Boiler emergency e-stop

[JeremyJones]

I have a boiler with a 20amp disconnect switch. The owner wants to add 2 mushroom head E-stops. If there is no e-stop terminals in the boilers control panel whats the best way going about this?

 

[SheffSimon]

I have a boiler with a 20amp disconnect switch. The owner wants to add 2 mushroom head E-stops. If there is no e-stop terminals in the boilers control panel whats the best way going about this?

Whats the reason behind wanting some estop pushbuttons?

If there is a genuine need highlighted by a risk assessment, then a method of removing the power from the boiler by means of a contactor might be suitable, or an emergency gas shut off valve. The design requirements all depend on the level of reliability required to put the boiler into a safe state. Whatever gets done, if its done properly, it will be more complicated than adding a couple of pushbuttons. And the responsibility will be yours as the designer, in the event of a accident.

You could just wire the buttons in series with the thermostat, or whatever fires the boiler. They won't be emergency stop pushbuttons in that case.

 

[Darkwood]

Are we talking a commercial or industrial boiler here?
As above - what warrants E-stop system for a boiler, is there a perceived danger trying to be averted here and what does the risk assessment classify the cat' of E-Stop system needed if any.

Let's just clarify here that the actuators usually used for E-Stops are not E-Stops unless the control system has an E-Stop system in place, even the twist release etc can only be called functional stops regardless of what they look like if the controls behind them are not designed around a suitable E-Stop system that would comply for the situation.

 

[JeremyJones]

Are we talking a commercial or industrial boiler here?
As above - what warrants E-stop system for a boiler, is there a perceived danger trying to be averted here and what does the risk assessment classify the cat' of E-Stop system needed if any.

Let's just clarify here that the actuators usually used for E-Stops are not E-Stops unless the control system has an E-Stop system in place, even the twist release etc can only be called functional stops regardless of what they look like if the controls behind them are not designed around a suitable E-Stop system that would comply for the situation.

It's a boiler at a commercial building for infloor heat.

 

[Spoon]

It's a boiler at a commercial building for infloor heat.

As above, so why have they requested an E-stop?

Oh, and welcome to the forum mate.

 

[JeremyJones]

As above, so why have they requested an E-stop?

I have no idea... it has a 20amp disconnect switch already. But there's 2 doorways they want the e-stops by. The best way I can think of is have it all in series with 12awg wire,thats if the e-stops can handle that load.

 

[Darkwood]

You can't just go fitting E-Stops without understanding why they are been requested or how they integrate into the control system as a fail safe option, it would require a risk assessment, I also think your customer is not fully understanding the difference between a latching functional stop and an actual E-Stop system, without knowing why these are to be implemented and the hazards they are trying to avert then we cannot advise.
If they are been implement to avert a hazard/danger then a risk assessment is needed and a suitable design regarding the cat' of safety system needed to be implemented, I think you need to have a chat with the customer just to clarify what we are looking at, I suspect the customer is loosely applying the term E-Stop simply to mean the style of actuator.

 

[JeremyJones]

You can't just go fitting E-Stops without understanding why they are been requested or how they integrate into the control system as a fail safe option, it would require a risk assessment, I also think your customer is not fully understanding the difference between a latching functional stop and an actual E-Stop system, without knowing why these are to be implemented and the hazards they are trying to avert then we cannot advise.
If they are been implement to avert a hazard/danger then a risk assessment is needed and a suitable design regarding the cat' of safety system needed to be implemented, I think you need to have a chat with the customer just to clarify what we are looking at, I suspect the customer is loosely applying the term E-Stop simply to mean the style of actuator.

They just want to hit the e-stop and kill power to the boiler

 

[Darkwood]

They just want to hit the e-stop and kill power to the boiler

Unfortunately it is not as simple as that, an E-Stop is a system implemented for safety and it needs to be carefully designed, you need to talk to the customer about why there is a need to stop the boiler remotely or in a emergency, what perceived dangers exist, until we establish that we cannot advise.

 

[Timbo]

I think that as the OP is in Florida we should call in @Megawatt to advise.

 

[JeremyJones]

I think that as the OP is in Florida we should call in @Megawatt to advise.

Now im thinking 2 e-stops to a shunt breaker

 

[Spoon]

Now im thinking 2 e-stops to a shunt breaker

Now I'm thinking that you are not quite understanding the function of an E-stop.
Please read @darkwood post #9 again.

