Longer life reccomendations for single-pipe steam boilers

cubicacres

We're new to our single-pipe steam system and wondering if the reccomended items would help prolong our replacement boiler's life: A dirt seperator to minimize intake water minerals, a spirovent to reduce oxygen in the intake water, or a water reservoir pipe (vs. a condensate tank & pump nor being reccomended in the boiler manual). Any thoughts or tips for lengthening our new boiler's life would be appreciaited. We had a Weil McLain EGH-85 315,000 BTU Nat. gas boiler that rusted-out with a hole in the block.

KC_Jones

The issue with make up water isn't generally what's in it, it's how much you use. On a boiler that size you should only be using about 3-5 gallons per year tops. The oxygen in the make up water is what corrodes the boiler. The more water the more oxygen the more corrosion. Many of us on here use a boiler water treatment (steamaster tablets) that can help slow the corrosion rate as well. For me the magic to a long lasting boiler is a proper install and maintenance. A boiler can't just sit in the basement unattended and be expected to last. I generally check on mine at least 3 times per week. Take some picture of your current install and post them on here. We can comment about what you have now and what you should be looking for in your new install.

Dave0176

Sounds like the boiler was constantly fed makeup water. I would look around for a leak, possible underground wet returns? Also why is there a need for a condensate return pump?

Has anyone done a good EDR check on all the rads to be shore an EGH 85 was needed? To big will cause water to surge into the system causing the auto feeder to come on, then when it shuts down the boiler flood causing a need for a condensate return pump? Just some thought.

gennady

How large is your building? 8-10 apartments? EG 85 is a pretty big boiler. Oversized steam boilers often may develop holes because they develop acidic condensation near exhaust or because condensate becomes acidic.

Hap_Hazzard

Near-boiler piping and no leaks in the system.

Make sure your new boiler is piped according to the manufacturer's specifications, with riser and header dimensions that meet or exceed their recommendations.

Dry steam not only maximizes the efficiency of the system; it also prolongs the life of the boiler, because allowing excess water to escape into the system causes greater fluctuation in the water level during heating cycles.

System leaks will also cause the water level to fluctuate as the water is continually depleted and replenished.

A fluctuating water line is a leading cause of failure in cast iron sectional boilers.

cubicacres

Thanks. It was a 1984 install with a 1994 block replacement, we think. We fixed the near-boiler piping leak and repalced a few feet last month. I did a radiator survey and have an EDR rating for the 1900 construction 10-yr old vinyl replacement windows, 4,200 Sq ft 5-unit 2 story brick building of 187,000 without any pickup factor. 248,700 BTU with a .33 pickup added. Most radiators are colum or pipe. Some radiator columns were about an inch smaller per my own measurements (my 8 in vs 9in in the charts), but I used the standard charts per WeilMclain manuals. One radiator was removed directly above the boiler room on the 1st floor. The 2nd floor rooms are hot, and the 1st floor rooms are ok or a little cold. Lots of rust per the attatched photos. We also have an outside chimney that seems to have a clay liner-do you think a stainless steel liner is needed-or just an inspection for the current liner's condition? It would be great to down-size the boiler, but don't want to prevent steam from forming in the system, and leaving people cold. I don't know if turning off, removing, or downsizing a few 2nd floor radiators would allow us to downsize better or not-or if it's more of a main & radiator vent sizing project.

Fred

Match the new boiler EDR to the total EDR of the existing radiators. You can do the same thing with slower vents on the 2nd floor radiators as you can do by replacing those radiators with smaller ones that will need faster vents to meet the demands on that floor. Make sure you have plenty of Main venting to allow the steam to move quickly through the Mains and to it's destination. Balancing the radiators/system is trial and error but once the Mains are properly vented, you can get the rads right. I like the adjustable vents, like Hoffman 1A's because they allow you to adjust the venting without having to replace the vent. Others say the Hoffman's are noisy and the adjustment is somewhat sloppy and, consequently recommend other brands but I've never had a problem with the Hoffmans.

cubicacres

Here's my EDR sketch for each of the 5 units and my calculations. The hot water pipe calcs at the bottom left are for another project.

Dave0176

You dont need to add the 1.33 piping factor in, its already added to every steam boiler. You will pick a boiler too large if you do this.

