Sizing cast iron radiators

McPhinn

Hello,



We were referred to this site as the best place to get knowledgable advice for our problem.



We need help sizing hot water cast iron radiators for two rooms in a gutted renovation of a 120 year-old house. We have installed underfloor radiant pex tubing (staple-up) in most of the rest of the house. The water temperature from the new boiler will run at 140 degrees for the heating system. We will insulate thoroughly.



The two rooms that need radiators are each approximately 170 square feet. They are bedrooms that will be used as offices/guest rooms. Our plumber calculated the heat loss at 6,000 btu/hr for room #1, and 7,000 btu/hr for room #2. He has said the bigger the radiator the better, but we are concerned about weight and getting huge radiators up the stairs.



The radiator for room #1 will go on a wall that is 4' long. Will a 38" x 38" (15 section) x 8" radiator be sufficient for this room?



The radiator for room #2 will go under a window that is 27" high. How large a radiator will we need?



Much thanks in advance for your help,

McPhinn

NRT_Rob

do you know the EDR

of the radiators you are looking at?



failing that how many "columns" in each section? 2, 3...?

McPhinn

sizing cast iron radiators

Thanks, I do not know the EDR. We are shopping for old cast iron radiators on Craigslist or from local vendors, so we need to work with what is available. Is there a way to calculate the minimum (and maximum) size radiators that would be appropriate for each of the rooms?

Much thanks,

McPhinn

VictoriaEnergy

rads

Room 1: A 15 section (2 1/2") 4 column 38" H would be too small (5737 BTUs), if you could find a 5 col 15 section, it would work better @ 6750 BTUs with a thermostatic rad valve.

Room 2:  at least 22 sec of 5 col. 26"h again you want a little bigger and add a TRV, especially when  mixing staple up heat with cast rads.

Ironman

EDR Table

See the attached table. Multiply the square footage x 110, if you're using 140* water, to get the btu output.

McPhinn

Sizing cast iron radiators

Thank you all for sharing your expertise and advice, we can now search for the correct sized radiators!

McPhinn

Bob Gagnon plumbing and heating

Radiators

Did you get them yet? I'm coming down today.



Thanks, Bob Gagnon

Charlie from wmass

WHat size are you looking for?

With the height and edr you need I could check my inventory.

sandrine182

Sizing cast iron radiators

HI,



We also want to calculate the BTU's generated from our old cast iron radiator. We are doing some renos in the kitchen and we need the space used by the cast iron. We are trying to replace the tube type radiator, for one at the wall or something similar that will use less space than the actual one.

The Tube Radiator contains 5 tubes, 12 sections. It is 8 inches wide, 3 inches long and Height is 20 inches.

The room size is 14X 13,5 X 9.

The actual cast iron is underneath a window. The plan is to convert that window into a door or patio door to access our newly built deck.

Would you have any suggestion?

We are trying to buy second-hand wall cast iron and we are a bit limited on what is on the market. What would be the smallest and the larger option to heat this room?

Thanks in advance for you advice!

Sandrine