Steam EDR and Boiler Capacity Double Check

mattyparas · October 2021

Hello all,

New to the board, thank you in advance for all the information you guys provided...I've been reading through the materials over the past couple of days and this site has been a wealth of information

Wanted to quickly double check and EDR and Boiler Capacity calculation I did for my steam system. The impetus for this is that some of my radiators are not getting hot/hot enough and I wanted to rule out the boiler being underpowered. I moved into this house last Winter and just dealt with it amidst the moving and settling in.

Here is my calc

Assumptions
1. Inventoried the radiators in my home, measured the width and height, took count of the number of tubes

2. Used the Smithfield 'Estimating radiator square feet EDR' tables that I found online to calculate the total EDR - Total for the house was 330 (not sure if a 1.25 factor was already built into these figures) https://www.smithfieldsupply.com/company_info/forms/radiatorest.pdf

3. Took the 330 EDR x 1.5 x 240 = 119,000 BTUs

4. My radiator a Crown Bermuda BSI1241 has an output BTU of 199,000 (on the label)

Am I good from a boiler capacity perspective? Did I do the calculation correctly, assuming my inventory and radiator measurements were correct.

Many thanks,
Matt

Jamie Hall · October 2021

Well,, I can't find the EDR rating of that boiler, but it should be on the name plate. Unless something is really weird, though, it should be more than ample -- in fact rather dramatically oversized, assuming your EDR addition is correct.

EDR ratings are straight for radiators, but the EDR rating of a boiler takes into account the pickup factor, so it's a straight comparison.

KC_Jones · October 2021

mattyparas said:
Hello all,

New to the board, thank you in advance for all the information you guys provided...I've been reading through the materials over the past couple of days and this site has been a wealth of information

Wanted to quickly double check and EDR and Boiler Capacity calculation I did for my steam system. The impetus for this is that some of my radiators are not getting hot/hot enough and I wanted to rule out the boiler being underpowered. I moved into this house last Winter and just dealt with it amidst the moving and settling in.

Here is my calc

Assumptions
1. Inventoried the radiators in my home, measured the width and height, took count of the number of tubes

2. Used the Smithfield 'Estimating radiator square feet EDR' tables that I found online to calculate the total EDR - Total for the house was 330 (not sure if a 1.25 factor was already built into these figures) https://www.smithfieldsupply.com/company_info/forms/radiatorest.pdf

3. Took the 330 EDR x 1.5 x 240 = 119,000 BTUs

4. My radiator a Crown Bermuda BSI1241 has an output BTU of 199,000 (on the label)

Am I good from a boiler capacity perspective? Did I do the calculation correctly, assuming my inventory and radiator measurements were correct.

Many thanks,
Matt

You did too much math

330 (if correct) is the only number you need.

The 1.5 you used is massive overkill for a pick up factor, 1.33 is the generally accepted norm, but you don't need to calculate that

For boiler sizing you compare the 330 to the sq ft rating of the boiler. The one you have is rated at 621, so that puts you at 88% oversized.

In that boiler brand and style the most you would need would have been the BSI138

https://www.velocityboilerworks.com/documents/Bermuda_BSI_Literature_Jan21.pdf

mattyparas · October 2021

OK thanks all, I think I can assume its not my boiler power preventing heat from getting to those radiators. I detailed my EDR calc below for anyone who wants to spot check me

A bit flummoxed as to why the two radiators are not getting hot then. They are brand new with all new input valves and gorton Cs. They are on a second floor at the end of the longest line, furthest from the boiler...

As an experiment yesterday I shut all of the other radiators in the house except those two thinking that would eliminate some variables to troubleshoot (let me know if this is a false premise)

Attempt 1: No heat
Attempt 2: Heat with water all over the floor from one of them, spit out the valve
Attempt 3: No heat

Any ideas from the group?