Dave0176

The way it looks a EG55 or if you want bigger an EG65 would be the biggest I'd use. The near boiler piping and the main vent play a bigger role in getting steam to the radiators quickly and evenly.

vaporvac

There's two posts going on this I think. sTeamhead also weighted in.

So, basically 780 square feet EDR. You do not need to add anything to this figure, since the pickup factor is already included in the boiler's Net rating.

If that were my project, I'd suggest the Weil-McLain 3-80 with a power gas burner, at 867 square feet. You do hear this type of boiler running, but it should last a lot longer than the typical EGH boiler which has a tendency to sag in the middle and leak.

Here's a link to a thread where we did just that- replaced an EGH with a 3-80 using a Carlin gas burner. This lady actually shows off her boiler to guests, she likes it so well:

http://forum.heatinghelp.com/discussion/148298/atmospheric-out-power-burner-in

Dave0176

The way it looks a EG55 or if want bigger an EG65 would be the biggest I'd use.

vaporvac said:

There's two posts going on this I think. sTeamhead also weighted in.

So, basically 780 square feet EDR. You do not need to add anything to this figure, since the pickup factor is already included in the boiler's Net rating.

If that were my project, I'd suggest the Weil-McLain 3-80 with a power gas burner, at 867 square feet. You do hear this type of boiler running, but it should last a lot longer than the typical EGH boiler which has a tendency to sag in the middle and leak.

Here's a link to a thread where we did just that- replaced an EGH with a 3-80 using a Carlin gas burner. This lady actually shows off her boiler to guests, she likes it so well:

http://forum.heatinghelp.com/discussion/148298/atmospheric-out-power-burner-in

Well he said 187,000 BTU output needed, thats were I came up with the EG65 pick, it puts out 209,000 BTU. And if it is indeed 780 sq ft I'd use the EG75.

I also had said the EG55 because these boilers already have the .333 pickup factor included, so I think the EG55 would work. Look at all the research ChrisJ has done with his boiler. He actually matched his EDR output to the boiler in choosing an EG45 at 392 sq ft and ended up dropping the boiler to an EG40 firing rate and dropping EDR to 325, and he feels its still slightly over sized.

Also the OP keeps posting numbers in BTU which is throwing this off. A simple EDR calculation is all thats needed. How many sq ft of radiation do you have connected??

vaporvac

I see where you were coming grom. I wasn't criticizing... just finding it difficult to make sense of the numbers and the two different posts, so I made a feeble attempt to consolidate. I have NO idea what boiler would be good which is why I find this post ineteresting. BTW, @Dave0176, I'm with you on the boiler sizing. One of my TR50s is down-fired and even with just the smaller boiler running, I make steam quickly once everything is heated up.

JUGHNE

I'm assuming ChrisJ is following this thread. This question is for him concerning his system as it pertains to this thread with the consideration of the controversial pick-up factor.

Did you comment that you have no pick-up factor figured in after downsizing your burner? And that your house heats fine? So what do you attribute this to? Low pressure....good pipe insulation.....not using set-back......very dry steam......main air venting??
Is your 1 or 2 pipe? Do they heat all the way across on a design day?

ChrisJ

Sorry for joining late, I just came across this.

My radiation is oversized for the building so even if the radiators don't heat all the way across it won't matter in my situation. My system is a single pipe and I'm running a boiler that is only 10% larger than the connected radiation. My heatloss is around 70,000 a few degrees below design day and my radiation is 94,000 @ 2 PSI. The undersized boiler heated fine @ 72F on a -8F day which is something like 12 degrees below design day here. The day I swapped the burner for the smaller one the system cooled down quite a bit and had to do a 9 degree recovery and it was like watching a well oiled machine. All radiators get steam within seconds of each other.

Please understand, I'm not a pro, just a DIYer that loves trying to get more out of his system. A lot of what I've done was influenced by Dave Brunnell aka The Steam Whisperer.

There are two old terms that somehow have become one and it's misleading. The term piping and pickup factor was combined into just "pickup factor". The piping factor is oversizing the boiler above your radiation a certain percentage to makeup for piping losses, you need this. The pickup factor is oversizing the boiler to help raise the temperature in the building during a recovery, like after a school shuts down in the winter. To me, this doesn't make sense if your radiation is already oversized. To make things worse, many that recommend using a 33% pickup factor also recommend never doing a setback so it's pointless even if your radiation isn't oversized.


