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Piping to Remote Indirect with (possibly) Lochinvar Knight?

Richard Miller
Richard Miller Member Posts: 72

I am leaning towards a Lochinvar Knight for radiant and the indirect water heater. I would be running the indirect as a primary loop with priority through the Knight. Not certain which indirect I will be going with.

The problem is, my indirect will be 30-35’ from the Knight. And I need to be putting the boiler-side piping in very soon.

Anyone see any issues with running that 30-35’ in 1” PEX with 3/4” wall pipe insulation under the slab? I can’t find pressure drop info for any of the indirects, and I don’t remember how to calculate it all.

Thanks again…

Comments

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,599

    Hi, I do have a suggestion. Looking into the future should there ever be a problem with the sub-slab plumbing, you're in trouble. A way around this is to use 3" PVC electrical conduit under the slab, and come up with those long sweep electrical ells. I've done this and it's not hard to pull insulated PEX through it. This gives you the ability to maintain it as needed, and it likely will perform slightly better, as it will stay dry. 🤓

    Yours, Larry

    ps. I know I haven't answered your main question about flow, but others with more know how certainly will!

  • GroundUp
    GroundUp Member Posts: 2,124

    Each indirect will have a given pressure drop for X BTU transfer using Y flow rate. That will determine the correct piping and circulator for the application. There is no way to properly do this without the specs of the indirect.

  • hot_rod
    hot_rod Member Posts: 23,400

    Depends on how much performance you want from the indirect. What size boiler , output?

    The PPI site has an excellent calculator for pex tube.

    Here is what 8 gpm looks like through 70' of 1" pex

    \

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream