cross-posted from: https://lemmy.dbzer0.com/post/26703241

This diagram is from the service manual of a combi boiler. It’s a flow sensor which detects whether hot water is running, which is then used to trigger on-demand heat and switch a diverter to take radiators out of the loop.

In English, the diagram shows:

  • X ⅔ red wire (+5V)
  • X 2/2 black wire (ground)
  • X 2/6 green wire (signal)

I need to know what those fractions mean. I took the voltage measurements in this video:

I cannot necessarily trust the model in that video to have the same specs as mine. My voltmeter detected 4.68 V on the red input wire showing that the sensor is well fed. The green “signal” wire is supposed to be 0 V at rest and 2 V with water running (or I think the reverse of that is used in some models). In my case the green wire is ~1.33 V at rest and ~0.66 V when water is running. I need to know if these readings are normal as I troubleshoot this problem.

update

@synapse@lemmy.world gave the right answer. Someone in another cross-post helped solve the underlying problem.

  • diyrebel@lemmy.dbzer0.comOPEnglish
    3·
    23 days ago

    Thanks for the effort. But actually @synapse1278@lemmy.world’s answer is right. It turns out the diagram is misleading by putting “X<space>2”. It’s just an abbreviated label for where the wire ends up on the circuit board; which for the green wire would be more verbosely written as “connector X2 pin 6”. So the diagram only tells me where the wires lead to not what the measurements should be. And in fact it’s disappointing that the service manual actually says nothing about what the voltage reading should be. It’s apparently undocumented.