Undersized Boiler/Hammer/Boiler Replacement Questions – One-pipe Steam

KevinK

As I discuss below, it appears to me that I have no choice but to replace my boiler. This is a major expense which I cannot afford; however, neither can I live with the problem identified. So:
1. I want to get second opinions on my analyses and conclusions; and,
2. If I do replace the boiler, this will entail a major expense, and, I only get one chance to get it right. So, I am seeking information, recommendations, suggestions.

I. BACKGROUND INFORMATION:

My current boiler was installed in 2000 for the previous home owner. I purchased the house in 2010. The boiler contractor made numerous significant mistakes in the original installation and in subsequent work. (Some of which are detailed in previous postings by me.)

I was ultimately able to get the contractor to correct the “fixable” problems that he created (completed in early 2015). Without going into the details of the mistakes/resolutions, the outcome is that, with one important exception, the system is finally operating wonderfully.

The noted exception is that I now get hammer. But ONLY under a very specific condition: when the water level in the boiler falls below the 1 inch level on the sight glass. This, in turn, only occurs for a brief period at cold start (boiler hasn’t fired for something more than 2 hr). The hammer is annoying when it occurs during the day. It wakes me up when it occurs during the night.

With regard to the cause of the hammer, my conclusion is that it is caused by an undersized boiler. It turns out that the contractor undersized the replacement boiler by 25%. I discovered this when I performed my own EDR/boiler sizing calculation.

The cold-start hammer had never manifested itself prior to the recent system corrections. This is due to the fact that one of the other major installation mistakes had “masked” the hammer. (To wit: the system had an open-to-air vent associated with an unnecessary and incorrectly installed condensate return tank/pump combination. I had this removed.)

Also, I have noted that when the boiler reaches steady state, the water level stays between 2 and 4 inches below the “set” water level (i.e., often only 1 inch above the bottom of the sight glass). I assume that this is too low. This suggests to me that even under steady state operation, I am overtaxing the boiler’s ability to make steam.

II. QUESTIONS:

1. My EDR is 491 ft sq. This equates to a “Net I=B=R Steam Rating” of 118,000 Btu/hr (240 Btu/hr per sq ft of EDR). It appears that when specing boilers, most people refer to the “Input” Btu/hr. How do I derive the “Input” rating from the “Net” rating?

1A. When seeking replacement boiler quotes, do I spec the EDR, the Net rating, the Input rating, or, all of the above?

2. Boilers are available in a limited number of capacities, and it appears that that different boiler manufacturers offer slightly different capacity boilers. This makes it unlikely that I will get quotes for a boiler that matches my EDR exactly. How “sensitive” do I need to be when choosing a boiler size? Do I have some leeway, whether up or down? … Is it better to be a little high or a little low?

My gut tells me that for my system, I would be fine with a “somewhat” undersized boiler. My logic goes as follows: The “only” problems I encounter with a 25% undersized boiler are: i. hammer occurring at a cold start; ii. low steady-state boiler water level; (and possibly, iii. getting “full heat” out of the one 3rd floor radiator that I have). This suggests to me that I have some leeway; e.g., 5%, 10%? Any thoughts?

3. Related to the preceding question: Generally, are there other issues or sizing “pitfalls” I need to consider related to up-sizing my boiler?
a. E.g., issues related to a 90 year old heating system that was designed to accompany a larger-capacity boiler tank and a system that heated more slowly. I.e., modern boilers make steam more quickly than the old boilers, and, a larger boiler will only exacerbate any associated issues (e.g., shorter cycling).
b. E.g., Could there a reason, other than incompetence, that the contractor installed a 25% undersized boiler in 2000?

4. Boiler brand options: any suggestions re brands, or brand review sources/articles?

5. Re: ball park est: I’ve been told that for this size boiler (~ 190,000 Btu/hr), a general replacement estimate is in the $4-to-$6,000 range (Upstate, NY). Is that accurate?

Thanks.

KevinK

III. ANCILLARY INFORMATION:

A. System Summary Information:
1. One-pipe steam. Natural gas fired. Original installation: 1927.
2. Current boiler: Utica Boiler PEG150C; 150,000 Btu/hr input; net I=B=R steam rating: 375 sq ft. Installed in 2000 for previous home owner.
3. Connected to: 491 sq ft of radiation. 13 radiators; each radiator equipped with a Vent-Rite #1 adjustable radiator vent (all new as of 2011). 2,100 sq ft heated space.
4. Boiler located in basement. Steam main (2-inch) has two legs with total length of 100 ft. Hoffman #75 main vents (new as of 2010) at the end of each main.
5. Steam main and near-boiler piping insulation: 1-inch insulation (all new as of 2014).
6. Operating steam pressure: approx 0.5 psi (measured by a 0-to-15 psi gauge; new as of 2010).
7. Condensate return lines: 1-1/2 inch copper (replaced in 2010).
8. Overall system assessment: near-boiler piping, steam mains, main vents, radiators, radiator valves, radiator air vents are all in very good shape and operating correctly.

