Eric Johnson (00:00)
Welcome back to Boiler Wild. My name is Eric Johnson. On this podcast talk about boiler industry topics as well as personal development. Hopefully you want to strive to get better. I know the listeners of Boiler Wild want to get better. That is why you are listening. And I want to thank everybody who has reached out to me and said that they listen. shout out to Beau you know who you are. Appreciate you listening and the the feedback and wear that hat with pride.
Eric Johnson (00:30)
Makes you better, makes you at least twenty percent smarter in the boiler room. And I appreciate everybody who hasn't reached out but has rated the podcast five stars. If you haven't rated the podcast five stars and you actively listen to multiple episodes, what are you doing? Rate it five stars. It helps me. It costs you literally nothing. It is a
Eric Johnson (00:56)
thirty second endeavor. But I know most of you drive on the road and then you get busy because you are actually doing real work and you're not just podcasting. I know podcasting all the big podcasters will have you believe that podcasting is real work. While it does get a little bit repetitive, this is not real work. Podcasting is very, very easy compared to actually solving real problems, especially in the boiler room.
Eric Johnson (01:23)
Today I I want to talk about something that is so simple, so basic and so important to know. And it's almost so simple and so basic that I didn't even know if I could make a whole episode about it. But I figured, hey, if the podcast is ten minutes long, it's ten minutes long. It is what it is, but the people have to know. And if they don't know the s information already, then y they will know at the end of this and they'll be like, yeah, I kinda knew that or I've I've heard of that. But
Eric Johnson (01:53)
I want to say this because while I am a more knowledgeable person about boilers, steam boilers and all that stuff, hydronic boilers, boiler systems, I always have to remember that people start at zero. You are not born with inherent knowledge. And if you are a traditional person, like just a normal American, you
Eric Johnson (02:20)
will not have this knowledge after you graduate through high school and then maybe not even through college. Depends on what you go for for a degree. when I think about boiler knowledge, everything has to be learned, even the most basic stuff. And being around boilers, you'll work around boilers, you'll pick up a lot of the basic knowledge and a lot of it becomes tribal knowledge or
Eric Johnson (02:45)
that's just the basics, or that's assumed you know that, or assumed you pick it up. I'm really trying to be intentional about helping others learn those basics and those that assume knowledge in every aspect of my trainings so that I am not assuming that they know the basics or know one thing or the difference between, you know, that and this. I don't have any specific things off the top of my head. Otherwise I'll go down a rabbit hole with it.
Eric Johnson (03:14)
But everything has to be taught, no matter the basics, no matter how basic it is, everything has to be taught. This is not like boiler the boiler industry is not like some other parts of life where people will just randomly pick it up. You know, if you go to high school and play football, they're probably not teaching you about football as in like what is football game, how many yards are in a football field?
Eric Johnson (03:43)
a hundred yards. Those are things that while they're not specifically taught like, hey, we need to sit down and learn about the game of football. People and kids at at that age will pick it up because they watch football, they experience football, they talk about football with others, and they're just around it. And those are things that they learn about the game. However, if you talk to somebody who has doesn't care about sports or maybe is outside of America,
Eric Johnson (04:12)
They wouldn't know anything about football because football is not a part of their world and I'm talking about American football. I know the football purest you know, soccer, what's soccer? But American football is not part of their world and therefore they don't know anything about it. They don't know what f the hundred yard field is or any of the rules or scoring behind it, and they have to be taught. So to the average American who likes sports, that'd be crazy not knowing what American football is.
Eric Johnson (04:42)
But once again, even though it's so popular, people are not born with American football knowledge, although it may seem like that if you are in America. So the easy topic today is the four water levels of a boiler. And you probably picked that up from the title. So I'm trying to get better with my titles. Sometimes I like to do some wild titles, but SEO, search engine optimization and the internet.
Eric Johnson (05:11)
Don't really like wild titles. So I'd try to describe what the topic is in the title. at least a little bit. But at the end of the day, I ain't getting rich and famous for boilers. So if I want to make a wild title for a podcast, I'm gonna do that because this is my podcast, Boiler Wild. Four levels in a boiler, and I wanna specifically say steam boiler. I will mention hydronic boiler.
