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piping cast iron radiators

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nace
nace Member Posts: 7
I have seen many different ways to pipe ci rads in a home. I am doing a reno on a home and we are putting all ci rads back in and converting some steam ones to water. I am looking for suggestions on piping layout and also supply and return on top and/or bottom. I saw a post from J Lin and had further questions on that one if J Lin is still on the wall. Thanks for the help

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  • SuperTech
    SuperTech Member Posts: 2,188
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    I strongly suggest going to the heating history section of this site. There's installation manuals for a couple different manufacturers. It definitely helped me figure out my system.
    nace
  • hot_rod
    hot_rod Member Posts: 22,271
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    I've been adding radiators to my system when I come across unique ones. I feed each one with 1/2 FostaPex, add a TRV.

    It's fairly easy to drill and tap a radiator to add a connection for S&R or an air vent up high.

    I've also found feeding in and out the bottom, like this corner rad works fine. All the iron gets warm after 20 minutes :)

    I feed these with fixed 130F supply.

    There is a fitting available from several manufacturers to allow S&R into one connection tap.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    naceSolid_Fuel_Man
  • Tinman
    Tinman Member Posts: 2,808
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    @hot rod the Honeywell Unique Valve has made a comeback?
    Steve Minnich
    SuperTech
  • JUGHNE
    JUGHNE Member Posts: 11,077
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    Bob, did you get that corner rad home in one piece?
    I would have been concerned about the corner connection on something that old.
    You know that is from Nebraska and should be in my house :'(
  • hot_rod
    hot_rod Member Posts: 22,271
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    Stephen, Caleffi makes a few versions of that conversion valve if ever you have a need. It is not in the US catalog however.

    Jug,I did support that corner section for the trip home, someone here warned me about the weak spot.

    It took 3 guys to slide it into my truck, we couldn't begin to lift it.

    I'm glad I didn't witness it coming down from the 3rd level! They must have built staircases plenty stout in those days also, knowing that iron was traveling up or down :)

    I scraped and wire brushed for 3 days to get 10 layers of paint down to a fairly smooth surface.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JUGHNEkcopp
  • nace
    nace Member Posts: 7
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    What about the actual piping of the s&r from the new boiler. There seems to be several different ways to do it. Anyone have pics to show which way they suggest
  • hot_rod
    hot_rod Member Posts: 22,271
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    Look at page 26 for an example of a home run with a typical cast iron boiler.

    https://www.caleffi.com/sites/default/files/file/idronics_19_na.pdf

    This entire issue is about various, proven piping methods.

    The piping options depend somewhat on the components that need to be connected.
    Piping and components need to be sized correctly and installed in the proper location.

    A cast iron boiler, pex home run, cast rads with TRVs and a Delta P circulator in this conceptual schematic.


    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperTech
  • nace
    nace Member Posts: 7
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    hot rod,
    I have installed baseboard heat primarily and this is the first CI Radiators that i am doing. Typically i have used hi efficient boilers and Grundfos 3 speed circulators with check valves. We are starting from scratch so we can pipe any way we want but there are some of the radiators that may possibly need to pipe from the same side. Supply in the top tap or bottom if i am doing that?
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
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    Home run with 1/2 pex is pretty much the norm for new install. My personal favorite is still reverse return though. Elegantly self balancing while still allowing individual control of each heat emitter.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • hot_rod
    hot_rod Member Posts: 22,271
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    nace said:

    hot rod,
    I have installed baseboard heat primarily and this is the first CI Radiators that i am doing. Typically i have used hi efficient boilers and Grundfos 3 speed circulators with check valves. We are starting from scratch so we can pipe any way we want but there are some of the radiators that may possibly need to pipe from the same side. Supply in the top tap or bottom if i am doing that?

    I supply in the bottom return from the top, add a coin or float vent at the top also to purge the radiator when filling.

    These hygroscopic vents are ideal for radiators, both manual and automatic mode.

    On the bottom connection I have used a piece of pex to extend that supply across the bottom so you get more of a cross flow thru it.

    I've also installed radiators with just a single connection with this type of retro fit valve. S&R goes in the lower bottom connection, a TRV can be added also.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
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    @hot rod I installed some CI rads for a customer which had open spud on top and one on opposite bottom. I assume originally two pipe steam. I supplied the top and return out the bottom. Thinking that would heat the cast the most evenly. Forcing the hot water to the bottom.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • hot_rod
    hot_rod Member Posts: 22,271
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    I'd guess the radiator would get hot with flow in either direction. I've found that the entire mass eventually warms. With big wide open sections I doubt floe happens in every section, the flow probably finds the easiest path, conduction warms the mass of iron I'd guess.

    I videoed a radiator heating up with an infrared camera a few years back. I tried it with various piping arrangements including the dual port type valve on one connection. I did not notice a huge difference in warm up time or how the heat moved across the sections, with the 3 piping methods I tried. The heat "picture"is not unlike what you see with panel rads, the metal warms first from wherever the supply enters.

    Like a cast iron fry pan, at some point the entire pan warms, regardless of the burner size below.

    I'm referring to radiators that are section connected across top and bottom. I have not tried a radiator with only the bottoms connected?

    The bottom in, top out speeds air removal sometimeso
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperTechSolid_Fuel_Man
  • nace
    nace Member Posts: 7
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    so home runs from the manifold to each rad? 1/2 hepex for this? and does caleffi make such a manifold to do 6 rads? Also 1 grundfos circulator per zone? I would like to zone each floor so I want to make sure i can use one circulator with one manifold per zone?
  • hot_rod
    hot_rod Member Posts: 22,271
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    Caleffi and others make easy to install hydronic manifolds. We offer 3- 13 ports and pex fittings from 5/16- 3/4" and PAP 3/8- 3/4"

    1/2" pex can easily move 20,000 BTU/hr

    A single circulator at the manifold would probably do the job, ideally you would calculate the heat load and required flow for each radiator to be sure.

    This shows panel radiators, they could be any heat emitter type, baseboard, cast rads, air handlers, radiant loops.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nace
    nace Member Posts: 7
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    Thank you i will let you know how i make out
  • SuperJ
    SuperJ Member Posts: 609
    edited March 2018
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    Better to use valves/TRVs instead of more circulators, even if the cost is the same upfront. Single circ pump is more efficient pumping most of the time. Look into delta p ecm pumps, well worth the small extra cost.
  • nace
    nace Member Posts: 7
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    I am in the USA and the customer is ordering the rads from the UK. They come BSP instead of NPT. They are going to supply a 15mm pipe for the compression fitting at the new valves. Does anyone have a way to go from 15mm pipe to 1/2 heat Pex? My supply houses do not have any fittings to convert BSP to NPT. Any ideas?