B. Hammer Occurrence Details:
1. Hammer occurs ONLY at cold start (i.e., when the boiler has not fired for something longer than approximately 2 hours);
2. Hammer occurs ONLY between minute 8 and minute 23 of the startup cycle:
- During this period, the hammer occurs ONLY when the water level in boiler drops to below 1 inch from the bottom of the boiler’s sight glass; and,
3. The hammer occurs ONLY in the piping directly above the boiler.

C. FYI: I can prevent the hammer from occurring by heating up the near-boiler and adjacent piping slowly. When I use the following manual cold-start ON/OFF sequence, the hammer does NOT occur:
1. ON for 8 min;
2. OFF for 4 min;
3. ON for 4 min;
4. OFF for 4 min;
5. ON for remainder of cycle.

D. FYI: I tested to see if I could avoid replacing the boiler by reducing the EDR of the system: I closed off several of the furthest-out radiators such that the effective system EDR was less than the EDR rating of the boiler. Result: this had absolutely no effect on the occurrence of the hammer.

Jamie Hall

An undersized boiler -- a rather unusual situation, by the way -- will not cause hammer. If this truly is water hammer, it's because somewhere in the system there is condensate being trapped and not being able to return easily to the boiler. What you need to do before you start thinking about new boilers and so on is trace every single pipe -- including the header -- and make sure that it is pitched -- full length -- to allow condensate to return to the boiler.

jumper

I agree with Jamie but I don't understand the water level issue.

KevinK

Thanks Jamie.
1. My current boiler has an EDR rating of 375 sq ft. My house has a connected load of 491 sq ft.
2. I have spent hundreds of hours studying my system and reading up on steam heat. And having mistakes corrected. At this point, all of the piping, including the near-boiler piping, meets spec and is pitched correctly. There are no low spots.

Fred

First off, a boiler that is too small isn't going to be the cause of water hammer. Hammer is caused by water sitting in a pipe and colliding with the steam when it hits that pool of water. Check that header and make sure it has a little pitch towards the equalizer end of the Main (where the pipe drops to the wet return). It is impossible to tell from the pictures if it has any pitch, especially with that insulation on it.
Second thing to look at is the Hartford loop (the copper pipe that rises and ties into the equalizer. It looks like it is only a couple inches below the steam riser. The Hartford loop should be a couple inches below the Normal water level (water level in boiler when boiler is not running). It is possible, if it is too high, that steam is entering into that Hartford loop and into the wet return, causing some hammer.
The very first thing I would do is skim the boiler. If it has oil on the surface of the boiler water, that will cause water to be pushed out of the boiler and possible up into the header. It looks like you have a skim port on the side of that boiler riser (Plug that is in the end of the Tee coming out of the boiler) Take that plug out and manually feed water into the boiler (with power to the boiler turned off) . Fill the boiler up until water starts to come out of that port then turn the manual feed down till you have just a trickle of water (no more than the diameter of a pencil, smaller is better) and let that water trickle out for several hours. That will keep the water calm and allow the oil on the surface of the water to flow out.
The water in the sight glass should not bounce more that a half to three quarters of an inch and during a full cycle, the water level should stay around half the glass.
When sizing the boiler, use the EDR of your total radiation and compare that to the EDR Rating on the info plate mounted on the boiler. The boiler manufacturers have built a 33% pipe and pick-up factor into the boiler over and above that rating and many think that is more than required so your boiler may well run very effeciently being the size that it is if you can find the source of the water hammer and fix that.
I suspect skimming will help a lot and making sure the Header has some pitcch and that the Hartford Loop is below the Normal water line may fix your problems.
If the boiler is, in fact a bit small, it should only be noticable during a very cold day and the outside temps are near the Design day for your area. Any other day the boiler is oversized anyway. The effect of an under-sized boiler is basically it can't keep the indoor temps at set point on the thermostat or all the radiators can't get enough steam to heat completely. Steam will take the path of least resistance. Also, one last point, make sure you have enough Vents on the Mains. I also use Hoffman 75's but they only have about half the venting capacity of a Gorton #2 so you need twice as many on each vent, mounter on a Tree. Calculate your venting needs by measuring your Mains. You need the equalivent of 1 Gorton #2 for every 20 ft. of 2" Main.

BobC

That PEG150 has a 390 sq ft of steam rating but it also has a 33% pickup factor (for piping losses) built in so it should actually produce about 520 sq ft of steam. If all the piping is insulated it could work but you might not be able to heat the house fully on the coldest day of the year. If the piping is all correct you will have no water hammer.

Are you sure it's consuming the right amount of gas? Clock the meter and make sure.

You might have a partially clogged return that is trapping water out in the system, has the return piping been checked? The water level in the boiler should not drop appreciably, if it's dropping a couple of inches you have a problem.

You need a lot more main venting on that system, if each main is about 50ft long you probably need 2ea Gorton #2's on each main.

Bob

vaporvac

Since you said you had piping redone, it's probably oils introduced to the system. As mentioned, skim, skim and skim again...this can take awhile and together with dirty wet return can affect your water level. Did you clean out any returns when doing this work. I suspect if all other pitch is correct that ist's the Hartford loop causing the banging, but the equalizer can as well under certain circumstances. I'd inspect the Hartford loop first.

KevinK

Fred said:

First off, a boiler that is too small ...

