Steam -- water hammer, subtle for few mins, then stop, would be from return line?

LS123

Hello and good morning,

(1) I have a single line steam system, works almost always perfectly.
(2) After about 15 - 20 minutes run on the steam boiler, I hear subtle appears to sounds like water hammering about 1 second a part from the noise.
(3) Then in about 10 minute (give or take the) noise goes away.
(4) All this happens during a steam heat cycle of about 45 minutes.
(5) I also occasionally hear rads making heat expansion sounds
(6) I also noticed my return line gets as almost as hot as supply line (pic attached)\
(a) new gorton #2 installed on return line


-----
I have check the following ...
(1) all rads are slightly leaning toward return lines ( by at closer to 1/4 inch)
(2) almost all supply lines insulated well except few places uninstalled perhaps a length of a foot
(3) All pipes are at a slopes by original design

** I wonder what else I may check to stop this noise. Again it is not loud, but my wondering ears can hear it. I want to find what it is. Since long term water hammering could damaged pipes, connection (as I understand.
*** I am not sure if that noise from a cold supply line getting heated and that's what is the noise come from...

Thank you all!
\-LS123

EBEBRATT-Ed

@LS123

Confused . You say 1 pipe steam, then you say radiators are pitched toward return lines. If it is one pipe they should be pitched toward the inlet valve.

The return line will get as hot as the supply....that's normal

The water hammer is most likely coming from a pipe that is not pitched properly. Water can't completely due to the improper pitch. On the next cycle steam hits the water and you get hammer.

Post some pictures of the boiler and the piping around the boiler so we can see if your getting wet steam

LS123

Hello @EBEBRATT-Ed , Please see below including pic of the steam boiler. Thank you!

(1) " Confused . You say 1 pipe steam, then you say radiators are pitched toward return lines. If it is one pipe they should be pitched toward the inlet valve."

** It is single line steam. only connection of steam and to return condensation from connection at inlet valve.

(2)"The return line will get as hot as the supply....that's normal"

*** Sounds good to me!

(3) "The water hammer is most likely coming from a pipe that is not pitched properly. Water can't completely due to the improper pitch. On the next cycle steam hits the water and you get hammer."

** I have checked the pitch of each radiator and supply steam pipes, and they seems to be pitched correctly. But there must be some place water gets collected and each steam cycle ( about 20 mins into it) I hear very small sound of what it appears to be water hammering ( hammering goes on for about 10 mins) then the hammering sound stops. boiler keeps pushing steam in to the rads until Tstat stop the boiler. The noise of hammering is very small.

(4) "Post some pictures of the boiler and the piping around the boiler so we can see if your getting wet steam "

** This is a very simple set up from 1940s. Boiler is oil fired, only one large pipe from the boiler and steam is sent to front half and back half via separated lines from Main supply line. Water is added manually. There is a return line that bring the condensation back to the boiler ( I think it is Hartford loop.)

*** What would make a boiler produce and push "wet steam" to the rads? I read wet steam could contribute to long term damages to the pipes?


Thank you!
\-LS123

neilc

is that picture in this first post where you're hearing the hammering?
or, can you narrow down where the hammering is being heard ?

EBEBRATT-Ed

Yeah that boiler is an old timer. Built when they were made to last

LS123

@neilc and @EBEBRATT-Ed thank you.

@neilc boiler is at the back of the basement, but the hammering noise appears to be from middle or front sides pipes in the basement. It is subtle ( most times, sometimes noticeable, but totally tolerably loud... hammering sound that is.) It may be that, I may need to use to special device to detect sound , exactly where the possible hammering at ( I have seen some device being used to detect sound with steam and or water rad heating pipes etc)

I like the fact the boiler is old (and simple,) burner is kind of loud enough to detect from first floor, when its running... [for some reason my hearing is selective and sharper, and hyper active than I would like it be at times] ]

Boiler is an old one, pipes are in a good condition, waiting until spring / summer to give it a high temp spray paint look.

Yesterday avg temp was probably few degrees above 30. I have .85 GPH nozzle, total burner run time was just about 5 hours (per Tstat.) Tstat gives me daily total run time and it helps me figure out estimated oil use. The Tstat is less 1/3 or about 1/4 of the price of high tech Tstats.

I think the steam system is well and I like to keep it that way for little while. Five hrs total burn time for 24 hours is incredibly good and efficient as far as I can understand, at least based on yesterdays temp.

Could somebody tell me what might cause a old cast iron boiler to possibly create wet steam? or in general what increase the chances of boilers would create wet steam?

Thank you!
\-LS123

chuckadoo

Is the .85 burner nozzle a recent increase? Boiler may be overfired for the pipe sizes, increasing steam velocity. 

LS123

Hello @chuckadoo,
No, its been always .85. perhaps chamber being clean more often, almost no soot, may be increasing the velocity. Thank you!

