Please point me to some gas steam down-firing threads

wcs5050

Weil McLain EG, 450k input. Potentially disconnecting 1st floor load.
Interested in correct burner arrangement, etc. I would think manifold pressure remains at 3.5"wc. I would also think manufacturer wants nothing to do with "alteration of original equipment".

Tim McElwain

Not a good idea to downfire steam.

Fred

Is it the EGH-115 ? Most of the larger WM boilers come with a two stage gas valve. It may be that you can run the boiler on the low stage but, if possible, it will need to be set up by a Pro who can do the combustion testing to set it up correctly.

Abracadabra

EG/EGH don't come with hi-lo gas valve. Only LGB

KC_Jones

Here's the problem I am theorizing, I don't think you will be able to downfire that boiler enough to compensate for taking out an entire floor of rads. Unless this is a small footprint multi story building?

Also I have to ask, why are you potentially removing all that radiation? The answer to that may help get a better answer or better solution to the problem.

Abracadabra

could just remove a bunch of burner tubes. would need to confirm combustion numbers tho

MilanD

Wasn't someone here on the wall that changed burner set up from one to the next egh boiler? It was a smaller boiler, something like 135-145kbtu swap... smaller burners on a larger boiler...

As to downfiring, before I was more familiar, our old lgb11 had 4-5 burners removed and worked just fine as far as I can remember. I can't attest to whether or not the gas pressure on the gas train was also reduced... but probably not. These lgb and egh are glorified boiling pots. There should be a way to simmer them down. If lgb comes with low high low, and I'm in the process of getting this done on our lgb7, there has to be a way for these smaller boilers to do the same.

MilanD

@KC_Jones, was it you that swapped burners?

KC_Jones

@ChrisJ did it, but his situation was making a 45 into a 40. Both of those use the exact same block, but different burner trays. That's 25k BTU's, if I was guessing the OP is looking for a lot more than that.

ChrisJ

I had to swap the rear burner support, burner manifold and drafthood to go from a 45 to a 40.

Not sure if there's a similar option on the much larger models.

You may be able to bust a section off of the block, and convert it to the next smaller size buy you'd need to buy new panels and all kinds of fun stuff. Could also be risky splitting the block apart.

@Dave0176 knows a lot about the EG series.


@Tim McElwain Why is it "Not a good idea to downfire steam" ?

Tim McElwain

Most steam boilers by design of the engineers who specified them require full input to obtain maximum steam production. This takes into consideration that boilers are sized and installed based on EDR and also a heat loss being done so that boiler sizing is accurate based on those criteria.

We all know that in a perfect world that would be the case.

The truth is many of them are oversized for the required heat loss. So the next thing we want to do is bring them down to the required firing rate. Some boilers will allow a 10% reduction in input per the manufacturers specifications.

Here in lies the problem. The boiler water capacity typically following the basic rule of 1 BTU to heat !lb of water 1° F. So from 32 ° F water up to 212° F we need 180 BTU's per pound. Then we have to change 212° F water into 212° F steam, this requires an additional 970 BTU' per pound. Called "Latent Heat of Vaporization. So in a typical pounds system single stage boiler we need all the BTU's we can get in order to make steam in a reasonable amount of time and satisfy the requirements of the system.

What happens when we down fire? The answer is we still have the same volume of water to deal with but now we have lower BTU to accomplish that. This will affect the efficiency of the boiler and increase the run time. In some cases that use the thermostat anticipator setting to determine cycle rte the thermostat may shut the system off before adequate steam production is accomplished. The combustion efficiency is also affected so all around we are less efficient.

Most manufacturers would also tell you removing burners and blocking off orifices is not a good idea as to ignition safety.

On commercial applications and CSD-1 codes downsizing may actually be considered a code violation. This depends upon the local Authority Having Jurisdiction and approval from the manufacturer and their insurance as to whether they will let you de rate their boilers.

As to staging boilers it is a good idea on commercial boilers to make sure the control package allowed by the boiler manufacturer will approve a two stage system.

It is never a good idea to reduce gas pressure to accomplish a particular input. Some who post here may not agree with me on this but I do not recommend reducing pressure too drastically if you must choose to do so. If you insist on reducing input then do so with reduced size orifices not messing with pressure and removing burners. On some steam applications removing burners can actually cause a boiler to crack on the cool side of the boiler.

MilanD

So @Tim McElwain how is LGB different from EG in terms of construction when LGB can be 2-staged and EG can't?

As to reducing the steam chest, can't one just lower the water level in the derated boiler to accomplish the same effect as to having a smaller boiler? Granted, one still checks all the combustion and all, but with the simple draft hood set-up and plenty of air flow to burners, this shouldn't be an issue.