Thanks Fred,
1. I will have to search my sources for the following: I thought that I had read somewhere that the hammer that I am experiencing is a classic undersized boiler problem; i.e., you get hammer occurring in the piping adjacent to the boiler, but only at a cold start. The steam generation capacity is over-taxed by the now-cold near-boiler, adjacent, and main piping. I’m not going to get this totally correct, but it goes something like this: for an undersized boiler, on a cold start, the extra steam-condensing demand caused by having to heat up the totality of the near-to-boiler piping can cause the water level in the boiler to drop so low (which it does in my boiler) that it ~ exposes the condensate return pipe/equalizer connection (and, critically, the water in it). … And that this, then, is the “source” of the water that meets the steam that creates the hammer.

Question to all: did I dream this up, or, is this make any sense?

E.g., my header connects to about 6 ft of 4-inch pipe before it tees into the steam main. I’ll see if I can find this. If I can, I’ll post it.

1A. Header pitch: it is pitched toward the equalizer.
2. Hartford Loop/equalizer connection: this is to manufacturer spec; center line is 2 inches below the water line.
3. Boiler skimming: You are correct; I do indeed have a skim port. Unfortunately, I have not been able to get it open, even after significant effort. It is likely that it has never been opened since the boiler was installed.

3A. General question to all: is getting a stuck skim port plug open a job that requires a pro?

3B. Additional information: “Contaminated” water is unlikely to be an issue here: until I had the incorrectly installed condensate return tank/pump removed in 2014 (detailed in previous postings), the boiler was taking on a 100, or more, gallons of water per year. For 14 years. And, for what it is worth, I drain the mud leg and two other adjacent spigots on a weekly basis.
4. Water level in sight glass: it does not bounce; it just remains on the low side.
5. Main vents: I appreciate the input/recommendations. I will look into this.

KevinK

BobC said:

You might have a partially clogged return that is trapping water out in the system, has the return piping been checked?

The condensate return lines were replaced in 2010. They were drained in early 2015 for repair work. I plan to clean them when the heating season ends, however, I think that it is unlikely that they are clogged.

Fred

That statement about near boiler piping and hammer at cold start just isn't correct or we'd all have some level of hammer on our systems on a cold start. Like it or not, the hammer is coming from the steam hitting a pool of water somewhere in the area you hear the hammer. It is possible that water is being sucked up into the header.
Contrary to the comment that was made about needing a skim, believe me, boilers all act a little different. My Burnham would push water out the returns and not much bounce in the sight glass, just the water line would drop to 1" to 1.5" from the bottom and sit there until I spent several sessions skimming the boiler. I wouldn't rule out needing to skim it, especially since you've had so many piping repairs/corrections. You have to find a way to get that plug out so you can do a proper skim.
I'm not crazy about having four 90 degree elbows on the equalier before it gets back to the boiler return port either.
As I look closer to your pictures, it looks like the pipe up from your header also ties into a Bull Tee where the mains go in opposite directions. Is that the case? If so, that Bull Tee is not a good thing and each of those mains should tie back independently directly into the header.
You hammer problem may well be a combination of a few small issues rather that a single big issue but I can almost assure 100% the hammer isn't from the boiler being too small.

EDIT: One other observation, That 45 degree elbow that ties that 6ft run of 4" pipe into the Main(s), it looks to me like the base of that 45 could hold some water. That elbow probably needs to have a drip leg at the bottom of it that drops down into the wet return. If it is, in fact tied into a Bull Tee, the Tee needs to go and both Mains (each going in opposite directions) need to tie into the Header as I stated earlier, using 90 degree elbows. Any horizontals to get to those mains need to be pitched away from the header and in the direction the mains are pitched.

KevinK

7/30 pm: I have to sign off for today. I will get back to questions and comments, hopefully tomorrow. Thanks.

Abracadabra

Although it's already been said, when I read your first post, the thing that immediately came to mind is that you need to skim more and the hartford loop might need to be lowered. Are your returns wet or dry?

KevinK said:

- During this period, the hammer occurs ONLY when the water level in boiler drops to below 1 inch from the bottom of the boiler’s sight glass; and,
3. The hammer occurs ONLY in the piping directly above the boiler.

Can you please take a video of the gauge glass as boiler is firing and post it on youtube?

How do you know that the water has dropped to 1 inch below the bottom? Your feeder should be feeding water before the water disappears from the sight glass.

How can you tell that the hammer is in the piping directly above the boiler? Hammer noise will travel easily in pipes and may fool you as to it's source.

What is the usual length of one of your boiler cycles?

What pressure has the boiler achieved when hammering starts?

I'm not sure of your abilities, so that's why I'm asking some of these questions.

KevinK

1. Thanks for the helpful input. I was hoping that my problem was relatively straight forward. But as I read the various posts I see that there could be a number of factors that could be causing my hammer. And, as one person points out, I may well have a “perfect storm” of factors. I will do my best to address the specific questions and suggestions that have been provided. Bear with me as I get to each.

2. I like Abracadabra’s suggestion to post a YouTube video showing cold-start firing. This will show what happens to the water level over the course of warm up and hopefully will capture the sound of the hammer. I have never posted to YouTube before, so this may take me some time to figure out how to accomplish. So bear with me. In the meantime, be aware that my 5th photo provides a clear view of the sight glass and water line. In the interim, see #4 below.

