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Which would you choose? - Mike T.

Am soom installing a "new old" hot water system, i.e. cast iron rads and black pipe. Rental home next door to mine. For cost sake, seriously doubt I'll be using TRVs even though I love them. Fortunately I have and have access to enough sizeable rads.

Would you:

1) Size the rads to work with 140 degree MAX water and use a condensing boiler? Largest rads.

2) Size the rads to work with 160 MAX water and still use a condensing boiler presuming it will be condensing most of the time in our yo-yo climate? Slightly smaller rads.

3) Size the rads to work with 180 MAX water and use a standard cast iron boiler? Smallest possible rads.

Thanks for your opinions.


  • Bill NTSGBill NTSG Posts: 321Member
    I would

    Who will be paying the fuel bill? Is gas available ? I like the idea of the lower temps and the TRV's. Being conservative i like #2. #3 is so 1950's! But again, retro is in.
  • hrhr Posts: 6,106Member

    I like the lowest temperature, condensing approch best. If you are the owner and the one responsible to maintain the system go "new wave". Talk to Pete or Matt at Monitor MZ or the Munchkin folks about the results they have had with this retro.

    hot rod

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  • Jon HarrodJon Harrod Posts: 7Member

    I think TRVs make a lot of sense when used in conjunction with outdoor reset. They can compensate for changes in relative heat output between radiators caused by varying input temperatures. I was at the Danfoss web site yesterday, and they were claiming a really good payback on TRVs. I like either 140 or 160 as a design temp.
  • Dave Yates (PAH)Dave Yates (PAH) Posts: 2,162Member
    condensing vs conventional

    I'd go for the 140, no question about that. If hell ever froze over, you'd have the ability to raise the delivery temperature to overcome almost any sub-zero wind driven design condition!

    If utilizing condensing, a straight shot at the boiler is feasible. If using conventional, then primary/secondary or, better yet, primary/secondary injection/zone pump loop would be my choice.

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