I have a Vaillant ecoTech Plus combi boiler. The central heating works fine. But the hot tap water became intermittent. If I got lucky and hot water would come from the tap, it never went cold as long as it was running. So I think it’s likely a flow switch because there were times when it simply did not seem to detect that hot water was on. I heard no boiler fan and the faucet icon did not appear on the display on the times it failed to produce hot water. The moments where it would work are now history. Now it’s cold water every time. So it was a gradual manifestation.

I popped the cover off and there’s some kind of scaling or buildup of something on the pump. The clip that holds something in place above the pump is corroded. So while the system behaves as if it does not detect water use, the pump does not look good. Would a faulty pump cause my issue?

About two years ago I had an intermittent hot water problem and it turned out the secondary heat exchanger was blocked by limescale. In that case the water would go cold mid-shower. The current intermittency problem is just with the initial switching on of hot water - no interruption once it was going. So I kind of doubt the heat exchanger is my issue.

Any theories?

  • diyrebel@lemmy.dbzer0.comOP
    1·
    3 months ago

    Are you certain you were looking at information for your specific unit

    No, I don’t have the tech details for my specific model. Both videos cover different models of the same brand. The first video (d8ucufoyUlQ) model in the video looks newer judging from the control panel but interior looks the same. The 2nd video (G4bO8MYqQKk) has a different looking interior with a black label on the pump, so I think that’s an older one. I was figuring if a newer and older model both have the same voltage specs then mine is probably the same.

    The voltmeter was set to DC voltage, 20 V (which should measure up to 20 V). My meter does not have a frequency function (Hz), so I don’t have the benefit of checking to see what flow rate is measured.

    I should also mention that my cold water flows at ~1 liter/5 seconds and the hot water circuit flows at ~1 liter/7 seconds.

    (update)
    I found the service manual… did not realise I had one. But it’s not too useful. It does not clearly describe the relationship between voltage and state. There seems to only be a diagram which I posted here:

    https://lemmy.dbzer0.com/post/26703241