Odd electrical item question.

When my boiler locks out it sends 240v to one of the terminals behind the control box.
This live signal is only there whilst the boiler is locked out AND the thermostat is calling for heat.

What I would like is an indicator that is in one state when the boiler is in normal/working/ready to work condition, but when it has experienced 240v it flips to a different position, and stays there until I reset it.

Any (constructive) suggestions or search terms to try?

Why dont you just have one light – lockout light – which comes on when it in lockout? You already have that ‘alarm’ 240v feed ready. If the lockout lamp isnt on, its ready to work (healthy).
Otherwise you’ll need a permanent 240V supply and a relay to flip between the 2 signals. Healthy/Lockout. By using 2 lamps, or a multifilament (multicolour) single lamp/led

sounds like what you want is a relay that triggers a mechanical flag/indicator/whatever on a spring that physically pops up until manually pushed down/reset?? No idea what it’s called but it sounds like it should exist!

Or a solenoid that triggers a physical mechanism that then needs to be reset. A quick google suggests that “latching solenoids” are a thing…

https://www.aliexpress.com/item/1005005361169807.html?

I’d use these (one of each or the red/green combo). Green light means call for heat, red light means lockout. You’ll obviously only see green, or red and green together, but it’s the easiest solution. Chances are your oil boiler is just switched on and off by the thermostat as opposed to anything more complicated.

but with that the indicator doesn’t persist after the live signal disappears, which is (I think) what the OP wants?

@zilog6128 – yes, I want the lockout indicator to stay in position even when the boiler is off. A button or flag would suit me best.

actually the simplest off-the-shelf solution I can think of is wire in a circuit-breaker (and maybe some kind of lamp or something to provide a bit of load) that is way under-specced so just trips every time the circuit is energised?

but with that the indicator doesn’t persist after the live signal disappears, which is (I think) what the OP wants?

True, but almost impossible to find off the shelf. You’d have to make your own and this solution addresses the problem of “has the boiler got power?” and “is the burner locked out?” simultaneously.

I wondered about a breaker, easy enough to house one and the necessary wiring (to trip it if it ever gets power) in a neat box.

@Flaperon the problem is that I want to know if the boiler is locked out both with and without power going to it, hence preferring a physical latch.

I wondered about a breaker, easy enough to house one and the necessary wiring (to trip it if it ever gets power) in a neat box.

Not sure what you mean by this. Are you suggesting creating a L-N fault in order to trip the breaker if a lock-out occurs? This is a terrible idea.

However, you can get something called a shunt trip which is designed to trip a circuit breaker when voltage is applied, and you don’t want it to restart without input. Imagine an emergency stop where pushing the button triggers this device, which mechanically trips the MCB or RCBO that it’s fastened to.

You could use one of these by itself and rely on it as an indication as to whether a lockout has occurred.

I would probably use a shelly controller with a battery powering it to monitor the voltage.

If you can’t monitor voltage directly you can use a small lamp or similar connected and monitor the power.

https://shellystore.co.uk/product/shelly-plus-1pm/?gclid=CjwKCAjwrranBhAEEiwAzbhNtbnp82PvpH8iHwMFPjcOGO9fbKgzoQd6n7QqecY7nztCfx_wHEENvBoCdQ4QAvD_BwE

Strikes me that the easy option is to feed the lockout contact with a permanent rather than the switched feed from the programmer/thermostat.

Failing that you want a relay latching circuit

Can we try and back up a bit to the real problem? I suspect you’ve got about halfway down your the first route of problem resolution and found the fix (an odd electrical problem) is proving a bit awkward. So what’s going on?

You want your boiler to heat water.

Cool

Sometimes the thermostat is calling for heat, but the boiler “locks out”. Right?

Tell us more about that. What type of boiler is this? Combi/system? Brand? Any problems with domestic hot water or is it just central heating?

This is STW. Once you tell us more the chief engineer from your boiler manufacturer will be along with the right answer. And a bunch of people will be along with the wrong answer and I’ll probably do a proper flounce.

OK, so my idea of a pre-arranged L-N fault is a duffer (could you tell me why?) but the latching relay looks good.

Is there a latching relay that can handle a 240v input/signal*, preferably with a push button reset. I’d just run a 240v indicator lamp on the output side.

*Or run a step down transformer to 12 or 24v?

Lol @goldfish24! Yes, it would be nice if the boiler never locked out, but it is very old, no longer manufactured, and I’m skint. Even the chief engineer from HRM would cry a little for me.

Oil boiler chap is coming out on Friday to give it a service, I plan to glean as much info from him as possible as well as hopefully gaining a reliable boiler.

But I still fancy an indicator in the house to tell me if the boiler is behaving or not. The current system component (wife) reports the issue hours late and usually at an inconvenient time, the audible signal is slightly annoying and goes on too long. On the upside it is linked to my phone so I can get alerts remotely.

It is not the hill I will die on, I’m just inquisitive as to whether there is a safe/simple/cheap solution to a problem I’ve experienced.

OK, so my idea of a pre-arranged L-N fault is a duffer (could you tell me why?) b

Because if for some reason your MCB doesn’t trip, your house will catch fire.

Presumably you’ve checked stuff like the photodiode / flame sensor? Rielo burners (assuming it’s one of those) are pretty bombproof when looked after.

If that was me I’d:

1) stick a raspberry pi near the boiler.

2) add a relay that’s triggered by the 240v lockout signal and connect the other side of the relay to a GPIO pin on the Pi.

3) little bit of code and the pi will detect when the boiler locks out (because the circuit to the GPIO pin has been closed by the 240 volts going to the relay ) and sends a message to IFTTT which then sends a push notification to your phone.

I already have the same thing except it’s to detect when the boiler is actually running so that I can calculate the oil usage.

The only difference with mine is that the signal voltage is 25 volts.

Works perfectly.

Presumably you’ve checked stuff like the photodiode / flame sensor?

My money is on it being the thermal cut out that trips which, on mine, is resolved by just pushing a button back in.

Another vote for – fix the underlying problem with the boiler

Old oil boilers are really simple and last for effectively ever. In order I would bet on

Spark electrode needs replacing

“Magic eye” flame detector needs cleaning/replacing

Jet needs cleaning (might indicate fuel filter needs replacing)

Fan problem

But I still fancy an indicator in the house to tell me if the boiler is behaving or not. The current system component (wife) reports the issue hours late and usually at an inconvenient time, the audible signal is slightly annoying and goes on too long. On the upside it is linked to my phone so I can get alerts remotely.

Made me chuckle !