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Recirculation for new Indirect install?

I'm about to install a Smart 60 Indirect WH on my about to be installed TT Solo PTE-110 Boiler. Their application and installation guides seem to suggest a recirculation pump would be a good idea. I like the idea of the benefits of doing this.

My questions is... how would I implement this with my home-run plumbing? I've recently redone all of my plumbing using PEX homeruns to a manifold (that sits in the same utility room as my DHW heater). At this point I'm still down to studs and joists, I can easily run a new return line (or multiple) if necessary.

The house is ~75 wide and the major water fixtures are at either end (kitchen at one end, master bath at the other). The utility room in the basement is smack-dab in the middle of the house. With our current direct fire WH and home-run PEX there is a wait for hot water that I would love to eliminate.

Is recirculation possible in this scenario? If so, what's the ideal way to plumb it?

Thanks in advance for any help!!


  • SWEI
    SWEI Member Posts: 7,356
    Home run manifolds

    I'd probably re-pipe with two smaller manifolds, one at each end of the house, and recirc to both manifolds.
    JUGHNE Member Posts: 10,315
    edited December 2013
    Gravity still works..

    I had the same situation with distance to mas bath.  About 65' of hard copper was run from the mas bath vanity to the bottom of the indirect water heater tank (drain port).  Under the vanity the recir line tied as high as possible to the HW (service ball valve installed here).   On the insulated horizontal run, slope back to the tank was maintained.  At the tank the vertical drop of 7' was not insulated.  A ball valve for throttling installed then a swing check then another service valve.  The throttle ball valve is as closed as can be and still have flow.  You have hot water before you get your socks off!!  Now factors I'm not sure of are: is slope necessary,  I have worked on gravity flow boilers and the dead men thought it necessary.  How much insulation;  I think of the last 7' as a cooling leg to promote gravity flow;  I used 1/2" OD for the first 30' (excess stock) and 5/8" OD for the remainder.  I have used this system before with success. (some time a 1/8" hole drilled in the check flapper might be needed to promote gravitation.)  The rigidity of hard copper may be a factor in promoting flow also. Think of PEX not so straight. You could try this and always add a pump later.  (Future headache and KW)  I know I lose some BTU to create the constant flow.  But all the water that went down the drain previously used to be hot water.  Also I have a 120 gallon tank and this flow thru the tank seems to help to maintain fairly constant tank temps.
  • Rich_49
    Rich_49 Member Posts: 2,703

    cut in a tee on the fixtures that matter and run them back to a recirc manifold near the IWH .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • hot_rod
    hot_rod Member Posts: 18,222
    the main benefit

    of a homerun system, like the Manabloc is it did not require a recirc.

    If all the fixtures were within 60- 75 feet the small diameter, usually 3/8 pex, to every faucet would purge out in a few seconds. Tub fillers were sometimes 1/2, as purge time is not so critical.

    Adding a recirc sort of defeats the purpose of a homerun system?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SWEI
    SWEI Member Posts: 7,356
    Homerun systems

    Can really shine with 3/8" for sure.  With shorter branches they work even better.  When I researched them a few years back for project, I did find it interesting that the Manabloc directions essentially prohibit recirc through the manifolds.  Seems like a logical fit for dormitories, hotels, nursing homes, etc.
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