A. A couple of points of clarification, since they come up in several posts:

3. The Hartford loop connection: regardless of what it looks like in some of the photographs, it IS piped correctly. It has a close nipple connection and the center line of the connection is exactly 2 inches below the boiler’s water line (this is per both the mfr’s spec and Dan Holohan, e.g., “Lost Art of Steam Heating”). See photo #5.

4. Water level: If you look at photo #5, you can see the sight glass very clearly. Several postings seem to suggest a typical “at rest” boiler water line is half way up the sight glass. I don’t know whether this is unique to Utica Boilers, but, as you can see from the referenced photo, my water line is approx ¾ up the sight glass. The gradation marks I added to the glass are in 1 inch increments. The total length of the glass is 7.5 inches: 5 inches below the water line and 1.5 inches above.

What I was trying to say is that the hammer occurs only when the water level drops below the minus 4 inch mark. This, in turn, occurs only during cold start, and, only for brief (several seconds) periods. And then, additionally, during steady state, the water level remains between minus 2 and minus 4 inches. The water level does not “bounce” per se, but moves relatively gradually up and down.

B. Some additional information:

5. I was attempting not to overload an already long conversation, but the following may be relevant to mention at this time - it addresses one of my reasons for considering replacing the boiler, and, perhaps it is relevant to the larger hammer discussion:
When the boiler was replaced in 2000, the contactor added a condensate return tank/pump combo. The overall installation was done incorrectly. (Steam traps and other necessary equipment were not added; the wet returns were turned into dry returns; live steam traveled through the CR lines and exited the vent on top of the CR tank; the temperature in the basement was in the high 70s.) The upshot is that from installation in 2000 until I had the situation corrected in late 2014, the auto water feed would kick on 8 to 12 times per day on a typical winter day. This means that for 14 years instead of receiving 10-ish gal/yr of makeup water, the boiler was receiving something like 100 or more gal/yr. Based on my reading, this means that I probably have a significant amount of scale build-up in my boiler (and the associated consequences thereof), and that the boiler might be subject to accelerated corrosion.

Let me be clear, if I don’t need to replace my boiler in order to correct the hammer problem, that would be good. But, so far, I am still not convinced that undersizing is not a factor, AND, I have the above-noted separate reason for considering replacing the current boiler. It probably would have been best to address this as a separate topic, but now that we have gotten knee deep in multiple issues, here it is.

Q1. Am I right to be concerned about the “over watered” boiler: e.g., scaling, corrosion, life expectancy, steam generating compromise, efficiency?
Q2. Might this be another factor in the hammer/low water level causation?

Jamie Hall

I'm thinking... I'm thinking.

Your cold level -- 3/4 of the way up the sight glass -- is fine. No problem with that at all.

One question which I don't think was explicitly answered: how fast does the water level recover to the cold level when the burner shuts off?

It's that drop of 4 inches or so (if I read you correctly) which occurs fairly quickly on start up that has me puzzled. That's quite a drop...

vaporvac

@jamie, I'm reading it's only falling to the 4 mark on the sight glass (out of 71/2"), but you could be right too. If so that's no a huge drop, but when he says between 2-4", that take it below the Hartford Loop.

Fred

A normal water line that is 3/4 of the way up the sight glass is not unusual. Burnham boiler are that way also. Given the additional info you just shared, It would be good if you could also take some pictures of the length of the main(s), the wet and/or dry returns ans a couple typical radiators. It sounds like a lot of modifications were made, probably out of ignorance, and there may still be a remnant or two of those changes that is affecting your system.
I did see a better view of the Hartford loop and it does look OK. You mention traps on the system. Typically a 1 pipe steam system doesn't have traps, just vents at the end of the mains or returns.
Also, while it certainly did not do the boiler any good to have all that feed water added for all those years, the boiler is in the age range where no one can gaurantee that it will last another year or another 10 years. I certainly would not replace it thinking that, by itself, will resolve the hammer issue. Let's see if we can identify the source of the hammer, fix that and you can add some water conditioners to the boiler to help clean any scaling that might be in it.
Look closely at that area around that 45 where the main(s) tie together. It looks like the 6ft section of 4" pipe may be pitched towards the 45 and that by itself will hold water and be a source of hammer.

KevinK

Jamie Hall said:

I'm thinking... I'm thinking.

Your cold level -- 3/4 of the way up the sight glass -- is fine. No problem with that at all.

1. Response: Thanks for that info.

One question which I don't think was explicitly answered: how fast does the water level recover to the cold level when the burner shuts off?

2.Response: 30 sec.

It's that drop of 4 inches or so (if I read you correctly) which occurs fairly quickly on start up that has me puzzled. That's quite a drop...

3. Response: Correct. To be exact:
min 00 - Cold start;
min 00 to 08 - water level drops gradually to approx -4 in;
min 08 to 23 - approx 4 to six episodes of approx 2 to 4 seconds of hammer; coincides exactly to 4 to 6 episodes of 2 to 4 sec of water level falling slightly below the -4 in level;
23 min to OFF - water level stay in the -2 to -4 range; no hammer;
OFF - recovery of water level from say -3 in to 0 in - 30 sec.

