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My understanding, so far, of the system

I am not a heating pro, but I want to understand how this will all work.

A house I designed, to be headed throughout with 140 F. max supply for TRV-equipped panel radiators, will require more or less 12 of these.

A mod-con boiler will be used, and the following diagram I clipped from a source provided me by a helpful <em>Wall </em>member here, shows the preferred arrangement of system piping from the ECM pressure-regulated circulator, out.  That is, supply and return manifold outlets and inlets are home-run to each panel radiator.

 In my understanding, the diagram is incorrect in that no boiler loop is diagrammed, complete with its circulator and the closely-spaced tees that "connect" it (isolate it, in fact) from the system piping outboard of those tees.

Is that it, sort of?

Inside the boiler loop, we desire to supply heat to an indirect DWH, and I sort of know how that looks, but my question relates to the heating system, the isolation of it from the boiler loop via the tees, and the apparent simplicity of control.


1.  Should there be a boiler loop separated from the system, via the tees?

2..Is the arrangement shown of manifolds and home runs a good one, when using panel rads and TRVs for each?

3.  Is the basic control means, for the system side, that being the outdoor sensor and its control module, providing input to the ECM pressure-regulated circulator, an effective and good means of getting that 140 F. max temp water to the emitters?


  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Only one correct answer to ANY hydronic heating question...

    and that answer is, "It depends".

    Your assumption of requiring a separate pump to serve only the modcon boiler is correct for 95% of the boilers out on the market.

    The Triangle Tube boiler has an option to use one pump, provided that you end up with enough residual head to maintain adequate flow through your emitters. You MUST follow the directions provided by the boiler manufacturer of your choice.

    Item 2, looks good. Personally, I'd rather run a long running parallel reverse return manifold out of copper, but I am looking at it from the amount of manpower consumed in getting it installed, and not from the point of simplicity. Your design is fairly simple, but I am a pipe fitter/plumber so I look at things differently.

    I'm also getting older, and the less time I spend in a crawl space, the better :-)

    Regards item 3, all modcon manufacturers send their appliances out with an on board control logic that is capable of doing everything you want and need it to do, except for indoor feed back. Indoor feed back can be as simple as a thermostat that can "see" when there is enough internal gain (solar, bodies, wood burner etc) to keep the heating plant shut down. The ECM pump is basically wired to the boilers space heat output pump relay, and it will wake up and do whatever it was programmed to do. It remembers, even with the power to it shut off.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
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