I have heard good and bad things about chimney caps.
What opinions are there about them, the general idea being to keep rain and
weather out of the chimney.
I have heard that they can alter the draft of the fireplace to make it hard
to vent a fire.
I've heard they aren't even necessary
I've heard they can improve heat loss problems.
Those are just a smattering of takes on the matter. I'd be inclined to
believe they aren't even necessary but I don't have sufficient experience to
say yes or no.
The only valid reason I would say for having a cap is to keep rodents and
other varmints from building a nest in your chimney or living room for that
matter. If that isn't a concern, and the amount of rain or snow that falls
in isn't a worry to you then you are probably right - the aren't necessary.
As for changing the draft of the chimney, if they are sized properly that
should be a minimum concern. And if by "improve heat loss problem" you mean
reduce the heat loss - likewise, there should be minimum effect on the air
flow. Use a good damper when not burning to prevent heat loss.
If your talking of a normal fireplace a good option is a top mounted
damper it seals the top unless you have actual fire going, chan from
roof goes to damper contro at fireplace
obviously this cant be used for gas fiored appliances like a furnace
Definitely get a good stainless steel one. On our previous house I put a
junky galvanize one on from Lowes and a bat still got in. Fortuantely he
could not get past the glass fireplace doors and eventually apparently found
his way out.
For a boiler chimney, it can improve draft a bit, because when the
boiler fires up, the flue will warm faster. It also reduces the chance
of a wind gust blowing DOWN the chimney.
For a steel flue, a cap to keep out rain is essential.
I was at a large reception once and here was a fireplace at one side
of the room. A gust blew down the chimney, and everything in the room
was instantly covered with a layer of ash and burning embers,
including the tables, food, and guests.
I have a cover cap but no screen to it and have had no problem with
animals at all. My damper is shot so I looked into a lock top chimney
cap damper but decided on using a chimney balloon instead. I have heard
mixed reviews on lock top dampers. Some say they are not durable and
they let in air over time. Also they allow air to convect (heat and
cool and sink) in the chimney so you get a draft feel from it in the
winter. A good thing is though is it shuts the chimney access when
closed. I dont think an ainimal could get past a locktop, I just dont
think it would maintain airtight over time.
I guess I agree that a stainless cap with a screen and a strong
traditional damper or a chimney balloon would be a good combo to stop
air, animals and not change your smoke escape draft.
I've worked as a chimney sweep in the past, and the Master Sweeps
taught me this:
True. If you have an under sized one installed it can really effect
your drafting. Make sure, like anything you get, you get a good
quality cap, that meets all the height requirements needed for your
size flue. Your sweep should help you with making a cap selection,
and if you already have drafting problems, he/she can help with a
product like (if I remember the name) posivent caps, or resizing the
opening of your fire place.
False, weather(rain, snow, etc) mixing with creosol forms an acid that
slowly eats away at the mortor and flue lining. Keep the weather out.
unsealed chimneys are a heatloss. Although I have no clue what you
mean by the cap, but a free burning fire willl force the air (the warm
house air) out through the chimney causing a negative pressure on the
house, and drawing in outside cold air.
This is what I've been taught, to try and provide as much information
for the customer to make their own decision. They buy a cap, it's a
few bucks profit. If they don't, in several inspections, gaps in flue
tile might be noticiable, which means big profits relining the
chimney. Offering caps actually reduced the chimney sweeps long term
Now I'm not a sweep, just repeating what I was taught. So check with
your certified Chimney Sweep.
tom @ www.NoCostAds.com
A cap is no problem for cleanings or inspections. Most caps (or lids) are
easily removed and reinstalled.
I second the suggestion to favor stainless steel over galvanized. You'll
likely get a lifetime warranty rather than a few years, and maintenance
won't be an issue. A galvanized cap will eventually rust, which can stain
Often when I've seen caps cause draft issues, it's been with multi-flue
caps that cover the entire chimney. If a multi-flue cap is causing draft
issues, baffles between the flues often corrects it.
Depending on the sweep, there can be some pretty significant markup on
caps. If you're comfortable with your roof and sizing the cap, you
shouldn't have major issues installing a single flue cap on your own. The
size of liners (and the caps that fit them) vary, so make sure you know the
dimensions before purchasing. Single flue caps usually grip the portion of
terra cotta extending above the crown of the chimney, while multi-flue caps
are drilled and bolted to the chimney. If you're looking at a multi-flue
cap, you'll need a hammer drill for installation.
It seemed all wood burning fireplaces we cleaned/brushed was from the
top, and all caps we found either had thumb screws or small bolts
keeping the cap on to the flue. Which made it easy to remove for
tom @ www.FreelancingProjects.com
I have one on my fireplace chimney and my oil furnace chimney. I
don't have any trouble lighting the fireplace. I roll up some
newspaper, light it, and put it high in the fireplace, so it starts
the draft. (I also use a rectangular cast-iron pan with a porous rock
in it (the two pieces are sold together for this purpose) which I pour
some kerosene on, to make sure it lights.
But when the cap blew off the furnace chimney and I didn't replace it
right away, white crud started coming out of the curved chimney duct
that went from the firebox to the actual chimney. It seems clear the
water was getting in and washing some of the soot in the chimney out
throught the cracks in the pipe. Turning it white somehow. Since I
got a enew cap it doesn't happen anymore.
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