_____________________
EDR details

5x baseboard style 5feet long = 85 EDR (3.4 x 25)
1 column style 20 inches tall by 2 columns = 10 EDR (2 x 5)
8 tube style detailed below = 234 EDR (see below)

The 8 tube radiators
5 tubes, 20 inches, 20 sections = 54 EDR (2.67*15)
5 tubes, 20 inches, 16 sections = 43 EDR (2.67*16)
5 tubes, 20 inches, 15 sections = 40 EDR (2.67*15)
5 tubes, 23 inches, 12 sections = 36 EDR (3*12)
4 tubes, 20 inches, 12 sections = 27 EDR (2.25*12)
6 tubes, 25 inches, 6 sections = 24 EDR (4*6)
4 tubes, 25 inches, 4 sections =11 EDR (2.75*4)

KC_Jones · October 2021

If you got water all over the floor that’s a solid clue.

You say nee radiators, how were they piped? Black pipe? There needs to be slope all the way back to the main. As well as no up and down creating traps, and no sags. Any of these can and will hold water blocking the steam.

What’s the main venting like? Balance and venting starts there.

JUGHNE · October 2021

So you have a single pipe system?
Main venting is what to check first.

Pictures of boiler and piping floor to ceiling would be helpful.
What do you have for main steam line vents now?

EBEBRATT-Ed · October 2021

@mattyparas

The reason you got water on the floor is you shut the other radiators off . That really doesn't tell you anything.

First thing to do is check the pitch of the radiators with a level. (i am assuming 1 pipe steam)

Make sure the rads are pitched towards the supply pipe.

Any pipe in the basement for the problem radiators should be checked for pitch.

Next step is pictures of the boiler and near boiler piping

And pic of main vents as others have mentioned

mattyparas · October 2021

Appreciate the help and patience. Try to answer all of the previous questions in one post to consolidate.

1. Pitch of the radiators are both toward the supply pipe which is almost straight off the riser coming from the 1st floor. I don't know what is beneath the floor can't imagine Also checked the pitch of where that riser goes into the basement and everything is pitched toward downward until it makes its way to the boiler. I didn't do this myself, hired a plumber to put them in.

2. It all looks like old cast iron piping. I put the radiators in the same spot and I didn't change any of the supply or return piping leading to/from those radiators. They got hot last winter...

3. Pictures of the boiler and near boiler piping attached - let me know if you need any other views

4. There are no main vents as far as I could tell. I just traced every line in the basement. If they weren't important you guys wouldn't be asking...so I am guessing someone messed up when they did the install?

5. I have it running now, and while I am down here taking pictures I noticed that the boiler is cycling on/off/on/off in various intervals, but not running consistently. Shouldn't it run for a few minutes before kicking off?

Think its time to just call someone in?

KC_Jones · October 2021

If I’m seeing it right you have a colliding header at the boiler couple that with being massively oversized and no main venting and you have a recipe for a poorly running system.

KC_Jones · October 2021

Also, just checked the manual and the header is undersized. That size boiler calls for a 3” header, yours is 2”.

I’d speculate that’s putting a lot of water up into the mains.

mattyparas · October 2021

Can you describe the colliding header, where is it exactly? Going to call a plumber and know what I am talking about a bit so he doesn't take too much advantage of me

The feed that goes to the front doesn't have a dedicated return line, while the other feeds do. Is that it?

The pipes are 3 inches counting the insulation. Does that count?

Attached a few more angles incase my first set of pictures weren't revealing enough.

What are my options besides replumbing everything? What I am hearing is that 1. Need a new 3 inch header 2. Make sure it doesn't collide 3. Install main vents...

Thank you so much!

Hap_Hazzard · October 2021

Since you need to re-pipe the header, you could go for a drop header. At least you should extend the boiler risers and shorten the system risers to raise the header and swing-arms. Longer boiler risers reduce carryover into the header because the water droplets fall back down into the boiler.

