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.