Eric Johnson (00:00)
gonna be talking about safety shutoff valves today. Welcome back to Boiler Wild. My name is Eric Johnson. On this podcast we talk about boilers, the boiler industry, personal development, getting better because that is the goal of life. Get better, enjoy your life, do the things you want, but the only way to do that is to set goals for yourself. One of the goals I have for myself is to
Eric Johnson (00:26)
Be able to teach more people about boilers. So that's why I'm doing this podcast teaching you about boilers. And we're gonna learn about safety shutoff valves and it's gonna be a little bit more in-depth conversation around safety shutoff valves and valve proving and event valve and some requirements around it. So let's get into it. But first things first, if you haven't already
Eric Johnson (00:51)
Please rate the podcast five stars. That really helps me and helps other people find the podcast. This is free. I don't get paid to do this. Don't have any sponsors. I don't want any sponsors. I hate sponsor ads. Whenever I listen to a podcast that has sponsor ads, I absolutely hate it. I gotta skip through It is the worst thing ever. some of the podcasts, they are, you know,
Eric Johnson (01:16)
multimillionaires and I'm listening to some ad about some health green supplements, whatever. I'm like, you you don't need to do this. This sucks. But I guess I'm probably the idiot for not monetizing every single second of my life. And that's why they're a millionaire and I'm not. So let's talk about safety shutoff valves. And this is specifically I'm gonna be talking about gas safety shutoff valves and this
Eric Johnson (01:42)
Also kind of applies to oil safety shutoff valves, but
Eric Johnson (01:48)
This is just gonna be about gas safety shutoff valves. Cause that's what I pulled up on my notes. That's what I prepared for. So let's get into it. So, what is a safety shutoff valve? And I'm big on terminology. So a lot of people will call things different things, which is okay, but I always strive and whenever I teach people or whoever I work with.
Eric Johnson (02:17)
I always strive to use the correct terminology because if you don't use the correct terminology and you just call things whatever you want, or you call things by their street name, and by street name I would mean like there's some stuff that the they have a technical term, but then it may be referred to by an informal term. I would always try to avoid the informal term because
Eric Johnson (02:46)
You are talking to a customer or you're writing a report, you always want to use the technical most correct name. like a safety shutoff valve, you can use gas valve, that's fine. That's assuming that you are shutting off gas. So I I I I wouldn't use gas valve for an oil valve. So oil valve, once again, you'd be shutting off oil.
Eric Johnson (03:13)
So CSD1 defines it as a fast closing valve that automatically and completely shuts off the fuel supply in response to a normal and safety shutdown signal. And then NFPA 85 defines this safety shutoff valve as an automatic fast closing valve that shuts off the gaseous or liquid fuel supply in response.
Eric Johnson (03:35)
To a shutdown or trip signal. So safety shutoff valve, that is the most proper term. And you can use gas safety shutoff valve or oil safety shutoff valve. That is just specifying the medium that you are shutting off. But if you just want to use a normal blanket term, that'd be safety shutoff valve. And I will mention this.
Eric Johnson (04:01)
Most safety shutout valves have two parts. One of them have a valve body, and then the the other part is the actuator. So you'll see this with the Siemens SKP series valves. You'll see this with the Honeywell valves with the Asco valves.
Eric Johnson (04:27)
You will have the the fluid powered valve. So the Honeywell I blanket on the mound number, but the the Honeywell s it's V something. But they have a fluid in them. They're fluid powered valves. And the the rectangular squares shape thing is the actuator. And then there's two little set screws on it and it gets attached to the valve body.
Eric Johnson (04:57)
So when you are talking about a safety shutoff valve, you are talking about that entire assembly, the actuator and the valve body that the spring and the seat is in, that the medium actually flows through. But if you were to say, hey, I'm gonna sh replace that safety shutoff valve, I would assume that you are replacing the actuator and the valve body.
Eric Johnson (05:23)
But you can just order the valve body and you can just order the actuator. But don't say I'm gonna replace the safety shutoff valve and then only replace the actuator or only replace the valve body because I believe that the per the definition that the safety shutoff valve is the entire assembly. But typically once again that assembly is two parts. Going back to that Siemens SKP series.