You might also want to raise the vent damper if you have enough wire to reach. If you can keep them away from the heat they last longer.

KC_Jones · October 2021

Marked up your picture to indicate the proper order on the header. Basically you have both system take offs between the boiler risers, they should both be after the boiler risers. The way it is will tend to suck the water out of the boiler and throw it up into the system.

Only one return, interesting. Either a return was disconnected or you have one parallel flow main and one counter flow main. For the main with the return it should be the highest at the boiler. If the other one is counterflow, the highest point should be at the end, the lowest at the boiler, if it truly doesn’t have a return.

Just thought of another possibility, is the return shared for both mains?

mattyparas · October 2021

Makes sense with your numbering. I get it now.

I will attempt to answer your question, but let me know if I miss the mark. Both long mains have separate returns. The returns are pipes that are elbowed off the mains at the end of the run and pitch back to the boiler. Not sure if I'm using the terminology right. The returns go into one pipe on the bottom side of the boiler.

What I was describing before is that there is a split in the main on the left where it goes to feed three radiators in the very front of the house...one for each floor. There is no separate return for this line.

Hope my color coded pic helps.

Yellow main #1
Red return #1
Blue main #2
Purple return #2
Pink offshoot of main #2 with no separate return, I guess any water goes back down the heater and into what you had as 5 on your drawing. Seems like another issue to me...

Must say it's been a blast learning about this stuff and you guys have been great. Thank you again.

KC_Jones · October 2021

So which main are the problematic radiators on? Yellow, blue, or pink? Not sure if that helps diagnose, but more information for the board never hurts.

BobC · October 2021

re these non heating units at the end of a steam main? How far down the main does the steam get/ go over all visable piping with a level to make sure there isn't a belly in a pipe that can stop the steam.

Are the non heating radiators baseboards or true radiators? Baseboards do not appreciate single pipe steam, they need a few inches of slope of they are 4-5 ft long. They generally are happier if hooked up with 2 pipe steam.

Bob

mattyparas · October 2021

It's the yellow main line. That line goes to the right and back and returns on the red.

Another thing to note is that the red return stems off the yellow main before the main goes and feeds the last three radiators located against the back wall of the house. Two of those three are the problematic ones, with the third getting hot consistently.

Thinking to my question above the red and blue are parallel returns while the pink is a counter flow.

I ran the boiler again last night and got heat to those radiators, this time without water spewing everywhere.

Thinking this issue is out of my league at this point. I ran down some old receipts from the previous owner and identified the plumber that did the installation. Still in business and will give him a call later today armed with all the info you guys have provided.

If you have any other insights or advice keep it coming, though I want to be mindful of your time. Really appreciate it, especially KC whose been quite active in responding. Thanks again!

KC_Jones · October 2021

Interesting scenario. If you aren't getting water anymore, could have been a fluke, but I don't typically believe in isolated flukes.

There will be a lot of speculation since we aren't there to look at things first hand. I'm wondering if cold start, which will typically produce more condensate, contributed to the water in the radiators. That combined with excess water in the mains from the boiler piping, and closed valves limiting the options for the condensate.

The issue of them not heating would most likely be a classic lack of proper venting. Until you get some main vents on the system, balancing will be difficult.

If you need help deciding on main venting, give us the length and pipe size for each main and we can recommend how much each one will need. Do you see places near the end of each main where main venting may have been?

mattyparas · October 2021

I drew this schematic to show how everything is laid out. Not sure if its clear enough, but let me know if you have any questions. Thinking at a minimum I need a main vent all the way at the end to draw heat up more evenly to those back two radiators.

I called a few plumbers who are going to come out and give estimates for all of the work you guys said needed doing...

Short term going to add main vents, change out the rad vents, clean the system, and fix a leaky radiator

In the Spring I will correct the header plumbing and any other major work

Thanks for all your advice. Helped me understand and come up with a strategy to move forward.

Steam EDR and Boiler Capacity Double Check

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