Jamie Hall

Thanks Kevin...

Where, exactly, is the water level when the hammering starts in relation to the Hartford Loop? That's the first question.

Second one is -- are there any wet returns out there which are close to the water level of the boiler, either slightly above or slightly below? Reason I ask: as your boiler gradually starts to warm up and make a little steam -- that 8 minute period where the water level is dropping slowly -- that water has got to be going somewhere, and that somewhere is somewhere it shouldn't be going (it's not going away as steam at that point!). I suspect that if you can figure out where, you may have found your problem.

The quick recovery when the boiler shut down shows you that your cold returns are not clogged.

KevinK

Fred said:

A normal water line that is 3/4 of the way up the sight glass is not unusual. Burnham boiler are that way also.

1. Response: Thanks for confirmation

Given the additional info you just shared, It would be good if you could also take some pictures of the length of the main(s), the wet and/or dry returns ans a couple typical radiators. It sounds like a lot of modifications were made, probably out of ignorance, and there may still be a remnant or two of those changes that is affecting your system.

2. Response: All of the modifications/mistakes were made to the near-boiler piping (see also Response #3 below). I can assure you that all other components of the system are in top shape, and, that the system works marvelously, other than the brief periods of cold start hammer.

I did see a better view of the Hartford loop and it does look OK. You mention traps on the system. Typically a 1 pipe steam system doesn't have traps, just vents at the end of the mains or returns.

3. Response: Agreed. I mentioned traps, etc, in the context of the incorrectly (and recently removed) condensate return tank/turning of wet returns into dry returns. When you turn a one-pipe gravity return system into a mechanical return system by adding a CRT/P with its open air vent, you have to add traps, etc. Otherwise, as happened at my house, much of steam goes out the CRT's vent, and into the basement. (Also, all of your non-steam-rated Armorall insulation on your CR lines get fried.)

Also, while it certainly did not do the boiler any good to have all that feed water added for all those years, the boiler is in the age range where no one can gaurantee that it will last another year or another 10 years. I certainly would not replace it thinking that, by itself, will resolve the hammer issue. Let's see if we can identify the source of the hammer, fix that and you can add some water conditioners to the boiler to help clean any scaling that might be in it.

4. Response: Thanks for the info. Agreed.

Look closely at that area around that 45 where the main(s) tie together. It looks like the 6ft section of 4" pipe may be pitched towards the 45 and that by itself will hold water and be a source of hammer.

5. You could be correct. Prior to my recent addition of insulation to the horizontal section of the 4" pipe, I recollect noting that it is possible that there could be a slight pitch in the "wrong" direction. Hence a potential (I would say "minor") source of pooled water. And certainly the location fits with the "location" of the hammer. But, to me, that still begs the question as to why the hammer occurs only at cold start/"very low" water level. In other words, my thinking: it seems that it is the water level that is the concern here, not possible minor amounts of pooled water. ... Otherwise, I would be getting hammer at times other than the very specific that I have id'd. Make any sense?

vaporvac

Before redoing wrongly pitched piping, mine also only banged on start up from a cold start. When we fixed the pitch the banging went away. I'm not discounting the hartford loop going dry on start-up, I just wanted to point out that hammer can occur at super predictable times and only at those times.

Fred

@KevinK, Im guessing there are two issues here, not just one. I think the hammer is coming from that 4" pipe, being pitched the wrong way. More obvious when cold because the water that is pooled there is also cold and it gets hit with Hot, Hot steam as the boiler starts to make steam. The second issue, the low water, I am almost certian it is due to the boiler needing a good skim, maybe several. It doesn't matter that you draw some water off of the two lower valves. Anytime pipe work is done, that new pipe is coated with oils. That oil sits on top of the boiler water and the steam bubbles can't break through the surface of the water like it should and the end result is that it pushes the boiler water back through the wet returns/Hartford loop. When you drain some water from drains that are below the water line, the oils on the surface of the water just cling to the sides of the boiler and then float on the surface as you replace the water you drained. Skimming is the only way to effectively get the oil out of the boiler.That also explains why the water returns so quickly when the boiler shuts down. The water is not out in the system (except that portion that is in that 4" pipe), it is right there near the boiler and it runs back into the boiler very quickly when the steam pressure is gone. It would take several minutes for it to return to the boiler if it were distributed (condensate) out in the system/radiators. The Hartford loop looks Ok from the close up picture. It's not going dry, it is filled with the water being pushed out of the boiler.
Focus on those two areas and I'm betting the hammer and low water issues will be resolved.

Charlie from wmass

skim it or use Squick if there are issues removing the skim plug. You can also replace one of the 90's at the boiler going to the header with a tee and skim there. Not an easy thing but perhaps easier then pulling out that plug.

KevinK

To-date Summary

Terrific input. Thanks. What I plan to do, over the next several days/week, is review and summarize the thoughts and suggestions, and implement whichever I can. I’ll provide a summary post.

For the immediate future, it seems clear to me that the first order of business is to do the skimming: i. this is called for based on the system mods that have been done; ii. it is “easy” to do (if I can get the damned skim plug out); iii. it is low cost; and, iv. I will know immediately whether it helps or not.

