loud banging after oil->gas conversion can't sleep

DanielD

So we just bit the bullet and did a oil to gas conversion. The previous system worked okay but oil was expensive! The old system had no banging. So after doing the conversion the system bangs really loudly when it first fires up and then eventually the banging stops but the banging sounds so loud it sounds like a pipe is going to explode so we've been a bit worried about what to do about it. We called the original plumber back a few times but they just haven't been able to do anything about the banging. They took some measurements and said everything was ok. We even had a second plumber come in and he said that a cleaning of the boiler should be done. We told the plumber who did the install about that and they came again to flush the system some more but couldn't find any problems with the install. At this point we're not sure what to do next as we're not heating experts and just looking to see if anyone has any ideas for us. I'm attaching some pics of the setup. The water in the one picture looks dirty to me but I'm not sure if that's relevant at all.



Oh I should mention, the system is a one-pipe steam system. And after the install when we first mentioned the problem to our plumber they had to lower the pressure which apparently was initially set to be too high.

nicholas bonham-carter

Can't find anything wrong

Is this 1-pipe or 2-pipe?

If they would look in the instruction manual, they would see :

A lack of swing joints between the risers and the header. I can't see the diameters of the pipes, so those dimensions should be checked. As it is, the pipes will put too much pressure on the sections of the boiler without those offsets. All pipe slopes should be checked as well

The equalizer seems to be connected to a secondary header, and is not doing its job of removing the water from the steam, as it goes up into the main.

Unfortunately, as I am typing, I cannot enlarge the pictures without losing my post, but I think I saw some odd arrangement of the connection to the main-a bull-headed tee? Some more pictures would help. The manufacturers rep could help as well.

I couldn't see a skimming tee, so they probably did not follow instructions for cleaning/skimming the boiler. This procedure takes 4-6 hours, and they should install the skimming port, and show you how to do it. Simply draining and refilling will not remove the oils from the system, and neither will adding any chemicals/powders/snake oil to the boiler.

Until you get this corrected, try to use no setback of temperature at night, as the boiler has to work so hard to regain its daytime temperature, and waste fuel.--NBC

Ps now that I have been able to study the enlarged picture, the piping corrections would be as follows:

Do away with the first horizontal pipe, and extend the risers up, and then back down into the second horizontal, which looks to be a bigger size. Make sure the order of connection is kept: equalizer, take off to main, and then supply risers from the boiler. There may be a need to split up the main, and feed each one from the header separately.

The installer probably thought that the same piping arrangement would work as on the old boiler, however the new one has a smaller steam chest, with more vigorous boiling, and needs this correct piping to avoid the symptoms you describe.

Was the new boiler correctly sized by measuring the capacity of the radiators? This would be a good time to make sure it is right, or change the boiler to one of the correct capacity.

EzzyT

Hit the nail on the coffin

Can't really say much any more then nbc has make those corrections and guarantee you'll see a huge difference.

BobC

Not right

but it can be fixed. I agree with everything NBC has gone over, the piping is not optimal and should be configured like the layout in the manual. The equalizer line that comes down to the boiler return should be at least 1-1/4" pipe and it should drop straight down off the boiler header (which is misconfigured). It can angle over after it's dropped down and it would be best if that drop could be 1-1/2" pipe and then reduce and be angled (for a nice steady water line).



You are probably seeing a lot of movement in the gauge glass and it looks like there may still be some oil in the system. It will take several long slow skimming sessions to get that oil out of the boiler, the installer should have installed a full sized skim port and valve so that can be done. Skimming has to be done anytime a boiler is changed or any work is done to the piping, it has to be done very slow so the oils can float off a calm water surface, it should take a few hours to fill a 5 gallon bucket. You ope the skim valve fully and just trickle water into the boiler to slowly raise the water level to the skim port.



Make sure none of the steam mains were moved during the install, use a level to make sure the mains all have proper slope and that there are are no dips that MIGHT TRAP WATER. If steam comes across standing water it will collapse and that can cause the bang you hear.



