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STEAM BOILER SYSTEM FAQ’S
WITH SOLUTIONS
Steam heating systems are seldom installed now in small residential buildings but are still common in many older ones. They are simple in design and operation, but require a higher level of maintenance than modern residential heating systems. When they are running right it is the most beautiful heat on the planet. It can be plagued with a combination of simple fixes that will create a homeowner to want to scream with frustration. Some of these systems are over 100 years old and you can just imagine how many techs have worked on them in that time. Some may have done things that should not have been done. We have been working on steam systems in Chicago since 1966 and have seen things we still can’t believe. I have put together some common problems that we see reoccurring in the field. I hope this helps. If you have a question about your system feel free to give us a call at 773HOT-COLD That’s 773 468-2653.
ONE PIPE STEAM SYSTEMS
The first thing you want to do is check the water level in the sight glass.Test
Next check the operation of the low water cut off. This is what protects the boiler. This is extremely important!
Test |
Lower the water level in the boiler and see whether the low water cutoff turns off the burner. Usually this test should be performed by a service technician. Most boiler failures are directly contributed to poor maintenance hence low water cut off failure causes boiler dry fire failure to the boiler |
The heat in the building is very uneven...
Chances are that the venting strategy is wrong. Your goal is heat the building evenly. Some installers get confused and install quick air vents on radiators far from the boiler. They don’t pay attention to the size of the radiator. Size vents by radiator size NOT radiator location. Another common problem is the operation of the vents themselves. Many homeowners have a tendency to use the least expensive adjustable vents to remedy this problem. WE DO NOT recommend this. Use a quality properly sized vent and it will pay you back sooner than you think with lower fuel bills and much more comfortable heat.
The air vents spit or make a hissing noise…
The system may be dirty. Steam systems are constantly corroding. If no one cleans the system, the rust, mineral deposits, sludge, driven by the steam eventually end up in the air vents. When an air vent can not seat tightly, it will spit water and hiss.
It may be that other vents are not working as they should. If the air in the system does not have enough ways out, it will get out any way it can. That means it will go out via the other radiator vents. Soon those vents will fail as well due to the high velocity.
There may be no main vents on the system. When this is the case or if the main vents have failed, the radiator vents have to do 2 jobs. They have the double duty of venting both the mains and the radiators. This causes higher velocity which causes hissing and also carries the debris to the vent causing them to fail prematurely and worst it causes HIGH FUEL BILLS!
The vents may be the wrong size for their location. This is usually the case when the inexpensive adjustable imported vents are used. Do yourself a favor and spend a little extra on the vents. You’ll be glad you did.
The boiler may be oversized. As you increase the steam’s velocity you are more likely to move debris towards the vents. Size the boiler to eh connected load. NO MORE, NO LESS.
The radiator makes a gurgling sound…
one pipe steam system the steam and the condensate share the same pipe. This is why it is important that the supply valve MUST be fully open. The only reason you would closed the valve is to service the radiator or to shut it off completely. If the radiator gurgles, make sure the valve is fully open. It is very common for these old valves seat to come loose from the stem. If this is the case replace the valve.
The radiator may be pitched the wrong way. This can happen with radiators that sit on wood floors. The heavy cast iron expands and contracts and over the years can dig a trench in the floor. Check the radiator with a level and make sure it is pitched back to the supply valve. Use a shim if you need to.
The radiator may be sagging in the middle. This happens from the carbonic acid in the system eating away at the push nipples in the center of the radiator. It slowly weakens and starts to bow. If this happens you need to shim it in the center. If it starts to leak you will have to get/replace the push nipples. Success depends the severity of the sag. It may be that the radiator will have to be replaced. We have many sizes of new and used in stock.
The vent may be installed improperly. Make sure it is in the upright position. Make sure the vent is not installed with a horizontal extention pipe. Also pull the vent and check the vent tongue. This is a short piece of metal that extends from the vent and hangs inside the radiator. It’s job is to drain condensate from the vent . These get twisted and bent and won’t drain causing the radiator to gurgle In a.
The riser is slow to heat…
The riser is the pipe that supplies steam to the radiators from the boiler.
This pipe must be sized properly to insure that enough LOW PRESSURE steam is delivered to the radiators. You may have too small of a riser.
It is also common to see to many radiators connected to the system which does not allow the steam to get to the farthest radiators.
There is a good chance that there is sludge in the horizontal runout to the riser. This happens when the one-pipe system floods all the way up to the radiators. The sludge in the radiators washes down into the horizontal runout to the riser. The sludge sucks the heat out of the steam and won’t let it get up into the riser. Flush it out with a garden hose.