Eric Johnson (05:51)
So typically you'll see the very famous SKP 15 and then the SKP twenty-five, the two actuators on the single valve body block. That is very, very common. But so that's two actuators. They're independent actuators, but then they have one valve body block. It's got two valve seats in it, but it's one block, so it's very, very tight, and you can have a very small gastrain.
Eric Johnson (06:21)
And a lot of components in a very tight area. And that's why a lot of people use that. It's also very economical, very parts are easy to get for it well in stock. So that's safety shutoff valves. So there are some requirements. If you've worked on a number of different size boilers, you will have seen a boiler with one safety shutoff valve, and then you'll see a boiler with two safety shutoff valves.
Eric Johnson (06:48)
And then you'll see a boiler with proof of closure in the safety shutoff valve. And you may be wondering to yourself, one is one required, when is the other one required? Well, let's let's get into it. And I will preface this that I'm going off CSD one 2024 and MFPA 85 2023, but also not every boiler is built to CSD one or NFPA 85.
Eric Johnson (07:17)
So those are two specific categories, the CSD one standard and the N F P A eighty five code. But if you're not in a state that regulates and enforces CSD one, most states I believe enforce NFPA eighty five, but not all states enforce C C S D one and have adopted it. So always check your local jurisdiction. I say states, I I should correct myself, it's jurisdiction.
Eric Johnson (07:46)
Always check your local jurisdiction on what they require, but I'm just going off the two CSD1 and MFP 85 since those are the most popular and most common. So inputs less than five million BTUs per hour. The main burner supply shall be equipped at least two safety shutoff valves in series or one safety shutoff valve with a proof of closure interlock function.
Eric Johnson (08:14)
So less than five million BTUs. You are going to have two safety shutoff valves in series. So that's going to be actuator and body, actuator and body. So once again, sit that's the whole safety shutoff valve assembly. That's the fast closing valve that automatically and completely sh shuts down the fuel supply in response to a normal and safety shutdown signal. Or you can have one of them.
Eric Johnson (08:41)
But it has to have a proof of closure interlocked. And that is typically shortened to just POC on a drawing or like a wiring diagram. How do you know that there is a proof of closure interlock? Well, you have to either look inside the valve actuator or you have to look at the model number, and the model number will say.
Eric Johnson (09:11)
The what it has. Typically, the proof of closure interlock cannot be added after you buy a valve actuator. So make sure you are ordering the correct valve actuator. Two valve actuators or safety shutoff valve assemblies can look identical, but they can have different model numbers. Also, you got to be careful, some valve bodies are meant for proof of closures, other are not.
Eric Johnson (09:39)
So make sure that you are ordering the correct parts before you find out that you need one with proof of closure or one without proof of closure. But once again, recap any boiler under five million BTUs per hour per CSD one twenty twenty-four, you can have two safety shutoff valves in series or you can have one safety shutoff valve with a proof of closure interlock. Typically manufacturers will just put
Eric Johnson (10:09)
The one safety shutoff valve with the proof of closure interlock, if they have no other requirements or input, because it is just cheaper than two safety shutoff valves and it takes up less space. I don't think there's any other reason for that. So then inputs over five million BTUs per hour to twelve and a half million BTUs per hour. So a little recap backstory, CSD one.
Eric Johnson (10:37)
Only goes up to 12.5 million BTUs per hour. So if you have a boiler that is larger than 12.5 million BTUs per hour, you're gonna be looking at NFPA 85. So that is why that cutoff is there. But 5 million BTUs per hour to 12 and a half million BTUs per hour. The main burner supply shall be equipped with at least two safety shutoff valves in series and one of the safety shutoff valve.
Eric Johnson (11:07)
Shall have a proof of closure interlock function. And this is normally the downstream valve assembly that is closest to the burner, but it that is not a requirement. So the five million to twelve and a half million, you need two safety shot valves, and one of them has to have proof of closure. So if you're ordering a gas train for a new boiler or you're gonna put a burner on.
Eric Johnson (11:37)
You would be ordering a valve assembly without proof of closure and you would be ordering a valve assembly with proof of closure in order to
Eric Johnson (11:48)
satisfy that requirement.
