Can EG-50 steam boiler be converted into EG-55?

Ori

Hello,

The 3 story building that I'm servicing has a Weil McLain EG-50 (SPDN, Series 4) boiler, with 142,000 btu DOE, 446 net sqft of steam. One pipe steam, 2 parallel flow mains.

Now with added radiators to the units (and basement) there is a total of 600 EDR (144,000btu) in load.
In theory, the existing boiler should be able to support that amount of radiation after dropping off the pickup and piping factor (say after the pipes are fully hot), but it doesn't. Far from it. Heating cycles are very long, averaging an hour and fifteen minutes each, while outside temp is about 33 degrees.
Yesterday the boiler had 8 heating cycles, of an hour and quarter each, totaling 10 hours of heating.
[Just for reference, at another building in the same area that I'm servicing, with similar amount of radiation (but way oversized boiler), it took only a total 3 hours to heat yesterday, (and as a result, generally it cost a lot less to heat that building).]

Moreover, some rads at the end and the middle of the 2" main get very little to no steam at all.
The problem is mainly with the 2" main rads. As you see in the pic attached, the mains split favors the 3" main over the 2" one.

I should mention that the rads off of the 3" can get very hot very quickly but I have installed Maid o Mist #4 on all of them, which are the smallest, that in order to induce more steam towards the 2" main. But smaller vents do lengthen the heating cycle quite a bit, as those rads could get hot quicker (and as a result cheaper to operate) if larger vents were installed.
The vents on the rads on the 2" main are getting progressively larger as they get further away. But that still doesn't help much...

Both mains have plenty of main venting: the 3" main has 2 bigmouth and a Gorton#2, and the 2" main has one bigmouth and 2 Gorton#2.
The vents on the 2" main usually close within a minute or two after the 3" main vents close.
The boiler is clean and skimmed, and so are the returns lines, pigtail and T. Near boiler piping is fine (please see pics attached).

The (0-18oz) gauge shows little pressure (~2-3oz) only at the very beginning, during the first 2-3 minutes, even before the main vents close, but then drops to zero, and stay like that through the entire heating cycle.
I read that the gauge can show zero pressure for a properly sized boiler, while all rads get hot, but that's not the case here, as it seems it needs even only few ounces of pressure to get all rads to heat.

I did an experiment where I closed off few big rads (fed by the 3" main), and immediately the gauge showed some 2oz of pressure, and the 'problematic' rads at the end of the 2" main got heat right away.
So I think it's a boiler capacity issue.

The existing EG-50 steam boiler and the next size up EG-55 have the exact same physical dimension. If correctly understand, the manual shows that the only differences between the two is the number of burner tubes (6 vs 7 for the EG50 and EG55, respectively), the gas control valve (1/2" vs 3/4" respectively), and the draft hood. The existing near boiler piping already has 3" riser and header as required for the EG55.

That doesn't look too difficult to change and upgrade, but I wanted to ask if that's legitimate thing to do.

The EG-55 has a 169,000btu DOE, which is 27,000btu more than the existing one (142,000btu DOE). It still might not be sufficient, but this boiler upgrading 'experiment' seems to be cheaper than replacing the boiler with a whole new one. This added 27,000btu might be just enough to create even say 1oz of pressure to fill the last rads.

What is your take on that?

Ori

Correction: unlike shown in the pics, the pressure gauge and vaporstat no longer sit on a snubber...the snubber has been removed.

Long Beach Ed

I can only say the obvious: That's a question for the Weil - McLain engineering people. Give them a call. Will they bless the conversion and provide a new rating plate?

If it is true that there is no differences other than those you mentioned; no difference in the breech, the casting, the burner mounting and air supply, etc. the answer should be obvious. It is not uncommon for installers to over-fire boilers, sometimes with larger nozzles and a favorable combustion analysis.

The question which then prevails is the legality of your doing so to equipment you don't own without the manufacturer's blessing. This could be a code and insurance issue, one which rides on your license, which should be your concern if you are a licensed professional. Is this within the scope of work permitted by your license in your jurisdiction?

Ori

Thanks. 

I’ve increased the gas pressure from 3.5” to 4”wc, but that still didn’t generate noticeable pressure to feed the last rads..

Long Beach Ed

Don't mess with the combustion unless you have the proper equipment to test for carbon monoxide and are qualified on that end. Especially here, refer to the manufacturer's recommendations. They should offer the gas pressure range that is acceptable.

Maybe someone else here has specific experience with the EG-50/55 conversion you are asking about.

Mad Dog_2

Are you talking larger gas orifices ?  Mad Dog 🐕 

Ori

No, I just increased the gas pressure to 4” without changing any gas orifice...

ChrisJ

IF the EG50 and 55 are the same as the EG40 and 45 then you need to swap the drafthood the burner manifold and the burner support as well as add burner(s).   

I don't know if they are.

However I am confused.
First, the pickup factor doesn't involve cold piping.  100% of the boiler output is used to heat the piping as no radiators are getting steam at that point.