The problem is: removing the skim plug (2” fitting). Mine is not budging. My understanding is that iron-to-iron fittings subject to steam temperature experience, … I don’t remember the exact term here: … something like: heat welding, or rust welding(??). Correct?

I am aware of three possible approaches to breaking such a seal:
1. Brute force (pipe wrenches w/ cheater bars) and percussion (tapping the fitting with a hammer) – this approach has been unsuccessful;
2. Heat/expansion: when my main vents were replaced, the contractor used a torch to heat/expand the outer fitting. I think that he used an acetylene torch. Would a “handy man” propane torch provide the “right kind” of heat?
3. Penetrating oil (eg, Liquid Wrench): can this be used/would it be of help in this application?

Any thoughts?

RobG

Use an impact wrench, much easier.

KevinK

Abracadabra said:

Although it's already been said, when I read your first post, the thing that immediately came to mind is that you need to skim more

1. Response: Agreed.

and the hartford loop might need to be lowered.

2. Response: Hartford loop is per mfr spec (ie, centerline is 2" below the boiler water line).

Are your returns wet or dry?

3. Response: Wet, all the way from the drops (two legs of approx 50 ft each).

KevinK said:

- During this period, the hammer occurs ONLY when the water level in boiler drops to below 1 inch from the bottom of the boiler’s sight glass; and,
3. The hammer occurs ONLY in the piping directly above the boiler.

Can you please take a video of the gauge glass as boiler is firing and post it on youtube?

4. Response: Great idea. I will do this as soon as I can/as soon as I figure out how.

How do you know that the water has dropped to 1 inch below the bottom? Your feeder should be feeding water before the water disappears from the sight glass.

5. Response: I was not clear. Not 1 inch "below the bottom" of the sight glass, rather, the water level drops below 4 inches below the "resting" water level.

How can you tell that the hammer is in the piping directly above the boiler? Hammer noise will travel easily in pipes and may fool you as to it's source.

6. Understood/agreed. Ans: because I have spent hours standing and sitting beside the boiler observing and recording the conditions that lead to the hammer.

What is the usual length of one of your boiler cycles?

7. Response: Typical winter day; outside temp in the 20s; t-stat maintaining set temp of 69 degrees: ON-cycle is ~ 25 to 35 min; OFF-cycle is ~ 1-1/4 to 2 hr.

What pressure has the boiler achieved when hammering starts?

8. Response: By minute 8 of the cold start cycle, when the first episode of the hammer occurs, the press is approx 0.5 psi. During steady state operation, the press stays w/in the ~ 0.2 to 0.9 psi range; mostly near 0.5 psi.

I'm not sure of your abilities, so that's why I'm asking some of these questions.

9. Response: I'm pretty handy and, while I am a lay person, I know my heating system inside and out.

Fred

Doing the skim first is a good plan. That will eliminate the low water issue (it may take several slow skims to get all the oils off the surface but you will see improvement with each skim. As has been suggested, try to find an impact wrench to remove the plug.
Once the low water issue is out of the way, it looks like you have two options to resolve the water hammer. Repipe that section of pipe so that the pitch is correct (if there is a Bull head Tee there, that would be the time to seperate those two Mains and tie them into the header individually. If you can't see your way clear to do that repipe in the near future, you can probably get rid of the hammer by putting a 3/4" or 1" drip leg on the bottom of that 4" pipe somewhere close to that 45, maybe 3 or 4 inches back from the 45, in the 4" pipe and drip that pipe into your wet return. That will probably get you by until a new boiler is installed and that piping is corrected. Putting the drip leg in will mean tapping the 4" pipe and having someone weld a thread-o-let over the tapping so that piping can be attached.
Keep us posted on how you make out.

KevinK

1. Cold start video: I made a video today. Super idea. It shows everything very clearly. As soon as I get it uploaded to YouTube, I will post a link.
2. Removal of skim plug: still no luck. I will keep trying.

Abracadabra

A basic "homeowner's" torch isn't going to cut it. The tee and everything attached to it becomes a big heat sink. You need quick fast heat applied to the tee to cause it to expand while rapping on the plug and the perimeter of the tee with a hammer. Be patient, use a large wrench with a long cheater and it will come out.

RobG

Abracadabra said:

A basic "homeowner's" torch isn't going to cut it. The tee and everything attached to it becomes a big heat sink. You need quick fast heat applied to the tee to cause it to expand while rapping on the plug and the perimeter of the tee with a hammer. Be patient, use a large wrench with a long cheater and it will come out.

Or just use an impact wrench.

KevinK

"Hold the presses." I have some new, potentially crucial, information that may explain what is going on. As soon as I get a chance to write it up, I will post. Hopefully tomorrow or Monday.

KevinK

RobG said:

Abracadabra said:

A basic "homeowner's" torch isn't going to cut it. The tee and everything attached to it becomes a big heat sink. You need quick fast heat applied to the tee to cause it to expand while rapping on the plug and the perimeter of the tee with a hammer. Be patient, use a large wrench with a long cheater and it will come out.

Or just use an impact wrench.

