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Rinnai i150s Circulator Pump Question

PurpleThumb
PurpleThumb Member Posts: 16
in Gas Heating

Hello All,

I Am Replacing An Old Cast Iron Natural Gas Boiler ( 35 Years Old ) With A New Rinnai Non-Combo Boiler, With Closely Spaced Tees For Hydraulic Separation.

The Previous System Has Three Zones Each With A Separate Circulator Pump.

My Question…

Do I Need An Additional Circulator Pump For The Rinnai Internal Loop?

Some Installations Show Separate Internal Loop Circulator… Some Do Not.

Thanks.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 26,403

    Probably. But check the Rinnai installation manual…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • GGross
    GGross Member Posts: 1,625

    i don't know what an internal loop is. In primary secondary piping both the primary and the secondary need, at a minimum, their own circulator. the close spaced tees hydraulically separate the 2 loops, the goal being that flow from one won't flow through the other.

    Some boilers have a circulator built into them (mod-con combis for example) in those installations the internal pump is the pump for the boiler loop.

    in your example each zone has a circulator, and the boiler is separated from those zones via close spaced tees. so yes there needs to be a pump on the loop with the boiler. if there is a pump built into the boiler then you are all set, if not you will need to install one.

  • PurpleThumb
    PurpleThumb Member Posts: 16

    Thanks.

  • PurpleThumb
    PurpleThumb Member Posts: 16
    edited September 25

    Here Is A Drawing Of The Proposed System…

    system Bitmap.jpg
  • Kaos
    Kaos Member Posts: 736

    I would double check, but I think only the combi comes with internal pump, so you have to add an external pump to the primary loop. You also want some purge valves on the primary loop to help with air removal.

  • GGross
    GGross Member Posts: 1,625

    if there is no built in circ I recommend putting the external circulator on the return pipe flowing into the boiler (blue vertical line under boiler) and yes you will want some drains and valves. webstone makes pump flanges with and without drains that are nice, they also make ball valves with drains built in.

    Alan (California Radiant) Forbes
  • GGross
    GGross Member Posts: 1,625
    edited September 25

    some other minor notes. I like to have a valve to shut off the auto feed, that way know there is a leak, taking on fresh water is typically not good for closed loop boiler systems, alternatively you could look into building a filling unit with an autofeed and an extra expansion tank that way you could control the makeup fluid. there are also pre-built systems for this. webstone makes an expansion tank service valve that will take the place of several fittings at your expansion tank and autofill setup . you also may be required by code to install an external low water cutoff device if there is not a flow switch safety built in to this. many have a pressure sensor safety that is sometimes accepted by local inspectors and sometimes not.

  • PurpleThumb
    PurpleThumb Member Posts: 16

    Thanks very much for sharing your knowlege.

    Your generosity is very much appreciated.

  • PurpleThumb
    PurpleThumb Member Posts: 16
    edited October 1

    FWIW….

    According to Rinanni…a user supplied circulator pump is necessary for the boiler loop, in addition to the radiators loop(s) circulator pump(s) for the Rinanni i150s Non-Combo Boiler.

    Thanks Again,

    Bill

    Alan (California Radiant) Forbes

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