Pump Problem Vaillant Ecotec Exclusive 838

Problem: The CH and HW all work fine with no problems and no error codes but there is rattle and vibration from the pump, sounds like pump is shot.

If I drain, refill and vent the system as per the Vaillant manual, using the P0 program to let the pump vent (as it’s a self venting type) there is no noise from the pump and it works fine, put on CH full load again all fine, but as soon as there is a DHW the pump rattles and does not stop even after hot water demand has ended and the CH starts, the only way to stop it is to drain the refill.

Bypass is set to 250mb and pump speed is set to auto

Any ideas? Anything else worth looking or is it as I initially thought that the pump is dead, which seems shocking as it’s only 1 month old, and yes the systems was flushed.

By the way when this is working properly the boiler is wisper quiet.

Call Vaillant, the pump is shot, the pump manufacturer is sh*te

As I feared! I can not belive that these pumps can be so poor what are they made out of? Cheese! The pump on the old Thorne boiler that this replaced was still going after 28 years of service. I expected more from Vaillant!

Thanks.

Low voltage pumps on these u should have bouth the 837 ecotec more reliable an cheaper using normal grundfos pump

The man at Vaillant on the training day said that the low voltage pumps were the future.

He made a bit of a mistake over the power saying it was one watt when its probably about 10-20w.

But as they sell them they should be man enough for the job!

Tony

Agile the 837 is just an all round better unit the low voltage pumps are ok but not as robust as the standard

That will teach me for falling for the marketing hype and the pretty blue lights!