Mains must be vented super fast and if it's a single pipe system you need to vent the radiators depending on their size and location. The further from the boiler, the more venting you're going to need because it has less pressure to work with. When you're running only a few ounces of pressure or less a Gorton C isn't as fast as most think. Larger radiators closer to the boiler need to be vented slow to keep them from hogging all of the steam. If you want a good vent to start out with go with Hoffman 40s and work off of that. Install TRVs vented on the slower side in rooms that tend to get a lot of sun or overheat. You can vent long pipes separately from the radiators as well.

The boiler must be piped well beyond the manufacturer's minimum. It looks like you have 2" risers in the current boiler? That needs to go, use two 3" risers if going with an EG series into at least a 4" drop header.

I run steamaster water treatment which, I feel, will greatly increase the boiler's life.


My opinion is going 15-33% over is likely safe for most but I wouldn't go over 33%. Meaning if your option is a boiler that is 18% over your radiation, or one that is 35% I'd go with the smaller one.



Right now assuming 187,000 for radiation, the EG-65 would work as long as everything is perfect and your piping is insulated well but the EG-75 is a safer bet. You could also consider running tandem smaller boilers.

How did the EG-85 run? Did vents hiss a lot? Do you know what pressure the system typically ran at?

cubicacres

I think we set the our single-pipe steam boiler pressure down to .5 cut-in & 1.5 cut-out with our contractor-it might have been a little higher at 1-2? All 5 apartments plus the front hall total 780 Square feet of radiation from all the radiators per the rating charts. 780x240=187,200 BTU, so about 187,000x1.33 piping pickup for a NET rating of 248,976 BTU or so? If I missed something in this calculation, please let me know-I'm getting conflicting advice from different contractors about which numbers to use. It would be great to downsize from our old Weil Mclain EGH-85, but I want to have enough to produce steam in all 5 units here in Milwaukee, WI on the colder days. The new EGH-85 series 5 is rated smaller than our current EGH-85 series 3, further complicating the issue. Different Weil Mclain employees I talk to say it's the same output, just a sticker change to reflect federal rating shanges, others say the boiler sections/burners have been reduced for smaller out put so I need an EGH-95 for about the same output as the old EGH-85 we had. Any thoughts about how flexible the BTU output is and how low I can go, or if I need to use the DOE Gross Output or NET AHRI ratings to size the new boiler properly?

KC_Jones

You are making the boiler sizing more complicated than it needs to be, that is why there is conflicting information. You don't need to calculate BTU at all. You get the EDR number and look right in the boiler brochure and it has a SQ FT rating for the boiler you look directly at that number. Look at the attached links and look at the charts at the top of page 2. They list Steam (sq ft) right there, that's all you need to look at. If you have your heart set on the EG series I would personally go with the EG-75 as it's close enough to your connected load without being oversized. I think Steamhead gave you the best recommendation for your application 3-80 with a power burner. Getting steam to all the rads efficiently is more a function of venting. You could put the biggest steam boiler in the world in there, but if the venting isn't right some people could still be cold while others are hot. If you aren't getting steam to some areas now, it's NOT the boiler it is almost definitely the venting.
http://www.weil-mclain.com/en/assets/pdf/EG-Brochure-Series-5_new.pdf
http://www.weil-mclain.com/en/assets/pdf/EGH_Sales_Brochure_1112.pdf

ChrisJ

cubicacres said:

I think we set the our single-pipe steam boiler pressure down to .5 cut-in & 1.5 cut-out with our contractor-it might have been a little higher at 1-2? All 5 apartments plus the front hall total 780 Square feet of radiation from all the radiators per the rating charts. 780x240=187,200 BTU, so about 187,000x1.33 piping pickup for a NET rating of 248,976 BTU or so? If I missed something in this calculation, please let me know-I'm getting conflicting advice from different contractors about which numbers to use. It would be great to downsize from our old Weil Mclain EGH-85, but I want to have enough to produce steam in all 5 units here in Milwaukee, WI on the colder days. The new EGH-85 series 5 is rated smaller than our current EGH-85 series 3, further complicating the issue. Different Weil Mclain employees I talk to say it's the same output, just a sticker change to reflect federal rating shanges, others say the boiler sections/burners have been reduced for smaller out put so I need an EGH-95 for about the same output as the old EGH-85 we had. Any thoughts about how flexible the BTU output is and how low I can go, or if I need to use the DOE Gross Output or NET AHRI ratings to size the new boiler properly?