Eric Johnson (05:36)
But this is specific for a steam boiler, and I'm thinking a full size process boiler. You could also do a heating boiler. If you are familiar with some cast iron boilers, some smaller boilers, they may not have four water levels. And this may be for any boiler. All of them may not have four defined water levels, but they're there to a point.
Eric Johnson (06:06)
let's start at the normal one. The normal operating water level. And this will be shortened to N O W L sometimes in writing, in P and IDs, in drawings. So that's what that means. Normal operating water level. N-O-W-L.
Eric Johnson (06:25)
Now you know, now you're smarter. But the normal operating water level is a water level that is set by the boiler manufacturer, and they have determined that this is the water level that the boiler is safe to run at. In a fire tube boiler, this is going to be about three to four inches above the top of the tubes. If we're talking about a Scotch Marine fire tube boiler.
Eric Johnson (06:51)
firebox boiler or an HRT boiler, they're fire tube boilers. once again, some the water level is gonna be somewhere above the top of the tubes, probably three or four inches as well, but I'm not a hundred percent on that. When I when whenever I think about fire tube boilers, I think about Scotch Marine boilers, but I wanna be careful in my assumptions because not all fire tube boilers are scotch marine boilers.
Eric Johnson (07:17)
So normal operating water level, this is the safe operating water level that boiler manufacturers have defined and they have set up on their boiler design. For a water tube boiler, I'm talking about a traditional water tube boiler, mud drum steam drum with tubes on the sides. The normal operating water level is gonna be somewhere in the top steam drum. And that is gonna be for most boilers.
Eric Johnson (07:46)
Water tube boilers will change here and there, especially the giant ones. But you are gonna have a water line somewhere in the top level of the steam drum. And that is where your sight glass and your water level controls are gonna be. And if you have water drop out of that top steam drum, you are going to have some issues. So that's your normal operating water level. You need to be mindful of where this water level is.
Eric Johnson (08:16)
Especially if you change your water level settings or however you get your water level. Traditionally, this is your low water cutoff will determine your water level, like where your feed water pumps fill up your boiler. But if you repipe a boiler, if you repipe the boiler trim, boiler trim is all the piping and stuff that is like bolted and attached to the boiler. If you re-
Eric Johnson (08:44)
pipe your boiler trim you have to make sure that the boiler is still operating at the normal operating water level or the safe water level that the boiler manufacturer has defined. If you don't know that go back to the drawings but it's gonna be in a Scotch marine boiler above the tubes probably three to four inches. It depends on every single boiler but three to four inches minimum next water level
Eric Johnson (09:12)
Water level number two is gonna be the low water.
Eric Johnson (09:18)
level or the primary low water level. And this is typically thought of as the primary low water cutoff level or the first low water cutoff. But this is gonna be the first level in the boiler or the first cutoff in the boiler that says, hey, the boiler water level is too low. We need to shut down the boiler
Eric Johnson (09:45)
It is going to become unsafe. Something is wrong. This is the level that is going to be below the normal operating water level. And it is still going to be above the top of the tubes because we want to keep the boiler pressure vessel and the tube safe. We obviously don't want to cause any damage, but the primary low water cutoff or the first low water cutoff, that is going to be
Eric Johnson (10:15)
Just below the normal operating water level. And by just below, I don't have a number for you. There's no set defined numbers with of the inches between these levels. It is all set up by the manufacturer. But they will be similar and around each other depending on the boiler designs. But each boiler design will be around each other of the differences between the levels. Then the third level is gonna be the
Eric Johnson (10:44)
Auxiliary low water cutoff or auxiliary low water or secondary low water. Those are two are the same thing. You have auxiliary or secondary are probably the two names that I would use for the secondary low water. And this is going to be the final water level before the top of the tubes or before the bottom of
Eric Johnson (11:10)
the mark in the steam drum where you can go too low in the steam drum on a water tube. But this is going to be where the boiler's gonna shut down and lock out and require a manual reset for steam boilers. If you are primarily working on hydronic boilers, not all of them have secondary or auxiliary there though it's the same thing.
