Vaillant TURBOmaxPlus 828 E not working when cold

5 Dec 2012
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United Kingdom
Dear all,

I moved into my house approximately 3 years ago. The house is fitted with a Vaillant TURBOmaxPlus 828 E boiler.

Since we have moved into the property, we have had an ongoing (but intermittent) problem with the boiler. I have had 3 different boiler serviceman out over the course of the three years, but like any intermittent fault – it never occurred when there was an engineer actually at the property, so they couldn't find anything wrong!

The issue I have is…during cold weather (so never during the summer) the boiler will stop producing heating and hot water. This happens most often early morning (presumably because the cold temperatures over night have caused whatever the issue is). The issue usually resolves itself (after a few hours or so) presumably as the temperature warms up. The boiler stopped working again this morning and I have made a note of the lights and status codes…

I turned off any demand for hot water/heating and the boiler showed the following:
- Display read 20C (usually reads about 70C)
- Red light off
- Amber light off
- Green light flashing
- When I press ‘I’ it shows the S.23 status code

I then turned the hot tap on to create demand.
- Exactly as above but now the S.13 status code is displayed

I have downloaded the manual for the boiler and see that the green flashing light, the S.13 and S.23 codes all relate to ‘warmstart’. I don’t know exactly what that is, however, it seems odd that the boiler is trying to ‘warmstart’ when the temperature outside must be freezing.

Does anyone have any ideas what the issue may be and/or how to go about getting it sorted?
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Warmstart runs the boiler every 20-30 min to keep the hot water part warm.

Read about it and turn it off.

The sensor that indicated the internal water temp might be failing.

Not starting in the morning can be the pump sticking!

You may need a new temperature censure, ntc, and you should try turning warm start off, this can be done by turning thermostat on boiler for hot water down to zero for a few seconds then back up again, to turn back on turn thermostat for hot water up to max then down to normal and warm start is back on again.
petertheplumber12 - sorry to ask such a dumb question...but when you say 'the thermostat on the boiler for hot water' do you mean the big green dial at the bottom left of the boiler with the tap symbol next to it?
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This is a known Vaillant fault with earlyb2002-3 turbos ,especially when the winter comes get a proper Vaillant engineer to help you check d24 ;)

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