Recalculating EDR - Which Type of Radiators are These?

a3inverter

A few years back I used information in one of Dan's books (Greening Steam or We Got Steam Heat) to calculate my EDR.

Recently, we've been looking into replacing our boiler - or at least preparing to do so - and based on some feedback from guys I've discovered through the "Find A Contractor" section of this site, I think I may be doing the EDR calc incorrectly. I arrive at 748 sq. ft of EDR and the contractors I've engaged tend to think that is too high for my 2200 sq. ft house. Their recommendations on a replacement boiler (all Burnham) have ranged from an IN-4 (on the suspicion that there is no way my size house could have an EDR of 748) to an IN-7 (probably based on the output matching my current boiler - I fully understand this is the wrong approach) to an IN10 (with the caveat of "we only put those in small apartment buildings"). A few have wanted to come out and measure the EDR for themselves.

So, maybe my EDR is wrong. I don't think it's a math issue, but more of a "what style of radiator is this?" issue. At least I hope it's not my math

In looking at this document from W-M, I now see THREE types of the traditional column/tube radiators (I only see TWO types in "The Lost Art of Steam Heating"):

http://www.weil-mclain.com/en/multimedia-library/pdf/weil-mclain-pdf/other-downloads/boiler_replacement_guide.pdf

I consider all of mine to be the "Thin Tube" (Water-Type) as described in TLAoSH, but can't tell what type they are according to this W-M document (it's a bit grainy). There is one in the upstairs bathroom that's a special case, but relatively small.

Also, I have been measuring the height of the radiators for calc purposes from the floor to the top, not from the top to bottom excluding the legs. The way I am doing it seems correct based on what I have seen.

Attached are some pics of the radiators I consider to be "thin tube" (TLAoSH parlance) as well as a PDF of my EDR calculation.

Thanks!

Dave0176

I would consider those tube type not thin tube or as Burnham calls them slenderized.

When I size a boiler I use this chart.

a3inverter

Thanks Dave. That doc appears to confirm I'm doing the calc correctly. 748 original vs 746 with your doc.

Dave0176

Thats good. Thats also a large boiler you need there. I'd install a Weil McLain EG75, or if everything is insulated and your main venting is reeeeeal good, and you rads are vented good, you can get away with a EG65.

Tell the contractor you want two 3" boiler risers a 4" drop header and a 2" equalizer all in steel pipe and cast Iron fittings.

a3inverter

Thanks Dave. One thing that I still can't wrap my brain around is that the recommendations of new boilers given my EDR are actually larger than the (really) ancient boiler I presently have (220k input/180k output BTU per the label). The existing boiler does a great job of heating our 85 year old house (with single panes and storms and no insulation in the walls). Perhaps this is all due to D.O.E ratings and such but I figured input BTUs were still input BTUs all these years later.

Fred

"A few have wanted to come out and measure the EDR for themselves."
Are you opposed to letting them? Let them come out and do that. How many radiators do you have in that house? I have 15 for a total of just over 700 sq.ft of EDR but I'm in a 5000 sq. ft house. Not that the size of the house is as critical as matching the EDR. It is hard for me to believe 748 sq. ft of EDR, unless you have 15 to 20 decent sized radiators, or some very large ones.

JUGHNE

FWIW I certainly would have them come and do an EDR calculation. I wouldn't tell them what you think it is if you haven't mentioned your number to that person. Also ask them to clock your NG meter, you could do this also. That would tell you what the old boiler actually has for input, the delivered output is still a guess. But you would know that you don't need more than the old input. Existing boiler could be over or under fired.

a3inverter

Fred said:

"A few have wanted to come out and measure the EDR for themselves."
Are you opposed to letting them? Let them come out and do that. How many radiators do you have in that house? I have 15 for a total of just over 700 sq.ft of EDR but I'm in a 5000 sq. ft house. Not that the size of the house is as critical as matching the EDR. It is hard for me to believe 748 sq. ft of EDR, unless you have 15 to 20 decent sized radiators, or some very large ones.

No issues here with having a pro run the EDR - I'd expect them to do that anyway.

For the record, we have 14 radiators. I can't really judge them to be large or very large as I don't have a point of reference. I have attached a picture of my spreadsheet detailing height, sections and tubes - perhaps someone can opine on their relative size.