 

[JeremyJones]

Now I'm thinking that you are not quite understanding the function of an E-stop.
Please read @darkwood post #9 again.

Hit the e-stop and the boiler shuts off,too easy

 

[Lister1987]

Hit the e-stop and the boiler shuts off,too easy

As you're stateside there will no doubt be local, regional or federal requirements around e-stops, Thier functions, mode of operation etc (NFPA 79, ISO 13850, 2006/42/EC and IEC 60204-2 come to mind).

 

[Spoon]

Hit the e-stop and the boiler shuts off,too easy

Glad you have digested all the advice you have received and now know what to do mate...

 

[plugsandsparks]

Many commercial boilers dont take kindly to suddenly have their power disrupted. Many boilers like to keep the pump running to dissipate heat to stop any damage to the boiler itself.

I agree with views here, what are we trying to achieve?

The last thing you need is an E-stop which stops the boiler firing, then as soon as you release the E-stop, the boiler fires up again, this is not an e-stop, this is a simple management of "Call for Heat"

A proper commercial E-stop for a gas appliance, for example would be connected to the gas supply, this would shut off the gas and the only way to reset would be a manual reset system, rather than just releasing the E-stop

Hope this helps

P&S

 

[Lister1987]

A proper commercial E-stop for a gas appliance, for example would be connected to the gas supply, this would shut off the gas and the only way to reset would be a manual reset system, rather than just releasing the E-stop

Hope this helps

P&S

BS6173 systems as an example, although I'm sure I've seen models that eset with just the single twist of the e-stop, once activated that is.

 

[Megawatt]

I have a boiler with a 20amp disconnect switch. The owner wants to add 2 mushroom head E-stops. If there is no e-stop terminals in the boilers control panel whats the best way going about this?

That’s simple just purchase 2 E-STOP buttons and buy 2 sets of NC contacts and wire your power feeding the boiler through the e-stops and then to the boiler. All you stated was it was 20 amps so we don’t know if it’s 120vac or 240vac but if you have a neutral you have to break it also. I’m assuming you have no low voltage controls so make sure the contacts are rated for 20 amps. You also could use a e-stop relay which would really be better but the wiring would be different

 

[JeremyJones]

That’s simple just purchase 2 E-STOP buttons and buy 2 sets of NC contacts and wire your power feeding the boiler through the e-stops and then to the boiler. All you stated was it was 20 amps so we don’t know if it’s 120vac or 240vac but if you have a neutral you have to break it also. I’m assuming you have no low voltage controls so make sure the contacts are rated for 20 amps. You also could use a e-stop relay which would really be better but the wiring would be different

Appreciate your advice

 

[Darkwood]

I think the problem here is terminology, I suspect what your client wants is 2 latching stops, there is a habit to call these E-Stops regardless but it is the circuit that protects it that denotes whether it is or not even if it is inscribed, having said that modern units that comply to E-Stops are defined by colour distinction and sometimes complemented by symbols.
A red actuator against yellow is classed as a E-Stop designation (UK/EU), if I were you after clarifying with the customer I would get a latching stop button that does not meet that colour distinction therefore will not be acknowledge as an E-Stop.
If a genuine E-Stop system is required then it is likely the boiler will not have the correct circuitry to do this, you would have to design and install yourself as a separate system that gives failsafe functionality and interrupts the boilers controls at 2 or more points allowing normal rundown procedures so as not to stop any overrun features of the boiler like fans or pumps that need to ensure safe shutdown.

I will reiterate, we need to understand what the customer is asking and why, what is the full reason for this to be implemented, if there exist no hazards to be averted and it is simply for convenience then latching 'functional stops' are a simple cheap and prefered option that just break the call signal.

@Megawatt - we must be careful on terminology here, you cannot call them E-Stops if they are not serving that purpose as well as having the correct control system to meet those standards, putting latching stops or even push stops that are colour coded to meet E-Stop classification does not make them E-Stops unless the system they are applied to meets the standards, they are functional stops otherwise.. I get this alot in my job where a customer will ask for extra E-Stops on the machine and they are told there machine has no E-Stop system to do that, they make the mistake of assuming the actuator design is what an E-Stop is and that is wrong, the control circuit is what makes that classification... Yes through out the industry we all call these points E-Stops regardless, they are advertised as such and sold as such but to be absolutely correct on this and the fact we are talking safety of a system we thus cannot be loose with terminology in this thread, we need to understand the reasoning on the customer and what hazards if any is trying to be averted.

