Sizing New Steam Boiler and EDR

rjfork

Or am I reading the chart wrong?  Are the #s after 5B the Edr for that size of the length of the convector.  

I’m losing it.  

random12345

I agree that table is confusing. My interpretation is as follows: the number after "No. 5B" is 20. I think that refers to the enclosure height. I think the numbers in the remainder of that row are the steam EDR ratings and do not refer to the lengths of the 5B convector. The 5B convector length is still read from the top of the table like all the others. The pdf of the NRC catalog indicates that the 5B convector was only designed to be used in an enclosure height of 20". There is a footnote on the bottom of page 18 of 20 that says, "Minimum enclosure height of 5C and 9B2 units is 21-in." Under the "20-in Enclosure Height" section of the ratings table, comparing the 5B and 5C for identical convector lengths and knowing the enclosure height differs by 1", the 5B ratings are always lower than 5C. Whether that is due to the 1" in difference in enclosure height, or because 5B is a smaller heat emitter is hard to say...but looking at the numbers, my sense is that 5B is in fact a smaller emitter than 5C and that 1" difference in the enclosure height is only responsible for a small part of the difference between the two. My conclusion is that if all of your convectors are 5B, then your EDR is somewhat less than 335.

random12345

If there is any doubt, and I know I said this before, but send an email to the Smithsonian at NMAHLibrary@si.edu, and reference this page: https://americanhistory.si.edu/collections/search/object/SILNMAHTL_33015

I just spoke with a librarian there today because I wanted to know if they had any plans to digitize their old trade catalogs, but unfortunately because of resource constraints and copyright restrictions, they are not planning to do that...But I was told that they "would be more than happy" to help individuals who send research requests as long as they search the library website first to find out if what they need might be in the collection. And they have a big collection of NRC trade catalogs. While you're at it, you can also reference this page for your Oriole rad: https://siris-libraries.si.edu/ipac20/ipac.jsp?uri=full=3100001~!226131!0

And if you know who manufactured your castrays, you can see if they have that too.

rjfork

Thanks, Random.  Ok so I guess my initial calculations were correct then. When I was looking at the chart again today I was having second thought of how I read it.  

Yes, I will be requesting them.  Just don’t know if I’ll get them in time.  

jhewings

Regarding the baseboard hot water loop, Dan suggests in the following article that the baseboard loop should not enter into the calculation of the boiler size.
https://heatinghelp.com/systems-help-center/how-to-run-a-hot-water-zone-off-a-steam-boiler/

mattmia2

the 5b and 5c etc. are different depth elements so they have more or less area for a given width.

rjfork

Thanks jhewings. This a pretty technical article for me.  

“This is a game of subtraction, not addition. Size the steam boiler first. Base it on the connected steam radiation load, plus a suitable pick-up factor, not the heat loss of the building. Then work with the available pick-up load to size your hot water zone or zones. You can't take out more than what's there.”

But the bottom line appears to be properly sizing the steam portion should allow for proper heating with the hot water heat without degrading the steam system…did I get that right?

mattmia2

Unless you are severely undersized, if you put good venting on the mains and balance the venting on the radiators and you make sure you don't have any piping issues like places that can trap condensate in the mains or runouts, all of the radiators will heat and the system will heat evenly even if not quite the entire radiator surface heats.

It is better that the system can consume all of the steam produced than the system cycles on pressure. There are formulas to calculate the load from the piping if you want to measure all of the piping. That likely will show that the standard pickup factor baked in to the boiler rating is far too big, especially if some of your piping is insulated.

random12345

jhewings said:

Regarding the baseboard hot water loop, Dan suggests in the following article that the baseboard loop should not enter into the calculation of the boiler size.
https://heatinghelp.com/systems-help-center/how-to-run-a-hot-water-zone-off-a-steam-boiler/

Thanks for that. Good article. I remember reading part of that last year. So basically he's saying size for installed EDR only and play with pick-up factor for the hot water loop. Might not work with uninsulated steam pipes though...

random12345

mattmia2 said:

the 5b and 5c etc. are different depth elements so they have more or less area for a given width.

Same depth in catalog, 5 7/8".

mattmia2

Oh , I see. It has a special row for 5b. i bet 5c is too tall for the 20" high cabinet so it is a shorter element(with less area) than 5c. Don't get too carried away, it is all an estimate.