Hi all. We have a Vaillant ecoTEC plus 937 combi boiler. It's about seven years old and was installed before we moved in. Been serviced every year and the only problem we've previously had was last summer when the hot water flow rate started to reduce - this turned out to be collapse of the plastic internal outlet pipe from the store (diagnosed with assistance from searching this forum!) - replaced and all good with showers, etc. again.
However, since we've started taking baths again this winter we've noticed that, with the bath mixer tap on full hot water flow, it only runs hot for a couple of minutes before going lukewarm / cool. This issue does not occur when running any of the two showers, or the bathroom or kitchen taps.
I've looked at the information codes on the boiler whilst running the bath: it starts with S.27, then goes through various combinations of S.24, S.20 and S.26. I've been into the diagnosis and checked the faults: one F.28, five F.22s and one F.29 ... although goodness knows how old these are, so they may have nothing to do with this.
We don't recall having this problem in previous winters so it occurs to me that, since having the plastic internal outlet pipe from the store replaced, the hot water flow is now generally greater and the boiler cannot cannot meet the demand from the bath hot water tap (perhaps the two minutes sizzling hot water is coming from the internal hot water store)? A work colleague suggested that the tap cartridge might be awry (replaced, no difference) or even a shower mixer in the house might be faulty and be causing cold water to mix with cold (no action taken on this as it seemed far fetched).
Any thoughts or possible simple things to check before we either accept it or call an engineer please? Thanks.
However, since we've started taking baths again this winter we've noticed that, with the bath mixer tap on full hot water flow, it only runs hot for a couple of minutes before going lukewarm / cool. This issue does not occur when running any of the two showers, or the bathroom or kitchen taps.
I've looked at the information codes on the boiler whilst running the bath: it starts with S.27, then goes through various combinations of S.24, S.20 and S.26. I've been into the diagnosis and checked the faults: one F.28, five F.22s and one F.29 ... although goodness knows how old these are, so they may have nothing to do with this.
We don't recall having this problem in previous winters so it occurs to me that, since having the plastic internal outlet pipe from the store replaced, the hot water flow is now generally greater and the boiler cannot cannot meet the demand from the bath hot water tap (perhaps the two minutes sizzling hot water is coming from the internal hot water store)? A work colleague suggested that the tap cartridge might be awry (replaced, no difference) or even a shower mixer in the house might be faulty and be causing cold water to mix with cold (no action taken on this as it seemed far fetched).
Any thoughts or possible simple things to check before we either accept it or call an engineer please? Thanks.