Bob

DanielD

wow thanks for the replies

So it sounds like the install definitely needs some fixing. Thanks to everyone for all the great replies. This is so helpful to someone who is not a pro. To answer some of the questions, it's a 1 pipe system and yes we do see movement of the water in the guage glass. And no, I do not know if they correctly sized the boiler before they did the install. I really hope we do not need to replace the boiler.



Does anyone know a good plumber in the westchester county, NY area who can correct the install for us? we've used 2 so far who it seems could not identify the problem.



Oh the other new thing I forgot to mention was the radiators now hiss and spit a lot more. The 2nd plumber we brought in just put in some verivalves but in some cases it even made things worse... Hopefully fixing the install will also improve the hissing.



Oh and if any more high def pictures of anything are needed I'm happy to put them up on the web somewhere.

BobC

They can cause problems

Varivalves can cause more problems than they fix if they are not used carefully. The best practice is to vent the mains very fast and the radiators slowly. You might try adjusting the lever on the varivalves down to the low end. At some point you might be best off replacing them with Gortons, Hoffmans, or Maid o Mist vents. Don't use the cheapo's they sell at the big box stores.



What kind of vents are on your steam mains and were they replaced with the new boiler?



Bob

DanielD

vents on steam mains

Hi Bob, thanks again for the advice. Unfortunately I don't know what they did and didn't do in terms of the steam mains. Is this a vent likely in the machine room? I'd be happy to take a picture but not sure what I'm looking for.

BobC

Where

A main vents job is to expel all the air in the boiler and steam main so steam can fill the mains. It;'s important that this air be expelled quickly so steam will be available  to all the radiators at the same time.



Someplace along the main there should be a spot to mount a main vent. They are usually located towards the end of the main. Some look like a large version of a radiator vent and others look like a tuna can on edge.



I see what looks like a wet return running along the floor, if you follow that back to where it goes up and joins the steam main you may find a main vent in that general area. One usually finds a main vent towards the end of each steam main.



Bob

DanielD

is this the vent?

Hopefully i found the vent. Here are the pictures...

BobC

Not there

That is a flue damper that restricts air flow through the boiler when the boiler isn't firing. This old ilustration identifies the common location of a main air venton a single pipe steam system.



Bob

DanielD

video

I took a video of the area. Maybe it will be easier to find where it is... sorry for the shaky quality.



https://www.youtube.com/v/QhMWjnpEmTY

Eastman

boiler channel

great idea. but where do those steam mains go. can you film the piping in the other parts of the basement.

vaporvac

Pipes near ceiling

hi daniel, good video of the interesting near boiler piping, but the vent(s) will most likely be on the high pipes that are insulated. Those are the mains. Try and take a video of them following them around, but especially where they return to the boiler.

DanielD

more info

I can't seem to find the steam vents. Is it possible we don't have any?



I'm attaching a schematic of the approximate basement layout. In orange are the exposed steam pipes I can see. In blue are where the other pipes run but are unfortunately behind sheetrock since the basement is finished.



I'm adding another photo of the insulated pipes and a video of the exposed pipes in the garage. In the garage there is a radiator in the ceiling but I believe it is disconnected from the steam pipes (you can see the cap on the steam pipe in the video). Should I temporarily remove the insulation in the machine to look for vents?



garage video:

https://www.youtube.com/v/xPIV_tKYt3g

Mark N

Uninsulated pipe

The steam mains running through your garage are uninsulated and running through an unheated space since the radiator is disconnected. Uninsulated pipe condenses a lot of steam and could be a cause of your water hammer. The main vents are most likely located behind the sheetrock in the finished part of your basement. Hopefully there is an access panel where they are located. Where are you located? Maybe there is a steam pro nearby that can rectify your issues.

DanielD

we are close to new york city

We are in Southern Westchester. Close to New York City.