Situational Water Hammer

clammy

I haven’t read through every post but if you have even 1 bad trap and steam is getting into your return this will be the end of any steam distribution plain and simple no if mad or butts very simple . The hammer your hearing is most likely from clogged wet returns . If your returns do not drains and isolation valve for flushing ,then you should looking into at a min having them flushed . Looking at your boilers near boiler piping it looks like there no equilizer off the end of the header timing into the boiler return . The piping leads a lot to be desired and from the looks of it it was not installed by anyone w a good knowledge of steam or proper near boiler piping practices and zero pride in workmanship ie looks like crap . Couple of easy question ,was a edr done of existing radiators? Is the boiler properly sized , is a decent readable and reliable low pressure gauge installed . I would think w only a few radiator taking steam that your building excessive pressure and w some bad traps your pressurizing your dry returns , the banging your hearing is most likely condensate backing in the dry returns or possible the end of your steam mains ,I ve seen this happen and have heard it . Being you have a older system which most likely never had the returns flushed I would believe you got some great mud and rust and crap built up ,you can waste as much time as you want dicking about w other theories but until you flush it out and make sure it s just futile . Do yourself a big favor have the boiler flushed wanded and skimmed and all wet returns flushed . When I am faced w replacing older steam boiler weather single or two pipe w wet returns either there getting isolation flush valves to flush out the mud if there not interested then I show just about the same interest which means zero and I move on or there gonna get a bill every time I have to come back and clean the boiler which usually after a couple of bills they realize that they should have had it done or replaced . Remembrance nothing last forever and the quality of the condensate does matter . Have you tried to boiler a pot of water loaded w mud and rust and possibly some oil well that’s what your asking your boiler to do make dry steam w a bunch of mud and debrie sitting not only in your wet returns but the bottom of your boiler ,lower heat transfer acting like insulation ,it’s where it all starts so by all means let the mud sit there .
Ok I ll back away from the coffee and be done w my rant for those who care and by all means sick to the hvac guys who are clueless plus the young guys do not want to cut and thread just press it baby . Remember the cheaping of a cheaper price is soon forgotten after the bitterness of poor quality . Words that I live by usually by myself lol
Peace and good luck clammy

KarlW

@clammy If I could find an actual residential steam boiler mechanic in Western NY, I would do all of this stuff you suggest, but I haven't found one.

That said, most of the return was replaced in kind and is now new just two years ago - you can see where the new piping starts on the first two pipe photos where the most banging is - I am skeptical that sludge in the pipes is causing this.

@mattmia2 I don't know precisely what you are asking on the vents - the two vents are where the supply elbows down and drops into the return system.

Relevant to both points is that the banging appears to occur at the points where the steam meets the wet return - where the pipe drops vertically into the wet return (closet picture) and where it drops from supply to wet return.

109A_5

Hello @KarlW,
Did you try ?
Ambrose mechanical https://ambrosemech.com
or
Isaac Heating & Air Conditioning https://www.isaacheating.com/

KarlW

109A_5 said:

Hello @KarlW, Did you try ? Ambrose mechanical https://ambrosemech.com or Isaac Heating & Air Conditioning https://www.isaacheating.com/

Ambrose stood me up and I feel like Isaac oversold me.

That said Isaac is a massive upstate NY chain, I’m not sure if they’d send out a dedicated mechanic. I’m also pretty sure they’re the ones who installed the boiler you do see.

109A_5

Hello @KarlW,
OK just checking, I'm certainly not against DIY, you will learn a lot about your system, and I believe that is a good thing, but that takes time and effort on your part.

mattmia2

Are the vents only on the returns or also on the mains? Are there any vents on the mains hidden up in a corner or are those all runouts to the radiators?)

I don't see any crossover traps(a steam trap connected from the main to the return) so the mains don't vent directly in to the returns.

If there are no vents on the mains and no crossover traps then the mains have to vent through the radiators to the returns. This is probably ok if most of the radiators are open. If most of the radiators are closed off that means it will take a long time for the mains to vent so it will take a long time for radiators far from the boiler to heat and it will be unbalanced.

