When I was stripping the wallpaper in the living room of my ca. 1916 brick Foursquare, I felt a place or two on the chimney breast over the mantel where the paste was sticky and rather damp.

Well, here it is probably three years later, the paste is still sticky, and something has to be done if the room is to be repapered.  After exploring different sources for the problem, it's been discovered that the flue my hot water heater is vented into is unlined, and said flue is blocked about 12' to 14' down with a bird's or squirrel's nest.  Hot exhaust on cold bricks equals condensation, especially in a confined place, and the damp place on the living room wall is slowly getting broader and higher.

Had a certified chimney technician out the other day, and he gave me a ballpark price for an insulated stainless steel liner installed with a new cap that'll keep out the critters (I'm still waiting for the official estimate).  Price is appalling, considering the other repairs I've had to make to the house in the past year.

I only recently bought a new water heater and don't want to replace it.  And I'm told that direct vent or tankless will cost about the same as the full rig with the chimney.  So assuming it's chimney work I need, I'm asking people's opinions on various options in descending order of cost, and wondering what your experience has been with these (they all assume clearing out the nesting material):

1)  Bite the bullet and go (further) into hock to get the insulated stainless steel liner and the new bird-excluding cap or caps (two flues).  Or

2)  Do the above with an uninsulated stainless steel liner.  This would be about $300 less.  What's the biggest advantage of having the insulation?  This would still be very expensive.  Or

3)  Spend around $500 for an aluminum liner and expect it to corrode out and need replaced in about three years.  Or do they last longer than that?  And forget about the new caps.  Or

4)  Settle for having the blockage cleared and see if the damp places dry out.  Then if it works, install the critter-excluding caps or just get the flue swept every couple of years.

Any reason why option 4 wouldn't work?  I've lived here eight years and the wallpaper over the living room fireplace wasn't damp for most of them.  The only drawback I can think of has to do with the higher efficiency of recent hot water heaters, which don't heat up the flues so much and can decrease draw and increase condensation.  But if the flue is cleared, will that make that much of a difference?

I don't want to be penny wise and pound foolish, but on the other had I don't want to give the house the royal treatment when it's not really needed and I can't well afford it.

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I would be curious as to what you are going to do. All 3 of my chimneys need work and I wanted to have liners put in them so I could burn wood/coal in them once again. I was thinking a cast in place liner and caps. But, as you found out, I hear any kind of chimney work is very expensive. I hope you get things fixed. My worst chimney that is connected to the dining room fireplace (which was coal burning, then gas burning) was also a vent for the coal/then gas furnace...as well as the gas hot water heater. Since the chimney was never lined, most of the upper top part fell apart and a lot of the mortar kind of fell out. I don't have anything gas anymore and I have all electric. But, I would still like to have working fireplaces..

After I posted this last night, I did some more online research, and was reminded that option 4 probably isn't an option, if I want my masonry to last and also to avoid any chance of carbon monoxide poisoning (so far so good on the latter, according to my CO detector).  Seems the way the physics run with current high-efficiency water heaters, furnaces, etc., the square inch area of the flue can't be more than three times the area of the vent pipe from the appliance if it's to draw correctly and avert condensation and CO backflow.  Mine is 11 times the size.

As for your situation, what I read tells me that for woodburning you absolutely have to go with stainless steel liners over aluminum.  And get your chimney rebuilt, of course.  I gather that the code people don't think a clay tile liner does the job any more, especially if you're using an enhanced-efficiency insert, but I could be wrong.   Now, cast-in-place, I haven't looked into that.  I doubt they'd be an option with a water heater.  For woodburning, how much heat will they withstand?

Thanks for the reply to your reply. I am not sure how well things worked in my house when stuff was vented in my unlined chimney, but I can tell you that the chimney that vented all the fumes had a ton of mortar in the clean out. I have a lot of repoint work to do on it bec it was used to vent gas fumes and not lined... If you are just going to use your chimney as a vent..is there anyway you can just run a vent pipe inside the chimney and connect your stuff in the basement up to it (kind of like using your chimney as a pipe chase)? Just a thought since your stuff won't vent as well due to the large chimney space.


I am not sure about the cast in place liners. I did a house tour last year on the restored houses that are actually behind my house and the people in many places had that done. They told me it is hard to find someone who will do it, but they had nice fires going in their fireplaces. Since I am not on that part of my project yet (I have a ton of other stuff I really need to do first unfortunately) it may be awhile until I get to that :( I think it is just easier to do cast in place rather than trying to slide a tile liner inside. I think my chimineys are partitioned as well on the inside so I am not sure how it would all work. I do know that whatever I end up doing.. it will be very expensive. The cost will dictate if I will even end up doing it in the future.


I'm not sure about a water heater, but my 90+ efficiency furnace vents through a pvc pipe through the basement wall, rather than the chimney like the old gas furnace from 1958.  There is a separate plastic pipe which snakes over to my basement drain to get rid of the condensate.  I don't see why a gas water heater shouldn't do the same.

Marlin brings up a good point(and also refreshed my memory). If I went with a gas heat pump (instead of electric) they were just going to vent it out through a window opening. This would mean I would not have a basement window anymore, but I wouldn't have to use the chimney. My heat pump also has a seperate pump and flex line that I hooked into the main drain in the basement that gets rid of the condensate as well.. So that could be another possible option.

