Pressure in a steam system

Hi all- Run across a confounding problem with my steam heating system. It is a one pipe system, Burnham gas boiler, has 6 radiators on two floors.
The issue I am having is that the Pressuretrol is set to 2PSI for the main tank, yet the internal syphon gauge regularly goes up to 8PSI. Around the time the internal gauge hits 8PSI, the furnace clicks off. The radiators are pretty darn hot when the cycle runs.
This has been going on for a few weeks and is, I think, the core problem.
However, just yesterday, the system turned on, went up to 8PSI, clicked off, but no heat came through the radiators.
Any ideas on the cause of each problem? I would guess they are related, but am stumped as to the cause.
Many thanks, Ryan
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Do you have any boiler experiance cause I think you need a pro, maybe the wrong question but is there any water in the boiler, and how do you know. Try draining and see if the sight glass lowers then refill it but try to measure what you remove and put in. My sight glass had a clogged feed and jumped around and I had the wrong level till I hired a pro to retap a rusted closed pipe that broke off in the boiler. Is the pressuretrol a mercury bulb, they can go bad and not move freely. Im no pro just guessing.
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can you feel the steam pipes leading out of the boiler,,,
are they hot?
where do they stop being hot?
Are the air valves in the radiators opening to allow the steam to travel towards them?
Mark
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There is water in the boiler. It was in the sight glass, plus I just drained it to flush it. Waiting now for it to completely cool off before I dump new water in.
So, the steam pipes are hot, and parts of the radiators heat up, just not a lot. The air valves are working, at least as of 2 days ago, and it is a system wide issue, so do not think it is those. Which leads me to believe somehow the pressure in the boiler is not escaping into the system, as the boiler seems to have sufficient pressure, but the pipes are not getting it. But I can not imagine there being a clog near the boiler as it was just installed in 2000, and those are big pipes, and i never have even heard of the pipes clogging?
Many thanks for the ideas, this is helpful.
I did have my local plumber come in to do the annual maintenance, but of course this problem did not occur while he was here. Not averse to calling him back, just want some idea of what is wrong prior to doing so.
Thanks again Ryan
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I just inherited a one pipe steam heating system in a house I just bought. I never had a steam system before and had no idea about how they work. The property was bank owned and vacant, and everything had been winterized. I had a plumber come out and get the system started and he gave me a crash course in how they work, what to do, etc. Mine had a ton of crud in it and he said it needed a new blow down valve and a new site glass (which had a leaking fitting). He didn't have the parts with him but was going to come back in a week to do the work. In the meantime, the newly turned on gas service had a slight leak in the main gas shutoff valve, so I called the gas company who came out and fixed that. The guy knew all about steam heaters so I had him fix the blow down valve and site glass while he was there.
In the process, it turned out that there was crud blocking the return flow into the float valve and also crud built up where the main bottom drain valve was in the return line from the radiators. Opening that main drain valve did nothing because it was so blocked up. So, just as a thought, in addition to opening up the blow down valve did you try opening the main bottom drain valve that is in the return pipe coming back from the radiators? If that had enough crud in it, maybe that would block the return and caused the pressure in the system to go up too high.
Keep in mind that I am completely new to all of this, so I am just taking a guess here.
wrote:

