Question about steam cast iron tube radiator size(btu) for upstairs room(s)

pendragon925

Hello, I live in a smallish Cape Cod in northern NJ My question is, what size cast iron radiator I should swap to in the two upstairs rooms in the house?

They are currently 25" high 4 pipe 14 section radiators (6720 BTU) which makes the rooms very hot (anywhere from 5-10 degrees warmer than the 1st floor) and it makes sleeping at night very uncomfortable. All of my information is taken from AF Supply which is likely where I would order the radiators from(welcome to suggestions).

Spec sheets for their radiators - ****all the BTU's listed in this post are based on this****

https://www.afsupply.com/pub/media/catalog/product/specsheets/radiator_specs.pdf

BTU calculator -

https://www.afsupply.com/btu-calculator
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-what I input-

step 1: steam

step 2: 25" high

step 3: 4 tube

step 4: width- 9'3", height- 7'3", length- 15'4", window area(x^2)- 18, type of room- bedroom, what is below the room- a heated living space, what is above the room- roof/attic with 4 inch + insulation, select type of outside wall- wood frame, select type of window- wood/plastic double glazed, select number of outside walls - three

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these yielded the result of "2137 BTU" required. this brings our tube radiators from the current 14 section (6720 btu) to these recommended sizes -

Lower power model 25" 4 tube 4 sections (1920 btu)

Suitable power model 25" 4 tube 6 sections (2880 btu)

Higher power model 25" 4 tube 8 sections (3840 btu)

...
So I guess my question is what amount of sections should I downsize too? 14 sections is way to much, but I guess I was worried that 4 sections may be too little? I just want to be able to sleep without having to close the radiators at night lol. I'm overly warm at night when they are on but my wife is too cold when they are off, we also have a baby on the way and the nursery will be in the other room(same size and specs) on the 2nd floor. Thank you, I appreciate any advice and information yall can provide!

mattmia2

You could put a cover over the radiator that would reduce the output. You could put a slow vent on it so it doesn't fully heat. You could put a TRV between the vent and the radiator to keep it from heating at the start of some cycles.

ethicalpaul

Yeah exactly what @mattmia2 said— you don't need to replace them, just cover them either with a box or even a blanket and slow venting, a Gorton or Maid o Mist #4

Jamie Hall

What tou don't say is if this is one pipe or two pipe steam. The vent trick works for one pipe. The blanket for either. But if it's two pipe it's even easier — partly close the inlet valves

pendragon925

Thank you all for the suggestions! It is a one-pipe system, it sounds like the TRV will be my best bet! I will try and cover it in the mean time =]

delcrossv

Just remember Vent, not valve. 1/8 npt.

RTW

I installed cast iron radiators in the two bedrooms upstairs in one pipe system in cape style house and used:

Higher power model 25" 4 tube 8 sections ( American Radiator bought used)

There existed electric baseboard heaters that I kept and sometimes use on the off or in-between seasons fall & spring when its not practical to heat up the entire house

All the best

RTW

dabrakeman

Personally I would just use Ventrite #1's to slow them way down and be done with it. $35 on Ebay w/ free shipping. Not saying TRV's wouldn't be an even more elegant solution, just your money and your decision. I tend to be a bit frugal…