Turbomax VUW 242 boiler problem with hot water

[Ifti]

Hi all
My old account has stopped working so here's a new one, so we still have this boiler but we have still having problems with the hot water, we have called out 3 repair engineer's, but as it's a old boiler everyone seems to guessing, so far they have changed the thermistor, secondary heat exchanger, primary heat exchanger, diverter valve also done a power flush, new radiators as well but for some reason the boiler seems to be turning off and on every few mins, and the hot water is from burning hot to warm.
Can someone guide us to what the issue could be so I can tell the repair engineer's exactly what to look at. I don't mind any experienced engineer on here who is local (west london) to me to come take a look, we have spent so much on this boiler we can't afford to get a new one at the moment. Thanks in advance

 

[Fitter30]

Never saw one of these combi heaters. Looking at the install manual theres a water flow limiter that the setting is suppose to set max flow based on temperature rise page 25. See the dhw temperature setting is knob goes to 9. Turn water on max flow on a bath tub and kitchen sink turn stat to 9 see what temp it's running and how much it varies. Then start turning water flow down in steps see what happens to the temp burner should back down temp should stay about the same. If temp stays steady turn stat down till it measures 120° then step down flow. If that checks out check minimum flow rate. With just the kitchen sink time a gallon of water a minute check water temp and if it varies.

VAILLANT TURBOMAX VUW 242 E INSTRUCTIONS FOR INSTALLATION AND SERVICING Pdf Download

View and Download Vaillant TURBOmax VUW 242 E instructions for installation and servicing online. Wall hung room sealed fan assisted combination boilers. TURBOmax VUW 242 E boiler pdf manual download. Also for: Turbomax vuw 282 e.

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