This can be a really dumb question... apologies

HenryT

Hi all.  I replaced a small fin tube type radiator with a 4 column cast iron radiator about 3 feet tall.

I feel like this radiator is undersized for my bedroom, assuming the bedroom is losing heat QUICKLY due to poor insulation and not properly insulated windows.

If I add a bigger radiator to this room will it retain the heat longer assuming all else is status quo (i.e. poor insulation and uninsulated windows).

This may sound like a temporary fix, but I just need some opinions before i move forward.



Thanks everyone.

Magnehelic

Well.....

Hot water or steam?  Generally, cast iron will hold it's heat longer than fin-tube, but is that really the consideration here?  Regardless of the material, you need to size the radiator for the room AND the medium the radiator is working with.  If it is hot water, can you turn the operating temperature up?  If it is steam, is it one pipe or two, and is it heating all the way across?  we'll need a little more information to assist you better.

HenryT

Thanks

It is heating all the way across but the problem is the room gets colder sooner than any other room.

It is for 1 pipe steam.

Thanks

jpf321

vented?

is it vented so that it gets hotter sooner than any other room? that might help since it will heat prior to the other rads...balancing the system in general may help with a little more venting preference given to this rad. is the venting near the thermostat too fast, causing the t-stat to satisfy too quickly?



a bigger rad is going to have more heated mass, so it should stay hotter longer.

what is the EDR of the fin-tube you removed vs. the EDR of the newly installed rad?

is there an enclosure over the rad? i take my enclosure covers off during heating season (although the subject is a bit controversial, i feel the room heats faster without the covers)



BTU = EDR * 240 at steam temp of 215degF .. did you do a heatloss for the room?

Charlie from wmass

What size is the room?

Then you need to get the ratio of square feet of radiation to square feet of room to have it in sync with the other rooms. If you size it to the room it will likely be very small compared to the other radiators in the home.

HenryT

thanks

Thanks. No i didnt do a heat loss, but its a master bedroom and i prefer it to stay heated longer... the fin tube would warm quickly but in a matter of minutes it will turn cold.



the thermostat is located in the living room where it holds the biggest radiator of the house. about 5-6 feet wide and 3 - 4 feet tall. So naturally while im freezing in my room, the thermostat will not kick in being that the radiator in the lving room is still retaining some heat.



what is the easiest way i can do a heat loss calc? thanks!

BobC

Cold room

That cast iron radiator will retain it's heat a lot better than the fin tube did but you have to get the steam into it fast so it can do the heating. How soon does that problem rooms radiator  get hot compared to the room with the thermostat? What kind of vent do you have on the bedroom radiator, if it is adjustable try adjusting it higher - ie go from 3 to 5. The higher the number the faster it will vent and the sooner you will get heat up there.



Also if you decrease the venting in the room with the thermostat the boiler will run longer and that cool room should get more steam and heat up better. Maybe you could move the thermostat into a room that doesn't heat up so fast. The problem there is that large radiator will likely overheat it's room unless you can turn it's venting down.



Of course this may not do much if the room is very drafty and has no insulation in the ceiling. Adding a radiant shield behind the radiator will put more heat into the room and less into the wall.



Look at the vents on the radiators and tell us what model they are. Take a picture of the radiator in the cool room and the vent on that radiator. Measure the size of the two rooms (L x W x H) and then the size of the radiators - how tall, how wide, and how deep, and if they are two column or three column. Then we can guess the relative capability of that radiator to heat that room. It's not as good as a proper heat loss calculation but it's a start.



In my house the front bedroom has a three column radiator that has 5 sections and is 38" tall, 13" wide and 9" deep. That room is about 12X10 and it's most of it's floor is over an open porch so the room is cooler than the rest of the house - but not freezing.



Bob