When the system was in use, do you know if the burner often turned off at 1.5 PSI or did it usually run for very long periods?

The fact you have a starting point like that EGH-85 is a good thing but we need to know details of how it behaved.

I'll look into the new EGH series vs old ratings and get back to you.

ChrisJ

The series 4 and series 5 EGH is certainly not the same assuming the way they are rated has not changed, but who knows.

Just going by the information you provided, I'm staying with my previous recommendation of an EG-65 if you're willing to spend time tweaking all of the venting and insulating everything or an EG-75 as the safer bet. Even though the new EGH-85 is rated less than your current one it's too big in my opinion. Bigger isn't better.

Fred

It looks like the EG-75 would be the choice I made. At 770 sq. ft of steam, it's right at your total radiator EDR of 780 and certainly the 10 sq. ft. variance (between the EG-75 rating and your total EDR) is not an issue with the built in pickup/piping factor that's already built into the boiler.

Dave0176

Your missing the point here.

As was stated, every steam boiler comes with the 1.33 piping factor already built into it. So if you want to find the actual size the boiler is capable of putting out take the boiler all are recommending the EG75 and times the 247,000 btu output by 1.33 and you will get 328,510 BTU and 997 sq ft of steam.

Now let's do the EG65 times the 209,000 output by 1.33 and you get 277,970 BTU and 869 sq ft of steam.

So you see how we do we it, what you are doing is adding another 1.33, like I said before you will choose way too big of a boiler like that and you won't be happy.

ChrisJ

Dave0176 said:

Your missing the point here.

As was stated, every steam boiler comes with the 1.33 piping factor already built into it. So if you want to find the actual size the boiler is capable of putting out take the boiler all are recommending the EG75 and times the 247,000 btu output by 1.33 and you will get 328,510 BTU and 997 sq ft of steam.

Now let's do the EG65 times the 209,000 output by 1.33 and you get 277,970 BTU and 869 sq ft of steam.

So you see how we do we it, what you are doing is adding another 1.33, like I said before you will choose way too big of a boiler like that and you won't be happy.

I think you did that backwards.

The EG-75's gross output is 247,000. Divide that by 1.33 and you get a net rating of 185,714.

Seems like WM made a typo on their brochure for the EG-75 though as it's saying only 750sqft and not 771. Not sure why that is.

KC_Jones

Dave0176 said:

Your missing the point here.

As was stated, every steam boiler comes with the 1.33 piping factor already built into it. So if you want to find the actual size the boiler is capable of putting out take the boiler all are recommending the EG75 and times the 247,000 btu output by 1.33 and you will get 328,510 BTU and 997 sq ft of steam.

Now let's do the EG65 times the 209,000 output by 1.33 and you get 277,970 BTU and 869 sq ft of steam.

So you see how we do we it, what you are doing is adding another 1.33, like I said before you will choose way too big of a boiler like that and you won't be happy.

Maybe I missed something in math class, but in your example of the EG75 you are saying it can output 328,510 BTU. How is that possible when the gross input is only 299,000BTU? It can't output more than the input?

BobC

FM

Bob

Dave0176

ChrisJ said:

Dave0176 said:

Your missing the point here.

As was stated, every steam boiler comes with the 1.33 piping factor already built into it. So if you want to find the actual size the boiler is capable of putting out take the boiler all are recommending the EG75 and times the 247,000 btu output by 1.33 and you will get 328,510 BTU and 997 sq ft of steam.

Now let's do the EG65 times the 209,000 output by 1.33 and you get 277,970 BTU and 869 sq ft of steam.

So you see how we do we it, what you are doing is adding another 1.33, like I said before you will choose way too big of a boiler like that and you won't be happy.

I think you did that backwards.

The EG-75's gross output is 247,000. Divide that by 1.33 and you get a net rating of 185,714.

Seems like WM made a typo on their brochure for the EG-75 though as it's saying only 750sqft and not 771. Not sure why that is.

Mayby I'm the one that's missing somthing here, I always assumed you multiply the output by 1.33 to get their built in factor??

Your right that makes total sense, you multiply the EDR by 1.33 to get the gross EDR. You know I never use BTU always EDR.

