Looking to replace the old large cast iron radiators with slenderized ones

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Guy in DC

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Hi,
I live in an old house, which has the old large cast iron water heat radiators. I would like to replace some with modern slenderized ones, such as Burnham. Could someone recommend anyone in the Washington, DC area who replaces the radiators? Also, where to buy them in my area? Internet has so limited option. I would appreciate any feedback. Thanks.
 

Jadnashua

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The typical boiler is way oversized. The old style radiators hold a lot of water, which helps with the thermal mass, potentially cutting down on short-cycling and longevity increases. While new ones may look better, they may not function as well efficiency wise or response.
 

Guy in DC

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Thanks for your feedback, which I need to understand the principles. Before I moved in to the house, one radiator was disconnected (most likely was leaking), which need to be changed. Another challenge (which leads me for replacement) that two large radiators (lower and upper level) are always very hot, but some - in distant locations - just lukewarm. I had the idea to reduce the size of these two hoping to increase water circulation. The way I think might be completely off.
 

Jadnashua

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The smaller, thinner radiators do not hold as much water, so they can react quicker, but they also don't typically work at lower temperatures well . Because they don't have a lot of thermal mass, they also cool off quicker - the heavy, larger radiators once hot, stay hot for longer, with a more even heat.

Those currently that do not heat up well, may not be getting the proper flow. That could be because of sediment, rust, bad valve, rusted supply line, or more commonly, air in the system.

Hot water systems can be made by looping through various radiators in series, or to plumb them in parallel. In series, each one will tend to be cooler along the line. IN parallel, done right, each should be similarly hot water. If on different zones, it depends on if they use zone valves or individual pumps...either one of those could be bad and not allowing the proper flow to the ones that are cooler.

Without knowing more of your layout, speculation makes it hard to give accurate results.
 

Guy in DC

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Thanks again for your consideration.
I have three zones (with valves) and all radiators are connected in parallel. Two zones are for two separate baseboards ; one zone is for all others (in total 15 radiators). The issue, which I described above is with this one zone; one is disconnected from the system, two large (one on the first floor and the other on the second) are turned off (no need to use them), one old Victorian doesn't heat much. I plan to disconnect one large on the first floor, replace the other large with a smaller, connect to the system the one, which is missing, and replace the Victorian one with a new one. I don't know if my plan sounds wise. Also, if I add thermostats for each radiator, would it help to have better heat on each?
 
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