EBEBRATT-Ed

@LS123
Wet steam will have a violent bouncing water line in the gauge glass. If you gauge glass level is steady and bounces an inch or so it's fine. I don't think your have that issue with that boiler

LS123

@EBEBRATT-Ed , thank you sharing what to look for if the boiler is producing wet steam. Fortunately my sight glass water level don;t move up and down really fast, and water level in the sight glass only move about 1/2 or 3/4 or an inch max I would say.. an inch may be overly for me to state since I dont think water level move that much on the sight glass when the boiler is running from start to the end for heating cycle.

I think since the chamber has been cleaned from layer of soot, filters have been changed, I added fuel for enhancement for better burning and to prevent any wax, water, varnishing etc. Perhaps steam velocity may be slightly increase like @chuckadoo mentioned.

Perhaps more heat is getting at the water chamber creating mid cycle, slight hammering noise.
Best!
\-LS123

EzzyT

Might want to also check for restrictions on the wet return piping.

mattmia2

Poor near boiler piping will cause water to be carried with steam in to the mains, oil on the surface of the water will cause it to surge and throw water up in to the mains. Your boiler has a large area above the water line where water separates out without needing piping to separate it. surging could still throw water in to the mains, but your boiler doesn't have that problem(assuming the gauge glass tappings are clear).

Is the return at the boiler or is there a separate return at the opposite side of the basement from the boiler?

EBEBRATT-Ed

@LS123

All steam lines have water in then but when the boiler is off the steam condenses to water and the piping is supposed to be arranged so that every drop of water drains back to the boiler. That's why the lines are pitched.

While the boiler is running. same thing any water from condensed steam flows back to the boiler.

Trouble starts when something in the piping is wrong. Usually from a pipe or radiator that is no longer pitched the way it was when originally installed.

How does this happen?

Pipe hangers can loosen
Insulation removed from the pipes and the hangers moved or removed
not enough hangers when installed and the pipe sags
house settles

etc etc

Or it could be a plugged or sluggish return line as @EzzyT mentioned

First thing, check the pitch on everything

ethicalpaul

The reason the noise goes away is (I believe) because after some time of steam hitting it (and hammering), the sitting water will get nearly "steam hot" and then will stop causing the steam to collapse.

But the water can still "kill" a lot of the steam in a more gentle fashion that doesn't cause hammer, but still causes the affected radiator(s) to fail to heat quickly.

So look for those "dips" in the pipes (which might be in the floor joists).

That short horizontal in front of the vent in your picture doesn't look very pitched but then the camera can lie.

LS123

@EzzyT how do i do check restrictions on the wet run piping? DO you mean return pipes, there are only two, on front and back of the house. thank u!

@mattmia2, there are two line that returns the water end of cycle. see above about the return water line. I beleive I have something call Hartford Loop. All water from rads get back to the boiler.

@EBEBRATT-Ed, thank you. I think I need to put insulation in few places. I should have check the pipes in the basements, that they are all being supported adequetly.

Thanks @Ethical Paul. I just increaed the Temp up by 5 degrees to see if it would make hammering noise mid cycle. its benn about 40 mins... no hammering yet. could out side wether play a part in this. Today was in mid 40s instead of supper cold days? I have most pipes with insulation. some arfe partly covered. the one in the front is the one I think make noise. But as of now, I have not heard anything. Also I did not have the boiler running most of the day. I wander if all the water managed to get back to the boiler, instead of being stuck in the main supply lines.

Will let you all know what I find in few days from now... Thank you all for the tips and I also learned alot of new things since this post.

Best!
\-LS123

JUGHNE

LS, do you have Dan's book, "The Lost Art of Steam Heating, Revisited"?
If no then I recommend one for you, If so then page 371...mid cycle water hammer.

11 points are mentioned, some possibly for you are sluggish return water and also Hartford Loop connections.

mattmia2

You might look for a spot where it is hot then cold for a while relatively speaking while it is hammering.

The hartford loop is just a high loop in the piping near the boiler to keep the water from leaking out of the boiler if there is a leak in a return below the water line. I'm not an expert on steam piping layout, but the return on the end opposite the boiler means the steam and the condensate should both be flowing away from the boiler in the mains.

You may be able to use a screwdriver or piece of tubing as a stethoscope to pinpoint where the hammer is coming from.

What is the pressuretrol set to/what is the pressure in the system? A particularly high pressure could push steam through water in the returns to someplace it shouldn't be. If that is a mercury switch type pressuretrol it has to be level and has to be perpendicular to the loop in the pigtail so it stays level as the pigtail expands and contracts.

LS123

@JUGHNE , no I don't have that book yet. Its on the list to get next week....thank you for letting me know where to look for mid cycle water hammering.

