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Member Posts: 11
Hi,

Hoping you can assist me with a few questions please. My goal is to add a 30 EDR radiator to an existing 1 pipe gas fueled steam system.

First, I feel like I’ve read conflicting info as to whether the boiler’s Net Steam SQ FT includes the pickup or not. My boiler (PB 63-03) is rated at 308. The manual for the boiler list this language, “Net Ratings are based on DOE Heating Capacity less an allowance for normal piping and pickup as determined by the Testing and Rating Standard for Low Pressure Cast Iron Heating Boilers of the Hydronics Institute.” I’m having trouble interpreting this. Does my boiler have capacity greater than 308? Based on my calculation, the total EDR for all radiators in the house is 258 EDR with the exception of one mystery radiator that I cannot access (See below). I’m thinking worst case scenario that the total EDR (258 + Mystery radiator + new 30 EDR rad) is no more than 400 EDR. If the pickup is already included in the 308, is anything above and beyond this too much?

Second, every radiator in my home is fairly straight forward column radiator with the exception of this one. Of course, I cant get this cover off to inspect further, but wondered if the experts here can help me determine what type of radiator this is? Its only a few inches deep and extends another 1-2 sections over behind the cabinetry. The length is approximately 5-5.5’ and height is approximately 30”. Can someone give me an idea of what the EDR of this radiator is please?

Lastly, capacity allowing, can this pipe, a 1.25”, be tee’d off adding another radiator? My understanding is a 1.25” pipe can handle 55 EDR. The radiator already attached is 24 EDR and I would be adding a 30 EDR.

Thank you so very much for the help!

• Member Posts: 23,310
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On the boiler ratings -- the 308 square feet is the amount of radiation it is rated to supply. The manufacturer has already accounted for the pickup factor in that, so that is the real number of square feet it is rated to feed out in the wild. Odds are that that unknown radiator plus the new one will bring you slightly over that, but that's not a problem at all. Just make sure your steam mains are insulated and there should be adequate capacity.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 5,702
edited April 2021
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I agree with Jamie, you have nothing to worry about capacity-wise. Especially with that mystery radiator in that cage. If some of your other radiators are in cages like that you have even more capacity since each one in a cage is actually shrunken in terms of capacity that the boiler can "see"

And to address your other question, you should be just fine capacity-wise adding another radiator off that supply line, but you must follow the rules. Make a drawing of your proposed change and post it here and you will get all the opinions
NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
• Member Posts: 11
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On the boiler ratings -- the 308 square feet is the amount of radiation it is rated to supply. The manufacturer has already accounted for the pickup factor in that, so that is the real number of square feet it is rated to feed out in the wild. Odds are that that unknown radiator plus the new one will bring you slightly over that, but that's not a problem at all. Just make sure your steam mains are insulated and there should be adequate capacity.

Thank you very much, Jamie! I should come visit/feel the steam heat at your museum before it gets too warm. I'm in Massachusetts.
• Member Posts: 11
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I agree with Jamie, you have nothing to worry about capacity-wise. Especially with that mystery radiator in that cage. If some of your other radiators are in cages like that you have even more capacity since each one in a cage is actually shrunken in terms of capacity that the boiler can "see"

And to address your other question, you should be just fine capacity-wise adding another radiator off that supply line, but you must follow the rules. Make a drawing of your proposed change and post it here and you will get all the opinions

Thank you very much, Paul! I'm dumbfounded at this caged radiator. I can't seem to find a reference or picture of what it is anywhere! As you can probably tell, I'm new here. I will get that drawing done asap and report back.
• Member Posts: 23,310
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On the boiler ratings -- the 308 square feet is the amount of radiation it is rated to supply. The manufacturer has already accounted for the pickup factor in that, so that is the real number of square feet it is rated to feed out in the wild. Odds are that that unknown radiator plus the new one will bring you slightly over that, but that's not a problem at all. Just make sure your steam mains are insulated and there should be adequate capacity.