Others can comment on this part, but if the mains are unvented you may need to add vents on the main in conjunction with the TRVs to make it heat quickly.(after you figure out the steam in the returns part. the steam in the returns closes air vents before the air is out of the system, return vents directly when the steam hits them and radiator traps when it hits the outlet side of the trap).

clammy

In an effort to trouble shoot and isolate your issue ,from a semi cold start program all your trv s to the highest temp so they are open and turn your thermostat up 4 or 5 degrees . After you feel that the end of your steam main is hot and your main vents or crossover traps are closed start checking your radiator traps and your dry returns for signs of steam passing . Plain and simple traps fail and over time they must be replaced . Do yourself a favor purchase a 0-32 ounce pressure gauge x 1/4 and a brass 1/4 tee ,elbow and a couple of nipples and add it before your vapor stat . Also some where on your dry returns there should be vent if you only have vents on dry returns then there’s a cross over trap from the supply main into the dry return . Even though you have had sections of the wet return replaced don’t discount mud . I also noticed in your boiler piping pics the extremely long nipple that was used for the Hartford loop . Generally a close or shoulder nipple is used and is specified in every installation manual for every steam boiler . A isolation valve on the vertical drop of the Hartford loop w a drain valve would have been nice but can’t always get what you need . Have you flushed out the boiler through the ball valve on the boiler return piping ,I would suggest draining a couple of gallons out w a fast flushing to see what condition your boiler water is in if it is chocolate I would suggest a draining and fill and flush until clean . It’s always a good place to start and it should be clean any way . Peace and good luck clammy

clammy

The near boiler piping again is a total mess when the boiler was replaced they should have correctly piped the boiler instead of connecting the dots best they could . Did this new boiler install ever work correctly ? A final thought has any one pulled the sight glass assembly and low water cut off off and cleaned them as part of annual service ? A higher then suggested water level in some boiler will worsen there production of wet steam and coupled w a dirty boiler can have strange results w a semi clogged sight glass assembly it happens . Clammy

KarlW

@clammy Trying to answer all of your insights (which I do appreciate)

• When I have everything on max I do not get the water hammer, but I will do what you suggest when it gets frigid again.
  
• I regularly flush through the drain on the boiler return piping, it is typically very dark after about a month.
  
• I have the gauge (although 1-5 psi - it does give me oz granularity to answer these questions)
  
• I have had regular service, including full draining at least every other year for the last decade - the local HVAC guys know how to do this but not much more in my experience.
  
• My water level tends to be slightly low rather than low, but my low water sensor is working and the boiler fills back. My sight glass is stained but largely clear.
  

@mattmia2 I really appreciate your insights as well, more traps is something I’ve suspect I needed - I was off base in thing F&T traps, but it does feel like my two vents blow out a lot of air at times, making me think they were undersized. I still very much think I have an broken trap.

KarlW

Here's my update on trying to stop the water hammer:

• I've replaced all my old Illinois Traps with new Tunstall capsules and covers, and they didn't seem to do anything.
  
• One by one, turned off every radiator with old and new traps for a night with no luck.
  
• I've drained about 8 gallons of water with moderate, but not massive, or thick sludge.
  
• I've checked the level of all visible high-level returns, and they have a mostly correct pitch - the most questionable spot is far from where I hear the hammer.
  

I've yet to have a truly cold day this year (below 25F), but in previous years, when the boiler ran full bore with all radiator valves open, I didn't get this problem. I believe this is the key to the diagnosis.

Any other ideas for me to try?

mattmia2

The returns shouldn't cause hammer. you have steam in the returns from somewhere if the hammer is in the returns. standing water in the dry returns can cause radiators from heating if it obstructs the pipe but it won't cause hammer unless you have another problem.

What is the pressure in the supply?

If the returns are blocked or close to blocked you have to flush with a hose. you probably need to add boiler drains and valves to do that.

KarlW

I absolutely have steam in the returns (too hot to touch). I systematically attempted to turn off all my radiators one by one to find where it is entering to no avail.

Pressure is 1psi with my vaporstat cutout set to 12oz. I’ve had it at various other settings, lower than 1lb means my attic doesn’t get much heat and I haven’t noticed anything from different cutoff points.

i am reasonably sure I don’t have any closed returns as this happens after the second or third boiler cycle (i.e. when the vaporstat cutout kicks it back on)

mattmia2

KarlW said:

I absolutely have steam in the returns (too hot to touch). I systematically attempted to turn off all my radiators one by one to find where it is entering to no avail.

