I read your column in the Free Press and thought you may have an answer to my question. My house was built in 1912 and is heated by hot water radiators. On the third floor there is a pipe sticking up from the floor, next to the radiator. There is an elbow on this pipe and the pipe is open. It protrudes 4 to 5 inches above the floor. We have been in the house since 1975 and have ignored this pipe up until now.
My wife was working on the third floor last evening and complained of an odour that was making her nauseous. I went up and checked but couldn’t detect any unusual odour. She was cutting fabric and it may have been that. But I noticed the pipe and wondered if that could be the source. I put a deflated plastic bag over the pipe and noticed today that the bag was inflated.
What would be the purpose of this pipe? Is it attached to the stack? If it is venting from the sewer stack why is it venting in the house? We have slept on the third floor and have never noticed any odour.
I would appreciate it very much if you could give me some information about this pipe.
There may be several possibilities for the origin of the pipe and the offensive odour emitted. The most likely of these is one component of the original heating system that may have been upgraded many years ago. I am not certain of the origin of the smell, but will offer some possibilities for the function of the smelly pipe.
Hot water heating systems typically fall into one of two categories, either an open or a closed system. A closed system is most commonly seen these days, and the name is indicative of the structure. It is simply a closed loop of pipes and radiators connected to the hot water boiler. With this type of system, a circulation pump is normally attached to the pipes to move the heated water through the pipes and radiators and improve efficiency of heating. Because this system is essentially a closed loop and water expands as it is heated, a mechanism is required to prevent bursting pipes when this expansion occurs as the boiler is activated.
Modern systems will have an expansion tank attached to the pipes, typically in the basement near the boiler, to allow for this change in water pressure as it is heated. Older ones may simply be a metal tank full of air, which gets partially displaced when the water expands. These are often seen on the underside of the main floor between the floor joists and have a small drain valve attached, which can be opened to drain excess water if the tank periodically becomes waterlogged. Newer expansion tanks have a bladder or membrane inside that moves and rebounds with different volumes of water in the system.
The second hot water heating type is an open system. In an open system, the loop is not completely closed, with an opening to allow for expansion of the water as it is heated. These older systems normally had an open reservoir of water to replace the function of the expansion tank. As the water was heated, the level in this open tank would rise and would then recede as the water cooled. This tank was typically located on the highest level of the home, and is likely the explanation for your mystery pipe. The pipe you have identified is probably the one that led to the old reservoir, which may have been removed many years ago. It is very likely that the old open reservoir was replaced with a modern expansion tank, many years ago, but the pipe never fully removed.
Now that we have a reasonable explanation for the original function of the pipe in question, we have to figure out why it has started to have an odour, after all these years. This will require considerable speculation, but the answer will depend on one of two conditions. Either the pipe is still connected to the original system, or it has been disconnected when the upgraded pressure tank was installed. We will explore the first possibility, first.
If the pipe is still attached to the hot water circulation system, it may have a small amount of water inside, from time to time. As the water in the boiler gets older, it may collect more debris and corrosion and become quite black and dirty. If this water expands into the old pipe due to a waterlogged pressure tank or other reason, it may rise fairly high. If this skunky water approaches the top of the pipe in your upper floor, you may be able to smell an odour. It may be difficult to assess the cause of this problem without a complete inspection and service by a licensed heating contractor.
The second scenario is if the pipe has been disconnected from the other distribution piping. If the old pipe is not connected, it may still have horizontal sections or elbows that contain a small amount of old water that may have grown mouldy or become contaminated. There is also the possibility of some debris, food or a small mouse getting into the open end of the pipe and rotting. I would recommend trying to locate the bottom end of this pipe in the basement or other area by tapping on the upper end while another person searches in these areas.
Once you locate the bottom end of this old heating pipe, you may be able to determine whether it is still connected to the old heating system, or not. If it is still connected, contacting a licensed boiler/heating contractor for further evaluation and servicing should yield an answer and a solution.