Target Flow Temp Being Exceeded

[Al Growler]

My boiler (Vaillant eco-Tec +418) was installed around 18 months ago and has been working fine.

However, I recently noticed that the target flow temp is being exceeded.

We control room temp via the room stat, so whilst it is on at the programmer, the CH obviously doesn't come on this time of the year.

The flow temp is set to 60, but when it comes on to heat water, it keeps going until the reading is 65. The tank stat is set at 55. The boiler was not set for cylinder charging.

Would be grateful for comments and advice. Should I be concerned.

Many thanks.

 

[Dan Robinson]

What type of cylinder have you got?

Older open vented cylinders have tiny coils so the boiler struggles to behave.

 

[Al Growler]

HI Dan, thanks for your reply. Had a new cylinder fitted when the boiler was installed (Feb 2017). I have a stat which is connected to the cylinder (Drayton), which have set at 55. Hot water temperature seems fine. I was wondering if it had anything to do with the fact that the boiler hasn't been set for hot water charging, but I am assuming that the diverter valve installed by the pump and cylinder takes care of that. So, both hot water and central heating are controlled, but just wondered why if the boiler is set at 60, why it keeps going until temp reaches 65. Would have thought it should cut out at 60. Cheers, Al

 

[Dan Robinson]

It's not a case of " keeping going", more that it can't regulate low enough quickly enough. But it's tricky to workout without knowing the rating of the cylinder coil.