Eric Johnson (11:49)
So if you walk up to a boiler and you only see one gas valve, it is either piped wrong or the input is less than five million BTUs per hour. But typically manufacturers know what they're doing, burner manufacturers know what they're doing. And I have never seen a gas train piped wrong from the factory.
Eric Johnson (12:17)
or pipe drawing from how you order it. It is typically maybe you have old equipment that hasn't caught up to current codes. So you'll have you can do a gap analysis. But when I was always starting off, I always wondered why there were two safety shutoff valves on some boilers.
Eric Johnson (12:43)
Or one safety shutoff valve on another boiler, or why proof of closure was randomly on a valve assembly and why it wasn't on other valve assemblies, because it seems like proof of closure you would always want to have, and why only one of them had one valve assembly had proof of closure versus the other valve assemblies that didn't have proof of closure. And I am just stating the bare minimum. So for CSD one.
Eric Johnson (13:12)
The five million BTUs per hour to twelve and a half million BTUs per hour. So you have to have two safety shutoff valves in series, and then one of them has to have proof of closure. And if you say, hey, we're just gonna order two of the same model number valve assemblies and we're just gonna wire the proof of closure in series, you do that. That is totally fine. You are going above the code and
Eric Johnson (13:37)
There's nothing wrong with that. It's just not required. Sometimes it is easier to just stock, you know, if you were to stock the one part number, you can just order stock of the proof of closure valve assemblies. Yeah, you're gonna pay an extra a hundred fifty dollars or whatever for the proof of closure function, but it's just a switch and it doesn't have to be wired. The
Eric Johnson (14:03)
Safety shutoff valve assembly is still going to work even if you don't wire the proof of closure. But if you have a safety shutoff valve and you need proof of closure and it's not part of it, very rarely can you add it. I believe, Honeywell, the hydro motors, you can add it, but don't quote me on that. And I also believe that they're the valve body is different versus
Eric Johnson (14:33)
the proof of closure ones versus the ones that are not. But I need to look that up. I did not prep prep that. But that is the details in the weeds. You don't really need to know that. You just need to make sure that you are ordering the correct model number for what you need. And if you're only wanting to stock one, you just order the proof of closure ones. And if you don't need proof of closure, you just don't wire the switch.
Eric Johnson (15:01)
I should. I forgot to go into it, but I don't want to assume that you all know. So the proof of closure switch is a typically it's a little finger switch, but it is a little I don't want to say sensor because typically it's a mechanical thing, but it's typically a little metal finger switch that senses where the valve seat of the valve body is.
Eric Johnson (15:27)
So when the actuator pushes down against a spring and opens up the valve, when the actuator isn't powered, that's that spring is going to push back up on that seat, and that seat could get stuck in the down position, it could get jammed, it could get corroded and stay open. And if that seat doesn't come up and hit the proof of closure switch.
Eric Johnson (15:52)
And change the position of the proof of closure switch, the burner is going to alarm because the burner thinks it has a open gas valve when it shouldn't be open, and you will get a proof of closure alarm. And it should just alarm constantly.
Eric Johnson (16:19)
I don't want to say gas valves, trying to be correct. safety shutoff valves cycle a lot. The proof of closure switch can they're typically very economical micro switches. They can fail to make or they get out of alignment and there's typically you can't really adjust them, so you just have to replace.
Eric Johnson (16:41)
The either the proof of closure switch, sometimes they're replaceable, most times you just have to replace the entire valve actuator. But you will walk up to the boiler, it'll be an alarm, you'll press the reset, and it'll instantly alarm again. It won't go into pre-purge. And because it thinks the the burner system thinks that the proof of closure or the you have a safety shutoff valve with the valve seat open, and if you had that.
Eric Johnson (17:08)
With both valves, or if you had a boiler with less than 5 million BTUs per hour and it just had the one. If it was open, you would have gas going into your combustion chamber when the boiler is off, and that is obviously bad. So proof of closure, it is a electrical switch that senses when the seat of the valve body is closed. You typically cannot order.
Eric Johnson (17:37)
A proof of closure switch to be added to a valve actuator. So always make sure you are ordering the correct valve actuator and the correct valve body if the valve bodies change for valve actuators with proof of closure versus ones that without proof of closure. Alright. Quick recap.