Thanks,

Scott

a3inverter

JUGHNE said:

FWIW I certainly would have them come and do an EDR calculation. I wouldn't tell them what you think it is if you haven't mentioned your number to that person. Also ask them to clock your NG meter, you could do this also. That would tell you what the old boiler actually has for input, the delivered output is still a guess. But you would know that you don't need more than the old input. Existing boiler could be over or under fired.

Excellent suggestion on clocking the meter...

BobC

This is how to clock that meter -

Bob

Dave in QCA

It seems that the issue of small tube vs large tube radiators continues to cause confusion. I have the greatest respect for Dan and all of his publications, the terminology he has applied to tube style cast iron radiators is not consistent with industry standards and it tends to cause confusion.

According to the AHRAE Guide and Data Book of 1965, common cast iron radiators are broken down into 3 main groups. Of course there are exceptions, but these are the 3 main groupings.
Column Type with section spacing at 2.5" or sometimes 3"
Large Tube Type, with section spacing at 2.5" (sometimes erroneously referred to as "small tube")
Small Tube Type, with section spacing at 1.75" (also referred to as slenderized)

See the attached,
I usually use the tables in this attached section unless I happen to have the actual manufacturer's data.

Perhaps the inconsistencies were created by the radiator manufacturers themselves. In 1928, U.S. Radiator Co. in their Capitol Radiator publication describe their new radiators as "Tube Type" with "slenderized ratings". However, these were the large tube configuration and were not what was later called "slenderized". Another example of industry inconsistency is the American Radiator Co. "Corto Radiator." When introduced in 1922 it had a section spacing of only 2". However, that was later changed to 2.5".

With all of this.... I have to say that Dan's "E.D.R, Every Darned Radiator" is a really great reference guide!

Dave in QCA

I was noticing the pipe connections to the radiators you have shown. This does not look like typical steam piping. I am wondering if perhaps this was originally a hot water system that was later converted to steam/vapor. This is not very common, but we have certainly seen some examples.

JUGHNE

Is that a manual air vent above the steam vent in photo one?

How about a couple pictures showing each end of some of the rads. Is this a 1 or 2 pipe system and are there traps at rads?

A couple shots of the boiler from a ways back would be interesting also.

a3inverter

Hatterasguy said:

a3inverter said:

For the record, we have 14 radiators. I can't really judge them to be large or very large as I don't have a point of reference. I have attached a picture of my spreadsheet detailing height, sections and tubes - perhaps someone can opine on their relative size.

Thanks,

Scott

They are of significant size.

Can you comment on where you are located and the type of insulation in the walls and the type of construction of this house?

Can you also comment on the age of the house?

I'd like to attempt a guess at the heatloss of such a house and show you the difference between the heatloss and the planned boiler size. It will be an interesting comparison and a caution regarding how large a boiler to procure.

We are west of Boston, 1930 ballon-framed cape with no insulation in the walls (we may get it done this year). We had 12" of cellulose blown into the attic last, rim joists insulated and air sealing done last year.

I too am ever more interested in why a house of this size has so much radiation.

@Dave - someone on this list also mentioned that it looked like it might have originally been a hot water system. Others have suggested early vapor.

@JUGHNE - Yes, that's a manual air vent. It's actually both a one pipe and a two pipe

The send floor are 2 pipe (as seen in photos 1 and 2) and two pipe that was converted to one pipe on the first floor (photo 3). I know this because there are filled holes in the floor on the return side of each first floor radiator.

No visible traps - I swapped 2 of the second floor rads back to their original positions (the previous owners had moved one of the big bedroom rads to the hallway as I don't think they used the front bedroom as members of the family moved out) and while doing so, I did not notice any "internal" traps in the elbows.

I have attached a few more pics of the radiators and the boiler. The rust in the area of the nipple on the business side of the radiator was from a leak predating our ownership of the house. We had it fixed last year. The silver rad in the pics is in the second floor hallway - both the supply and return side. The white radiator is an example of a one-pipe radiator on the first floor.

JUGHNE

If this was originally hot water heating then your radiation would had to have been more EDR for lower temp water (170* avg) giving you 150 btu/EDR and with steam at 240 btu/EDR. Maybe the system was changed and the new boiler sized based on heat loss of house? Didn't you have more connected EDR than boiler and still heat OK? 150/240 =.625.......so if those were sized for HW you would need only 62.5% of the radiation you now have for steam. Hopefully some else chimes in as I can go off on a tangent at times.

They had 2 pipes going to the second floor and used the returns to drop into a "new" lower wet return. The existing HW return would have been too high above water line? But why 1 pipe on first floor....... short run outs and it would still work??

