What does BMU Err mean when displayed on the thermostat for my Vaillant system?

Kaz, November 2009

i had the same issue, it was no gas pressure.

uvby, March 2014

Thank you so much for these tips, worked a treat all back up and running

Burton ZL, March 2014

This 'fix' works well, but i am now having to do it 'daily' which makes me wonder why it keeps losing pressure so quickly?

Gary, September 2013

Works a treat,
Turn on hot water tap.
Turn right tap
turn left tap
Wait for gauge to rise in to red.
The turn boiler off for a few seconds . Then switch back on and wait. It will reboot itself.

Alan Wardle, February 2013

Thanks a lot. It worked great.
--> Just open the 2 taps under the boiler for a few seconds, the neddle indicating the pressure (gauge) goes back to normal, and that's it! (Don't forget to close the tap )

Laurent, February 2012

Just wanted to say thank you to Peter, as I found myself facing the same problem upon my return from holiday and I did what you did and it worked!

Thank you so much for saving me so much hassle and money!

Svilena, April 2011

Peter Warren response worked well. Remember to turn the grey taps back to the original position. Pressure gauge should return back to the grey bar( Middle). During the procedure, keep a hot tap running to get the pressure increasing. Matt M

Matt Mathurin, April 2011

Thank you for posting this about the taps..Mine stopped working this morning and I was able to sort it out thanks to you.

regards
Wendy

Wendy, February 2011

I have an answer which cost me £175 today for an engineer to fix today. I had drained a radiator then got the BMU error message on the thermostat for my VRT360. I switched it on and off but it wouldnt restart and also pressed in the "flame" button the the front, as recommended by other people on these sites. Nothing happened. The engineer showed me the 2 grey taps underneath the boiler. U turn the right one first then the left one and the system fills up!!!! The small pressure guage is on the front of the boiler.All working now. An expensive lesson. The engineer said that I was lucky the pressure hadnt dropped to this low level before as you need to top it up every 6-7 months.I hope this helps other users.

Peter Warren, February 2010

The instruction book says - "Fault on Boiler" & the when you go to the Boiler manual it says "Heating system water pressure too low" you need to fill the sytem, how I am not sure, as I have the same problem which has occurred today, as my system is under warranty I have called the company out to repair it this coming Friday.
Hope this helps!
Wednesday 25th November

Gary, November 2009