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TRV question

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Vad
Vad Member Posts: 55
    Hello All,

I am working on installing a home run at the moment. Each radiator connects separately to a Manifold. I am thinking to get TRV on almost each radiator. Till today, I was thinking that it is the easy part. I looked at TRV specs and found that some of them rated for 2 pipe systems and some are for 1 pipe system (monoflow, etc.). Looks like it is because of the fact that two pipe system have a higher flow rate compared with one pipe.

   The question now is  TRV for which type (1 or 2 pipe) I can use for home run? I need TRV head mounted horizontally and looks like TRV for 2 pipe systems offer this.



Thank you,

Vad

Comments

  • Charlie from wmass
    Charlie from wmass Member Posts: 4,322
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    hot water models

    you need hot water trv's you can only have 2 pipes for hot water systems. 1 or 2 pipe refers to steam systems.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    edited October 2010
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    Now now Charlie...

    there ARE some one pipe hot water systems out there. I've worked on numerous. Rarer than hens teeth, but work amazingly well for their time. The worst thing one can do to one of these systems is add a pump to it. Changes the system dynamics completely.



    They used a fitting called a Eureka fitting. http://images.oldhouseweb.com/stories/bitmaps/830/heating_p20_300x141.gif



    Also, an OS fitting, which stood for Oliver Schlemer, who invented it.







    I had one one time that was running backwards, until it got hot enough, then it changed direction. I suspect cold radiator input probably had a lot to do with it, but no one complained.



    Back in the Good Ol' Days they were trying to compete with one pipe steam systems, except safer :-) Most were an open system with an expansion tank in the attic, but I ran into one once where the RADIATORS were the expansion tank. There was no other expansion tank to be found. I thought I was doing good by bleeding the air out of the radiators when we refilled the system. Phone rang the next day telling me there was water all over the basement floor near the berler... Coming from the pressure relief valve....



    Remembered reading about it in one of Dan's publications, re-drained the system, refilled system, didn't vent the radiators, and system worked fine.



    Live and learn...



    ME



    ME

    There was an error rendering this rich post.

  • Vad
    Vad Member Posts: 55
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    Thank you for reply, Please look at pages 5-9

    The document is talking about Hot water and not steam.

    I am talking about Danfoss RA-G (1pipe) and RA-N, RA-FN - 2 pipes

    Back to my original question. For Home Run do I need TRV for two pipe or one pipe system?



    Thank you,

    Vad
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
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    The confusion...

    You are correct in calling it a one pipe system, but it is more often referred to as a MonoFlo or diverter tee system. And if you are doing home runs from the mechanical room or a remote manifold to each individual radiator, it is no longer a one pipe system, but a two pipe system.



    And if you are using upright cast iron radiators, then make sure you have at least one zone that has no flow control, or install a pressure bypass valve or a constant pressure pump.



    Got pictures?



    They're worth a million words...



    ME

    There was an error rendering this rich post.

  • Vad
    Vad Member Posts: 55
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    Thank you, Mark,

    You confirmed my own view on this. Now I have to choose which one to get.



    Thank you again,

    Vad
  • Vad
    Vad Member Posts: 55
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    Thanks, Rod

    I am familiar with this chapter. This is how I started with the Home Run.

    One think that kind of unknown to me.

    The idea is to operate Boiler from Outdoor reset as an example. But it means that boiler will be operating all the time from Fall to end of spring (in my area). With the standard setup where I have thermostats in each zone, Boiler will operate only when the Thermostat is calling for it.

       From my unprofessional point of view it will be inefficient if the boiler will be working "full time" for 3/4 of the year with the TRVs on each radiator. Can you collaborate on this?

          I also seen article where the author  also suggest to put thermostat in the coldest room (in addition to TRVs in the whole house). It makes more sense to me, but what if all rooms are heated more or less equal? It is a rhetoric question :)

       I have heard about electric TRVs but did not have yet time to look at it closely. Too much info and not enough time. I have to concentrate on getting heat at my house :)



    Regards,

    Vad
  • Gordan
    Gordan Member Posts: 891
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    Keep reading

    The boiler doesn't FIRE all the time. The boiler only fires to maintain the supply water temperature that the ODR control tells it to. In a system without ODR, the boiler fires to maintain a fixed supply temperature (which is the worst-case temperature for all year, so it's far too hot for the vast majority of the heating season) whenever there is a call for heat.

    In each case, the boiler simply won't fire if the water is already hot enough. The circulator will keep running, though, as long as there's a call for heat. The ideal of ODR is to have very long (approaching constant) calls for heat, because that means that you're MAINTAINING the comfort level, and not overshooting/undershooting the way that a fixed supply temperature system has to. Why is it more efficient? Primarily because it uses lower temperature water for the vast majority of the season, so you benefit from condensing.
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