Pressure is 1psi with my vaporstat cutout set to 12oz. I’ve had it at various other settings, lower than 1lb means my attic doesn’t get much heat and I haven’t noticed anything from different cutoff points.

i am reasonably sure I don’t have any closed returns as this happens after the second or third boiler cycle (i.e. when the vaporstat cutout kicks it back on)

The steam in the returns could be coming from a water seal that is not far enough below the water line or even one that was eliminated altogether by someone that repaired or altered or replaced something. This is most likely also why your 3rd floor isn't heating, the steam keeps the radiator from venting through the return. Figure this out and most likely all your problems go away.

The 3rd floor should heat just as easily as the first floor at a pressure that is too small to measure.

neilc

think about slow returns,
the boiler cycles a few times and fills the a return(s) on the later cycles,

why are you getting up to 16 oz, if you're set to 12 ?
traps, other than the attic, are backfeeding the attic, not allowing it to vent(?)

KarlW

@mattmia2 What am I looking for to figure out if the water seal is too low - I've posted plenty of pictures, but I can pull out my tape measure and shoot a pic in a particular area.

neilc

do you have horizontal returns that are at or near to your boiler water level?
or dry returns up high above water line, that don't separately drop down to the floor(well below the water line) before connecting to the wet return?

Jamie Hall

If you have steam in a return and you have replaced all the traps... including any at the ends of the steam mains crossing into the dry returns -- it almost has to be a water seal problem.

What you are looking is a water seal which is too high. The seal itself can take two forms. One is a simple loop of pipe which drops down from a steam main and then goes back up to a dry return. These usually don't give trouble unless your pressure is too high, but what you need to check is the vertical distance from the dry return down to the bottom of the loop. That must be at least 28 inches for every pound of pressure that the boiler produces, and more is better. The second is a little more subtle: in this there is a drip from a steam main going down to a wet return and, quite likely, a nearby drip to the same wet return. The trick here is that the wet return they go to must be below the boiler low water line, and again, preferably well below. To check this one you must run a level from the boiler water line to the suspect drip, and unless your basement is open this may require some ingenuity. This second type of problem is oddly common, as most modern boilers are shorter than older boilers, and unless the installer was careful about matching the water line of the new boiler to that in the old one he or she may have created this problem, quite unintentionally.

leonz

KarlW said:

@clammy If I could find an actual residential steam boiler mechanic in Western NY, I would do all of this stuff you suggest, but I haven't found one.

That said, most of the return was replaced in kind and is now new just two years ago - you can see where the new piping starts on the first two pipe photos where the most banging is - I am skeptical that sludge in the pipes is causing this.

@mattmia2 I don't know precisely what you are asking on the vents - the two vents are where the supply elbows down and drops into the return system.

Relevant to both points is that the banging appears to occur at the points where the steam meets the wet return - where the pipe drops vertically into the wet return (closet picture) and where it drops from supply to wet return.

-----------------------------------------------------------------------------------------

You should give the folks at Angelo Chiodo heating and plumbing in Syracuse, NY as they make long commutes to service the local ford dealership in Ithaca.

KarlW

neilc said:

do you have horizontal returns that are at or near to your boiler water level?
or dry returns up high above water line, that don't separately drop down to the floor(well below the water line) before connecting to the wet return?

My horizontal returns are well below the boiler water line (I posted the dimensions above).

On the other hand, I do have long dry returns at about 6' high running halfway around my house that one radiator after another drops into.

Jamie Hall said:

If you have steam in a return and you have replaced all the traps... including any at the ends of the steam mains crossing into the dry returns -- it almost has to be a water seal problem.

I'm as sure as I possible can be - as far as a I know I don't have any traps at the end of my steam mains, just vents (see the picture near the circuit breaker box).

Jamie Hall said:

you are looking is a water seal which is too high. The seal itself can take two forms. One is a simple loop of pipe which drops down from a steam main and then goes back up to a dry return. These usually don't give trouble unless your pressure is too high, but what you need to check is the vertical distance from the dry return down to the bottom of the loop. That must be at least 28 inches for every pound of pressure that the boiler produces, and more is better. The second is a little more subtle: in this there is a drip from a steam main going down to a wet return and, quite likely, a nearby drip to the same wet return. The trick here is that the wet return they go to must be below the boiler low water line, and again, preferably well below. To check this one you must run a level from the boiler water line to the suspect drip, and unless your basement is open this may require some ingenuity. This second type of problem is oddly common, as most modern boilers are shorter than older boilers, and unless the installer was careful about matching the water line of the new boiler to that in the old one he or she may have created this problem, quite unintentionally.

