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Brazed plate heat exchanger: connections and maintenance

caryatid Member Posts: 11
I'm working on installing an underfloor hydronic heating system in existing joist spaces. I feel like I have gotten a grip on how it is supposed to work, but I am a little bogged down in exactly how to connect up the brazed plate heat exchanger. I assume that at least the open side needs descaling sometimes, so I want to put isolation valves and a purge on the inflow and outflow. Does that make sense?

I also imagine that I MIGHT need to change the thing out now and then, like the pumps. Is that a valid assumption? If it is, then I want some kind of connection that will allow me to do that without draining the whole system, right?

The heat exchanger has four MNPT connections and generally I am planning to plumb the mechanical room portions of the system with sweated copper.

It is tempting to use the same flanges for these connections as for the pumps; those specialized diamond-shaped pump connections from Grundfos or Taco. They are expensive, but otherwise is there a reason NOT to use those here?

I feel certain there is a part made just for this purpose, but I haven't found it yet...

Thank you.


    EBEBRATT-Ed Member Posts: 15,335
    Depends what you fluid is. If both sides are a closed loop system hot water/glycol I wouldn't be concerned with cleaning. But that's just my opinion.

    If one side is a "open system " then I would make provisions for cleaning.

    I would just use unions on the brazed plate connections. Then you can pop the whole thing out and put it in a sink...flush with city water
  • hot_rod
    hot_rod Member Posts: 21,868
    Many of the FPHX have 1" threads, so a gasket tailpipe can be added to allow removal.

    On an open potable side use a few Webstone or other brands tankless valves for super easy access for de-liming.

    I like these Webstone as you can flow the purge from both directions.

    As for how often you will need to de-lime, really depends on how hard, how much, and how hot the water runs.

    Keeping flow velocity high helps scour them clean also.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • caryatid
    caryatid Member Posts: 11
    Thanks Rod. I was wondering if those Webstone ones would work; thanks for the pictures showing me they do.