Anyway the EG75 would be more then enough then.
And like you said the EG65 could work fine if he tunes everything real good.

cubicacres

Thanks for the advice. We now know that the venting wasn't optimized with the EGH-85 and our plan to improve the venting this winter would help us get a better sense whether the boiler itself was running efficiently & meeting the building's needs. The leak came along before we could adjust any venting and experiment.

It didn't hiss. The pressure was turned down recently to a .5 PSI cut-in and a 1.5 PSI cut-out. It was set a little higher at 1-2 PSI range when we bought the building in Feb, I think.

The residents main complaints were uneven heating between apartments-the 2nd floor was hot & the 1st floor cold.

ChrisJ

Too many seem to think the pressurtrol should be controlling the pressure. It's my opinion the radiation should be controlling it. If you condense steam as fast as you make it the system will run at low pressure naturally.


My pressurtrol never does anything. It's just there for safety.

cubicacres

Using 10% instead of 33% would be nice. Did you mean compare to the Gross output of the boiler vs "net" in your comment above when doing the EG-65 fit for 780 sq ft?

ChrisJ

Please also buy TRVs for most if not all of the 2nd floor radiators.

You can install TRVs on any radiators that are guaranteed not to interfere with the thermostat controlling the boiler.

If you're going to have a lot of TRVs, then using two boilers may be a better option for you as well. Two EG-45's for example give you either 125,000 output for one, or 250,000 for both running. You can set it up so one boiler cycles on pressure at something reasonable like 4 or 8 ounces using a Vaporstat and the other runs continuously.


A TRV won't let a radiator heat unless the room needs heat. They will make people happy and will save you money in the long run.

Is your system single pipe or two pipe steam?

RobG

Another thing about TRV's is that the tenants don't have to use the window as their thermostat. Every BTU that leaves the building you have paid for.

Steamhead

Hatterasguy said:

I'm convinced this 33% pickup factor is a figment of the imagination of the boiler manufacturers who wish to cover their proverbial asses for the worst possible steam installation in the entire United States that will still heat the building.

The fact that certain individuals on here continue to promulgate this 33% figure and continue to suggest that new folks use it makes you wonder if they are employed by said manufacturers.

That's not a fair comment, HG- anyone who has worked on steam systems for any length of time knows that some simply require a larger pickup factor than others, hence the 33% piping/pickup factor now in use for steam boilers. In the past, boiler manufacturers used a 60% piping/pickup factor, but since 1958 it has been gradually reduced to where it is now.

This is one reason I suggest power-burner rather than atmospheric gas boilers. It is much easier to down-fire a power-burner unit and still get good combustion, than it is on an atmospheric. So it's easier to fine-tune a power-burner boiler to the system characteristics.

KC_Jones

I have been thinking about this lately. What if everyone is right and it's a combination? What if you need 33% based on the EDR, but the required output to heat the building was based on the heatloss? Lets use Chris's system as an example. @ChrisJ correct me if I am wrong, but your calculated heatloss is 60k. The pickup (based on 392 EDR of his system) at 33% would be 129 sq ft or 30960 BTU. Add that to his heatloss and that gives 90960 BTU. He has an EG-40 that has a net output of 104000. So looking at the numbers like that he is very close. Just another thought to add to the discussion.

ChrisJ

My radiation is 94k. Heat loss is around 70k but calculated at 66k I think. Boiler is as you said rated 104k and I think piping losses was around 1500 btu

Steamhead

We actually have run into steam boilers that were sized smaller than the radiation but within those smaller pickup factors, and they didn't heat well. I don't doubt that there are systems where this would not have been a problem, but we've obviously found a few where you needed the larger pickup factor.

This, again, is why I like power burners. You can usually tune out the larger pickup factor if that's appropriate, when using a power burner, and still get good combustion numbers. Not so easy on an atmospheric.

