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Old Boss Therm BZV22...trying to find one..

Discussion in 'Plumbing and Central Heating' started by Funkyfreddy, 27 Apr 2020.

  1. Funkyfreddy

    Funkyfreddy

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    Bit of a long shot...don't suppose anybody has, or knows of any of these “old” Boss Therm (BZV22) 2 Port 22mm valves gathering dust by chance, trying to get hold of one seems a tall order ?

    Needing to replace one for a relative as the plastic gearing has worn so it doesn't open completely, trigger the mircroswitch for the boiler and constantly “clicks” so was hoping for the easy option an just swap out the complete head unit without removing the valve.

    The current Boss Therm BZV22 head is a different design so can't make use of the that, likewise for other mfr's.

    Replacing with a complete new valve and motor doesn't look too easy a job as it's all quite tight with not much room but looks like that will have to be the way unless I can locate some old stock or a source for just the gear component if used on any other valves ?

    Any help much appreciated, many thanks.

    BZV22_HW.JPG
     
  2. CBW

    CBW

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  4. Funkyfreddy

    Funkyfreddy

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    Thanks for the reply Chris.

    I'm not sure it will though unfortunately - this mentions compatibility with the “Metal Head” BZV22 whereas this dead unit is an older Plastic Head BZV22 - several questions on the product page asking if compatible with the older plastic one with the answer no.

    It's just the worn plastic actuator “gear arm” that needs replacing if I could somehow find one of those !
     
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  5. Funkyfreddy

    Funkyfreddy

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    By way of follow up & just in case anybody in the future might be looking at a similar issue of worn gear teeth on the plastic cam in these that results in it slipping and giving a constant knock throughout the pipework and comes across this thread.....

    The BOSS Therm BZV22 valve is badged version of the Siemens Landis ZA-V222C.

    Other than a different PCB and wiring loom to provide a mid position the actuator and synchro appear just the same on the 3 port Siemens Landis MA-V322C.

    The snychro motor is housed in the plastic housing that lifts off the actuator leaving the “actuator” attached to the valve body (as per photo above). This can be removed completely in situ if needed from the valve body without any issue although you'll need to remove the retaining circlip on the cam, two springs and two screws securing it to the valve (one of which has the earthing cables attached).

    A complete new actuator could be refitted if necessary alternatively if it is just a case of needing to replace the plastic cam that triggers the microswitch due to worn gear teeth then this can be replaced from a donor unit in which case just the retaining circlip needs removal after releasing the two springs.

    At the time of writing the older grey plastic housed Siemens Landis ZAV-222C and MAV-322C appear to crop on a well know auction site from time to time rather more than the BOSS Therm badged units.

    I got hold of 3 port MAV-322C and just made use of the plastic cam from that but had the complete actuator needed replacing I could have used the one from the MAV-322C and just looped White & Grey wires together and it would work as a two port valve head – as far I can tell anyway !

    If you see the Siemens “RMH” available this is just the grey plastic housing and synchro.
     
    Last edited: 30 May 2020
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