I'm not an engineer so I am not familiar with all the science going behind this. I'm looking at it from a strictly cooking pot, nay, pressure cooker on a stove scenario as that's what most these gas-fired boilers are in essence cast iron sitting on flame, cooking water.

Forgive my simplicity.

ChrisJ

@MilanD I don't know, but I don't like the idea of lowering the water level.

I intentionally run my EG-40 over filled because in my mind, it means more surface area absorbing the heat. The boiler doesn't complain, so I don't complain. My water level is just under the skim port, I think 3/4 of the way up the gauge glass. I typically add when it gets down to the normal level of half the gauge glass or so.

Tim McElwain

I would prefer with the 700-064 to use a vaporstat. My experience in going from full opening high fire only to a two stage is that the overall efficiency is affected. The last job I set up doing this actually saved the church 35% from the previous cost.

ChrisJ

Hatterasguy said:

Tim McElwain said:

I would prefer with the 700-064 to use a vaporstat. My experience in going from full opening high fire only to a two stage is that the overall efficiency is affected. The last job I set up doing this actually saved the church 35% from the previous cost.

Just for clarification please:

The use of the two stage gas valve saved the church 35% as compared to the single stage gas valve?

This is despite the efficiency loss due to the excess air increase on low fire?

Is that correct?

And without converting it to hot water and installing a modcon.

wcs5050

All great stuff. Thanks everyone!

wcs5050

> @KC_Jones said:
> Here's the problem I am theorizing, I don't think you will be able to downfire that boiler enough to compensate for taking out an entire floor of rads. Unless this is a small footprint multi story building?
>

Agreed. Boiler is oversized for the load, and would need significant downfiring, not just one or two sizes. Small church meetinghouse, steam serves 1st and 2nd floor, one side only.


> Also I have to ask, why are you potentially removing all that radiation? The answer to that may help get a better answer or better solution to the problem.

Issue is zoning. Multiple after-the-fact partitions built perpendicular over steam boiler wall convector have 2nd floor chopped and uncomfortable. TT on first floor. Meetings on 2nd floor while 1st is unoccupied mean fuel waste.

> @Abracadabra said:
> could just remove a bunch of burner tubes. would need to confirm combustion numbers tho

Maybe remove every other tube from boiler ends to avoid cold ends, leaving middle/core intact?

Fhw 40 yr old does rear addition, so modcon replacement with zoning shift to it is on the table. Just don't want to throw away this beautiful steam installation, whether it does 1st or 2nd floor.
Zone valves considered, but those appear to be a nightmare, as @Tim McElwain mentioned system designed to operate as a whole.

Abracadabra

wcs5050 said:

> @Abracadabra said:

> could just remove a bunch of burner tubes. would need to confirm combustion numbers tho



Maybe remove every other tube from boiler ends to avoid cold ends, leaving middle/core intact?

No.. that's dangerous.. you won't get reliable ignition carryover then.
You need to remove a couple of the end tubes, only after the burner tube with the flame sensor attached.

MilanD

... Agreed with Abracadabra

Tim McElwain

@Hatterasguy

Sorry I did not make myself clear on the two stage job. The boiler had been drastically downsized by changing the orifices thus reducing input to what basically was the unit was running on low fire all the time. By restoring to full input and staging we not only reduced the fuel usage but increased the comfort level in the church. This church was in operation seven days a week versus some churches only needing heat on Sundays. The boiler had a damper arrangement that reduced or increased secondary air based on fuel demand. All that along with eliminating the draft hood and putting in a barometric.

I had a similar condition in another church with a boiler that was on oil and the oil company had set up the low fire/ high fire arrangement with pressuretrols so that the unit was on low fire all the time. We installed a Powerflame dual fuel burner and cleaned up some of the steam problems. Clean the boiler and changed the venting setup. The savings again was in the 30% range.

ChrisJ

Hatterasguy said:

Tim McElwain said:

@Hatterasguy

Sorry I did not make myself clear on the two stage job. The boiler had been drastically downsized by changing the orifices thus reducing input to what basically was the unit was running on low fire all the time. By restoring to full input and staging we not only reduced the fuel usage but increased the comfort level in the church.

Clearly, changing from low fire to staged fire must result in savings as the excess air is eliminated on high fire.

What I would like to see is a result that confirms increased efficiency from a change that begins with full fire and ends with staged firing.

There is an agreed loss when the boiler is operated at reduced capacity due to excess air, but IMHO, this loss is more than offset by gains that result from the elimination of short cycles.