Eric Johnson (18:00)
Repetition is the best form of learning. So when somebody asks you CSD one requirements, what do you what do you need for gas valves? Five million BTUs and down, two safety shot valves in series, or one safety shutoff valve with proof of closure interlock. Five million BTUs to twelve and a half million BTUs, two safety shutoff valves in series.
Eric Johnson (18:26)
And only one has to have a proof of closure interlock. If you want to do two proof of closure interlocks, you go for it. That's on you. There's nothing wrong with that. But the minimum is one. So the next time you go work on a boiler, go look at the safety shutoff valves, specifically the gas safety shutoff valves. This is what I'm talking about. The gas safety shutoff valves. And typically you'll see two. But if you have a smaller boiler, less than five million beat to use.
Eric Johnson (18:56)
per hour and you only see one, you now know, hey, if I open that up, there should be a proof of closure interlock, assuming that the boiler complies with the CSD1 requirements. Once again, this is just for CSD1 and NFPA 85. If your jurisdiction hasn't adopted this or you have more stringent requirements, you're gonna have different requirements, but these are just the two most common ones.
Eric Johnson (19:24)
for most jurisdictions. So NFPA eighty five requirements. So this is gonna be burners greater than twelve and a half million BTUs per hour. so you need two safety shot valves in series, each with a proof of closure switch.
Eric Johnson (19:39)
This is different than the CSD1 requirements as only one of the safety shot valves is is required to have a proof of closure switch. So NFPA differs than CSD1 is both of them now need to have the proof of closure. So if you were just ordering valve actuators and you just wanted to order all of them with proof of closure and you had a boiler that is bigger than twelve and a half million B2 input.
Eric Johnson (20:07)
You would be fine because now you have the correct valve actuators and valve bodies for the proof of closure to be wired in both switches, whereas in CSC one you only would need it in one. But it's all about simplicity and the extra little cost of having a proof of closure switch versus having to stock two part numbers and have multiple part numbers of valve bodies and
Eric Johnson (20:35)
everything can add a little complication. But you would be prepared for FPA eighty five, twelve and a half million BTUs per hour, boilers and greater. So two valve bodies, both of them are required to have proof of closure interlock. So they're going to typically be wired in series and a series circuit if you don't know is kind of like a daisy chain. A
Eric Johnson (21:04)
like Christmas lights one after the other. So the wire is going to come off the burner control or the flame safeguard or the PLC. Depends on your setup. Depends on the burner. And it is going to go into the into the first proof of closure closure switch. And then out of the other the other terminal of the proof of closure switch, it is going to go into the
Eric Johnson (21:31)
The second proof of closure switch, and then out of that terminal, it is going to go back to the burner control. And the burner control, anytime that the boiler is in the off or standby, or pre-purge or post-purge or even pilot functions, the proof of closure switches that it should see voltage back on the terminal. If one of those switches open, it it's gonna cut off voltage.
Eric Johnson (22:00)
And it is instantly going to stop an alarm because the
Eric Johnson (22:05)
Burner control thinks that one or both of the valve bodies is open and you do not want to try ignition when your gas valves are supposedly open. It doesn't know any better. Typically, once again, proof of closure switches will alarm you'll you'll get a service call or you'll have issues with them. They'll alarm just because they're wore out and they're not making anymore. Don't try to like
Eric Johnson (22:31)
bend the switch or do whatever, like replace it. It is a safety component. It is there's no repair there. If if the valve manufacturer says you can replace the switch and you can buy a switch, do that. But don't bend the finger of the switch. Don't try to bend or add something to the finger of the switch. it just needs to make a little bit more. No.
Eric Johnson (23:01)
It is a safety system. Do not touch it. You are just going to replace it.
Eric Johnson (23:07)
One time I can think of a service call that I went to. It was a little after hours. It was later in the day. I wouldn't say after hours, maybe four PM. And I went with somebody else and I walked in and the it was a fire tube boiler, probably 150 horsepower. It had a honeyball 7800 and the other person I was working with was New Er, New Ish.
