Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.

If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
Need to contact us? Visit

Bosch Greenstar - no heat/DHW

Hi - I have a Bosch Greenstar combi boiler (model #ZWB...) in my apartment that isn't working properly.

I have a contractor doing work in my apartment; yesterday they shortened one of the baseboard radiators, and I haven't had heat/hot water since. The unit heats up and hot water comes out of the tap for a moment, but the temperature on the unit quickly gets up to 199 (not normal - DHW is set to 122) and shuts back off. After the boiler cools down, this cycle repeats.

Today the plumber who originally installed the unit came to take a look, replaced the circulator pump and purged the air out of the system using one of the valves below the unit, but it's still not working. Any idea what might be the issue? Thanks so much.


  • neilcneilc Member Posts: 803
    pictures of the boiler and the pipes around it,
    do you see any valves closed ?
  • DZoroDZoro Member Posts: 1,032
    You're probably still air locked. The entire system should be purged of air. Pictures would help, boiler room and the shortened base board.
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!