Brazed plate heat exchanger: connections and maintenance

caryatid

Hello.
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

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

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.

caryatid

Thanks Rod. I was wondering if those Webstone ones would work; thanks for the pictures showing me they do.