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250 Pleasant Street
Dunstable, MA 01827

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Q. I had a new boiler installed a year ago and ever since that time I get ungodly banging noises in the piping system when the heat comes on. It sounds like someone is banging the pipes with a hammer. When I asked the man who installed the boiler about it he said that the noise was steam hammer and nothing could be done about it. Was he telling it like it is?

  • A. Steam hammering noises are not uncommon in one-pipe steam heating systems. However, the presence of the noise indicates that something is NOT RIGHT with the system. The hammering noise is the result of the steam trying to get by condensate that is flowing back to the boiler. It is NOT inherent in a steam system. A properly installed and functioning steam system is as quiet as a mouse. There are numerous possible causes of your noise problem and I cannot diagnose the problem properly without actually looking at the system, but some likely culprits are 1.) Improperly installed supply piping coming off the new boiler. 2.) An improperly installed Hartford Loop. 3.) A sagging steam main that is trapping some condensate and blocking the free flow of the steam in the system. 4.) The removal of insulation from the near boiler piping. 

Q. I have a second floor radiator in the upstairs back hallway and it never seems to heat up. I have had several heating people in to try and fix the problem, and each one said it is probably a venting issue. They installed some new vents, but the problem doesn’t seem to be fixed. Could the pipe be blocked?

  • A. Most likely the pipe is blocked, WITH AIR. There is an old saying about steam systems: Steam up, air out, water back. The process does not get any more complicated than that. Steam is a gas, and it travels at a pretty good velocity (about 20 mph), but it won’t go anywhere if it has to push against trapped air. Twenty miles per hour is a little over 30 feet per second. If the pipe run from the boiler to the radiator is 60 feet long, it should only take 2 seconds for the steam to get there. You should have vents on your main pipes in the basement. If they are there, they could be clogged with sediment due to improper installation. There should be vents on some or all of your risers. These also could be malfunctioning due to improper installation. Finally, you will have vents on the radiators themselves. It is very common for them to become clogged with sediment and therefore malfunction. If you cannot hear air hissing out of one or more of these vents, then remove them and install new ones. If these procedures do not solve the problem or if you can hear the air coming out but the problem remains, then your problem is probably one of balance. You will need adjustable vents and they will need to be adjusted according to the length of the pipe run and the volume of the radiator they connect to. If the vents on the risers or mains are blocked then someone needs to look at how they are installed to determine if they have been properly installed. Also, the last plumber who worked on the system may have cranked the pressure up too high. That should be checked also.

Q. I used to have a big ole’ boiler that looked like frosty the snowman. It worked great, but my fuel bills were high and a friend told me I should get a new, efficient boiler. I purchased an installation form a major department store. The new boiler is less than half the size of the old boiler, and now it is forever turning off and on and most of the radiators only get hot in about half of the tubes. The subcontractor that installed the boiler for the department store said that the problem is the new boiler doesn’t have enough steam capacity to fill all the pipes and radiation. Is that what is happening? My neighbor is mechanically inclined and had steam heat in his last house. He came over and turned up the pressure. The burner runs longer, but the house still does not warm up the way it used to before the new boiler was installed.

  • A. It is possible that the boiler does not hold enough water to fill the system. However, it is an unlikely possibility. It is much more likely that you either do not have vents on the steam mains in the basement, or they are there but are broken as a result of having been improperly installed. The new boiler does have much less water in it than the old “snowman” boiler and the cast iron is much thinner and the burner is firing with much more push. It’s like heating up your cup of coffee with a blowtorch. The new boiler is making steam faster than the system can handle it. You need to get rid of the air in the system faster, especially the main piping loop in the basement. You can’t use the radiator vents for this job, they simply aren’t large enough to vent their intended radiator AND the main.

Q. We have a relatively new boiler (its about 15 years old. The house is almost 100 years old). We have a rambling old Victorian style house with many, many radiators. The heating seems to be very uneven. Some of the radiators heat all the way across. Some heat half way. Some only have a few hot tubes. We have changed some of the vents to the adjustable style, but we cannot seem to get things coordinated. Is there anything we can do to correct this situation?

  • A. It sounds like you may have a hodge-podge of vents in the house. It is very important to have all the vents on the radiators by the same manufacturer so the system can be properly balanced. Once all the vents are the same make, then a radiator capacity and pipe capacity chart can be used to properly balance the venting times of each vent. The steam should arrive at the first tube of each radiator at about the same time give or take a few seconds. Then you know the system is working properly.

Q. A friend that works for one of the large property management firms in Boston told me I should get someone to “clock” my meter. She insisted that her firm has this service performed religiously every couple of years. I didn’t want to appear dumb so I didn’t ask her what she meant. Can you tell me what she was talking about and why will it pay me to have it done?

  • A. Clocking the gas meter involves running the boiler for a period of time and comparing the running time to the amount of gas that ran through the meter in that timeframe. By doing this you will be able to determine the exact BTU production rate of the boiler while it is in operation. You are then in a position to compare that consumption rate to the connected load of the boiler to determine if the boiler is over or under fired. If your boiler is significantly over-fired, much of the heat you are paying for could be racing up the chimney. You are almost literally burning money.

Q. I own some five and six story Brownstones in Boston and I have some radiators on the top floor that I cannot seem to get the right amount of heat out of. We have put in quick vents on the radiators and I have had several plumbers come to look the situation over. These guys were at a loss for what could be done. Can anything be done, or is the situation hopeless?

  • A. More than likely you do have a venting problem and need some top of the riser vent s installed. When this procedure is properly implemented it can get the steam quickly to those far away radiators on the upper floors of the mid-rise apartment buildings in the city.


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