SIZING UP YOUR RADIATOR
HOW DO YOU KNOW IF YOU HAVE A STEAM OR FORCED HOT WATER SYSTEM?
First, it is necessary to determine whether you have a steam or hot water radiator. Steam systemsgenerally have only one pipe feeding the radiator. The steam comes in this one pipe and heats the radiator. When the radiator cools down, say when you turn your heat down, the cooled steam condenses to water and trickles back out the same pipe through which it came. Steam radiators have a torpedo shaped vent usually half way down on the side that hisses when steam pressure is being released. Hot water systems needtwo pipes. One pipe feeds the radiator where the second pipe runs cooled water back to the furnace to be heated again. Hot water radiators have a small bleeder near the top of the radiator. The bleeder is operated by using a radiator key or a screw driver to open it in order that you can let any air out that has become trapped within the radiator. This might be done on a yearly basis just to be sure all is well.
IS IT A ONE PIPE OR TWO PIPE SYSTEM *One note of caution (but nothing to be frightened of), there are rare circumstances where homes are set up with a twopipe steam system. This is rare and not often seen, but it is possible. If you have a twopipe steam system you probably already know it.Now that you've figured out what type of radiator system you have, the next step is to size.
There are a few different approaches to take when sizing a radiator. First, a plumber or heating specialist usually should have the last word on the matter. If they have been to your home and seen the task at hand, they already know what you need, so just ask.If you are replacing a leaking or broken radiator, the best thing to do is to get an exact radiator or one that is equivalent in size and output.How?
THERE ARE A FEW KEY MEASUREMENTS THAT WILL SUCCINCTLY DESCRIBE ALL RADIATORS....
·How many inches high is the radiator?
·How many sections('coils') does it have?
·How many tubes or columns?
Column style each column is about 34" wide TWO COLUMN RADIATOR

Corto style each tube is about 12" wide FIVE TUBED RADIATOR


One last consideration is what is the measurement from the floor to the middle of the radiator inlet pipe? There are really only two sizes here. Older radiators (like the Column style and the Corto tube) are 4 ½ “ from the floor to the center of the pipe, while newer “slenderized” radiators are 2 ½” to the center. Maybe you don't want an exact replica of your old radiator. Maybe you are trying to move an old radiator to another spot in the room where it won't fit correctly. A common example of this scenario is where you try to put a radiator under a window….In this case you will need to consult the E.D.R. chart. What the Equivalent Direct Radiation chart does (see table below) is help convert tall radiators into short ones, vice a versa and everything in between.
EDR RATINGS CHART For Column and Large Tube Radiators as seen above for slenderized radiators see below
HEIGHT OF RADIATOR
TUBES PER SECTION


16"

18"

20"

22"

23"

26"

30"

32"

36"

38"

45"

3 TUBE







1.72



2.00

2.33

3.00



3.50

3.50



4 TUBE







2.25



2.50

2.75



3.50

4.25





5 TUBE







2.67



3.00

3.50

4.33

4.25

5.00

6.00



6 TUBE







3.00



3.50

4.00



5.00







7 TUBE



3.50



4.20





4.75











1 COL







1.50



1.67

2.00



2.50



3.00



2 COL







2.00



2.33

2.67



3.33



4.00

5.00

3 COL





2.25



3.00



3.75



4.50



5.00

6.00

4 COL





3.00



4.00



5.00



6.50



8.00

10.00

5 COL



3.75

4.50

5.00



6.30

7.00



8.50



10.00



This slenderized chart has already added the total Square Heating Feet of the radiator for you.
Radiators are big hunks of cast iron that are squeezed into a variety of sizes in order to fit any situation. If you are installing a radiator where there has never been one before, you will need to size up your room. How many square feet is the room? A good rule of thumb is that 45 BTUs of heat per square foot of floor space in a room with and 8' ceiling will adequately keep you warm. If you have many windows or face the north, then you could up this # to 50 BTUs/square foot. The same could be said for a 9' ceiling.
The converse is also true. If your room is incredibly well insulated you can lower the 45 BTU s per square foot rule to 40 or even 35 if your ceiling is only 7 1/2' high. So what does this mean? If you have a 10' x 10' room you have a total of 100 square feet. Easy. Now since the room is a normal room, you estimate that you will need 45 BTUs per square foot or 4500 BTUs. Hot water runs at 160170 degrees F and steam runs at 230240 degrees F. If you need 4500 BTUs and are trying to figure how big the radiator should be, then divide 4500 by the either the Hotwater temp or steam temp. In this case we will use Hot Water @ 165 degrees. 4500 divided by 165 =27 and change. Essentially now we know that you need 27 square heating feet of radiator to heat this room. Each section of any given radiator has a certain amount of surface area. Take this 27 and divide by the per section rating of the different styled radiators and you'll find how many sections you will need. If it were a 20" high radiator that you needed you would go with about 10 sections of a 5 tube corto. Or an equivalent slenderized radiator would be an slenderized 4 tube 18 section radiator. Comp rendezvous?
Total square feet of room X BTUs/sq. ft. needed (4060/square foot, see above) then: BTUs needed divided by temperature of steam (240) or hot water (165) This nets you the TOTAL SQUARE HEATING FEET needed.
From here you then use the chart to determine how many sections of each style of radiator.
For Converting a tall radiator to a shorter radiator, use the following:
(Use the height and number of tubes or columns) The E.D.R. numbers are a measurement of the square heating feet per section of any size radiator. If the E.D.R. is 5 and you have a 4 section radiator, multiply the E.D.R. of 5 by the # of sections 4. This totals 20. Essentially you have approximately 20 square feet of iron if you flattened out the radiator. The more square feet of surface area on the radiator, the more heat.
Now, what does a square foot E.D.R. mean? One more calculation and you’ll have a number you can warm up to. Hot water runs at about 175 degrees Fahrenheit, steam runs at about 240 degrees. Simply multiply your square foot E.D.R., (in our previous example it was 20) by either 175 or 240, depending on your hot water or steam system and what you have left is the number of BTUs per hour that your radiator will emit.
OK, now you know the E.D.R. or BTUs for your radiator. Let's do a reverse process to change the shape of your radiator. Let's say you have a tall 38” high radiator with 5 sections and 5 tubes. Its E.D.R. is 30. (5 sections X 6 E.D.R. = 30) You want to put your new radiator under the living room window which is 25” off the ground. So your thinking a 23” tall radiator would be perfect. How many sections, then?
Look at the E.D.R. for a 23” tall radiator. If its a 5 tube 23” tall radiator you want then the E.D.R. would be 3 per section. Simply divide the total E.D.R. for your old tall radiator, 30, by the E.D.R. per section for a 23” tall replacement, 3, and you will determine that you need 10 sections of a 23” tall 5 tube radiator to equal the same amount of heat that your 38” tall 5 tube put out.
*This process works for any conversion, regardless of whether your moving from 3 tubes to 5 tubes or 2 columns to 6 tube and everything in between.