From your previous postings: you had 2nd floor rad not heating; with hot water there would have been maybe no hesitation with a tee above your ceiling on the supply. You could cap the rad that works and see if the cool one heats up.

a3inverter

Lots of great information here...trying to digest it all...

a3inverter

Dave in QCA said:

Column Type with section spacing at 2.5" or sometimes 3"
Large Tube Type, with section spacing at 2.5" (sometimes erroneously referred to as "small tube")
Small Tube Type, with section spacing at 1.75" (also referred to as slenderized)

OK - mine classify as "Large Tube Type" and my EDR doesn't change (748 vs 747).

Fred

It looks to me, from your PDF file, that yoy don't have huge radiators, you have a lot of medium sized radiators and several rooms have two of them in each room. For those rooms thnat have two radiators, do you actually leave both on during the winter months? If not, try to recalculate your EDR without those that are turned off. If you leave them all on, try running your current system with only one radiator open in each room and see if that radiation is adequate to meet the requirements of each room. If possible, maybe removing a couple radiators in rooms that don't need that much capacity, leaving only one radiator per room, might allow you to down-size the boiler.

ChrisJ

How is that tiny boiler driving 700+sqft of radiation?

ChrisJ

Hatterasguy said:

ChrisJ said:

How is that tiny boiler driving 700+sqft of radiation?

180K net is supporting 179,520 radiation..............would you look at that!!

A system close to your own heart................and it heats the building just fine.

Can't be.
It can't be!

Fred

ChrisJ said:

Hatterasguy said:

ChrisJ said:

How is that tiny boiler driving 700+sqft of radiation?

180K net is supporting 179,520 radiation..............would you look at that!!

A system close to your own heart................and it heats the building just fine.

Can't be.
It can't be!

Depends on how many of those radiators are turned off ???

ChrisJ

Fred said:

ChrisJ said:

Hatterasguy said:

ChrisJ said:

How is that tiny boiler driving 700+sqft of radiation?

180K net is supporting 179,520 radiation..............would you look at that!!

A system close to your own heart................and it heats the building just fine.

Can't be.
It can't be!

Depends on how many of those radiators are turned off ???

I guess we'll have to wait and see, won't we?

Dave in QCA

Hatterasguy said:

ChrisJ said:

How is that tiny boiler driving 700+sqft of radiation?

180K net is supporting 179,520 radiation..............would you look at that!!

A system close to your own heart................and it heats the building just fine.

No, not 180K net, it is 180K Gross Output. If it were 180K Net, it would be sized according to the books.

ChrisJ

Hatterasguy said:

Dave in QCA said:

Hatterasguy said:

ChrisJ said:

How is that tiny boiler driving 700+sqft of radiation?

180K net is supporting 179,520 radiation..............would you look at that!!

A system close to your own heart................and it heats the building just fine.

No, not 180K net, it is 180K Gross Output. If it were 180K Net, it would be sized according to the books.

Semantics again.

This reminds me of the "electrons flow - to +" "No they don't, they flow + to -" argument. Hole flow vs electron flow.

An engineer I work with that has a PhD in electrical engineering said it best. "It doesn't matter which way it flows, all that matters is we all agree on the same thing so we can communicate."


The boiler ratings are what they are and it doesn't matter if you or I like the terms. We need to use what is understood by everyone.

ChrisJ

Hatterasguy said:

You're right.

I just need to reprogram my brain. It naturally refers to "net" as the boiler output, not some artificially reduced value created by the boiler manufacturers. That is "less than net" for those that are installation challenged.

It is what it is.
We've got bigger issues to deal with.

Dave in QCA

When I compare the terms gross and net to profits.... It makes sense and is consistent.... I think.... ??
In a store, you would have total sales. Then you have Gross Profit, which is the total sales minus the cost of the goods. Then you have Net Profit, which is what is left after you subtract for operating costs, such as rent, utilities, salaries, etc.

Input is what is burned. After subtracting the combustion products are lost up the chimney, you have Gross Output. That is that what comes out of the boiler, Net is what is left for the radiation, after subtracting for piping losses and pickup. And, you're right. It is all a theoretical guestimate at best.

Just for the record, I am on the side of reducing the piping and pickup allowance on systems that are significantly oversized for the actual heat loss, and making the system work by reducing the radiator venting. Or on two-pipe, by the use of inlet orifices.

