Bellingham, Whatcom county and the great Pacific Northwet have enough rain that the title of this post is among the more called out items at home inspections -- especially at older homes. Often we see the brick chimney or a clay flue liner and there is no chimney cap over it. In other words, it is like an open tube down inside the home. Hence the title of this post. When one suggests such a cap, the first reaction from the homeowner or the buyer might be: "What, no Christmas presents, how is Santa gonna get me my Christmas istuff if I block off the chimney." Despite this initial resistance, which of course does have some logic behind it, an inspector can usually provide evidence of why rain is a problem. Chimneys serving fireplaces tend to have metal dampers and, when there is no cap, these poor creatures rust badly. Additionally, the water running down the chimney is hard on the masonry: bricks and mortar. A combination of the exhaust gases that collect, and the water, leads to general deterioration and efflorescence. Sometimes, when a metal chimney connects into a masonry chimney, one will see rust and a big leak or drips around and below the metal pipe. Despite the problems this condition creates, the solution is not so difficult -- have a cap or caps put on by a qualified chimney contractor. Of course, if the condition has been going on for years, bringing the system up to snuff (whatever snuff might in fact be) could also include having to rebuild or replace parts of the chimney, the damper and even the fireplace or stove below.
No caps
In fireplace, damper: rust and general signs of past water
Thanks for the view,
Steven L. Smith
Bellingham WA home inspector
Check out "This Day In History" -- music and vintage television from the 1950's through the 1980's. I enjoy writing these articles because they take me back to my days in radio broadcasting. Click on Elvis' gold record, below, to revisit those golden hits of yesteryear.
David,
I'm back!;-) I would disagree with you in part about the need for caps on chimneys. Most specifically on a heating flue for oil fired appliances. They can cause problems with venting and condensation.
Sometimes, when a metal chimney connects into a masonry chimney, one will see rust and a big leak or drips around and below the metal pipe.
Often what are thought to be rust stains are in fact condensation stains from flue gases. Putting a cap on a chimney flue with this condition will exacerbate the problem. The solution may be to simply clean the flue or in more extreme cases inserting a stainless steel liner.
The reason this occurs is newer heating systems are more efficient. What this means is the heat from the burner is better utilized and the flue gases are much cooler. The gases in the flue (which contain water) cool down to quickly to exit the chimney effectively. The ideal temperature at the top of the flue should be 180 degrees.
Long chimneys, large area flues, exterior chimneys can all contribute to this problem. In my area now it is becoming a common practice when a new heating system is installed to also install a liner in the chimney. I find this on both gas or oil fired units. A properly sized, round liner will vent flue gas much better than the large, rectangular chimney liner.
As far as capping a fireplace flue, good idea.
David,
Oil is very common in my area. But I did say that in my post, so if this doesn't apply to your area that's fine, but it may in other areas and the blog wasn't being region specific. Some of what I said is relative weather your in WA or any where concerning venting into masonry chimneys.
Long chimneys, large area flues, exterior chimneys can all contribute to this problem. In my area now it is becoming a common practice when a new heating system is installed to also install a liner in the chimney. I find this on both gas or oil fired units. A properly sized, round liner will vent flue gas much better than the large, rectangular chimney liner.
This especially important now as the systems are becoming more efficient and the flue gas consequently cooler.
Also I'm sorry I meant to address my reply to Steven. I seem to get you two guys mixed up.
David,
I wasn't referring to unlined chimneys, although if they are unlined they are old and almost always very far gone and dangerous. And don't be to sure about HVAC installers.
I have a good relationship with an instructor here for the oil heating trade. The guy is an invaluable resource and an unending source of good information and knowledge. Heating guys do not generally know about or bother to check chimneys before installing a system. What the instructor tells all his students is to have a level 2 interior chimney inspection done by a sweep or mason before beginning any work. Also to confer with the chimney guy on the sizing of the system to properly and safely vent it.
As I was saying a chimney flue can be too large which can be as equally dangerous as to small flue. That is the reason (too large) that new heating system installations are beginning to have flue liners installed. The industry is catching on to this problem.
James,
In light of the discussion about qualifying information to a region, due to regional concerns with another blogger this weekend, I thought I put out a valiant effort to make it clear this was meant for my area.
The intro and topic was preceeded by "Bellingham WA home inspections", which I usually add on when I am focusing on the northwest and my territory. Add to that, the first line talked about inspections in Bellingham, Whatcom county and the great Pacific Northwet, which is a term we locals sometimes use for Pacific Northwest.
As David said, around here there are basically two calls related to this (1) put a rain cap on the chimney for the wood burning device (2) put a liner in for your gas furnace. As inspectors we see water heaters and furnaces vented into masonry chimneys and we call either as a defect period. They can choose to make it an issue or not, but that is the recommendation.
Thanks.
Steve