I will be sitting in one place mostly unable to much after RC surgery planned soon. 6 weeks on a sling to support the hand... sucks .. how am I going to play with my steam boiler?

Hello @Mattmia2, once steam is running thru the rads, the way pipes are configured, my return pipe gets almost as hot as the supply lines (most of the times) I was told this is normal behavior for the system and piping I have. Fortunately almost all the pipes are visible... whoever designed the system back in 1940s did a really good job. System is so simple... but I still have a lot to learn.... its become a hobby for me P-rtol set to cut off at 1.5 psi. Within last 4 years, I have only seen this year P-trol work, few weeks ago P-trol kick in ( when it was supper cold in North west CT) I have a low Pressure gauge... it indicates, almost all the time, steam psi from 0.25 to 0.5 PSI. yes the P-trol is good old mercury beauty... it is level and works... although for a while I thought P-trol didnt work... but sub zero temp this year, made the P-trol do its job... I was excited to see it worked...
best!

LS123

all my apologies...
this line shouold be read as "Within last 4 years, I have only seen this year P-trol work, few weeks ago P-trol KICK in ( when it was supper cold in North west CT) I have a low Pressure gauge...

@Erin Holohan Haskell if possible please correct where there is a typo in above posted comments. thank you!

mattmia2

LS123 said:

Hello @Mattmia2, once steam is running thru the rads, the way pipes are configured, my return pipe gets almost as hot as the supply lines (most of the times) I was told this is normal behavior for the system and piping I have.

Look at the main and any dry return a it is heating up and look for a spot where it is hot then cold and stays there indicating it is heating up some water, not just the pipe. Once all of the pipe has been heated it should all be hot, but how it heats may be a clue to where the water hammer is.

LS123

Good morning all!

I think I found what was doing the hammering although it is just a guess... but no hammering since last night. I am 100% sure the boiler, all the pipes need a good cleaning this summer.

I had a good sized rad in a room, I had dropped my phone and it was stuck. when I moved the rad, it broke from the valve. I closed the valve and was going to hire a pro to fix it. But I am loosing steam, one less heater, plus other things.... I decided to go to local home improvement store and connect the pipes. As you notice there is no valve. thats because I could not find one.

Although I thought all is well... mid cycle hammering seems to be coming from front of the house. check the supply line and noticed there can be more slope on that line. I put two pieces of wood in the front and much larger piece of wood in the back of the rad.

Soooo far hammering has stopped.

Dont laugh at my impressive steam heater connection. Attached below. It will get fixed by a pro in the summer... Also I was put the Rad on the opposite side, now I can get closer to the window... ( yes I know its standard to have the Rad right near the window... this is all temp for now. No more hammering SO far... Thank you all!!

Erin Holohan Haskell

LS123 said:

all my apologies...
this line shouold be read as "Within last 4 years, I have only seen this year P-trol work, few weeks ago P-trol KICK in ( when it was supper cold in North west CT) I have a low Pressure gauge...
@Erin Holohan Haskell if possible please correct where there is a typo in above posted comments. thank you!

@LS123, I've corrected this typo. If you ever need to edit your posts, you can click on the three dots at the top right of the post and then click Edit. Thanks.

LS123

perfect. thank you @Erin Holohan Haskell !

neilc

so, as I see it, you lifted that pipe about a 1/2 inch thru the floor, correct?
is there any more give there to raise it more?
it will be good on you if this is it

LS123

hello #Neilc, We did the following.

1) radiator was connected to the pipes and made them super secure.
2) Put a 2x4 wood and lifted the from the front with metal pole, until we could not get get any space from the supply pipe.
3) We put two pieces of wood that gave total of 3/4 inch
4) as much this sound crazy, back of the rad has 2 inch lift.
5) Definitely really good slope on rad. No more space between the supply pipe connection to the rad pipe and the basement sealing.

* But will put a Rad cover to hide that.

* No hammering at all now....

All... Question?
* Until I get the book "The Lost Art of Steam Heating, Revisited", having such large slope on the rad, would there be negative impact on the pipes, rad, or boiler? ( I don't want to guess nor wonder... I want to take well care of my old steam system)

Thank you!

mattmia2

that concentric reducer will trap some condensate in the radiator and the spud. maybe the spud is where the hammer was happening. you can fix that by using the right size steam radiator valve. There are also eccentric reducers, but that spud for the valve isn't designed to seal to a nipple anyhow, so better to replace the valve and spud (and maybe bushing in radiator)

LS123

hi @mattmia2 , i got these in a rush from a large home improvement store. they did not have correct size valves...

... Just got back from major RC surgery, i am suppose to keep my primary arm on a sling for 6 weeks

We made the connection SO tight, not a single indication of steam leak

I probably will move forward with your recommendation. it is sensible, have a pro do all the work.

By the way.... no more mid-cycle water hammer.... but better get it done with correct parts for long term protection of the system.

thank you!