ChrisJ

Dave in QCA said:

When I compare the terms gross and net to profits.... It makes sense and is consistent.... I think.... ??
In a store, you would have total sales. Then you have Gross Profit, which is the total sales minus the cost of the goods. Then you have Net Profit, which is what is left after you subtract for operating costs, such as rent, utilities, salaries, etc.

Input is what is burned. After subtracting the combustion products are lost up the chimney, you have Gross Output. That is that what comes out of the boiler, Net is what is left for the radiation, after subtracting for piping losses and pickup. And, you're right. It is all a theoretical guestimate at best.

Just for the record, I am on the side of reducing the piping and pickup allowance on systems that are significantly oversized for the actual heat loss, and making the system work by reducing the radiator venting. Or on two-pipe, by the use of inlet orifices.

No, I did not pay him to say that.......

Dave in QCA

Chris... YES YOU DID!! LOL Not Really.

But, keep in mind my system has a 2 stage burner, but I leave it on low fire all the time. Second stage is for down the road when the back building is put back onto the steam system.

Right now, I have 1259 sq ft EDR. If I go by the books, I should be firing at roughly 506,000 BTU. But, I get a long just fine firing at 375,000 BTU. It works just great. On mine, its the magic of inlet orifices.

a3inverter

If I may summarize what I've learned thus far...

1. It would appear that the EDR that I have calculated is accurate.
   
2. It would also appear that, for the size of my house and steam heat at atmospheric pressure, I've got too much radiation.
   
3. This may be due to the current system having been modified from it original state, that state being either hot water or vapor.
   
4. That even with a slightly undersized boiler (Input 220k, Output 180k - gross I guess) the house gets warm enough (save for that last radiator)
   
5. That purchasing a boiler directly based on the EDR calc of 748 would get me a boiler that was way too big (not to mention expensive) and one that would likely have high fuel bills and a shorter life.
   

My next actions as I see them are to:

1. Investigate the heat loss of my house, calculate the true EDR necessary for that heat loss and consider the article written by the Steam Whisperer referenced by HatterasGuy.
   
2. Do more reading. Do more experimenting. Look for traps in the piping for the two-pipe rads.
   
3. DON'T run out and buy an IN10
   
4. Consider forced hot air
   

Thanks to all for the suggestions and feedback so far. Any other ideas on next things to investigate?

Dave in QCA

Cross out Item 4 in the second group. You must have misunderstood something. Forced air is not an acceptable option.

a3inverter

One other thing - any thoughts as to why a homeowner would switch from hot water TO steam?

ChrisJ

Yeah,that item 4 will get you crossed off my xmas list in no time.

Forced hot dust and I don't get along.

a3inverter

Just some levity on a Monday. I would never consider ripping up this house to put in forced hot air.

@Hatterasguy - agree. Just trying to dig a little deeper into what the system might have been originally. Not sure the financial ramifications were as great way back when, but yes, doing it today would be a very bad decision.

JUGHNE

You have a 1930 house. According to Dan's book of "Classic Hydronics" the first circulator showed up in 1928. A new thing that most contractors might not wanted to try when gravity still worked for them.
Hypothesis: So maybe your house was gravity piped originally. So that piping sloped upwards away from the boiler for gravity assist. If you have parallel flow steam then the conversion would have required raising the boiler end of supply or lowering the return end. The return piping would have sloped in the correct direction but would be too high above the boiler water line for 2 pipe vented rads to return to the wet return. So it was replaced with smaller pipe for the 2nd floor 2 pipe system. The 2nd floor risers were too small for 1 pipe steam, perhaps.
Your radiators were sized for hot water, about 37.5 % larger than needed with steam.
So at some point in time the gravity was thought to be too slow or if it was pumped they has one of the first troublesome lemons. So a steam guy shows up and offers quicker and hotter heat to homeowner.
The rad valves may not have been steam compatible and it was cheaper to install ell unions. Perhaps inlet orifices were installed on the 2 pipe system upstairs.
Steam person installed smaller boiler than connected EDR either thru careful calculation or by accident but it heated the house.

So do some of your radiators not get steam hot all the way across, but still deliver enough heat to the rooms? (Oversized EDR connected to a "too small" boiler, (actually almost correctly sized). Also if a rad doesn't heat all the way across there may be no steam reaching the outlet, and therefore no problem with steam getting into the return, if it is not individually dripped into wet return.

Do most of your rads have a HW manual air vent at the top or evidence of one having been there?

