Am I sizing the boiler correctly - need advice

Mark Eatherton

It's almost a perfect match.

And once someone comes out with a good steam pressure modulation package, you can save even more fuel.

ME

Chris_105

My EDR for radiators versus contractor estimates

This site has been a great help to me. I am getting quotes to replace a single pipe steam boiler. House was built in 1938, 1500 square feet, no insulation in walls, attic well insulated. Three contractors have given a wise price spread for the work and a wide spread of the EDR/square feet of steam for sizing the boiler. From 350 to 460. Two of them spec'd the same Burnham V8 4 section boiler.

They all did some degree of measuring of radiators, but not that detailed as far as radiator type etc.

I just did my own calculation and came up with only 262 sq ft EDR for the radiators. I am hoping you folks can check my numbers. I ID'd the radiators as large tube column types thanks to this website. They are all branded as "H&C", sections are 2.5" wide, individual tubes are about 1.25" in diameter if looking down the long end of the radiator. I used the follwing table from Burnham for my calcs:
http://burnham.com/tool_box_sizing.htm

Here are my values (ID#, height, tubes, sections, sqft/sec, sqft/rad:

BR1-20-5-12-2.67-32.04

BR2-36-5-5-5-25

BR3-36-5-7-5-35

Bath-36-3-4-3.5-14

LR-20-6-14-3-42

DR-20-5-14-2.67-37.38

Kit-20-3-14-1.75-24.5

Porch-38-2-13-4-52

Total 261.92

The porch radiator is a column type, very different style, so I used the other table on that one.

I am thinking about losing the last (porch) radiator on the list since it never gets used anyway. That would get me down to an EDR of 210 or so. By my calculation, I can go with the V83 Burnham model sized for 283 sq ft of steam, not the V84 they spec'd at 396 sq ft of steam. Or go with the Megasteam MST288, rated for 288 sq ft of steam.

I would love to hear some thoughts on whether I'm doing this right. The main in the basement is insulated, as is the piping in the walls. I'd like to know how to estimate if I need to add more than my 33% based on size and lenght, but cant find values for doing that. I'll post some pics tomorrow. Thanks in advance.

Chris

Stewy_2

Here is another chart to help you

not sure how the Burnham chart is setup but, this one is definitely geared towards the layperson (worked great for me)
Just a little extra validation before you pull the trigger.

And something else I learned on this site as I just want through this same situation, the boiler manufacture already figures the pickup load for you (33% - which is sufficient provided you don't have extravagant piping)so all you have to do is measure the radiators and use only that EDR to pick your boiler.

Not seeing exactly what you have for rads I came up with 250(246.4)sqft EDR

Stewy_2

Here is a pipe chart

to use this get the total lenght of all your different size pipe, multiply it by the given number under the 210 degree category and divid by 240 that will give you the EDR of your bare pipe (do this for each size pipe and add the numbers together,that will give you your total pipe EDR)

ex 20 ft of 2" pipe - 20 x 212 = 4240 / 240 = 17.6

Mad Dog_2

Listen to Eatherton.......

MEGASTEAM > mAD DOG

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Stewy_2

Chris_105

Pipe chart

Thanks Stewy,
I came up with a number of 108 EDR for my piping, but my pipe is all insulated, including in the walls. Does this change the value of that number?

Anyway, 108 * 240 = 25920 BTU which is only 28% of the 92000 DOE heatng capacity the boiler is rated for, which is less than the 33% deduction built into the 288 sq ft of steam (or 68000 BTU) the boiler is rated for. Which means (tell me if I'm wrong) that I should be fine.

Chris_105

so does 260 EDR...

Does an EDR of 260 sound reasonable for a 1500 square foot house. Or if I don't count the three season porch and its radiator, then about 1350 square feet and an EDR of 210?