Eric Johnson (11:35)
Secondary or auxiliary low water cutoffs, but sometimes a jurisdiction will require them to be installed. Typically, hydronic boilers will only have one low water cutoff, which will be the first low water cutoff or the primary low water cutoff. So I just want to make that distinction. But we are talking about steam boilers today, but just don't assume that every single boiler, it's it's a boiler, it must have two low water cutoffs because you may be searching for a little bit for the secondary low water cutoff on that hot water boiler.
Eric Johnson (12:05)
So the third water level is the auxiliary low water, and this is going to be the minimum water that the boiler manufacturer has set that is going to keep the boiler safe. But this is the last line of defense before we cause damage to the pressure vessel, before we cause overheating to the tubes. In a Scotch Marine boiler, this is going to be.
Eric Johnson (12:27)
Three inches above the tubes.
Eric Johnson (12:29)
If the normal water line is four to five inches above the tubes. So the whole difference between these is only going to be a couple inches in the water levels. But the auxiliary low water, just above the tubes, three inches. I know three inches of water doesn't seem like a lot, but in a boiler, it isn't really a lot, but in a boiler that's enough to still keep the tubes cool. However, that is also why you need to make sure that the boiler is sitting level.
Eric Johnson (12:58)
And this isn't so much of an issue with installations that are permanent as hopefully your concrete guy or your mechanical contractor is able to set up a level pad and level out the boiler front to back and left to right. But this is an issue with rental boilers. And sometimes you'll see on a rental boiler they'll stack wood under tires or they'll have to jack up the trailer.
Eric Johnson (13:26)
This is because they have to level the boiler or get the boiler at least close to level because if you do not have a level boiler, you could have plenty of water in the front and the front of the tubes could be covered at the tube sheet. But if you go to the back, 30 feet down at the end of the boiler, at the rear of the tube sheet, the water could be below the tops of the tubes and you will have damage to the tubes. So that is why you need to level your boiler and make sure that.
Eric Johnson (13:54)
If you are working on a rental boiler or a temporary boiler, you need to make sure it's level. And that should be one of the first things that your rental company or installation company should check. Pull out a level, check it. But just keep that in mind. Don't assume somebody else did their job correctly. You're there to keep yourself and others safe. So always be checking that your boiler is level and piped correctly. And I'm sure there's installations out there that are permanent where the boiler isn't leveled.
Eric Johnson (14:22)
And you can have issues. Always be mindful of where you're sensing the water level and do appropriate things in order to make sure that those things you're sensing the water level in the correct locations if the boiler is not perfectly level and you can't really fix it. I know everything's not perfect, but sometimes you
Eric Johnson (14:49)
just have to maybe move the level up in the boiler or adjust where you're sensing to make sure that you always have water up in the appropriate areas in the boiler. The fourth water level in a boiler is the high water level. And this one isn't required by code. If you look in CSD one, there's no mention of requirements for high water, which I think will change.
Eric Johnson (15:20)
And I don't this isn't inside information or anything, but it's interesting high water, how it's treated in the boiler industry. It is an optional add-on to most boilers, but if you run a boiler in high water or consistently have it in high water and you start it up, you can get water hammer in the header and
Eric Johnson (15:41)
you will or can cause issues with piping that can become dangerous and with water coming out of the boiler that can become dangerous. And I think high water level cutoff, which is above the normal water line or normal operating water level, I think they are a good idea, but they're not required as far as
Eric Johnson (16:10)
from like boiler safety. They may be required in your jur jurisdiction, always check with your jurisdiction. But from a general boiler safety, if a boiler is operating in high water, there's real no
Eric Johnson (16:23)
Issue with damaging the pressure vessel, it is more of damaging the system, damaging your steam piping, damaging your steam control valves due to wet steam, water droplets in the steam, and all that fun stuff. So if you have the option to include a high water cutoff or high water level sensing device on a boiler, I would do it if the customer is.