 

[JeremyJones]

I think the problem here is terminology, I suspect what your client wants is 2 latching stops, there is a habit to call these E-Stops regardless but it is the circuit that protects it that denotes whether it is or not even if it is inscribed, having said that modern units that comply to E-Stops are defined by colour distinction and sometimes complemented by symbols.
A red actuator against yellow is classed as a E-Stop designation (UK/EU), if I were you after clarifying with the customer I would get a latching stop button that does not meet that colour distinction therefore will not be acknowledge as an E-Stop.
If a genuine E-Stop system is required then it is likely the boiler will not have the correct circuitry to do this, you would have to design and install yourself as a separate system that gives failsafe functionality and interrupts the boilers controls at 2 or more points allowing normal rundown procedures so as not to stop any overrun features of the boiler like fans or pumps that need to ensure safe shutdown.

I will reiterate, we need to understand what the customer is asking and why, what is the full reason for this to be implemented, if there exist no hazards to be averted and it is simply for convenience then latching 'functional stops' are a simple cheap and prefered option that just break the call signal.

Why they are doing this makes no sense. It's a boiler for in floor heat. Incase of an emergency or situation they want to be able to kill power with mushroom head e-stop. At another location we just had 2 single pole switches as "e-stops"

 

[Darkwood]

Why they are doing this makes no sense. It's a boiler for in floor heat. Incase of an emergency or situation they want to be able to kill power with mushroom head e-stop. At another location we just had 2 single pole switches as "e-stops"

This is why you need to have a long in depth discussion with the client, it may be the case it is a zone they want to close off and not the entire system, it may not be a hazard but simple convenience which does not warrant any kind of E-Stop system.

 

[JeremyJones]

This is why you need to have a long in depth discussion with the client, it may be the case it is a zone they want to close off and not the entire system, it may not be a hazard but simple convenience which does not warrant any kind of E-Stop system.

Email I received says "e-stops interlocking with boiler". Ill have a chat with them. If I use single pole switches instead of e-stops I'm sure they will be ok with that

 

[Darkwood]

Email I received says "e-stops interlocking with boiler". Ill have a chat with them. If I use single pole switches instead of e-stops I'm sure they will be ok with that

The lack of info from your client means you are guessing here, they have requested E-Stops, your job is to query they understand the difference here, if it is a E-Stop system they really do need then the design, implementation and liability for it will lie permanently on your shoulders.
If you can establish like I expressed in my recent post that there is simply confusion here based on terminology then it may be a simple job as you suggest but I wouldn't want to be in your shoes if you make a fundamental mistake at this stage and in the near future someone is hurt or property damage occurs.

I hope this all is just a mixup that is causing confusion, I fit E-Stop systems for a living and one of the first things you do is establish what is been requested and how it would be implemented, this is all done at the risk assessment stage. I would also like to mention that if this is indeed a genuine E-Stop system you are installing then are you insured to do this work, my insurance for machinery control and upgrade (which essentially this is if you are installing a E-Stop circuit to a commercial boiler) means my insurance is about 5X higher than a standard installation Electricians, you may need to consult with your insurance company to see if you are covered here, the amount of people I see with basic cover and playing about with machines is gobsmacking in my industry as they never consider they are not covered for the work when asked.

 

[JeremyJones]

The lack of info from your client means you are guessing here, they have requested E-Stops, your job is to query they understand the difference here, if it is a E-Stop system they really do need then the design, implementation and liability for it will lie permanently on your shoulders.
If you can establish like I expressed in my recent post that there is simply confusion here based on terminology then it may be a simple job as you suggest but I wouldn't want to be in your shoes if you make a fundamental mistake at this stage and in the near future someone is hurt or property damage occurs.

I hope this all is just a mixup that is causing confusion, I fit E-Stop systems for a living and one of the first things you do is establish what is been requested and how it would be implemented, this is all done at the risk assessment stage. I would also like to mention that if this is indeed a genuine E-Stop system you are installing then are you insured to do this work, my insurance for machinery control and upgrade (which essentially this is if you are installing a E-Stop circuit to a commercial boiler) means my insurance is about 5X higher than a standard installation Electricians, you may need to consult with your insurance company to see if you are covered here, the amount of people I see with basic cover and playing about with machines is gobsmacking in my industry as they never consider they are not covered for the work when asked.

