Connecting Old Radiators to New Boiler

Discussion in 'HVAC Heating & Cooling' started by Kiwikid, Oct 2, 2008.

  1. Kiwikid

    Kiwikid New Member

    Oct 2, 2008

    We have a four level house in Brooklyn. Previously the house was heated using cast iron radiators (many new) connected to a boiler in the basement. This is two family home (two floors per apartment) and we have recently instated a new combi boiler in the top apartment. It is providing hot water to the bathroom etc but we have yet to hook to a heating system. It seems a waste to do away with the existing radiators. The radiators are located at the front and back of the house (the building is connected on each side). There are four radiators per floor (2 front, 2 back) for a total of eight.

    My question is, if we run new lines to the existing radiators (PEX with oxygen barrier) should this be done in a home run system or in a loop? The boiler is in the middle of the house 15 feet from the front and back walls. If we do home run can it be to a manifold at the front and a manifold at the back? Pipe sizing suggestions?

    Any advice appreciated.

  2. sibi1972

    sibi1972 New Member

    Oct 3, 2008

    I'm curious about something. When you say "home run system" do you mean that each convector is run to the boiler and that's where the series connections are made? Because if that's what it means, then that is a lot of piping to pump hot water through, isn't it? Wouldn't it be better to connect all of the convectors in each zone with as little piping as you can?

    I'm just trying to understand what you mean so if I'm off base here, please accept my apology.

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  4. Kiwikid

    Kiwikid New Member

    Oct 2, 2008
    Remote manifolds

    Hi Sibi,

    I should have said that if I do the home run it would be to remote manifolds located at the front and back of the house. The distance to each of the radiators would be less than eight feet from the two manifolds. The manifolds would be 25 feet from the boiler

    The alternative is run a main line in front and back and branch off to each radiator.

    I am wondering if there are advantages to the manifold design in terms of performance (controlling flow rates to each radiator etc). It has the advantage of allowing each radiator to be isolated should we need to.

    Thanks for help.

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