I believe you can do that with water heaters, but not with the ordinary kind.  There's a special direct-venting variety, but they cost a fortune.  More than venting the existing one in the existing flue would.

A liner  is a good idea ,get more estimates its not that big of a deal. Or a through the wall vent if possible, Im not a big fan of the chimney vent , it was explained to me that gas appliances like a water heater or dryer vented into a chimney create condensation and will cause the top of the chimney to suffer freeze and thaw damage  quicker than normal ,there is not enough airflow and high temp to get rid of the moisture , Having said all that I would not hesitate to clear the blockage and use like its been for the last 50 years if money is an issue.

We just had a liner installed in one side of our main chimney. First off, we HAD to do this per code since we were going to have to vent our new gas boiler up that chimney. At 110 years old it was mandatory if it was to be used. I am not sure of the cost, since it was mixed in with the bid to install a new boiler, rerun all the heating and hook up the old radiators. But, I think it was pretty low as our total bill was not that high for the work that was being done.

But any roof work is expensive. The liner will be about $1000 give or take depending on the length. Ours was unlined.

We need to do the same thing in our other double flue chimney that supports two fireplaces, one in the living room and the room above it, if we eventually want to use them.

In our case, I would never have considered using these chimneys without new liners. It could/would be dangerous. Especially, the main chimney in the center of the house. The other is mounted on the outside and being so may not be as bad. But, you never know and that's the point.

I've learned that the danger of damage from condensation is actually greater for a chimney on an external wall.  It gets and remains colder in the winter and you know what does.  Whereas a central stack stays warm and up go the gasses.

The price I got from the CSIA certified technician I'm pretty sure I'm going with (no problem with him; just wish I didn't have to spend money on this at this time) is indeed around $1,000, more or less depending on whether I go with 316 stainless steel or 2-ply insulated aluminum.  That will include clearing the blockage.  The additional fun comes with the new chimney caps I'll need to keep the critters out, if I don't want to need to have the sweep out every year to keep the flue clear and the carbon monoxide backflow out.

I could smack my brow and cry that I could have avoided all this had I been content with my previous owners' boring beige wallpaper.  But no.  The stains would have been showing by now and as others have said above, the condensate would have been playing merry hell with the mortar and brickwork.  So I guess it's a matter of a stitch in time.  A very big stitch.

That is not a bad price. Others here have mentioned 3-5x that per flue. The caps sort of take a bit away from the looks of the chimney top, but if you drive around town you will probably note that there are many who have had to do the same thing, so it soon looks the norm. The chimney we have left to do is pretty ornate with the way the brickwork is done at the top. Hopefully, putting a double stack on it will look ok.

I'll be getting the powdercoated steel kind with the hipped "roofs" on them, one for each flue, so they shouldn't look too bad.  And this way the stone dressing at the top of my chimney will be visible.  Right now I have a pair of turbine-looking caps mounted on a single flange that covers the stonework up.  Not exactly period.

If I had my way, I'd mount a pair of beautiful terracotta chimney pots and then cap those, but considering that I have conscientious objections against playing the lottery, the money for that simply does not and will not exist.

We had our chimney and clay liner extended for a second floor addition. Then I called three co's. to inspect the work. All three co's. advertise both inspection and repair services. The first two gave a half-hearted inspection (one barely an "inspection" at all).

One gave a $10,000 quote for a tile drop and double-walled flu liner install.

The other gave a $3,000 quote for a single-walled flu liner install.

When I called the third, I told them up front that I wouldn't be hiring them to do any recommended repairs and just wanted a conscientous inspection of the chimney and existing clay flu. While this third inspection was better they didn't go on the roof to look down...just to the basement to look up. Within three minutes the $80 "inspection" was over.

What the third inspector said was less concerning than what the inspector wrote in the inspection report. So I took about an hour to inspect the chimney myself (I'm a qualified NYS home inspector...we aren't specifically trained to evaluate chimneys per NYS law).

I came to the conclusion the first two "inspectors" were nothing more than sales reps. The third "inspector" may have been a qualified inspector but may not have believed I wouldn't call their co. for repairs and, therefore, was more concerned with finding a reason for a new liner rather than evaluating the chimney.

What I deduced: the first 12' of the chimney was built when it was on an exterior wall and venting an oil-fired furnace (known from the history and 'tells' in the house). This is when the mortar, clay liner spalling, and staining most likely occured (from 1945-1995).

The next 7' of chimney height was built during a 1st. floor addition on the chimney wall in 1996  (putting the 1st fl. of the chimney inside and the former cap in the new attic) 7' of chimney was added to penetrate the new attic roofline. A new natural gas boiler replaced the old oil furnace at this time.

It may have been during this chimney extension work when demolition of the old cap caused debris to fall into the chimney and damage the clay liner at the cleanout in the basement.

This is the situation when we bought the house. The chimney was now located in an improperly flashed valley causing water flowing down the gable reverse to penetrate the building around the chimney and run down the exterior of the chimney's masonry.

What the chimney "inspectors" (and I use the term loosely) saw was a 35' chimney with weathered masonry (which not one inspector scribed) and a damaged clay cleanout with some spalling in the first 10'. None of the "inspectors" went up to the new second floor or roof to look down. Only one used a mirror and flashlight to look up the chimney!


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