Thanks to both for your useful input. Still no luck w/ plug via my "pea shooter" approaches. I/friends don't have an impact driver. Will consider renting/buying. ... I'm going to put the skim plug/skimming aside for the moment (see my above posting) but will return to.

vaporvac

You can't keep us in suspense like that.

Abracadabra

vaporvac said:

You can't keep us in suspense like that.

Yeah... what he said...

ChrisJ

Ah, I'm glad to see yet another boiler with practically no pickup factor is heating a house completely fine. Makes me happy. That's not undersized in my book, it's called perfection. Especially if all of your radiators heat at the same time. I'm heating 392sqft with a boiler that is rated for 325sqft. Originally, it was sized properly and I converted it to the next size smaller boiler, pictures can be found at the link in my signature.

My guess is your hammer is likely caused by a hartford loop that is mounted too high.

Is the hammering the only reason you want to replace the boiler? If so, forget it.

KevinK

vaporvac said:

You can't keep us in suspense like that.

I apologize. I had a "light bulb moment" last evening shortly before I had a commitment to be elsewhere. Since the suspense is obviously killing people, I will provide the condensed version. I will provide details, if needed, later. Although, you have to admit, this was like a TV cliffhanger, no?

In short, it appears that I have an "intermittent" clog in the condensate return piping somewhere between the equalizer "drop" and the boiler inlet. It seems to be acting like a flap valve with a mind of its own: sometimes letting water pass, other times (and generally, briefly) stopping or significantly impeding the flow.

Here's some of the background/what I think happened:
Because of space limitations (and, partly, because I was convinced that the "undersized boiler" explanation was a slam dunk. ... I have been disabused of that notion thanks to multiple commenters), there are some things I have not mentioned prior to now.

Per my request, in September 2014, the contractor: i. removed the incorrectly installed condensate return tank/pump; ii. lowered the replacement condensate return lines (replaced in 2010) back to their original "gravity feed" height; and, iii. restored the Hartford Loop. As always, this contractor's physical work was super. Unfortunately, he once again snatched defeat from the jaws of victory. To wit: he did not follow spec when he restored the Hartford Loop. The Loop's connection w/ the Equalizer was 3/4" below the water line (vs the spec of 2"), and the instead of a "close nipple" he installed an 8-inch nipple.

At this point: 1. I made the contractor aware of the the non-spec dimensions, and the well-established likelihood of hammer generation. He responded that he didn't think it would create a problem. 2. Upstate NY had a relatively warm fall, so there wasn't much demand put on the heating system. When the system did operate, it operated MARVELOUSLY for the first time since I had purchased the house. ... Quiet (no CR pump every 7 min; no auto water feed every 2 hrs); the radiators/house heated nice and evenly; the basement was no longer a sauna from all the CR tank steam "leakage."

Skip some details here. ... Fast-forward. ... Temps get significantly colder. ... In late November, I get awoken by some God-awful noises coming from the basement. I put my PJs on, run down to the basement, ... it only takes a moment to come to the realization: "Oh, so that's what hammer sounds like" (I had never consciously experienced hammer before). After this episode, the system starts to exhibits hammer regularly at start-up, mid-cycle, and at shut-down. Per my previously-noted comment to contractor, all "classic" signs of non-spec near-boiler piping.

Skip details. ... I convince the contractor (despite his "this isn't going to work") to make the dimensions conform to spec. This is done in January 2015. The result: PERFECTION. The hammer goes away completely. The system continues to operate MARVELOUSLY.

An aside: Through out all of this, the contractor never explicitly acknowledged that he made any mistakes. In fact, he made numerous attempts to refute the irrefutable. He only took action when I sent him in-writing irrefutable evidence of the mistakes. (Again, many thanks to Holohan, Linhardt, others, and this site.) Implicitly, he acknowledged the mistakes, since he performed well into the thousands of dollar of work with only a nominal charge to me. However, in our last communication, he made it clear that I should consider myself lucky that he undertook the corrective actions that he did, and that he had no intention of providing any further corrective actions at his cost.

Skip details. ... Several months pass. I start to get the "cold-start-only" hammer that I address in this posting.

What I think happened:
1. The system experienced significant periods of hammer in late 2014/early 2015 because of incorrectly installed near-boiler piping;
2. The hammer was occurring in the Equalizer and/or the piping directly above the Equalizer;
3. The piping directly above the Equalizer consists of approx 6 ft of 4-inch pipe that is original to the house (i.e., it is 90 years old);
4. I'm guessing here (and seeking input), but it seems very likely that said 90-yr old 4-inch pipe would/could have held a significant amount of rust, etc.
4A. In fact, I'm now remembering, when the hammer started to occur there were periods when I was draining the mud leg spigot, but more particularly, what I call the "Equalizer clean-out" (the clean-out spigot located approx 1 ft downstream of the Equalizer) multiple times per day. There were times when the Equalizer clean-out was so clogged, I had to insert wire to break the clog.
5. These spigots are nominally 3/4-inch; the actual opening size appears to be 1/2-inch, or less.
6. It seems very possible, if not likely, that there could be chunks or clumps of detritus that the hammer knocked free, "sitting" in the CR return between the Equalizer and the boiler inlet.
7. This detritus it too large/"too far away" to pass through the clean-out spigot.
8. This detritus is acting to impede, and at times, stop the flow of CR to the boiler.
9. This would explain the "extreme" water level variations that various commenters have focused on. And, it would explain the somewhat lock-step variation in the pressure readings. (This all shows very clearly in the cold-video I made. Unfortunately, I've not had time to figure out/post to YouTube. ... And, maybe not necessary at this point??)