There is water in the boiler. It was in the sight glass, plus I just drained it to flush it. Waiting now for it to completely cool off before I dump new water in.
So, the steam pipes are hot, and parts of the radiators heat up, just not a lot. The air valves are working, at least as of 2 days ago, and it is a system wide issue, so do not think it is those. Which leads me to believe somehow the pressure in the boiler is not escaping into the system, as the boiler seems to have sufficient pressure, but the pipes are not getting it. But I can not imagine there being a clog near the boiler as it was just installed in 2000, and those are big pipes, and i never have even heard of the pipes clogging?
Many thanks for the ideas, this is helpful.
I did have my local plumber come in to do the annual maintenance, but of course this problem did not occur while he was here. Not averse to calling him back, just want some idea of what is wrong prior to doing so.
Thanks again Ryan
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Where are the blow down valve and main drain down valves? My site glass has a small valve int he bottom, but not sure if this sevres much of a purpose? As to the main drain, it comes down from the ceiling, and is then fit into a pipe leading into the boiler. All of these fittings are soldered on, and there does not seem to be a valve near them?
I have drained it a couple of times using the drain valve off the main furnace, and it seems to drain fine. Took three fill and empties for the water to run clear, so maybe there was some crud in there.
Thanks Ryan
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Where are the blow down valve and main drain down valves?
------------------------
Sorry, I am already out of my league on this. I have an old gas-fired steam heater -- circa 1981, I think. On the outside of the heater, in the front, near the bottom, there is a "blow down" valve with a bucket under it.
Both the plumber I had come out and the gas company service person said I am supposed to open the blow down valve every so often (maybe every 2 weeks or every month) so it drains off some of the hot water -- about a gallon or two at a time, I think. That's supposed to keep it clean and keep crud from building up and messing up some of the safety valves etc. I never had a steam heating system before and having to do this all seems too weird for me. It's a house that I bought that I am going to rent out, and I just can't picture tenants being expected to do that. Plus, the hot water coming out could scald a kid if they got the bright idea to turn the valve themselves.
Maybe this is because I have an old steam heating system and maybe newer models don't have all of that nonsense going on. So, maybe your system doesn't even have a blow down valve. If newer systems are different and don't have all of this craziness maybe I'll get a replacement heater put in. I do know that I have to stick with steam heat because it is a single pipe system which means it can't be converted to hot water radiator heat unless I replace all of the radiators, piping, etc.
I went to the http://heatinghelp.com website and saw the message you posted there. Seems like a very good website although I have no idea what the siphon tube is that the person replying mentioned. But I may end up posting some questions there of my own since I am new to this whole steam heat concept.
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Can I assume he also showed you how to blown down the boiler? Do it at least once a week to get the crud out. Probably the most important step in maintaining a steam boiler. Be sure the low water cut off works too.
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Yes, he showed me how to do that.
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Sue,
if the radiators are getting warm but not hot, it sounds like bad air valves. These are the most common problem in a one pipe steam system.
Carfully take one valve off and see if that radiator then gets hot.. wear gloves remember live steam is invisible and burns badly...
On each radiator, the air valve first is supposed to be open when cold allowing air to leave the radiator so steam can enter the radiator. When the raditor is filled with steam (it will then be HOT, not warm) and the steam gets to the valve, the valve gets hot and then it closes. Steam is bascially at 212 deg F. If the radiator is not near 212 F then there is not steam in it.
If you are reading steam pressure but your radiators are not hot then unless you have a massive clog (unlikely) then the air valves are the problem. It is very common for ait valves to go bad. Try this before you waste any big money.
Mark
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Since it is the whole system maybe a bad mains return air vent, the pipe that clogged on my 50 yr old thing was a 1/2" pipe to the sight glass. Make sure the low water saftey works. For real boiler pros that help go to www.heatinghelp.com and post at "the Wall" Every year I have to replace a few radiator and main air vents as they go bad.
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I'll try heatinghelp too, thanks ryan
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wrote:

A steam boiler is a very interesting animal. Simply put, in a residential 1 pipe application, the water boils, steam goes out the pipe, pushing the air ahead of it and the condensate water returns back. Very simple process but it must be able to get rid of the air first before the steam can travel. This requires properly installed main air vents and radiator vents. The piping must all be properly sized and pitched. You also need to drain the crud from the bottom periodically but by adding fresh water you also introduce fresh minerals. Its all a balancing act. By the way, 8lbs of steam is WAY WAY TOO much. Most resi apps dont even show any pressure as less than 0.5 psi is enough to do most homes. Start out with a heating company that has someone trained in Steam boilers or read a book such as one produced by Dan Holohan "The lost art of steam heating" . Good Luck Bubba
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Yes, the book seems like a good idea, seen it a couple of times. Thanks for the help.
Ryan
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