Eric Johnson (23:37)
Only been around boilers a couple years and they pressed the reset and instantly the boiler went back into alarm. And they typically were used to pressing the reset and having the boiler try to start. But in this case it instantly went back into alarm. And I I forget what Honeywell shows on the screen, but I I knew j just because of how fast it alarmed that it was a proof of closure.
Eric Johnson (24:07)
issue and I had them take off the cover of the second safety shutoff valve and these were Honeywell fluid powered valves and we found the switch, played around with the switch a little bit and the boiler would start. We replaced the valve actuator because that is the correct thing to do.
Eric Johnson (24:29)
But we just wanted to make sure that that was the issue and that there wasn't other issues outside of that. But the person I was working with was like, How'd you know that? How how'd you know to go right to that valve actuator and that that was the issue? I'm like, Well, experience, but two, I understand what a proof of closure switch is and that
Eric Johnson (24:51)
When I have a Honeywell 7800, the blue burner control, probably the most famous flame safeguard burner control out there, it instantly alarms and will not even go to pre-purge. And if you press the alarm or reset alarm and it just alarms again, there is a pre ignition interlock. I think I believe that's what it says. Pre ignition interlock. And that is typically the proof of closure circuit. And
Eric Johnson (25:21)
Knowing from experience, if you only have one proof of closure switch, it's typically the downstream safety shot of valve that is closest to the burner. So you take that off and you check out the switch with your multimeter. You put it on voltage, and if you have voltage across the switch, that means the switch is open, even though it's supposed to be closed when the burner is off. So that's how I know, and that is how you get good. You
Eric Johnson (25:47)
You learn these little tricks, you learn these little things by listening to the Boiler Wild podcast. But you can impress customers, you can impress other people you work with by not hunting and pecking for problems. but this is what comes with the territory of understanding why things are the way they are and how things work, and understanding why a proof of closure switch is there and why.
Eric Johnson (26:16)
the switch exists and when you will see the switches can greatly help your troubleshooting and understanding of boiler systems and gas trains. And you can troubleshoot proof of closure issues very, very quickly or at least get close to the issue without hunting and packing and look at the manual and doing all this stuff because you listen to the Boiler Wild podcasts. And that is the whole goal.
Eric Johnson (26:44)
I want you guys to be educated. And if you are experienced, you probably already know all this stuff, but I appreciate you listening as well. The the best people out there that are know it all, even they are students of the industry. I always strive to learn things. So always be learning. That is a great mindset to have. So let's get back to it.
Eric Johnson (27:09)
So along with the two safety shutoff valves that each have to have proof of closure, one of the following also needs to be added: an automatic vent valve between the safety shutoff valves or a valve proving system. You can have both if you want to have a vent valve and a valve proving system, but only one is required. The vent valve is more common to see as it requires less parts and complexity in the burner system. So what is a vent valve?
Eric Johnson (27:38)
The vent valve is a normally open power closed valve piped between the two safety shutout valves and is vented to a safe point of discharge.
Eric Johnson (27:46)
So typically this is going to be a Asco solenoid valve, although it doesn't have to be. But the biggest trip-up is this is a normally open power closed valve. So if you have two ASCO solenoid valves on the shelf, and if you have ASCO solenoid valves as your safety shutoff valves, a uninformed person will pick up the valve and say,
Eric Johnson (28:16)
This is what we need to replace that safety shutoff valve, and they'll replace it, and then the valve will be open when the boiler is in standby, and it will be closed when the boiler is in the gas phase, and then you will figure out really quickly that it is not the correct valve. But typically, what happens is the vent valve gets replaced with a normally closed valve.
Eric Johnson (28:46)
valve and how a vent valve works is it is normally open so it's gonna be not powered on standby and pre-purge and probably pilot as well depending on how things are wired and where your vent valve is if it's on the main between the two main valves or sometimes you can have a vent valve on your pilot
Eric Johnson (29:15)
But I'm talking about the two main safety shutoff valves, which is gonna be your largest pipe, your pilot pipe is gonna be your smaller pipe on your gas train.