There is water hammering at the start of the heating cycle…
Water hammering is just what it sounds like. This is steam traveling at a very high rate of speed and crashing into the pipe. I have seen fittings completely ripped of the pipe from this.
The pipes MUST BE pitched properly. If condensate lays in the mains between cycles, it will hammer when the steam reaches it on the next cycle. Steam mains MUST BE pitched a minimum of one inch per 20 feet when the steam and the condensate travel in the same direction. If they travel against each other than you need to have a pitch of at least one inch every 10 feet.
There might be a concentric fitting in the steam main which allows water to collect. I have seen this quite often. You will need to change the fitting to a eccentric fitting or drip the main just before it enters the concentric fitting.
There is water hammering in the middle of the heating cycle…
I can’t tell you how many times I have seen the Vertical space between the water line and the bottom of the lowest steam main. This is commonly known in the business as the “ A Dimension”. IT MUST BE A MINIMUM OF 28”. If it isn’t the water will back up into the returns and cause water hammering like no tomorrow. This usually happens when a new boiler is installed and it was taken out of a pit and filled in. DON’T DO THAT!!!
Condensate lines get clogged up and the water is left out there in the system to create hammering like the building is under construction at 4:00 am. Not a good thing.
I have seen time after time when guys come in and try to save a few bucks or just don’t know by sizing the Hartford loop smaller or using a long nipple at this connection. Again, Pleeaaase DO NOT do this!
There is water hammering at the end of the cycle…
Again this is a problem that can be directly attributed to the Hartford loop piping. The connection between the steam equalizer and the return must be far enough below the water line. If steam can work its way into the wet return IT WILL HAMMER and it usually happens at the end of the cycle.
Long nipples will cause the hammering at the end of the heat cycle too. Make sure that a close nipple is used at this point in the system.
2 PIPE STEAM SYSTEMS
Here are some problems and solutions that plague 2 pipe systems
There is no heat in part/s of the system….
This is a classic example of steam traps failing in the closed position. If it is failed closed it will not allow air to pass through shutting down the flow of steam. Check that the traps are letting air through when the system is running if not change the bellows.
The boiler keeps going off on low water…
This usually happens on a gravity return system with the pressurtrol set too high. Crank the pressure down to get the water into the boiler and check those traps.
The main vents are squirting water…
If these vents are not located in the proper location they will be destroyed in one heat cycle form water hammer. Ideally they should be installed 15 inches back form the end of the main and at least 6 inches up on a nipple. Do it right! Those vents aren’t cheap and if they aren’t working it will cost a fortune in gas bills.
The biggest problem I see in 2 pipe gravity return systems is that the pressure is set toooooo high! The old timers sized the pipe to run on ounces of pressure NOT POUNDS! Turn the pressure down and see what happens.
Make sure the boiler is not over firing and that the steam quality is good. It is very important that the water is clean. Take some water and boil it in a pot on your stove. That will give you a good idea of the condition of your water.
There is water hammering at the start of the heating cycle…
This is the same as a one pipe steam system in respect to the pitch.
The steam traps have failed in the open position. The traps job is to open when air/water is present and to close when steam reached it. If it is open all the time then you will get heavy hammering as a result.
There is water hammering in the middle of the heat cycle…
In a 2 pipe system there is no steam at the end of the mains to help the water back into the boiler. It has to rely on gravity. It takes 28 inches of water to equal 1 pound of steam pressure to help the water back into the boiler. Keep this in mind when you are running high pressure. DON’T DO IT!
Here is a list of problems that can cause water hammering in the middle of the heat cycle… Clogged returns, steam traps failed in the open position, end of main or base of riser F&T traps failed in the closed position, F&T traps are sized wrong, dirty water, improper piping pitch and/or sizing. So you see there are many causes and solutions to this problem and a professional steam heating service technician should be consulted.
There is water hammering at the end of the heating cycle…
The condensate pump should never discharge into the Hartford loop. I see this all the time and I don’t know why? You could potentially lose the boiler in the event of a leak in the return side of the system. Pump into the bottom of the boilers equalizer with a check valve.
A steam system is a basic system that can be plagued with an array of problems if you don’t know what your doing. Citywide Supply & Service has been installing and servicing everything from extremely large fire tube boilers, supplying heat to huge buildings, to the simple single family home. If Good Quailty work at an affordable price is what your arter than Citywide is the company for you. Give us a call today at 773 HOT-COLD That’s 773 468-2653. We will solve your steam heating needs.
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