The dry return is 4.5-5 feet above the water line and another 2 feet or so above the bottom of the loop (in the dirt, as shown above).

I also have two-three radiators that drain into the wet return and likely share the pipe - this is also where I feel like the water hammer starts.

mattmia2

KarlW said:

I also have two-three radiators that drain into the wet return and likely share the pipe - this is also where I feel like the water hammer starts.

What do you mean by this? they have to go in to a dry return first because that is how the air vents out of them.

mattmia2

So thinking about this some more, there are 2 ways you can help narrow this down (someone experienced with steam would do it more by looking and thinking about what the various fluids are doing but you might need to narrow down where to look).

Start with the system cold and start feeling returns so you can figure out where it gets steam hot where it isn't supposed to be. This will narrow down where you need to look.

Feel all of these drips to the wet returns. They should all be relatively cool, they should not be steam hot. Any place a pipe drips in to a wet return make sure it is not steam hot:


These should not ever get steam in the bottom of the pipe if the water seal is functioning because they will be full of air and the steam will sit on top of that air. The only way that steam can get to the bottom of the drip is if the pressure exceeds the distance below the water line and it pushes the water out(or maybe if there is a leak in the pipe).
Soemthing like this, assuming that is a drip from a main and not a dry return connecting to a wet return:


Dies the 3rd floor radiator that won't heat properly connect to a dry return before it connects to a wet return? It needs to connect to a dry return so it can vent.

KarlW

I greatly appreciate the explanation!

I will borrow an IR gun over Christmas and see if I can trace it.

mattmia2

It should be enough of a difference between condensate temps and live steam temps that you should be able to feel it with your hand(though an ir camera could help with the tracing where do the returns get steam in them first)

KarlW

Update: maybe the problem is much simpler than the traps…

I took this picture the moment the boiler cut out:

The pressure is a cutting out at 3psi despite the vaporstat behind it set to 1 psi.

The water hammer starts at 1.5psi and I can see the needle bounce from it.

Yet at the same time it does seem to be cutting in at around the 7oz it is set for.

I've seen a bunch of posts about vaporatats going bad, could mine be bad as well?

mattmia2

Vaporstats can be adjusted. also make sure the passages from the vaporstat in to the boiler are clear. they could fail but being out of adjustment is more common. i think @Gordo is the one with the video on how to adjust them.

At 3psi the connections to the wet returns need to be about 7 ft below the water line to keep steam from blowing through them.

your 3rd floor radiator could have some other issue like no vent on that section of the return.

KarlW

mattmia2 said:

Vaporstats can be adjusted. also make sure the passages from the vaporstat in to the boiler are clear. they could fail but being out of adjustment is more common. i think @Gordo is the one with the video on how to adjust them. At 3psi the connections to the wet returns need to be about 7 ft below the water line to keep steam from blowing through them. your 3rd floor radiator could have some other issue like no vent on that section of the return.

That makes sense then. I've finally had the time to watch many cycles - the air vent in my boiler room is dripping water at 3psi.

I may reinstall my old pressurestat behind it and see if it still works and can cut it out at the minimum 1.5psi.

109A_5

mattmia2 said:

At 3psi the connections to the wet returns need to be about 7 ft below the water line to keep steam from blowing through them.

Don't you mean the Dimension "A" would become about 7 feet ? Which is above the waterline and may result in condensate in the main or other places you don't want it.

Or Dimension "B" if there is a F&T Trap at the end of the main.

The pressure need to be better controlled.

EBEBRATT-Ed

Until you have every trap in the system rebuilt or checked you haven't got a chance of getting this working right as @clammy mentioned. And fixing the traps is just the starting point.

Unfortunately Upstate NY is a mess as far as any kind of contractors goes. I am in Western MA and the company I used to work for ventured up that way for a few jobs. What I saw on jobs up there was pretty bad and sloppily installed

mattmia2

109A_5 said:

mattmia2 said:

At 3psi the connections to the wet returns need to be about 7 ft below the water line to keep steam from blowing through them.

Don't you mean the Dimension "A" would become about 7 feet ? Which is above the waterline and may result in condensate in the main or other places you don't want it.

Or Dimension "B" if there is a F&T Trap at the end of the main.

The pressure need to be better controlled.

Actually i guess if the equalizer is doing its job then the returns should get pressurized through the equalizer and that shouldn't push water through the what should be wet returns between the mains and dry returns.

neilc

are you 100% sure the pigtail, and all the sightglass fittings, are clear and breathing, all the way back into the boiler?
any chance gunk got up to that small port hole under the Vstat?