I really appreciate you're advice, friday I asked for more information based off our discussion and they emailed me what I said above. "E-stops to interlock with boiler for emergency shutdown "

 

[Darkwood]

I really appreciate you're advice, friday I asked for more information based off our discussion and they emailed me what I said above. "E-stops to interlock with boiler for emergency shutdown "

That reply for me does not tell me the client understands the difference between E-Stop and Functional Stop, there is no mention of reasoning here to maybe give us a better idea and like what was mentioned by another member, most boilers will have a shutdown sequence, is that clearly understood by your client, pump circulation, venting fans etc may continue for a preset period IE a controlled shutdown.
I guess you have emailed the client to get that response but if you fail to give all the information and ask the right questions you will get ambiguous answers as such, from that reply I am still no clearer as to what your customer is asking for, the cost difference here could be shy of 1K if we are indeed fitting and integrating a compliant E-Stop system but the category of the system needed will have to be determined by risk assessment and the outcome may simply warrant a small adaption of the boiler controls all the way to an independent safety control board that meets a higher category system.

What confuses me here is what perceived hazards warrant a Emergency Stop system on a standard commercial boiler for heating that it doesn't already have implemented itself, this is why I think your customer may be at crossed purposes and mixing up terminology here.

 

[netblindpaul]

The requirement for an e-stop on the system is down to the integrator, by LAW.
The boiler installation must have been CE marked as an assembly to comply with the LAW.
Forget BS 7671 totally irrelevant.
You are now into EN 60204-1, ISO 13850, ISO 13849-1 & ISO 13849-2.
Then the C-Type standards for boilers.
An emergency stop does not HAVE to shut everything down immediately.
It is written into the LAW and standards such that it can shut things down as quickly as possible in a safe manner.
Examples are cited of exothermic process reactions which may take hours to stop completely in response to an e-etop safety function command.
Other things may have fastest possible deceleration to a standstill under power, with power remaining on to the actuators.
The other thing that MUST be considered is that an e-stop function has a limited life before the components must be changed in accordance with the harmonised standards.
This is taken as a 20 year life, and if the e-stop is going to be used to shut the equipment down at the end of a day then that is 365x20 = 7300 operations in 20 years, the ISO 13849-2 validation needs to reflect that.
This is a minefield that could end up badly if the correct procedures are not followed.
For your own benefit make sure that you are insured to work on boiler controls, and under EN 60204-1 as in the Machinery Directive (UK Supply of Machinery Safety Regulations) and to design and implement safety functions.
You are stepping into an area that most electrical contractors policies do not cover you for.
You could easily end up in prison or bankrupt if things went wrong.

 

[JeremyJones]

That reply for me does not tell me the client understands the difference between E-Stop and Functional Stop, there is no mention of reasoning here to maybe give us a better idea and like what was mentioned by another member, most boilers will have a shutdown sequence, is that clearly understood by your client, pump circulation, venting fans etc may continue for a preset period IE a controlled shutdown.
I guess you have emailed the client to get that response but if you fail to give all the information and ask the right questions you will get ambiguous answers as such, from that reply I am still no clearer as to what your customer is asking for, the cost difference here could be shy of 1K if we are indeed fitting and integrating a compliant E-Stop system but the category of the system needed will have to be determined by risk assessment and the outcome may simply warrant a small adaption of the boiler controls all the way to an independent safety control board that meets a higher category system.

What confuses me here is what perceived hazards warrant a Emergency Stop system on a standard commercial boiler for heating that it doesn't already have implemented itself, this is why I think your customer may be at crossed purposes and mixing up terminology here.

Hahahaha im right there with you on that, it isn't needed.

