Valiant TurboMAX plus 828 E - hot water fault

[Richard888]

I've read a number of threads and, whilst there are number of similar faults listed, I can't find anything that matches my symptoms exactly.

My boiler has recently developed a fault where the domestic hot water alternates between hot and Luke warm. The central heating works fine.

When running the hot water the boiler fires up for about 10 seconds then stops for about 10 seconds before it fires up again. This cycles continues for as long as the hot water is running.

I don't think it's the diverter valve because the feed and return to the heat exchanger get hot but not to the heating. The status codes cycle around: S.11, S.13, S.14, S.16. The diagnostic codes: d.24 and d.30 cycle between 0 and 1 as the boiler fires down and up. Codes: d.10, d.22, d.35 display 1 throughout.

When the heating is on the status codes show: s.0, s.1, s.3, s.4 and stays on s.4 until the room thermostat turns off the heating. The diagnostic codes: d.10, d.22, d.24, d.30 = 1; d.35 = 0. As expected I believe.

Ideas?

Many thanks

 

[Cpplumber]

I would be checking the plate heat heat exchanger for scale/sludge. I haven't looked into the codes you mention but the plate heat exchanger is usually the first thing to check, particularly with the symptoms you mention.

 

[Agile]

Yes, I agree.

The test is to see what the temperature differential is across the primary of the plate.

Best measured with a contact thermometer but you can look them up in d40 and d41 on some variants of that model.

Should be about 10-15 C ideally. If over 20 C then a good indicator that its rather blocked.

Can also be caused by a blocked or weak pump.

Tony

 

[Richard888]

Many thanks for the useful advice.

The temperature difference was 22c (77c vs. 55c). I've cleaned out the heat exchanger and now I have hot water (as well as central heating).

Once again many thanks.