Wow. This post is much longer than intended. Got on a roll/it all "coalesced."

Final info: the "source" of this epiphany:
1. As of yesterday, I was still unable to remove the skim plug;
2. So, as an interim measure, I purchased/added the Squick that some had suggested;
3. I ran the boiler; let it cool a bit; drew water out of the mud leg spigot in order to drain some of the gunk.
4. When I opened the water feed to refill the boiler, I noticed that boiler's water level did not change.
4A. I was suddenly reminded that this is an unexplained circumstance that has been occurring intermittently over the past several months. With my other concerns, I never had time to pursue the reason/cause.
5. And then, just as suddenly, the light bulb went on - an "intermittently clogged" near-boiler condensate return could explain ALL of the problems I have been experiencing for the past several months.

Before proceeding any further, it seems to me that this is a good point to seek input. Does the preceding make sense? If so, then I believe I know where to put my near-term focus. (I.e., getting the clog resolved.) Agreed?

KevinK

Hatterasguy said:

It's going to be tough to make a good case for an "intermittent clog" in a 1.5" copper return line installed in 2010 unless this contractor did something really stupid.

No. Not in the copper portion. In the 2" iron portion "downstream" of the bottom of the Equalizer. If I am not being clear/wrong terminology, let me know.

KevinK

ChrisJ said:

Ah, I'm glad to see yet another boiler with practically no pickup factor is heating a house completely fine. Makes me happy. That's not undersized in my book, it's called perfection. Especially if all of your radiators heat at the same time. I'm heating 392sqft with a boiler that is rated for 325sqft. Originally, it was sized properly and I converted it to the next size smaller boiler, pictures can be found at the link in my signature.

1. Response: Thanks for the confirmation of the adequacy my "undersized" boiler. VERY helpful and informative along with others' similar comments.

My guess is your hammer is likely caused by a hartford loop that is mounted too high.

Is the hammering the only reason you want to replace the boiler? If so, forget it.

2. Response: Understood.

Abracadabra

KevinK said:

Hatterasguy said:

It's going to be tough to make a good case for an "intermittent clog" in a 1.5" copper return line installed in 2010 unless this contractor did something really stupid.

No. Not in the copper portion. In the 2" iron portion "downstream" of the bottom of the Equalizer. If I am not being clear/wrong terminology, let me know.

Sorry... I'm not convinced that's your problem.

Fred

It may well be that that piping needs to be flushed just to be certain that it is not clogged but I still think it unlikely that a 2" pipe would be intermitenly clogged but I guess anything is possible. I still think the low water issue is water being pushed back into that near boiler piping, another reason I doubt that pipe is clogged. If it had that much rust material in it, that 4" pipe would have been eaten through by now. On top of that, there simply isn't that much water rolling back to the boiler from that 4" pipe. It there is, there is something else seriously wrong with the near boiler piping. Maybe a quart or so sitting in the low spot and a trickle back to the header and down the equalier. All the rest of the return water comes from your wet returns at the ends of the mains. What I still suggest is the same two focal points plus a third: 1) Skim the boiler, 2) fix that low point in that 4" pipe and the adder, 3) open and flush that near boiler wet return. Pick the sequence that makes you most comfortable but the skim is essential. We all know the havoc any new piping and its associated oils have on boiler water stability.

KevinK

Fred said:

It may well be that that piping needs to be flushed just to be certain that it is not clogged but I still think it unlikely that a 2" pipe would be intermitenly clogged but I guess anything is possible. I still think the low water issue is water being pushed back into that near boiler piping, another reason I doubt that pipe is clogged. If it had that much rust material in it, that 4" pipe would have been eaten through by now. On top of that, there simply isn't that much water rolling back to the boiler from that 4" pipe. It there is, there is something else seriously wrong with the near boiler piping. Maybe a quart or so sitting in the low spot and a trickle back to the header and down the equalier. All the rest of the return water comes from your wet returns at the ends of the mains. What I still suggest is the same two focal points plus a third: 1) Skim the boiler,

1. Response: Agreed. Will do as soon as I/a pro can get the plug out. I will work to resolve this coming week.

2) fix that low point in that 4" pipe and the adder,

2. Response: due to the cost/difficulty associated with the various "between the header and the mains" piping issues identified by you and several others (eg, the bullhead tee that several correctly identified), I will wait on addressing these until i. end of heating season; and ii. I see what comes of addressing your items #1 and #3.

3) open and flush that near boiler wet return.

3. Response: Agreed. As soon as I/a pro can get this section open.

Pick the sequence that makes you most comfortable but the skim is essential. We all know the havoc any new piping and its associated oils have on boiler water stability.

4. Response re "... new piping associated oils": isn't this precisely what the Squick was intended to address? Or, are there varying opinions on what Squick can accomplish?