Front Page Forum: Boiler Primer

This guest post is from John Cataneo (aka Master Plvmber) of Gateway Plumbing. In addition to being a long-time advertiser, John was the star of some plumbing videos we did a couple of years ago.

The change of seasons is such a beautiful part of life in New York. Except for that boiler thing. Did you forget about what it takes to keep your boiler running safely and efficiently throughout the heating season? Here’s a primer for your gas-fired, steam-heating boiler:

Burner Tubes: In most gas boilers, fuel flows into horizontal tubes, mixes with air and is burned to heat the water contained in what is called the heat exchanger. When dirt and dust build up on those burner tubes, efficiency declines because complete combustion of the air/fuel mixture is impeded. As a result of rising levels of unburned fuel after the combustion process has taken place, carbon monoxide begins to rise proportionately. The heat exchanger may also become coated with carbon brought on by the burning impurities creating far greater carbon monoxide risks.

Low Water Cut Offs: There are two basic types of low water cut off devices: the float-type (most often used is the McDonnel-Miller model # 67) and probe-type (yours would probably be the PS-800 series also by McDonnel-Miller). The float type should be blown down (flushed) weekly. It is made to last for ten years. After that, get a new one. Bad things can happen when they fail. The probe type should be disconnected from the boiler and cleaned and inspected annually. It is made to last fifteen years.

If you think you’ve been maintaining your boiler because every week or so you push down on that lever that lets out that dirty cruddy water, you’re wrong. You haven’t done much of anything for the boiler at all. That valve is there only to maintain the low water cut off device to which it is directly connected. Fresh water corrodes a boiler. Every time you flush it out, you’re creating the need to add more fresh water. If that new water doesn’t boil right away, it corrodes the cast iron and steel that surround it.

Flue and Chimney: Flue piping and chimneys need to be looked at by someone who knows how a problem presents itself. Surface rust and discoloration are signs of something going wrong. The causes are often one or a combination of the following: inadequate intake (or make-up) air for combustion, a collapsed or compromised chimney, or a serious issue inside the boiler. The grey, metallic flue piping should connect to the boiler, its lowest point, and continue upward from there to the connection to the chimney. There it should be sealed to the bricks without gaps or holes in the penetration.

Skimming: Newer boilers need to be skimmed to get rid of the oil used in manufacturing that lies on top of the water, which prevents steam from rising and moving toward the pipes and radiators. Every boiler contains an installation package naming a very specific connection, factory-installed in the boiler called a skim port or surface blow-off location where the skimming procedure is best performed. It is the installer’s duty to screw a pipe and valve into that connection to allow for the safe and effective removal of oils from the boiler water. If this is not done, efficiency, boiler longevity and system balance suffer. In the boilers I see, about one in four has any provision for skimming installed.

Pressure: Steam heating systems operate on the principle that steam pressure created in the boiler moves the steam to areas of lower pressure throughout the building. Areas of low pressure are created by adding air vents in places like the ends of radiators and piping runs. It doesn’t take a lot of pressure to do this, little more than just enough to be different from one end to the other of the system. That being the case, having the boiler run long enough to make more pressure than is necessary is nothing but an expensive waste of fuel and money.
A trained boiler mechanic and technician knows how to set the pressure regulating device, found on every steam boiler, properly.

The device is mounted on a curled length of pipe called a pigtail which protects it from the hot steam in the boiler. The pigtail should be made of brass (yellow metal) by Code as of July 2008. If yours is made of steel (black in color) have it replaced. They inevitably clog and fail.

Insulation: The NYC Building Code now requires all *new* boiler piping to be insulated. But, there are two schools of thought here: one is that the heat produced by the boiler is best utilized if carried to the heat emitters (radiators, etc) in its hottest form with minimal transfer losses. The other is that heat lost in transfer to within the envelope of the building is not lost at all. There are lots of reason to insulate or not insulate sections of piping, but right now new boiler piping should be insulated after a reasonable period of being in operation and observed to be free of leaks.

While I’m on a roll (rant?) here:

A Word on Water Feeders: Increasing occurrences of having to add water to a steam boiler is NOT a reason to buy an automatic water feeder. If your boiler is less than 400,000 BTUs (in your 1-to-3-family building, your boiler is probably less than 400,000 BTUs) and you’re adding water more than about every two weeks, you’ve got a problem that needs to be identified and repaired. Adding a water feeder to deal with it would be like putting a band aid on a gunshot wound. You haven’t solved your problem. Water feeders have their place and their people. I happen to be a fan of the Hydrolevel VXT model. There are countless benefits to their digital display (in number of gallons fed) and their flexibility made possible by their settable flow rate options (how much water per feed cycle) and its lockout feature which effectively prevents things like flooding a house while the family’s away.