Eric Johnson (29:24)
So when you go to the main trial for ignition, the valve will get power and if the valve is normally closed, it's gonna open. So the boiler will still light, you'll probably have a a lean flame and if you're not careful, some contractor will come out there and they will tune it for the vent valve being open and
Eric Johnson (29:49)
The gas bill will shoot through the roof. But if the facility is large and they don't really keep track of things real well, which is very common, they won't know the difference and you can pay for pumping gas right out of the roof and not know the difference. So if you're gonna be replacing a vent valve, make sure you are ordering the correct valve. It is a normally open valve.
Eric Johnson (30:19)
Valve, not a normally closed valve like most solenoid valves you would find off the shelf are normally open, power closed, vent valve. That is also an indicator. This is why when you walk into the boiler room and your customers having issues or somebody previously worked on the boiler, this is the observation phase of walking in. Once again, we don't want to just get right on the tools, we want to observe. And you were looking at anything brand new.
Eric Johnson (30:46)
Where's my brand new pipe dope? Where are the are there tools laying around? Are there electrical boxes open? Does it look like somebody just replaced something? And if you have that normal industrial grime, the brown, gray dust over everything, and all of a sudden you see this brand new Asco solenoid valve for the vent valve with some brand new pipe dope and tape on the vent valve line. You know, you got the green.
Eric Johnson (31:15)
So annoyed that the silver is shining off the aluminum body, yet everything is covered in the dust, and the customer's saying that they're having issues, or we just need to tune our boiler because it doesn't seem to be lighting all the time. That is a symptom in that case because you would instantly go, Okay, is that the correct valve for a vent valve? And in my experience, a lot of people
Eric Johnson (31:43)
a general maintenance person will not check or will not know the difference. They just go into the parts shelves and they pull off a valve and they go, this is like for like because they look alike. Well, that's that's not what the listeners of BoilerWild do. listeners of Boiler Wild actually check the model numbers and make sure that the valves have the same function because they understand that two valves or valve assemblies can have two different functions.
Eric Johnson (32:11)
and to not look at the
Eric Johnson (32:14)
Looks of the assembly and we want to check it against the manufacturer's data and the model numbers. So that that has happened to me. I've seen that. I've had people replace vent valves with normally closed valves, and it just doesn't work out well. And it defeats the purpose of a vent valve. The vent valve, I don't believe I said the purpose, but it is just in case your
Eric Johnson (32:44)
First safety shutoff valve is leaking, it will vent the gas to the atmosphere. So you have two safety shutoff valves in series. If the first one t were to leak, it would vent any gas that came in between the two safety shutoff valves to atmosphere. And this would be in exchange of or to prevent If the the second safety shutoff valve in series were leaking, then you would be.
Eric Johnson (33:11)
leaking gas into the combustion chamber, which wouldn't be good. So that is the theory of the vent valve. Do they work? Yes, how effective that are they? I am not sure. I don't want to say that they're not effective or that they don't work. But typically I've seen more issues with vent valves being incorrectly applied or leaking.
Eric Johnson (33:37)
even if you have a correct vent valve, one that is nor normally open, power closed, they can start leaking at the valve C and people don't check them. So when the boiler is on, you could still be dumping some gas out of the vent valve line to the atmosphere, which is hopefully outside. But it is a requirement of NFPA eighty five. So you will typically see it on most boilers over twelve and a half million or
Eric Johnson (34:07)
You can have a valve proving system. So a valve proving system is an automatic system that proves the valve seat integrity of safety shutout valves in series by detecting a leak, which indicates a failure of the valve seat seal and prevents the main burner or igniter light off if the test is not satisfied. So what is valve proving? This is gonna be a system that you may see if you have a valve proving system,
Eric Johnson (34:36)
you'll notice an extra either pressure sensor or you'll have a pressure switch in between the two safety shutoff valves. I am going to read from the Honeywell valve proving system from the manual on how it works. This is just for Honeywell. They all work in the same way but how they sense the pressure between the valves
Eric Johnson (35:03)
and how it in the minute details will change from Honeywell to Siemens to FireEye, but they all work generally the same. So the Honeywell seventy eight hundred will have input to terminal seven for the valve testing. So it needs to have power.