Eric Johnson (16:53)
gonna pay for it and the best ones they sometimes alarm s the high water level will alarm and then maybe shut down the boiler. Sometimes the high water level will just alarm and not shut down the boiler. But I think the best high water setups are the ones where I don't really care about the alarm. The alarm is fine. But ones that have an automatic valve and that they actually shut off the feed water because
Eric Johnson (17:20)
On a modulating feed water system, the ball valves will wear out and or whatever you're using, but typically it's a ball valve c connected to an actuator and they'll wear out and even though they're closed, the valve will be feeding through. And when the boiler's off and is being depressurized as it's cooling, it will keep feeding water into it. So you want a valve to close to a hundred percent isolation.
Eric Johnson (17:50)
So that you keep water from just keeping to go in the boiler. Because if you have a high water cutoff and that high water cutoff is just an alarm, if you have operators around, they will be able to tend to that alarm pretty quickly and be able to drain down the boiler. But if the operators are out doing everything else, because now boiler operators are basically just maintenance personnel and they're off doing real problems in instead of
Eric Johnson (18:18)
watching the boilers and making sure the boiler room is running safely, they are gonna come back to the boiler system and see that one of the boilers is in high water and then have to drain a ton of water out of it or there could have already been an issue with the boiler filling up and into the header space. So it all depends on what the boiler installation is, but if you have a open close valve that will actuate when you have
Eric Johnson (18:44)
the high water alarm, it will be able to close off that feed water. And it's essentially a secondary setup to making sure that feed water doesn't just keep leaking into the boiler when it shouldn't be leaking in. But if your boiler always has demand, typically it will stay at a good level. It's those in between periods and it's the plants that have multiple boilers and you're cycling between boilers. And maybe you have five boilers and only three of them have to run.
Eric Johnson (19:12)
And you're rotating in between those boilers. It's those off boilers where you're not closing the header valves and not isolating all the piping. That's when you're really gonna see high water, which becomes an issue for operators. So let's recap. We going from top to bottom in our boiler, we have high water level, we have normal operating water level, we have low water level or primary low water level.
Eric Johnson (19:41)
Depends on how you want to call it. Or some people just call it the low water level. And then the second one or the last one in our four water lines is our auxiliary low water cutoff or secondary low water cutoff or auxiliary low water. That is going to be the last water level before you reach the minimum point that the manufacturer has set. That is going to be
Eric Johnson (20:09)
where damage will occur to the pressure vessel, which we obviously don't want. If your boiler is constantly tripping on auxiliary low water, and if you if the water level is getting down to that, you know how you know where that water level is? You gotta look in your sight glass on a Scotch Marine boiler. And I think all boilers, but I'm not super well read on all the requirements of a
Eric Johnson (20:38)
water tube. I'm thinking larger water tube steam boiler. So chime in if I'm wrong. But I know on a Scotch Marine boiler at least. Because that's what I deal with. When I think of boiler, I think a Scotch Marine boiler. Those are the average ones. I'm not this person going around saying, if your boiler isn't 150,000 pounds an hour, that's not a real boiler. Well whatever. So Scotch Marine Boiler
Eric Johnson (21:08)
Lots of people work on Lots they're very common. Anywhere between a hundred horsepower and a thousand horsepower. I would say that's probably the most common boiler in the United States is Scotch Marine or even the vertical fire tube boiler for steam boilers.
Eric Johnson (21:24)
But if you look at the sight glass, the auxiliary low water, it has to trip or actuate, and that water level has to be below the water, exits the bottom of the sight glass. So the length of your sight glass on your boiler is actually critical. I know some people would love to have like a three foot-long sight glass, but that's not really necessary, but it's also
Eric Johnson (21:52)
wrong per the boiler codes because the boiler codes say that the bottom of the auxiliary low water cutoff or the secondary low water cutoff, that water level has to be before the water level exits the bottom of the sight glass. And if you had a three foot long sight glass, now that would be way, way down on the boiler and the boiler would have way too much metal exposed. That would be unsafe and dangerous.