Fred

We have been having this same discussion for as long as I can remember. I happen to believe the 33% factor is very forgiving of systems that are not perfectly tuned and where the HO has no interest in standing by his boiler every night thinhing about what he/she can do next to make it even better than it is. My boiler, which I inherited some 25 years ago when I bought this house is about 20% over-sized for the radiator EDR, and the pick-up factor is on top of that. I have tuned and balanced the system to what I believe is about as good as it can be and I don';t experience the "bang, Bang" that Hat is talking about. My radiators heat evenly, quietly and all within about a minute of each other, 700+ sq.ft od radiation. As it relates to over-shooting the thermostat, even during the shoulder seasons, it just does not happen, at least on my system. As I have said on previous posts (lest year) my temp will only vary between .5 to 1 degree. Like it or not, believe it or not, that's the way it is. As far as short cycling, the only time I have seen a short cycle is when the outside temps were -20 and then the boiler only short cycled once or twice during the heating cycle. I attribute that to the boiler being over-sized, not the result of the 33% pick-up/piping factor.
HAVING SAID ALL THAT, I understand that there are many ways to skin a cat and many ways to get what you personnaly want out of a steam system. If a negative pick-up, or a 10% pick-up or a 15% pick-up, or a 20% pick-up, or a 33% pick-up floats your boat, so be it. My boat sails smoothly at 33%. Let every man/woman and child (not so much child ) take pleasure in the system and performance of their choosing. We are on this site to help people find/fix problems, not hold them to our beliefs/truths. Let's install our own systems the way we want them and let's help people fix real problems.

Fred

The other possibility is that, perhaps you don't know my system, or my home and consequently don't know what you're talking about. I don't want to get into a pissing contest with you about my home or my system. I have told you how my system operates and it is exactly as I have said many times before. The conundrum is on you. If one doesn't agree with the theories you put forth, one is subject to you having some kind of tantrum or kniption fit or recieving a series of insults. I'm not interested in any of that. Let's be here to help posters fix steam problems. At the moment, I don't have any.

Steamhead

Hatterasguy said:

Can you clarify this, please.

Were they truly below the calculated EDR, or were they below the traditional accepted figure of EDR + 33% pickup factor and above the calculated EDR?

This is a very important point.

And, were such boilers piped well with regard to near boiler piping? If they didn't heat well with poor near boiler piping, you cannot blame that on the size of the boiler....................

Also, did said boiler have all of its mains and all of its near boiler piping fully insulated? If not, then the failure to heat would be expected and you, again, cannot blame that on the size of the boiler......................

I make the statement that you can pipe an atmospheric boiler with a 10% pickup factor and get it to heat perfectly fine provided that the near boiler piping, and the insulation is perfect. This includes 30" risers and a drop header.

I don't remember all the piping details, but I think I would if they were piped really badly. We've only seen a few undersized steamers- many of those we encounter are oversized. I will say that none of them had drop headers- we seem to be the only ones in the Baltimore area to use them.

Regarding capacity, the Net EDR ratings on these boilers were smaller than the installed radiation. But if you figured a smaller pickup factor, say 10-15%, the resulting Net rating matched or slightly exceeded the installed radiation. Obviously I'm not in a position to ask those who installed these boilers how they sized them, but my best SWAG was that they used smaller piping/pickup factors- either that or they missed some radiators or used the wrong radiator rating charts.

Fred

Hatterasguy said:

No, the conundrum is not on me.

There is a fundamental violation of the laws of physics and it has nothing to do with "my theory".

Either you don't have the connected EDR that you believe or the output of the boiler is less than the specification.

Your constant admonition of a 33% pickup factor based on one system is simply in error and you cause others to use larger boilers than required.

Take a look at the extensive writings of Dave Bunnell and explain how ChrisJ can possibly heat his building if you think I don't know what I'm talking about. I didn't make this stuff up.

Like I said, I'm not interested in a pissing contest with you or anyone else. I don't know Chris' building or system but I do know mine is a lot larger, about 5000 sq. ft, not counting another 2000 in an unfinished basement, with a couple hundred feet of 2.5" mains and another couple hundred feet of 1.5" radiator run outs. Mine works to my satisfaction. I know it would work if it were right sized to the EDR and it might work with less pick-up but you can bet when the time comes to replace it, I won't be reducing the pick-up factor. Virtually every boiler installed today and for the past several decades have that 33% pick-up factor and if properly sized otherwise and properly installed, they work beautifully. Mine works beautifully even being over-sized (as most boilers are). I'll take that data any day, all day long.

Steamhead

Hatterasguy said:

Steamhead said:

Regarding capacity, the Net EDR ratings on these boilers were smaller than the installed radiation. But if you figured a smaller pickup factor, say 10-15%, the resulting Net rating matched or slightly exceeded the installed radiation. Obviously I'm not in a position to ask those who installed these boilers how they sized them, but my best SWAG was that they used smaller piping/pickup factors- either that or they missed some radiators or used the wrong radiator rating charts.

