Burner / Boiler BOOM noise, house shakes

ST140

Does this sound familiar at all to anyone? System comes out of setback from 65 deg to 68 deg. at 6am. Around 645 am, system started making this quick but strong BOOM noise. I went down to the basement, and sure enough, the floor was shaking each time it did it, and each time the damper door would shoot open as if there was a burst of something happening inside the boiler. Any ideas? From the second floor, it sounds as if somebody slammed a car door really hard and is accompanied by a thump vibration... It's probably happening about every minute.

Mike Kusiak_2

Pressure cycling?

You mention that the booms occur after about 45 minutes of firing. Is the burner shutting down on pressure each time you hear a boom or does it occur while the burner is continuously firing?

ST140

Cycling

No, it's not shutting down. And actually, I just turned the system back on so that I could see if it would do it for the plumber when he came, it started doing it again, getting progressively louder after only about 5 minutes. So, yes, during continuous firing.



I might also add, and I'm not sure that has anything to do with it, but the one change I did make was I replaced my 2nd floor radiator vents with #6 Gortons last night. The old one's ("Volunteer" was the label on them, and they looked OLD) never shut and just hissed and hissed and hissed...

Dave in QCA

Burner problems

You indicate that when this loud boom occurs, the damper, and I am going to assume that you mean the barometric draft damper, slams open or closed.

If this is the case, it would certainly indicate that something relating to the burner is happening.  If you are feeling this through the house, and its making the floor above the boiler jump... it sounds very serious.



If this was my house, I would turn off the boiler and not run it until a competant burner man could make repairs and/or correct the problem.  A really big bang could blow the glass right out of your windows!

ST140

Burner.

Installer just showed up on short notice and is having his oil man come out to check the nozzle, combustion, etc. using some sort of analyzer tool. It sounds like the guy knew what it was right away, so that's encouraging. Said something about small bursts of oil causing "mini explosions"...



Would now be a good time to downfire the system, or at least talk to him about it? My most recent couple of posts I've asked about this, and some people seemed to think it would be a good idea, others said to look at other stuff first...

Dave in QCA

Don't put the cart in front of the horse

Glad you have your burner problems on the way to being corrected. 

Regarding downfiring, I would not do that at this stage of the game.  You have not resolved the rest of the little problems in your system and you don't even know if you really need to downfire yet.  You may, or may not.  I just re-read the thread, and I think the consensus was that you may get some benefit from downfiring, but "may" is the operative word and you just don't need to try an fix a problem that may or may not exist.



There was a pretty long thread on the subject of whether or not a setback with steam produced any savings.



Additionally, Jamie pointed out that on most any system, when you are recovering from a set back, you are almost always going to see some cycling at the end of the recovery period.  You are better to be slightly oversized, which will produce pressure after a long period of operation, i.e., 40 minutes.  If you are undersized, you will never be able to build pressure, and possibly will not be able to get proper steam distribution.  Trying to find that magical fine line is difficult, and since you are still in the process of working out the wrinkles in your system such as the venting, skimming and cleaning, insulating, etc., it would be a folly to adjust the firing rate, to only later have to call the burner man back to set the burner back where it was in the first place.

Mike Kusiak_2

Discuss the possibility

While you may not want to downfire at this very moment, it might be a good idea to discuss it with the burner guy while you have the opportunity. He can tell you what your current nozzle and oil pressure are at this time, and what combinations would result in a slightly lower firing rate.



As I recall, your boiler piping is not yet insulated. When you do insulate, you will reduce your effective EDR even more and make the boiler relatively more oversized. So eventually you will probably want to reduce the firing to more closely match your actual EDR. Since you know the boiler was oversized by design, a 5% downfiring should not cause any undesirable effects on performance, and would reduce your cycling on pressure.

ST140

Burner Guy

To update, I had to leave and go to work this morning so the burner guy did his tests, etc. while I wasn't there. I was told that he replaced the nozzle and ran some combustion tests and that the system is noticeably quieter now compared to when they left after installation last Thursday. Apparently the old nozzle was "gunked" up they said probably due to misfires from the botched install the first installer left us with... Not sure if that makes sense at all, but here's the thing that's driving me nuts: When my wife got home tonight she noticed white smoke coming out of the chimney. She immediately called me when I was still on my way home and she said nobody else's house in the neighborhood had anything showing... Are you kidding me? This is where it all started a month ago.....

Dave in QCA

white smoke.....

Some vapor is normal.  Natural gas burners produce much more vaport than oil.  But, oil will produce a smaller amount of whitish vapor, especially at very cold outdoor temperature. 

A boiler with a hole in it will produce a ton of whitish smoke!   I doubt if you have a hole in your new boiler.

Steve_175

Filter

Ask your boiler tech if he replaced the filter on the oil tank. That could be part of the reason the nozzle was gunked up.