 

[Timbo]

The requirement for an e-stop on the system is down to the integrator, by LAW.
The boiler installation must have been CE marked as an assembly to comply with the LAW.
Forget BS 7671 totally irrelevant.
You are now into EN 60204-1, ISO 13850, ISO 13849-1 & ISO 13849-2.
Then the C-Type standards for boilers.
An emergency stop does not HAVE to shut everything down immediately.
It is written into the LAW and standards such that it can shut things down as quickly as possible in a safe manner.
Examples are cited of exothermic process reactions which may take hours to stop completely in response to an e-etop safety function command.
Other things may have fastest possible deceleration to a standstill under power, with power remaining on to the actuators.
The other thing that MUST be considered is that an e-stop function has a limited life before the components must be changed in accordance with the harmonised standards.
This is taken as a 20 year life, and if the e-stop is going to be used to shut the equipment down at the end of a day then that is 365x20 = 7300 operations in 20 years, the ISO 13849-2 validation needs to reflect that.
This is a minefield that could end up badly if the correct procedures are not followed.
For your own benefit make sure that you are insured to work on boiler controls, and under EN 60204-1 as in the Machinery Directive (UK Supply of Machinery Safety Regulations) and to design and implement safety functions.
You are stepping into an area that most electrical contractors policies do not cover you for.
You could easily end up in prison or bankrupt if things went wrong.

I re-iterate the OP is in the USA.
CE markings and BS, EN, standards therefore don't mean a thing.

 

[plugsandsparks]

Boilers no matter country you are in need to be shut down correctly according to the MI's.

I suggest OP forwards the email request from client to the boiler tech support team and ask them how best to "shut down in case of emergency" - AKA, lazy mans way of turning off at night, lol

 

[Spoon]

I re-iterate the OP is in the USA.
CE markings and BS, EN, standards therefore don't mean a thing.

The USA have their own standards that they have to work to, so the principle still applies.

 

[Darkwood]

As an overview here to simplify it a bit, you have to treat an E-Stop actuator like a normal stop button, on it's own it is not an E-Stop even it it complies with the standards by design, it is only an E-Stop when part of an E-Stop system that meets relevant standards.
It is like sticking a Lamborghini badge on a Fiesta, the badge does not change the car to a Lamborghini and on its own the badge is not a Lamborghini even if it is made for one, the same applies to the various stop actuators that comply to be used as E-Stops.

 

[JeremyJones]

As an overview here to simplify it a bit, you have to treat an E-Stop actuator like a normal stop button, on it's own it is not an E-Stop even it it complies with the standards by design, it is only an E-Stop when part of an E-Stop system that meets relevant standards.
It is like sticking a Lamborghini badge on a Fiesta, the badge does not change the car to a Lamborghini and on its own the badge is not a Lamborghini even if it is made for one, the same applies the various stop actuators that comply to be used as E-Stops.

I think you're right about that. They are using the word e-stop wrong. They just want something to kill power to the boiler if there's an emergency or issue

 

[netblindpaul]

I re-iterate the OP is in the USA.
CE markings and BS, EN, standards therefore don't mean a thing.

I didn't see that stated anywhere. ?‍
The USA are catching up with the ISO & IEC standards requirements as they are members of both organisations.
They are just a bit slower than the rest of the world because of the difference in the way they blame people and mandate PPE rather than addressing the real hazards.
Also their equipment design is about 20 years behind the world that has embraced the IEC standards, having assessed both, the US equipment is positively dange in comparison to equipment to base IEC requirements.
Almost all BS & EN standards are derived from ISO & IEC source document, some are identical, and if North America was not so stuck in its ways and arrogant about their so called supremacy, they would accept the standards they had a hand in writing, and save millions in currency and massive global resources.
Plus some of the documents I have quoted are ISO standards so the USA are bound to implement them in the same way the UK has to implement IEC 60364.
The control philosophy in the US is aligning and the intent is similar.

 

[Lister1987]

I didn't see that stated anywhere. ?‍
The USA are catching up with the ISO & IEC standards requirements as they are members of both organisations.
They are just a bit slower than the rest of the world because of the difference in the way they blame people and mandate PPE rather than addressing the real hazards.
Also their equipment design is about 20 years behind the world that has embraced the IEC standards, having assessed both, the US equipment is positively dange in comparison to equipment to base IEC requirements.
Almost all BS & EN standards are derived from ISO & IEC source document, some are identical, and if North America was not so stuck in its ways and arrogant about their so called supremacy, they would accept the standards they had a hand in writing, and save millions in currency and massive global resources.
Plus some of the documents I have quoted are ISO standards so the USA are bound to implement them in the same way the UK has to implement IEC 60364.
The control philosophy in the US is aligning and the intent is similar.

They do have NFPA 79 which would be their regional variant of the ISO standard