Some make the conclusion that one can never run the boiler at a reduced firing rate due to excess air killing the efficiency. I do believe these individuals are factually incorrect for any boiler that is clearly oversized for the EDR.

This individual believes, when possible, it's better to install an "undersized" boiler that will never cycle as compared to installing an oversized one with a 2 stage gas valve, resulting in reduced efficiency albeit slight, the majority of the time.

The whole "high fire needed to heat the pipes" is completely unnecessary.


Making an already installed grossly oversized boiler work better is another story I suppose.

MilanD

@Tim McElwain @Hatterasguy

You know, this whole full on only and no modulation on steam boilers is to me analogous to always using a firehose for any water need. Esp. on oversized boilers, or boilers firing into zoned mains, which essentially make boilers oversized each time the zone closes.

Several people here on the wall were able to successfully 2-stage gas fired boilers. I can't remember if there was someone with oil one too. Lgb models 6 and up have low-high-low option. So, it's possible. I think of it as simmer or full fire, like a pot on the stove.

It seems like it comes down to having a tech like Tim or Hatt, or ChrisJ, Abracadabra, KC_Jones... who know how to exactly do this go ahead and get the systems to do this.

What I wonder and don't understand is why the various manufacturers don't apply this as at least an upgrade option. Valve train upgrade and an extra vstat, and 30% fuel savings. This alone would sell itself imho.

MilanD

@ChrisJ

So you essentially underfire the larger boiler by 15-20% with smaller btu burners setup, and have also raised the water level? This is exactly what @Tim McElwain said would be an issue with longer burns to get to steam on downfired boilers and why I asked if one could lower the water level, the same way you rasied yours. You also have added ecosteam, right? So does your boiler water ever cools down completely between cycles? Probably not in cold weather but how well does the system run in shoulder times - not too cold bit still needing a little heat? Does it take longer to cook the water to boil point of there is more water and less btus cooking it?

ChrisJ

MilanD said:

@ChrisJ



So you essentially underfire the larger boiler by 15-20% with smaller btu burners setup, and have also raised the water level? This is exactly what @Tim McElwain said would be an issue with longer burns to get to steam on downfired boilers and why I asked if one could lower the water level, the same way you rasied yours. You also have added ecosteam, right? So does your boiler water ever cools down completely between cycles? Probably not in cold weather but how well does the system run in shoulder times - not too cold bit still needing a little heat? Does it take longer to cook the water to boil point of there is more water and less btus cooking it?

I "converted" an EG-45 to an EG-40 using Weil Mclain's parts. The boiler is exactly as an EG-40 ships from the factory, which is 125K input vs the EG-45's 150K input, so 25K less.

Of course it takes longer in mild weather, there's 25,000 less btu's going in per hour. Who cares? You're putting in 17% less heat so it's going to take 17% longer.

This is a big part of the problem. Everyone is so concerned about speed they forget about what they're trying to achieve.

For some odd reason with steam the faster we heat the radiators the better, and yet no one cares about speed when it comes to radiant heat. All of a sudden with radiant, slow is acceptable.

Here's a cycle from a fairly cold night.

90 second preheat time. This is the total time from when the thermostat calls for heat, until steam hits the main vent on the longest main. This includes the time it takes for the damper to open, pilot to light and water to boil.

On a more mild night, this is around 3 to 4 minutes.

MilanD

@ChrisJ

That is sweeet! We talked about this when I was looking for solutions for our lgb.

Do you happen to have an opinion as to why is something like what you do not more a standard when it comes to steam upgrades? Trols and vents alone are, essentially, reaching back to coal conversions and nothing more has been done on a larger scale (by manufacturers) to try to modulate steam delivery by heat loss anticipation, running times averaging and alike?

Mark did the ecosteam and it didn't take off. Some people here (PMJ) built their own plc controls to do this same thing: mimic what the coal used to do. Lgb has 2 stage capability, but noone uses it... unless one of you guys who are knowledgeable do it (and there aren't many of you).

What gives? I am a customer, not a steam guy or an engineer, or in the steam business. I happen to want to save our small non profit school costs of fuel and am, perhaps, a little ocd about this, so I dig. But if something can be engineered to deliver savings, and is really not that complicated, why is it not the standard? I.mean, 65-70 years after first conversions from coal we are still using, out there and in the majority of cases, original controls technology from that era (perhaps only minus the mercury in tstats and trols/vstats). I don't get it.

wcs5050

So to summarize... downfiring is not ideal; but with smaller orififices (sizing tbd), no burner tubes removed, and a staged gas valve in communication with a vaporstat, a down-fire is feasible at the expense of some efficiency loss.

Gas train flow tbd with meter clocking, and combustion performance to be adjusted/legitimized with combustion analysis.

