Two Pipe Bang

RAF

I have what seems to be a two pipe steam system. The only trouble I have with that statement is that there isn't any F&T traps anywhere on the system return and no condensate pump. The boiler is piped with a Hartford Loop there is one large vent in the boiler room that is the only vent on the system. The return line is about 90' long and has what I would call traps in it . Meaning that the return runs under the floor about 40ft the comes up out of the floor to a bull tee a drip comes off the main into the top of the tee and the return runs across a closet then under the floor under a doorway then up out of the floor through a closet then back under the foor where I assume that it hits a tee to pick up another return on oppisite side of house then back to the boiler room . The floor is concrete and flag stone.

The bang seems to come from where the drip off the main ties into the return.

I am thinking that this return was at one time a wet return but the boiler was replaced about 10 years ago and I am wondering if the water line is to low.

I guess my guestion is do all two pipe systems have F&T traps or did they pipe them with gravity returns also ? I am thinking that steam is coming down the drip leg off of the main and hitting the water that collects under the stairs.

Any Ideas?   The boiler is WM 568

Jamie Hall

Traps on two pipe

most -- but not all -- two pipe steam systems have traps on the radiator outlets.  There are some vapour systems which do not, and depend on other means to keep steam out of the returns.  Most -- but not all -- two pipe steam systems do not have traps anywhere on the returns, although they can be piped that way depending on a number of factors.  They are gravity return systems -- or were, as originally built.  Meaning here by "traps" various devices which open to allow air and water through, but close against steam.



If you have only one large vent in the boiler room, then there should be dry returns running to it -- otherwise air has some trouble finding a way out of the system.



The return you describe running under the floor, then up, then down and so on has to have been a wet return at one time.  Up and down piping like that is quite acceptable in a wet return.  It is absolutely unacceptable in a dry return, as water will accumulate in the low spots (which might be though of as badly formed plumbing waste water traps -- not steam traps) and prevent the free flow of air to a vent.  Drips from mains (and dry returns) were commonly tied into wet returns wherever it was convenient.



If your water line was lowered when the boiler was replaced, that line could well be above the current water line.  In which case it could hammer -- as well as causing a variety of other problems, some of which may be quite subtle.  First thing to do is to check the elevation of the water line in the boiler against the elevaton of that return line, and then we can proceed from there.

RAF

Was loosing hope

First let me say thanks for your input.

First let me say this house is completly finished meaning you can't see 95% of the piping but seeing the house I have to beleave that whoever installed this system new what they were doing and I am thinking that who ever replace the boiler may not have. Let me correct some infomation The boiler is a W.M 580s on oil, the radiator all have Banes and Jones Traps I replaced all the cage unit about 4 years ago #2818s. The main vent is a hoffman #75 I am guessing that this is a dry return coming back from the Main can not see Pipes.

The boiler room is about 5' lower than the basement foor the only visable return in this room is about 2' off the floor coming through the end wall and runs into the H/L( someone installed a check valve on this line) both primary and secondary cut offs are installed to W.M specs. The water line is a 321/4"  assuming (as I am not at the house) a 62" differance I would say this water line is around 30" below the traps in the return and at this point the drip leg of the Main runs right into a dry section of the return between two wet sections. If I were to put a loop in the boiler room that would raise the water level in the return do you think that would work? Again thanks for your input Jamie

Jamie Hall

Verily

installing a loop to raise the water level in that roller coaster return should help a good deal -- it's referred to as a false water line, and it isn't either uncommon or difficult.  If you have a copy of the Lost Art, it's explained very nicely.  If not, it is basically an inverted "U", with the top of the "U" defining the new water line.  The only trick to it, really, is that it needs to be equalized to the steam pressure -- that is a line needs to come from a steam main to the top of the "U".  Doesn't have to be large, as there's no flow in it, but it needs to be there.  Also, there needs to be a vent at the top of the "U", so it can't act like a siphon under any circumstances.



Not hard to do, if you're handy with the plumbing...

RAF

Jamie Hall

I thought you might like an update.   This past Monday we installed the false water line on this system.  On start up as described in Lost Art there was noise and some water hammering until the air vented and the  return lines filled up but after that the system settled down and now after about 5 years of banging this system is  running  as quiet as a church mouse.

Thanks You for input and  pointing me in the right direction.  Rich

Jamie Hall

Bravo!

Congratulations!  Must be a pleasant relief, eh?

RAF

Its back again

Thought I had it cured but got a call over the weekend that she was having more noise now then before we installed the false water line.

Took a run over to the house today fired up the system and sure enough the false loop was knocking like someone was building a house and hammering nails.

What I noticed was at some point water was coming out of my #75 vent as the vent was facing the boiler and the top of the boiler as a rust stain on it now.

Something else I noticed was that there is no vent at the end of the steam main I am wondering if this is causing a problem here.

Question 1 should there be a vent on the end of supply main.

