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Radiator Size

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hotquestions
hotquestions Member Posts: 10
Hi All, we're moving into a rowhouse with ~40" tall two pipe steam radiators in every room (including rooms as small as 70/80 sq ft). The system is run off an oil boiler (also does DHW though no indirect tank) that is a few years out from replacement. Would switching to smaller radiators in some of the rooms help us make the system a little more efficient. We're probably disconnecting the gas line but wondering if cold start oil boiler for heat, smaller radiators, and a heat pump DHW heater would be more efficient than the current setup?

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  • bburd
    bburd Member Posts: 917
    edited March 2
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    The short answer is no. The system will run long enough to satisfy the thermostat, assuming the radiators are big enough to meet the heating load. Smaller radiators will just mean it will take longer to reach the set temperature, short cycling the burner and reducing efficiency.

    The best thing you can do is make sure the system is operating properly and is balanced so you do not get uneven heating. We can help you do this.

    Bburd
  • Jamie Hall
    Jamie Hall Member Posts: 23,313
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    Two pipe? Do the inlet valves work? If they do, the easiest thing to do is to turn them down... will do the same thing as putting in smaller radiators.

    Cold start boiler will help. Some. Won't pay for a new boiler, but that's another problem.

    Heat pump water heater will reduce your oil use, and is slightly more efficient than fuel fired electricity.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 16,842
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    @hotquestions , where are you located? We might know someone who can look at this and give you an answer that means something. Meantime, post some pics of the boiler and several radiators (without covers)- let's take a look.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • hotquestions
    hotquestions Member Posts: 10
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    Thanks for the input! As it turns out, the radiators are two pipe hot water. Assuming the wisdom above still applies?
    Can get photos in soon too.
  • Jamie Hall
    Jamie Hall Member Posts: 23,313
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    Most of it. Except my suggestion to try partly closing the inlet valves. If it's hot water, that may result in noise at the valve, which may or may not be noticeable.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    GGross