So, if I read this correctly, the installed EDR was about 15% less than the net output?

And, such a boiler would fail to heat the building? We have to discount this statement if the building is unbalanced. It is agreed that balancing a building with a 15% pickup factor is more difficult and it is easy to walk away and make the conclusion that a small boiler won't cut it. In fact, most of those who install these boilers cannot spend the time to play with vents on 10 return trips so it is quite easy to make such a conclusion.

If such a boiler, 15% greater than the EDR, won't heat the building, you have to ask................where is the 15% disappearing?

I spoke with Dave at length on this subject and he's pushed the limit on a zero pickup factor without any issues. He doesn't even know where the bottom lies. The vents are the key, however.

Remember, even with a zero pickup factor, the boiler is still typically oversized as compared to the heatloss and the energy has to go somewhere.

Of course, it could absolutely disappear into unconditioned space if there is no insulation.....................????

No, you have it backwards. The standard Net ratings on these boilers, which included the 33% piping/pickup factor, were less than the installed radiation- though not by much.

If you worked the math to remove the 33% factor and add a new one of 10-15%, that "new" Net rating matched the installed radiation. But they didn't heat well- never really did according to the owners.

My solution:

1- Install a wet base/power burner using the usual ratings;

2- Dial the firing rate back, keeping the combustion parameters correct with an analyzer, if the system heats up quickly and short-cycles. On larger systems, use lo-hi-lo firing.

If the system runs for roughly an hour or so before all the radiators fill with steam and the pressure builds, I generally consider that OK. The only time that system will cycle on pressure is when it's coming out of setback, which is typically once or maybe twice a day. The rest of the day it just maintains temperature, never getting far enough to cycle on pressure.

Hap_Hazzard

Hatterasguy said:

I will, very shortly, reconfigure an existing system that uses the infamous nine section Dunkirk. It will have a connected EDR of 901 and it has a net output of 245MBTU.

What model is this? I can't find a nine-section Dunkirk model with a net output of 245 MBH. The PSB-9D has a gross output of 245. Is that what you mean?

Hatterasguy said:

I'm taking bets as to whether it will heat properly with careful venting, twin 3" risers, a 4" drop header, and full insulation.

If this is a PSB I'll take a piece of that. The boiler's about 17% undersize. I don't think you can get back that much.

Hatterasguy said:

I am a bit concerned about it as one of the mains runs counterflow for 1/2 the basement and then turns back into traditional downflow (after reaching the ceiling) for the return trip. Strange deal.

As long as there's a drip I don't see any problem. It was probably necessary to keep the end of the main above living-space.

cubicacres

Thanks for all the great advice! (This post is also on my other post about Milwaukee area steam professionals.) So to sum it up, are these the things to keep in mind for a great, long-lasting boiler install for our 780 sq ft EDR 5-unit building?

1. Work with a knowledgeable single-pipe steam professional
2. Use a good quality boiler (any thoughts when selecting similar size header pipe diameter & heating capacity boilers across various manufacturers?, Push nipples in blocks are better than seals, etc.)
3. Maintain it regularly (annual tune-ups, and consider water treatment like steamaster tablets to reduce rust buildup in the system)
3. Size it correctly for EDR Sq Ft (pickup factors debateable on this site from 0-33%, it seems :-)
4. Install it with something to minimize adding fresh water over time (a generous reservior pipe, or something else along with a water meter to measure intake and fix leaks as detected?)
5. Consider a dirt seperator (to minimize minerals coming in the in intake water)
6. Consider a Spirovent or something else? (to minimize oxygen in the intake water)
7. Use 2 larger drop-headers of 4in or more to exceed the total diameter of the risers.
8. Insulate well
9. Vent the mains well (faster), radiators slower
10. Consider vari-vents for tennant's individual comfort levels in warm 2nd floor rooms. Keep the thermostat in the cooler room on the 1st floor.
11. Outside sensor & thermostat upgrade reccomended with the new system install? 1984 LCD thermostat & missing sensor dial currenly on the wall.
12. Low-water cut-off probe-type ok with less blow-down vs. float style LWC to keep water within the system? I suspect the probe installed in 2009 was still being blown-down each week as if it were still a float-ball type LWC with the previous owner, increasing our fresh-water intake & rusting the block faster.
13. Anything else I missed you'd reccomend we consider?