Back to 2 stage valve operation and control... are you using 2 v-stats to engage 1st and 2nd stage, and/or a timer...? This method is preferable than single stage, as the shift between 1st and 2nd stage is more fuel efficient than running one flow rate (?).

What about alteration of draft damperage and exhaust convection with diminished combustion?

What can we say would be a realistic/safe down-fire from factory setup?.... 10%,20%,etc..?

MilanD

My question still stands as to what the difference is between LGB and other boilers, that allow LGB to be 2-staged, and others not, at least not by manufacturers' specs. It's being done, as written on this very thread by @Hatterasguy, @Abracadabra and @Tim McElwain.

I would also suppose that keeping the water lower might also work, or even keeping the water level the same, which will increase the pre-heat time due to lower btu input, but should work nonetheless, as Chris has done, in a smaller capacity boiler.

Tim McElwain

Some CSD-1 systems actually have the ability to reduce secondary air (excess air) when on low fire by the use of damper system which is coordinated with the call from low fire (less air) to high fire (more air).

We even had some conversion burners and also Series 10 DPST systems and Series 20 SPDT power to open power to close which included an attachment to a motorized gas valve which changed the air requirement. These could be adjusted when an ORSAT (combustion test was done). Remember in those days we did not have electronic combustion analyzers it was the bottles so it required some expertise to set these up.

I wonder how many have ever heard of Republic Gyroscopic Burners?

jumper

Multiple atmospheric burners with constant negative flue pressure?

Marc_18

ChrisJ said:

@MilanD I don't know, but I don't like the idea of lowering the water level.

I intentionally run my EG-40 over filled because in my mind, it means more surface area absorbing the heat. The boiler doesn't complain, so I don't complain. My water level is just under the skim port, I think 3/4 of the way up the gauge glass. I typically add when it gets down to the normal level of half the gauge glass or so.

Seems to me that raising the water level only serves to reduce the “A” dimension and increase the possibility of wet steam.

ChrisJ

Marc_18 said:

ChrisJ said:

@MilanD I don't know, but I don't like the idea of lowering the water level.

I intentionally run my EG-40 over filled because in my mind, it means more surface area absorbing the heat. The boiler doesn't complain, so I don't complain. My water level is just under the skim port, I think 3/4 of the way up the gauge glass. I typically add when it gets down to the normal level of half the gauge glass or so.

Seems to me that raising the water level only serves to reduce the “A” dimension and increase the possibility of wet steam.

Responding to a really old post?

In my case I can run my boiler with the gauge glass full and not have wet steam or any other issues.
So......

In my opinion it helps keep the block cooler up higher.

That's my story.

Marc_18

ChrisJ said:

Marc_18 said:

ChrisJ said:

@MilanD I don't know, but I don't like the idea of lowering the water level.

I intentionally run my EG-40 over filled because in my mind, it means more surface area absorbing the heat. The boiler doesn't complain, so I don't complain. My water level is just under the skim port, I think 3/4 of the way up the gauge glass. I typically add when it gets down to the normal level of half the gauge glass or so.

Seems to me that raising the water level only serves to reduce the “A” dimension and increase the possibility of wet steam.

Responding to a really old post?

In my case I can run my boiler with the gauge glass full and not have wet steam or any other issues.
So......

In my opinion it helps keep the block cooler up higher.

That's my story.

Hi Chris, I found this older thread from a search about down-firing boilers. I have an EG-45 which I believe is oversized. I plan to do an EDR calculation, but the boiler does short cycle at times especially during a recovery from a thermostat set back. Would be great to get some modification details from you at some point to help me determine whether it might make sense to convert to an EG-40.

ChrisJ

Marc_18 said:

@MilanD I don't know, but I don't like the idea of lowering the water level. I intentionally run my EG-40 over filled because in my mind, it means more surface area absorbing the heat. The boiler doesn't complain, so I don't complain. My water level is just under the skim port, I think 3/4 of the way up the gauge glass. I typically add when it gets down to the normal level of half the gauge glass or so.

Seems to me that raising the water level only serves to reduce the “A” dimension and increase the possibility of wet steam.

Responding to a really old post? In my case I can run my boiler with the gauge glass full and not have wet steam or any other issues. So...... In my opinion it helps keep the block cooler up higher. That's my story.

Hi Chris, I found this older thread from a search about down-firing boilers. I have an EG-45 which I believe is oversized. I plan to do an EDR calculation, but the boiler does short cycle at times especially during a recovery from a thermostat set back. Would be great to get some modification details from you at some point to help me determine whether it might make sense to convert to an EG-40.

Let me know