Thank you very much, Jamie! I should come visit/feel the steam heat at your museum before it gets too warm. I'm in Massachusetts.
You would be welcome anytime! That's what PM's are for...
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 16,842
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That's probably a standard radiator that someone built a strait-jacket cover for. You'll want to remove the cover anyway, it's probably quite dirty in there and you'll need to check it for leaks at the vent, shutoff valve etc.
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting
• Member Posts: 9,655
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I that pipe 1.25" or just 1"? The nominal size is the ID.

It looks like some sort of common commercial wall hung radiator like American Radiator/American Standard.
• Member Posts: 11
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Make a drawing of your proposed change and post it here and you will get all the opinions

• Member Posts: 887
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Based on what was said I do not find a problem with that size boiler.

Here is a possible problem.

If the house is more than 50 years old the radiation and boiler sizing was done at 0 degrees outdoor temperature unless you live in an area where temperatures go below 0 degrees.

What happened in later years when fuel became in short supply the federal government raised the outdoor temperature to 20 degrees outdoor temperature which now made the heat load sizing a bit undersized.

Hopefully in most cases the under 20 degrees outdoor temperature was not a lingering problem.

Jake
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Ah... the Fed may have raised the temperature. At risk of pointing out the obvious, nobody bothered to tell the weather...
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 11
edited April 2021
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Based on what was said I do not find a problem with that size boiler. Here is a possible problem. If the house is more than 50 years old the radiation and boiler sizing was done at 0 degrees outdoor temperature unless you live in an area where temperatures go below 0 degrees. What happened in later years when fuel became in short supply the federal government raised the outdoor temperature to 20 degrees outdoor temperature which now made the heat load sizing a bit undersized. Hopefully in most cases the under 20 degrees outdoor temperature was not a lingering problem. Jake
Oh boy, my home is almost 150 years old. I’m not sure I understand this though. The boiler is fairly new, but maybe the piping is outdated for modern day steam heat? I do live in an area that can dip under 20, although seldom. Thanks Jake!
• Member Posts: 9,655
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You can do a heat loss calc on the house and compare it to your installed edr. It almost always is more than the heat loss.
• Member Posts: 23,310
edited April 2021
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Based on what was said I do not find a problem with that size boiler.

Here is a possible problem.

If the house is more than 50 years old the radiation and boiler sizing was done at 0 degrees outdoor temperature unless you live in an area where temperatures go below 0 degrees.

What happened in later years when fuel became in short supply the federal government raised the outdoor temperature to 20 degrees outdoor temperature which now made the heat load sizing a bit undersized.

Hopefully in most cases the under 20 degrees outdoor temperature was not a lingering problem.

Jake

Oh boy, my home is almost 150 years old. I’m not sure I understand this though. The boiler is fairly new, but maybe the piping is outdated for modern day steam heat? I do live in an area that can dip under 20, although seldom. Thanks Jake!

There is no such thing as piping "outdated" for modern day steam heat. There are specific ways in which various boiler designs need to be piped to get the steam to the rest of the system, but outdated? No.

Second, and perhaps far more important, with steam heating -- once the radiation is installed -- the design day temperature has absolutely nothing to do with the size of the boiler. The size of the boiler in terms of power rating (EDR, net BTUh, Gross BTUh) has to be matched -- using the EDR figure -- to the amount of radiation.

Now if you change the amount of radiation, you need to change the boiler size -- that's true. But if you are installing a boiler in a building with existing radiation, forget about heat loss, forget about design day, and simply match the boiler to the installed radiation. End of story.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 5,478
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If your going to feed an additional radiator with an existing riser that is already feeding a radiator it has to be done carefully (pipe slope and size) so both radiators share the steam. If it's not done right one of the radiators might not heat properly.
A 1-1/4 riser should be able to handle the additional radiator just make sure it's done carefully so it all works right when they are done.

Bob
Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
Vaporstat with a 12oz cut-out and 4oz cut-in
3PSI gauge
• Member Posts: 5,702
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That's a good drawing but I should have been more specific. "Zoom in" on the area where you are going to put the Tee to show how you will arrange the Tee, including the angles of the pipe coming off of it.

And I wouldn't worry about the overall size of your system. They are almost always oversized. Even my tiny house has had about 3 radiators removed from it by previous owners.
NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el