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  1. #1
    Join Date
    Sep 2012
    Location
    thomaston, ct
    Posts
    389
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    Viega mixing block setup help.

    Hey all,

    My company recently had a turnover and I had to pick up the pieces on a few big jobs that were in late phases and try and sort out the fine details and the setup processes that I’d normally enjoy on an install I have designed/installed from day 1.

    Anyways One job was a fairly large house with radiant installed in climate panels throughout, 4 manifold stations and two mixing blocks.

    I installed the low voltage using boiler sensors outdoor sensors and got all the water side of the boiler end of it working as it seems it should but am now having trouble dialing in the comfort for the customer.

    I have set:
    room design : 67’
    Mix design : 115
    Mix min: 100
    WWSD: 70

    With the system set to constant circulation the house overheats drastically even on a negative temp day. We had to set the mix design temp to 103’ on a -5 degree day so it wouldn’t shoot past 70’.

    I’m new to the radiant side of things but I’m assuming the lack of thermostat and constant circulation must be why it overshoots so far.

    Other possibilities?

    Any experience?

    Would connecting the mixing block to a thermostat solve these issues?

    We also have hydro air in the house so I could stage the heat through the thermostats if the radiant isn’t keeping up but that doesn’t seem to be an issue.

    If the system is set to constant circulation it seems like there must be a room thermostat or it will never work right.



    Sent from my iPhone using Tapatalk

  2. #2
    Join Date
    Jan 2015
    Location
    Bellevue, Washington, United States
    Posts
    1,631
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    Your design is strange to say the least.

    Normally I design my controls where if the thermostat calls for heat the pump, and boiler will activate and the aquastat on the boiler will regulate water temp around 180 degrees.

    Your plumbing is probably just fine but you'll probably need to install some kind of controller like a taco sr503.

  3. #3
    Join Date
    Sep 2012
    Location
    thomaston, ct
    Posts
    389
    Post Likes
    Thread Starter
    Quote Originally Posted by James Colver View Post
    Your design is strange to say the least.

    Normally I design my controls where if the thermostat calls for heat the pump, and boiler will activate and the aquastat on the boiler will regulate water temp around 180 degrees.

    Your plumbing is probably just fine but you'll probably need to install some kind of controller like a taco sr503.
    Design is not my own, started with a few manuals and a rats nest of wire. The control side and the communication between the Viega mixing block and the viessman boiler is fine. Mixing block calls opens valve and send target water temp to mixing station to whatever percentage to achieve water temp I think the missing link is the thermostat as simple as that sounds.


    Sent from my iPhone using Tapatalk

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