KarlW

neilc said:

are you 100% sure the pigtail, and all the sightglass fittings, are clear and breathing, all the way back into the boiler? any chance gunk got up to that small port hole under the Vstat?

I literally just took it all apart and rebuilt it. All was clear.

My old pressuretrol wasn't working either. I wonder if it is electrical (I haven’t touched any wires other than the pressuretrol/vaporstat leads) further back to the shutoffs.

neilc

well take a wire off the Vstat and see if the boiler will fire,
It better not.

109A_5

Hello @KarlW,

KarlW said:

I literally just took it all apart and rebuilt it. All was clear.

My old pressuretrol wasn't working either. I wonder if it is electrical (I haven’t touched any wires other than the pressuretrol/vaporstat leads) further back to the shutoffs.

I would verify the pressuretrol / vaporstat functionality.
First, by disconnecting a wire to it while the boiler is active (assuming it is in the 24 VAC control circuit), the burner should go off.
Second, verify the calibration of the pressuretrol / vaporstat and your gauges.
It seems like you really need to get the pressure under much better control.

https://youtu.be/mE1-QuUx4_c
https://youtu.be/3w6-Ypn9_bs
https://youtu.be/mwLNeDeYW64

KarlW

So I tested my vaporstat and pressuretrol.

Vaportstat - I had to take the setpoint screw out altogether to get minimum settings and I was still at cut out of 3.5psi and cut in at 2.5psi

Pressuretrol - mine is broken, no matter where I set the screws, the cut out was over 4psi and the cut in was around 0.5psi.

So what I did (and I should have taken pictures) is to open up the diaphragm and raise the little pin on the screw to maximum height.

End result - the broken, modified pressuretrol reliably cuts out at 2psi and cuts in at about 0.5 psi - way too high, but enough to significantly reduce the hammering.

It’s a Christmas miracle! At least until I can order another pressuretrol - although it may not be worth it if I stopped the water hammer.

109A_5

Hello @KarlW,
As much as pressuretrol / vaporstat are relatively simple they certainly have their issues working correctly and holding calibration, if they ever had it. You may be able to re-calibrate it. I suspect in some cases if the system falls into a vacuum the vaporstat diagram may be damaged.

Did you catch "Money-Well" in the one video ?

If you want better control, you may want to look into controls like the Dwyer Photohelic 3030 or similar.
The Down sides;
Cost, may not be too bad, new, new old stock, used on eBay.
You have to think in inches of Water Column.
It needs its own AC power.
You have to install it, connect it to your system.

Up side, You may have much better control of your pressure and differential setings. And / Or maybe just use a timer to limit the run time and duty cycle.

Leave the other barely functional stuff connected as some marginal safety factor and to make the inspectors happy.

EDIT: Forgot the picture.

KarlW

I'll look into this, it seems like something I'm looking for, and I do have nearby 120v outlets I can use, so the power is no problem.

I'm a civil engineer by trade, so inches of water is just pressure expressed in terms of head right?

109A_5

KarlW said:

I'm a civil engineer by trade, so inches of water is just pressure expressed in terms of head right?

Correct, 1PSI = 16 Oz = 27.7 in. WC = 2.04 in. Hg

mattmia2

KarlW said:

I'll look into this, it seems like something I'm looking for, and I do have nearby 120v outlets I can use, so the power is no problem.

I'm a civil engineer by trade, so inches of water is just pressure expressed in terms of head right?

it is the pressure exerted by the weight of the column of water. i believe that is different from head if i understand head correctly. it is just a convenient unit to measure small pressures especially when using a manometer.

you can use a piece of tubing to build a manometer to verify the accuracy of the gauge.

KarlW

I did stop the water hammer entirely by using that tiny hex screw on the pressuretrol. I have it kicking on off at about 9oz and off at .5 oz or so (so low it doesn't register on my now not working correctly gauges).

Now I have a short-cycling boiler (less than 30 seconds short), exacerbated by the fact that it is 40-50 degrees here. I did order the Dwyer so I will deal with a couple of weeks of the short cycling before it arrives.

At least it was a Festivus miracle to stop the hammer.

neilc

congrats on stopping the hammers,
the short cycling,
how is your main venting?
and,
EDR,
boiler, and installed radiation,
R U oversized?