Properly Balancing a One Pipe Residential Steam System
Many techs believe that balancing a residential steam system is done by adjusting the automatic radiator air vents, dependent on the radiator location. Unfortunately, this is not the way to balance a steam system. You should adjust the air vent according to the radiator's size. An important tip on balancing a single pipe steam system is to verify that there are working main line vents. Below is a Hoffman and Gorton main line vent.
Steam system efficiency is all about venting. The steam produced in the boiler must first move to the end of the steam main. The only way to get the steam to move through the insulated steam main piping is to vent the air from the main. Yes, I said insulated steam mains. No steam system should be operated without insulated mains, as it can create multiple issues.
- Noisy systems
- Slow heating
- Systems that cannot be balanced
- No heat in some areas
- fuel bills
Venting One Pipe Steam Mains
The main line vents vent much faster than the radiator vents. It may not be unusual to see multiple main line vents connected near the end of the steam main. They come in different sizes and shapes.
It does not matter if there is one or multiple main line vent(s); they should never be at the very end of the steam main. Stay back about 6" to 12" from the end of the main. Raise them as high as you can within reason.
Venting Radiators
Ahhh, now we’re getting somewhere. All this radiation can be connected to the same single pipe steam system. All the radiation must be vented with radiator vents. I have always liked adjustable style radiator vents. All the radiator vents should be from the same manufacturer and style.
In the heated rooms of the home, there will be one, two, or more radiators. Contrary to belief, it does not matter if the radiator is on the first floor, second floor, closer or further from the boiler. Balancing the one-pipe residential steam boilers is not related to the geographical location of the radiator in the home, but rather to the size of the radiator.
Balancing Radiators
It is common in a residential steam system that, if you look at all the radiators, there will be multiple sizes. This makes it easy to balance. In this example, let's assume there are two five-section radiators, two eight-section radiators, and one fourteen-section radiator. Again, ignore the location of the radiator in the home. Verify you have good working main line vents. The only thing we are concerned with is venting on the largest radiator. Set the radiator vent wide open on the air vent scale (9). The 2-eight section radiators may be set to about 50% (5 or 6), and the 2-five section at about 25% (2 or 3) on the radiator vent. Explain to the customer that if a room is a bit too warm, close one number; if it's too cool, open 1 number, and wait about a week before making another adjustment, but only one number at a time.
One last thing, a radiator that would be 30 sq. ft. of steam or larger. One radiator vent may not be enough. It is good practice to add a second vent to any radiator larger than 30 sq ft of steam. Drill and tap the second air vent below the existing air vent. The second reason to add a second air vent is due to an exceptionally long pipe from the steam system main to the radiator.
Double Venting Radiators
Disclaimer: The information found on this website is for informational purposes only. All preventive maintenance, service, and installations should be reviewed on a per-job basis. Any work performed on your heating system should be performed by qualified and experienced personnel only. Comfort-Calc or its personnel accepts no responsibility for improper information, application, damage to property, or bodily injury from applied information found on this website.