Eric Johnson (22:21)
So that sight glass is actually a good length or required length that the boiler manufacturer has set up. So if you are modifying the length of your sight glass on your boiler, keep that in mind. They are probably set up the way they are for a reason. I'm not saying it's always correct if you're modifying it, but if you're modifying it from its original, do your homework. Ask the boiler manufacturer, and if anything, go back to the original boiler drawings.
Eric Johnson (22:50)
And the original specs of the boiler and see what the sight glass length was, and just copy that and do that same thing, and you'll be alright. So, repetition. Once again, we're about at the 25 minute mark, and then I'll let you guys go. We're girls. Appreciate the 10% girls listening. The top of the boiler on the steam boiler, high water cutoff. This is optional. Sometimes it can alarm and shut down the boiler. Sometimes it is just a personnel alarm.
Eric Johnson (23:18)
This one is optional. Then you have the normal operating water level. This one is in all steam boilers, and this is where the water should stay in the boiler for normal operation. It is in the name. Then we have the primary low water cutoff or first low water cutoff water level. That is going to be just below the normal operating water level. And that is going to be the first instance for the boiler to shut down when the water gets too low inside the boiler.
Eric Johnson (23:47)
Then we have the secondary low water cutoff or the auxiliary low water cutoff. And that is going to be the second instance for the boiler shut down or for the boiler to protect itself before the water level gets too blow, too far below, and you start exposing metal, which can overheat the tubes because you don't have water to pull away the heat from the metal. If you
Eric Johnson (24:14)
Don't know what I'm talking about when I say pulling heat away from the metal, try to burn or light. have a water bottle full of water about halfway and put a lighter on the bottom of it and you won't be able to burn the plastic. But if the water bottle was empty, it would start burning the plastic. Same thing happens in a boiler. If you always have water covering your metal surfaces that are supposed to be underwater, the water will always pull heat away, and that is essentially
Eric Johnson (24:43)
The boiler works because it transfers heat to the water, the water turns to steam, and then the steam moves up into the water because steam bubbles rise in the water and they will exit out of the water and then go into the steam space and then leave the boiler. So that is the four water levels of a steam boiler. Just note for your own sake, if you are a hydronics person, once again that
Eric Johnson (25:11)
The auxiliary low water cutoff or the secondary low water cutoff is not super common on a hot water boiler and it's not always required. A lot of jurisdictions do not require it, it is not normally required. It is more of a special requirement to require require it. And that is gonna be on the smaller, and I say smaller, you know, 10 million and down BTU hot water boilers. If you have a really big hot water boiler, it probably will have two low water cutoffs.
Eric Johnson (25:41)
But don't be surprised if it doesn't. And on a hot water boiler, there obviously isn't going to be a high water because a hot water boiler is flooded. There is no water line. So there's no operating water level or normal water line. The normal water line is boiler is completely full, so you obviously can't have high water. Otherwise hot water boiler wouldn't work. You'd have air in the system. So that's all I have today. That's
Eric Johnson (26:08)
I know I've been slacking on these podcasts. You know, write write me some hate mail. I wanna hear it because I I just haven't been I've been busy. I lost my my voice for a week and I couldn't record and it's just I I fall I've I almost fell apart in August. But I'm back. Better than ever. We're gonna close out August. Great. Like we always do. Always bounce back.
Eric Johnson (26:37)
That I'll I will try to do better, even though I've said I've tried to do better multiple times when I've had some absences of the Boiler Wild podcast. But I am trudging along, trying to educate you all. I appreciate everybody once again who reaches out. If you have anything positive to say, or even some hate mail, that's fine too. But if you have anything positive to say, please
Eric Johnson (27:01)
Send me an email, E-R-I-C period, J O H N S O N at Boilearn B-O-I-L-E-A-R-N.com, Eric.johnson at boilearn.com or send me a DM on LinkedIn. That works too. Connect with me on LinkedIn. I appreciate you all for listening and stay wild.