Eric Johnson (35:28)
And you are going to program the Honeywell 7800 for when you want the valve test. So it's either going to be before or after the sequence. So before pre-purge or after a run cycle. So after post-purge, you can have a test or you can have it both times. NFPA 85 recommends after, but
Eric Johnson (35:54)
Typically I've seen it happen before. So you'll get a call for heat on the boiler and you'll see valve proving and the honeywell will be cycling the valves and going through its
Eric Johnson (36:07)
steps or any other system will be cycling the valves going through its steps and this is just a sl small delay on the boiler starting and if you're not familiar with a valve proving system you may be wondering what's taking so long but typically you will see that something is happening and that the display will be showing valve proving and that it'll be doing something
Eric Johnson (36:34)
And you just kind of have to stand there and watch it. So if you are totally in the dark about what valve proving is, you just are kind of confused for about thirty seconds to a minute, and then the boiler will start, you'll hear the f the fan start, and you'll just be like, that that's weird. I typically don't see that. the valve proving system is less common than having a vent valve installed just because it costs a little bit more.
Eric Johnson (37:01)
And a little bit more wiring, it's another pressure sensor or another pressure switch. And you gotta make sure that your flame safeguard or burner system has valve proving. Most of them do, it's just not enabled, but don't assume that it has valve proving. But going back to the steps, so that's step one.
Eric Johnson (37:24)
So then main valve two will be commanded open. Main valve two is the downstream valve closest to the burner. So main valve two is commanded open while main valve one remains closed to depressurize the space. So we're going to be depressurizing the space between the two safety shot valves in series. And then after four seconds, the main valve two is commanded closed again. So this can s kind of freak.
Eric Johnson (37:51)
new people out they'll see the gas valve open when the burner is off. This is valve proving and that is totally normal. So don't freak out when you see that. So the second valve in the in the series will open to let the pressure that has built up in between the two spaces if it has built up, let that out. it is not that much
Eric Johnson (38:18)
pressure or gas volume, so letting that out down main valve two and it'll go down the downstream pipe. And if there is any gas, it'll get pushed out in the pre-purge period, but it is a very, very small amount of gas. So it's not really seen as a safety issue. Then there's a three second delay during which the valve proving pressure switch is ignored and then
Eric Johnson (38:45)
After the valve proving pressure switch, which is the pressure switch between the two safety shutoff valves in series. So we're gonna go between them, and that is the area that we just made sure had no pressure. That valve proving pressure switch is monitored for the duration of the valve proving test time. And if it turns on, aka the pressure switch changes.
Eric Johnson (39:09)
State the valve proofing system will know that main valve one or the first safety shutoff valve in the series is leaking. And if it changes state, a lockout occurs because the gas pressure has increased due to a leaky upstream valve. So then main valve one is commanded to be open while main valve two remains closed to pressurize the space after four seconds. Main valve one is commanded closed again.
Eric Johnson (39:35)
So now we have two safety shut off valves in series, but we have pressure between the space, and then there'll be a slight delay for the valve proving switch, but then the valve proving switch is monitored for the duration of the valve proving test time. And if the switch changes state, so it'd be a drop in gas pressure, it no the valve proving system would assume that the
Eric Johnson (40:05)
Downstream or main valve two is leaking and because it can't hold pressure between the two valves and it would lock out. So that is how valve proving works. That is general for Honeywell, but most of them work that way. Not all of them will use a pressure switch. Some of the systems will use a pressure sensor and
Eric Johnson (40:32)
They'll just read the pressure between them. You can also have a bolt-on valve proving system where it won't use the gas pressure or the fuel pressure. It will have a little pump in the bolt-on system and the pump will pump up between the valves. That is a little less common. I don't see that all the time. Typically, you'll just use the pressure of the fuel and you'll cycle the
Eric Johnson (41:01)
main valve one and main valve two to move the pressure around between the valves or get the pressure out of out of between the valves. But that is what valve proving is. if you want to look at it more, look up the Honeywell seventy eight hundred valve proving system or read about valve proving on any other system. They're all going to be generally the same. But that's what it is. It is very, very simple,
Eric Johnson (41:25)
The whole point of valve proving is to make sure and try to ensure that you have the valve seats closed on your two safety shutoff valves and that they do not leak more than the allowed amount of leakage. There is a leakage rate depending on the valve bodies that you use. So they are not always a hundred percent bubble tight.
