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KHN and V/S pump

Has anyone installed one of these direct piped with a variable speed (0-10) system pump? Manual is not very clear on this procedure and seems to indicate that p/s piping would be required?


  • hot_rod
    hot_rod Member Posts: 22,107
    I think a ∆T circulator on the boiler side of a P/S ,buffer, or hydrosep would have some value.

    If it were a modcon and had control of the ∆T pump from the boiler control, the VS function could be used to help assure low return temperatures, as distribution flows changed.

    That is one issue to be aware of with P/S or seps, there is most often a blending and it may be sending higher temperature to the boiler return, preventing highest efficiencies. The VS boiler pump could help mitigate that within the boilers acceptable flow range. With some fire tube type allowing down to 1 gpm flow, this should work.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Solid_Fuel_Mandelta T
  • Northernmax
    Northernmax Member Posts: 7
    Proposed system is in slab. (2 zone, 3 manifold, 1000sq garage and 2000 sq basement, 1/2" helio-pex circuits under 250', supply mains 1" ) Page 56 of I/O manual describes variable speed requirements, a Grundfoss UP26 V/S series is recommended on boiler side. Would like to use one boiler controlled circulator direct piped with zone valves.