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Location of Spirovent/ H20 feed when using a LLH .. what about purging the system?

TAGTAG Member Posts: 237
My previous old house restorations have all used radiators --- So I have always used Buderious CI boilers and followed the basic "pumping away" layout. My new house is all new floor radiant. Viessmann wall boiler w/ Indirect using the Viessmann LLH ...... there does not seem to be a single spot that everybody uses for the Spirovent and water feed. Viessmann seems to shows them together on the hot out-feed of the LLH to the manifolds .. so w/o any advise countering this .... my plan was to do it that way with the H20 feed using the lower tap of the Spirovent.

Purging the system is another question -- the nice thing about "pumping away" is with a 1 1/4 valve prior to the Spirovent and a 3/4 purge valve with hose fitting prior to the 1 1/4 valve -- it was an easy thing to close the 1 1/4 and use the H2o feed to purge the whole system back out through the 3/4 and hose. Opening and closing each manifold one after another

How do you purge a system with a LLH


  • hot_rodhot_rod Member Posts: 13,738
    Either of the top connections is fine for air elimination. The expansion tank can connect at any port it turns the entire LLH into the point of no pressure change. I prefer one of the bottom connections as the tank is in a cooler fluid, not a big deal if you are running a low temperature system

    If you do another, consider a Sep 4 LLH, it does everything in one “container”
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • TAGTAG Member Posts: 237
    How do you set up to purge ...? The LLH makes a bit more complex

    I do like how the sep 4 has the air elimination -- The Viessmann has a sensor in the LLH
  • hot_rodhot_rod Member Posts: 13,738
    A shut off and purge cock at the return to the sep for purging.
    All flow to the distribution needs to return to the sep, purge it there.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
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