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Bosch Tankless - Piped Correctly?

I bought a house and this system had already been installed. There is no record of a sign-off at the local building department for the Bosch Direct Vent Boiler ZWB 42-3 A Greenstar Combi 151 used for baseboard hot water heat and domestic hot water.

It seems to work ok.

I think I need someone to inspect and correct if necessary, probably a Bosch certified installer.

Hempstead NY


  • BoschGuy
    BoschGuy Member Posts: 5
    Post a pic! I can help you.
    Sal Brunetto
    National Sales Manager
    Bosch Thermotechnology
  • SuperTech
    SuperTech Member Posts: 2,032
    It's not what I would consider correct.  It looks like a mess. 
  • TAG
    TAG Member Posts: 751
    Get the manual on line .... If you take off the cover there will be a model and serial number and you can figure out how old it is. No information at all in and around the unit?

    Combination boilers often need more servicing due to the domestic heating aspect --- so looking into who in your area services them is a wise move so you are not searching when something happens. It's always smart to be proactive .. find someone and have it looked at

    You have a tight space and the piping looks older than the boiler -- maybe it had the same boiler previously as I can't see new piping directly to the unit. I guess you have two heat zones .... I see where there is a line caped off (maybe from an even older boiler). You have a mixing valve for the domestic hot water. I also see some evidence of water drips -- this could be from the vent above or the pressure valve dripping. See any evidence of water ?

  • Ironman
    Ironman Member Posts: 7,225
    It’s not correct, but if it works without any issues, I’d leave it alone.

    And FYI: it’s a mod/con combi boiler, not a tankless water heater.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • JohnNY
    JohnNY Member Posts: 3,225
    That's a mess. I'd be concerned about how it's vented to the outdoors.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.