Next, does the building heat evenly?

Maid O Mist 4s are awfully small.  I'm running #5s,6s and Cs.   I think I have one #4 but that may be gone by now as well.

The building requires X amount of heat.  If the boiler is providing that and evenly then a larger boiler isn't going to be cheaper to run.  


I would make sure your main vents are keeping up first.  I had to use main vents to balance my mains by restricting one a bit.

I would not hesitate to use Cs or even Ds on further radiators.  Further includes the run outs to the radiators basically total piping distance from the boiler to the radiator.

It's a game... You don't need much pressure.  See how fast you can vent the further radiators and then how fast you can get the closer ones without overheating those spaces.   If the further ones get starved you'll need to slow others down, but don't do it until you've got good big vents on the further ones first.  

Make sure the steam hits the ends of the mains before any radiator gets anything.

Ori

Thank you ChrisJ. Yes the EG 50 and 55 are similar to 40 and 45, as both are of the same size.
And no, the building does not heat evenly; the rads off of the 3" main heat very well while those on the 2" are challenging. That's why I 'suffocate' those of the 3" main with vent #4, so as to push more steam to the 2" main rads. And unfortunately, the 3" main runs through the south side of the building (which gets sunny), and the 2" through the north, where radiation is needed more frequently.

On those that don't work well or at all, I do have C's and D's, to no avail, (except when I purposely reduced significant amount of radiation to see if they get hot, which they did right away).
I used to use Gorton #5 (or Hoffman #41) on most and it worked great on them, but then had to wait forever for the problematic rads to finally kick in. Maybe those problematic ones are just not plumbed correctly. Don't know. But I do know that increased pressure (even to 2oz) solved it right away.

What do you mean "I had to use main vents to balance my mains by restricting one a bit." Do you think I have too much of main venting?
The 4" coming from the boiler is 13' long, then it splits to 63' of 3" main and 53' of 2" main.
At the end of the 3" there are 2 bigmouth and 1 Gorton#2 (about 5CFM @ 1oz of pressure), and at the end of the 2" main there are one bigmouth and 2 Gorton#2 (about 4CFM @ 1oz of pressure).
Too much do you think? I see that they close within a minute or two from each other, within about 7-8 minutes of the water is hot..(at least I see the bigmouth close you can see some steam coming out before they close...

EBEBRATT-Ed

Maybe a few TRVs on the first to heat rads would solve the problem. Not the right fix though.

I know you increased the gas pressure but have you combustion tested it to check the efficiency?. If the fireside of the boiler clean?

Ori

Did not combustion tested it.
How to check if the fireside of the boiler is clean? I do clean the burner pipes with a steel brush before every heating season, if that's what you mean...?

TonKa

Are your mains insulated all the way to the ends? They don't look like it. Considering your predicament and the mains sizes and lengths, you may want to consider 2 inches of insulation.

ChrisJ

Plenty of insulation is important.

But also I thought an EG50 needed two risers and at least a 3" header?

Is that what's hidden under that insulation?

Ori

All the mains are insulated all the way past the tapping to the last riser. I will insulate the mains further into the boiler..

Ori

All EG need only one riser. I checked the Installation manual.
The EG55 needs a 3" boiler riser, and a 3" header, which we currency have...
https://www.weil-mclain.com/sites/default/files/field-file/eg-peg-egh-series-4-manual_1.pdf

TonKa

Ori said:

All the mains are insulated all the way past the tapping to the last riser. I will insulate the mains further into the boiler..

Are the pictures old? The 4 inch to the 3 inch and 2 inch split *really* doesn't look like there's any at all.

Can you show a picture of the piping around the Hartford loop?

How much water needs to be added to this system?

Ori

Thanks TonKa. Yes those pics are older. Here is the updated ones.
I'm missing insulation on the mains in the boiler room itself, and I'll insulate them soon. I use 1/2" thick fiberglass insulation that is available at our local store.
Not sure how much water is added as I've been skimming it several times recently. But I'll start monitoring that soon.

Long Beach Ed

The boiler's rated at 446 ft of steam for your connected load of 600 feet. It was sized with no pickup factor. I believe you're on the right track to consider upsizing the boiler.

ChrisJ

1" or thicker insulation should also be considered.

1/2" is less than great, and expensive at local stores.

TonKa

Can you see any way steam can "short circuit" back to reach the 2 inch branch's main vents prematurely?

Is the 2 inch branch properly pitched toward its end or sagging anywhere allowing condensate to pool? What about the problematic radiator risers and runs? (Use a level. Don't eyeball it.)

Do you have vents at the tops of any of the risers to the radiators? If so, make sure they work (and vent fast), at least on the ones to the problematic radiators.

Could there be a coincidental steam leak in one of the radiators you tried shutting off? Try temporarily reducing EDR by shutting a few working radiators on the 2 inch branch to see if you get the same pressure response.

FWIW, you should have at least an inch of insulation. (Again, with your mains sizes and lengths, consider having more.) I have bought from here in the past: https://buyinsulationproductstore.com/