chimney base re-flashed in lead and copper along with slate repairs. Once this was done, I too started to get brown ooze down the sides, all the way to the basement. Very little down the inside of the chimney, most down the sides.

The way it was explained is that wind-driven rain soaked through the brick from the outside (and some on the inside at the top of course), absorbing the old creosote/crud, then leaching back out where the flashing was regletted into the brick. Seemed odd but the flashing was the only variable which changed that I can think of. The old common brick is very porous.

I had the flashing cut out and re-done not as deeply but the problem persists somewhat, just not as badly. And the chimney has been cleaned yet stuff still comes out, both soot and leaves. It now serves as basement shop exhaust, my boiler being direct vented now.

My point is, I suspect at some level that this is old crud is possibly rainwater-leached, rain being the catalyst in this case.

D107

interesting points as usual Constantin......

The idea of getting a larger Delta T by running boiler longer, getting chimney hotter. Maybe with outdoor reset that's not so easy in the shoulder seasons. Boiler fires for such a short time to maintain 120 water temp; but of course when it's warm out less risk of condensation......Perhaps the G-115 aquastat could be adjusted for a higher differential which would keep the boiler on longer to bring the water up to temperature.

As of now the problem hasn't recurred, but my plan is to get someone to check that the thermix insulation is complete,get a close look up top, then install the added collar, round cap (and top plate if not there already). I am hoping that as well as Buderus boilers are engineered they would have made it known that a 5" liner in a 7" square chimney (meaning one inch of thermix all around) would provide inadequate insulation.

I opened the cleanout end cap myself and looked into the point where the liner comes into the breeching and saw only the white powder, no sign of the brown. I suppose they could pop the screws on the connection to the liner and get a closer view maybe with a mirror and a light to check liner inside up to the top....

Thanks,

David

Bob Harper

sci fi project

David, I recommend you remove that chimney cap and have it replaced with a stainless steel inverted cone cap from Copperfield. Your chimney guy will know what this is.

I think Mark Hunt is barking up the right tree. That Thermix included about 20+ gallons of water when installed, which can take months to evaporate out of there. Now, our hero installed a regular chimney cap. The massive condensation from this furnace is well known and documented. Even with an insulated liner ( which does not insulate while still wet btw but actually exacerbates condensation until it dries out) there will be tons of condensate forming on the underside of that lid. It drips down into the Thermix because our hero failed to use a top plate. Some liners are allowed to be cemented in at the top, which will allow only minumal water. However, if this is open to where you can still see the Thermix, it will act as a sponge.

The white stuff is most probably efflorescence from the Portland cement in the Thermix. It is leeching out of the chimney throug the mortat joints btw flue tiles then through the brick joints. The brown stuff is probably from old oil soot. If our hero didn't sweep the chimney well before installing the liner or possibly even if he did sweep it.

Ask your chimney guy to install some stainless vent tubes while he's at it. Again, he should know what I'm talking about. Next spring, have this chimmney cleaned with Chimney Saver masonry restoration cleaner then treated with their excellent water repellent, which is 100% vapor permeable. Do NOT treat this chimney with Thompson's or similar crap, which will only kill it faster. Must breathe.
Bob

D107

Thanks Bob, was hoping you'd stop by

Unfortunately the company didn't specify a new cap originally, just replacing the old; you'd think they would have wanted to make a little more money. A top plate certainly was specified though--I know the angle of the photo might make it difficult to say for certain there is none there. I'd like to get out there and take some close up pictures so I can post them on the wall for interpretation. As you may have noted from prior posts, a collar was also recommended. Though flu was supposed to be cleaned as per contract, it wasn't. I unfortunately was too preoccupied with enjoying the boiler install to watch the chimney work as I should have done.

This certainly fits in with one of the general tenets of the wall: Why can't this here job be done right?

On the other hand most of us homeowners assume chimneys inside and outside don't require maintenance. We don't realize a good insulated stainless steel liner in a chimney with a deteriorated terracotta flu is probably the best, cheapest and safest way to go.

I'll be happy if those ooze streaks turn out to be attempts by Elvis to contact the Madonna, but I've been fooled too many times before to get my hopes raised too high...

Thanks,

David

D107

Closeup photos of chimney in question

Got out to the house today to go up the roof and shoot these photos. Wish I'd felt comfortable enough up there to take the top off and look down in liner...but....

Looks to me like there is a top plate, but Bob and others are recommending an inverted cone cap and a collar. Looks like it was sealed with some kind of silicone. It was probably around 50 degrees and photo #4366 shows some condensation at top. 4362 seems to show need for some pointing; bottom--not fully pictured is some green copper flashing to roof that could probably be shored up. 4367 shows a crack in the 'crown?' which conceivably could leak water into thermix.

Oozing problem has stopped. Am curious what say ye.

Thanks,

David

Mark Hunt

Get off the roof!


That is Santa territory this time of year!!!

Perhaps I was right? I believe I predicted that it might just stop???

That close up though convinces me that it was NEVER rain to begin with. It was the Thermix moisture the whole time.

Now go have a nice scotch David.

Mark H

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Constantin

Nice pics...

Looks like silicone from the texture and color.

Based on the picture from this side, I don't think I'd be concerned about water going down via the fluepipe. Based on how it is mounted, I would verify however that all flanges/interfaces on the bottom received the same copious amounts of silicone all around to prevent puddling water from draining down.

I am surprised that these sorts of collars do not feature a steeper pitch to ensure that they always drain well and that no standing water can accumulate.

D107

yes Mark may be right

about the cause and also the scotch suggestion...I agree with you about the pitch. I'd like to hear what more Bob Harper has to say about proper caps and collars based on these photos. As a layman it also seems strange to me to see the uninsulated liner top sticking out 4-5"--seems to be just asking for condensation in a cold wind.

I don't know if silicone is used on the bottom at all. Good question. Maybe on the joints that make up the Tee? Hydraulic cement seals the breach, and the bottom of the tee should have thermix. I wish Dan had a book for sale on chimneys if there is a definitive one.

Thanks,

David

Constantin

Hi David!

I didn't mean for silicone to be applied at the base of the chimney. Rather, I thought it might be useful where the screws hold on the bird screen to the chimney cap and where the outer (B-vent?) flue pipe penetrates the collar up there. Anyplace with a joint is a potential leak spot. I see some goop seeping out between the bird screen and the flat plate of the collar, so my guess is that sealant was applied there.

If the collar were pitched a bit more, then less water could accumulate and hence potentially leak into the place.