Question 2 when we installed the false water line we installed it in the return in front of the Hartford loop which  picked up the dry and now wet return should I have installed it to only pick up the wet return  I have about 14'to 16' of vertical pipe coming down from the ceiling on the dry return so my thinking is it shouldn't make any difference.

Jamie Hall

Rats

let me think about it... and sleep on it.  Back to you tomrrow...

Jamie Hall

PS

I don't suppose you can send a sketch showing water lines and all the piping in question?  (Not all the piping in the house, but the dry return and the connexion to the boiler and the Hartford and equalizers and vents)

Jamie Hall

The usual suspects...

What pressure are you running?  with only 14" to 16" from the dry return down to the false water line, pressure is going to be really critical.  It would be better if that dry return went all the way down to the wet return after the false water line, if you can do it.  However, even so the pressure will be critical, as the water in the far end of the roller coaster will also stand at about that relationship to the dry returns at that end.  Can you lower the false water line and still keep the roller coaster wet?  (I know, I know, you just put it in!  However, as Charlie just said in another post, much easier to do now when the threads haven't corroded together!).  One way or another, can you keep the pressure below 8 ounces?



That asked, the next question is when in the cycle does this hammering happen?  Right at the beginning?  Middle?  Towards the end, after pressure has built a little?  That will help to know?  Or is it all the time?!



The vent shouldn't spit -- that tells you that water is getting to it, which it really shouldn't.

RAF

What happened

Jamie I just spent about an hour and a half typing a responce I dont know where it when't when a posted it?  Dry returns are about 12 ft up on ceiling I hope my other post shows up.

RAF

Right And Wrong

Wrong 

Near boiler piping. Two risers on boiler to header then center of header riser goes up 12' to 3" main  header go over to 2" EQ they pick up all returns in one 11/2 line.  I have to live with this I know it is wrong

My guy welded a nipple on top of the 4x2 ell making a bull tee at the EQ Drop. I have to live with this now.

FWL is piped as show in Lost Art  only my guys used a 6" nipple in the U instead of a Street 90 this will be fixed. I raised the # 75 vent up 3' instead of 1' .

They put a 10" nipple on the header and ran over to the top of the FWL  I think this may be to low given the location of the nipple on the header.

Wondering the basement radiators are two pipe with no traps I guess this is ok as they return into the return we are now making wet again. The first and second floors return into two dry returns and the radiators all have  traps the dry returns come into the boiler room at about 11' on the ceiling then they are teed together make a short drop  into one return with a # 75 vent then down to the wet return on the boiler room floor before my FWL . All returns run into the FWL at 20" the Hartford loop is set at 28" I droped the line to the floor and this rund into the tees at the bottom of my FWL . the boiler water line should be 32.25 but it is 35" the bottom of the header is 75 inches making my EQ to the FWL 85" making the top of the FWL about 79"  The boiler room floor to the basement floor is 53" the basement floor to the bottom of the 3"main is 80" messured in a closet about mid way across house. The return we are trying to wet is about 60" above the boiler room floor are A diminsion was measured off the lowest radiator return in the basement at the far end of the house about 90' away from boiler room. Pressure control is set at .5 on dif is 1 PA404 set as low as it goes I ordered a vaporstat today for this job.  My guess is the noise starts at about 12 to 14 oz  hard to tell on gauge with one pound increments also ordered a new gauge that will read oz. This is a short version of my first post .  This has really become a personal challenge for me now. Thanks Jamie for your help on this. Rich

RAF

Rough Drawing of what I think we have mains and returns

What I think the piping does.

Jamie Hall

I guess a couple of questions

Looking at the diagram, it looks as though there is a line connecting the bottoms of the two vertical pipes for the false water line loop.  Is there?  If there is, there shouldn't be -- or there should be a closed valve in it.



Second, I think that the line from the header and equalizer to the top of the false water line loop is too low.  I would raise that up a couple of feet at least -- maybe all the way to the ceiling.  Not that I can see how that would get condensate in it, but... I suppose... just about every time I think I've seen everything in steam, something comes along and makes a monkey of me.



Hang in there.  We'll figure it out...

RAF

Yes

Yes there are two valves in the FWL.

Jamie Hall

I'm still thinking

about this...  The hammer -- is it now in the false water line loop or that vicinity?  And not in the roller coaster any more?

RAF

Yeah up all night

Here is my plan

Install L408J1017 vaporstat it came yesturday.

Lower boiler water line to recommended level of 32.25"

Change to of false water line to close nipple

Maybe lower FWL closer to top of return piping (will see)

Raise Equlizer line to about 6' going to FWL

Install four G2 on the Dry return to help the short cycle

Lower the firing rate a little.

Thinking the Stat should Be about 2oz on and may 8-10 off to start

Any other ideas?

RAF

Yes

Yes most of the noise is coming from the FWL now. I had it running the other day I didn't get the big bang from that return. 

Jamie Hall

Well, not up all night --

at my age, can't.  Seems to me that all the things you are proposing can't hurt, and may well help.  At the moment, I'm out of ideas...