Eric Johnson (41:52)
There is a leakage rate, so look at the manufacturer. Don't be surprised when you bubble test a safety shutoff valve. If there is a couple bubbles coming out, you have to check the leakage rate per the manufacturer and see if the leakage rate is above or below the amount. I also know if you have a new maxon safety shutoff valve, typically they recommend you break in the valves by cycling the valves. I believe it's
Eric Johnson (42:22)
fifty times open closed and that breaks it in and a new valve will sometimes have leakage and you'll think that the valve is bad. Cycle the valve fifty times and it'll break the valve in and now you won't have leakage or you'll have below the the leakage rate.
Eric Johnson (42:40)
So once again, going back to NFP 85, you either have to have an automatic vent valve, which is going to be your normally open power closed valve. Typically, that's a solenoid valve. It doesn't have to be, though. They just typically do that for cost. A solenoid valve is cheaper than a fluid-powered valve. Or you can have a valve proving system, or you can have both.
Eric Johnson (43:08)
Both is not required, but I have seen it, and you gotta make sure that your vent valve is working correctly. Because on the second part of the valve proving system, if your vent valve is not working correctly and it leaks, you're not going to be able to build up pressure between the main valve one and main valve two, the two safety shutoff valves, because the pressure will leak out of the vent valve and it will assume that the main valve two is leaking and the valve proving will fail.
Eric Johnson (43:36)
But you don't have to have both. Sometimes you can have both. I don't know why people put both. I am not a fan of putting vent valves if they're not required. It's a lot of piping. It's a lot it's another hassle. And you gotta run that vent. You can't combine the vent with a regulator vent. And you gotta run it to the outside, which can be a hassle on some systems where the boiler isn't close to the outside. It's just more complicated to
Eric Johnson (44:03)
fail. Always try to reduce complication. That is my view, but you gotta do what you gotta do or you gotta do what your jurisdiction wants. And vent valves are commonly put in when they're not required, be due to insurance reasons. There's also insurance requirements, FM requirements. I won't go into that, but FPA requirements
Eric Johnson (44:27)
12 and a half million BTUs or more, two safety shutoff valves, both have proof of closure. And you either need a vent valve between the safety shutoff valves or you need to have a valve proving system. And you will know that you'll have a valve proving system when you have a pressure sensor or pressure switch installed between the two safety shutoff valves. This will be in addition to the low gas pressure switch that will be on the upstream side, typically on the upstream side of the safety shutoff valve.
Eric Johnson (44:56)
One and then the high gas pressure switch that will typically be on the downstream side of the C shutoff valve two.
Eric Johnson (45:04)
Just last thing to note, and I briefly mentioned it, vent valve lines are different than regulator vent lines. NFP 85 defines vent valve as valve used to allow venting of air and gas from the system to the atmosphere. NFP 85 does not allow the combination of vent valves from different boilers together and then running the vent piping to a safe location. So if you have a vent valve on a boiler, you can combine
Eric Johnson (45:31)
the pilot vent valve and the main vent valve on the boiler, but then you have to run you have to upsize the line and then you have to run that line to to the outside. Typically I see vent valves combined with regulator vents, that is incorrect. but really all you can do is just write them up.
Eric Johnson (45:55)
A lot of inspectors don't know that it's incorrect or don't care that it's incorrect. How do how do you tell a customer that it's incorrect when their boiler's fifteen years old and it's been inspected every year? And you say, Hey, this is really incorrect. You need to spend four thousand dollars rerunning another line all the way to the outside over two hundred feet or w whatever. Are they gonna listen to you? Probably not, unless they're boiler inspector or insurance inspector or whoever.
Eric Johnson (46:23)
says hey this is incorrect this needs to be changed but that's why we as BoilerWild listeners don't assume things are correct when we walk into a boiler room just because it's been like that. We always are observant, we always look for problems and we are always trying to strive to be better. So I hope you learned something about about safety shutoff valves, proof of closure, vent valves or valve proving systems.
Eric Johnson (46:50)
Or something about CSC one and NFP eighty five, the difference between why there's one valve sometimes on a burner versus two and why proof of closures required or not required to be installed on your valve actuator. Thank you for listening. I appreciate you all. Please rate the podcast five stars and stay wild.
