Boiler burner status

I have a Ideal Logic Heat 15 boiler and would like to know when the burner is active. It has an Blue LED on the front of the boiler which has that status. Can anyone tell me if Optical Utility Meter LED Pulse Sensor sold in the shop would be suitable for this application? Thanks

Welcome, Andrew, to the O|EM forum.

Unfortunately, my Optical Pulse Sensor is in use, so I can’t test it for you. However it seems to respond equally well to both red and white light, so it’s probably worth a try.

Do you actually need to know the burner is running? Can you not simply attach temperature probes to the flow & return pipework, which will show a rise in temperature when the burner is on?


Yes, I reckon the pulse sensor it will work, especially if the boiler is located in a dark location.

However, as @moojuiceuk suggested I reckon attaching temp sensors onto flow and return pipes will be more useful; you’ll be able to tell when the boiler is running and also see what the flow/return temps are to figure out if the boiler is in condensing mode or not, assuming it is a condensing boiler. Condensing mode requires a return temperature of 54°C or lower.

Also, if your house stays warm enough with a flow temperature of 50 deg C or lower your radiator system is heat pump ready.

Thanks for your help everyone, @moojuiceuk I plan on monitoring the flow and return temperatures but would really like to know when the burner is active as well.

@glyn.hudson sadly I have a hot water tank rather than a combi…

Has anyone got any pictures of how they have attached the sensors to the flow and return pipes?

Nothing wrong with that, it means you be able to more easily fit a heat pump in the future.

Thermal paste, zip tie then insulate over the top is what I do. @johncantor has written an excellent blog post which lists the different ways of attaching sensors:

Thanks @glyn.hudson for the advise and pictures. So I have gone ahead and purchased a pulse sensor. In terms of the sensor, if it has power to the sensor and the sensor is placed on top of an LED that is on (not pulsing), should the LED on the front also be on as well (not pulsing)? Thanks

Indeed it should. But note that the LED on the back of the sensor is not a totally reliable guide to the state of the output.

The output is not in fact a pulse, in that there is no control of the shape of the output using (say) a Schmitt trigger. I measured pin 6 at 3 mV in darkness and VCC - 35 mV in reasonably bright light. The output goes to an acceptable ‘high’ state long before the LED on the rear of the sensor lights up.
Measurements & a circuit diagram are here: First try with EmonPi - Pulsecount stuck at 1 - #16 by Robert.Wall
And some more Adjusting sensitivity of Optical Pulse Sensor - #21 by Kempson
Wire colours: 3.3V power: red, GND: black, output: blue.