Have you looked in the attic for the open expansion tank or any evidence it could have been there. This could be in attic (maybe boxed in to prevent freezing) or high wall mounted on top heated floor. It may have been a square or round tank and would have had at least 2 pipes connected, one to the system main and some means for overflow (to sewer or onto roof). There may be pipes in the basement or attic connected to nothing or capped. (A rare chance that the top rads were not bled completely of air and those became the expansion tank for the whole system).

Traps would not be needed in the 2 pipe system if the returns dropped all the way to the basement wet return individually.
No traps or orifices on the 1 pipe system.

Your last rad that doesn't heat, is there that chance it is tee connected to another. If so you could install an orifice into the union elbow of the "good one" and divert steam to the cool one.

So tell me if I'm way off base or just crazy.

After this far on the wall with your system, any change to forced air would have you looking for a witness protection program.

(And you thought you would come here for just a couple ideas and a little advice)

Wait, there is more. With insulation you have now reduced the heat loss of the structure. Maybe a lot if you had none before, I would calculate the heat loss as if the walls were insulated, that will give you the incentive to go ahead and do it. You pay for insulation once, but the fuel bill shows up every month forever. Do the heat loss without insulation and then with insulation, you will see the savings, let alone improved comfort. That is why we live in houses, to be comfortable. Also may get you down on the boiler size. It could tip the scales on size selection.

a3inverter

@JUGHNE,

Yes, the radiators do not heat all the way across but still heat the room. I have read in Dan's books that this is "normal". The big ones (except the last) blast heat to the point where we have considered disabling a few.

The 2 pipe rad returns are each individually piped down to the wet return which is below the water-line of the boiler.

Several of the radiators have the manual bleed valve associated with hot water.

Not sure if the cold rad is impacted by a "T". If I follow the main on that side of the house I count a supply line going up and a return line going into the wet return for each of the 2nd floor rads on that side of the house.

Nothing in the attic of the sort you describe.

Again, thanks to all for all the expert feedback and effort.

gennady

just install steam trvs, this will cut radiators capacity down to heat loss of the corresponding room. Install master vents to vent mains and risers quickly.
This will resolve issue of oversized radiators and oversized boiler. there are few more very important things to implement, but you get the idea.

JUGHNE

You could tone down the 2 pipe rads with a simple orifice in the inlet union. Much less money than valves or TRV. You start with a small opening and increase drill size to comfort point. You want your operating pressure figured out first though.

Have you tried just removing the vent on the cold rad, an 1/8" valve of some sort would allow you to control the air manually and see what is going on. Maybe the riser pipe itself needs a separate vent, a second vent on the inlet side of the rad might vent that riser enough, it would close when steam arrives.

Have the steam main air vents been discussed somewhere here?

JUGHNE

Gennady, that is all good info, but he has the opportunity to not have an oversized boiler as he changes it out.

a3inverter

JUGHNE said:

Have the steam main air vents been discussed somewhere here?

Based on information gained from this forum, I replaced the existing single Dole 3c with three Gorton 2's...

WRT the cold rad, I have put a larger air vent on it (a Maid o' Mist) and even removed the vent orifice at one point to see if I could get the air out faster. The occupant of that room tells me that the heat is better, but not sure if that is because of improvements we've made (she had the hatch to the attic - we've moved it out into the hallway, the closet had huge air leaks, etc.) or if she just wants me to stop going into her room

Certainly willing to try a vent in the riser.

I will also investigate orifices for the supply on the big rads...need to figure out operating pressure. For what it's worth, I adjusted down the Pressuretrol based on what I read in Greening Steam.

gennady

You definitely must install Gortons #2 on the top of risers. Do not increase radiator vents. keep them smallest. Don't vent risers through radiators. vent them separately. Bring steam pressure down to 1 psi top if you don't have vaporstat. Your current boiler is sufficient more or less. You can even downfire it if needed.

Regarding your Gortons. Move them out of that tee no less that 20" upstream. install on the pipe side, not the top. Steam is moving on the top of the pipe. It will shut off vents before all air is removed.

Regarding TRV. They are single biggest contributor to your comfort and savings. I would recommend to spend money on trvs rather than replacing perfectly good boiler, even old one. That would be money better spent.

a3inverter

@Gennady - Thanks for the suggestion...I will look into that.

Also, based on some investigation this morning I am going to say that this system was previously a gravity-fed hot water system - based on the suggestions in this thread, plus the fact that ALL the radiators either have a hot water manual bleeder or evidence of having one (air vents on some of the rads are actually in the top hole, not halfway up).

Might make sense to switch it back to hot water...