sell me on a power gas burner

TomM

im planning on putting in a new steam boiler this summer.  and switching to gas. 



I've been looking at the smith G8 and Slant Fin Intrepid oil boiler setups with power gas burners.  On new installs.  you guys are claiming that they get mid 80ish % efficiency.



Why then, do the best gas fired steam boilers only get 80% efficiency?  Wouldn't they all move to an oil three pass system and slap a power gas burner on there instead of selling gas fired systems?  does it cost more for the extra cast iron or something?



(i'm sure this has been covered before)



Thanks!



Tom in Conshohocken PA

Rod

Wet Based Boiler with Gas Power Burner

Hi- Probably the best answer to your question is that most people are only interested in the lowest replacement cost and from the manufacturers standpoint adding a gas power burner is more costly than a tube atmospheric burner so they provide people with what they want rather than what is most efficient.  Factored into this is that the steam boilers are basically just a replacement market and a small segment of the overall heating market.



The big advantage to the Smith and SlantFin (oil boilers) , is they are wet based, that is, the boiler (with water) surrounds the burner flame where with the standard atmospheric gas boiler, it is just sits over the flame like a pot on a stove. The wet based allows better heat transfer.  We are all waiting for Burnham to approve the 3 pass Megasteam for gas, but they seem in NO hurry to do so. Why not? Who knows? 



    Steam boilers could be made very efficient if they had modulating burners but we aren't likely to see these in residential size unless fuel goes up and the market demands it.  It is more likely if it gets to this point that steam heating in homes will be banned first which is too bad as steam has really great potential. If you want to take a look at a really modern steam system go to Gerry Gill's website and take a look at the Mini Tube system he put in his own home. http://www.gwgillplumbingandheating.com/

- Rod

Tim McElwain

What Rod said is correct

there is also something else to be considered however. First of all there is a difference between AFUE (Annual Fuel Utilization Efficiency), combustion efficiency (determined by using an electronic combustion analyzer) and thermal efficiency the actual BTU being directly transferred to the medium being heated. In this case water which must be changed into steam. The wet base boiler gives much better thermal efficiency.



The other consideration is the atmospheric gas design steam or hot water boiler are less efficient than any oil designed system unless you go to gas Mod/Con 90 + equipment. One of the reasons for this difference in efficiency has to do with the required amount of excess air for the atmospheric burners as compared to a power burner. The power burner both oil and gas use much less excess air as compared to design gas. Oil and gas power in the range of 15 to 25% excess air the design gas 40 to 50% excess air. Excessive excess air lowers efficiency.



The gas power burner installed into a modern designed oil system will first of all be using a fuel whose cost at the present times is at its lowest since 2002. It is also a fact that properly installed and set up a gas power burner will actually give a higher combustion efficiency than the same system with oil. I have installed over 3,500 conversion burners in my career. Since the Carlin G3B which I stated using back in the 80's I have never had a system I left under 82% combustion efficiency. The Midco E-20 of the 60's up through the 90's never below 75%. Even going back to the old inshot and upshot atmospheric burners anything less than 75% on a conversion from coal was not acceptable.



The other plus is the gas burns cleaner so you will not have the need for annual cleanings like you need with oil.You should however still have it looked at annually and retested for proper combustion.



It is also perhaps the case that some oil mixtures Bio fuels etc may operate at a lower BTU than typically we think of with #2 oil which is 138,000 BTU's per gallon. Estimates as low as 137,000 BTU's are the most accurate I believe. Some report as low as 118,000. The argument still goes on concerning that.



As for converting the Burnham Megasteam the only reason given for Burnham not approving has to do with their findings as to efficiency not being able to satisfy what they have set for a company standard. A company I work with has done three of them with Carlin EZ burners and they are firing at the following 81% on one 79.5% on another and 82.5%. So they are very comparable with what is able to be reached with other oil design equipment.



I have several conversions that I did back when I was doing this full time that tested out at 85% and 86% combustion efficiency. They are still operating in that range today.



I am thinking about doing some experimenting with using a two stage gas valve on residential gas conversion burner and using a vaporstat to control the low fire side. I just need a willing customer to let me do the experiment. I may also try it with a design gas boiler. It remains to be seen if it can be done.



The problem right now is high efficiency modulating/condensing warm air is taking about 80% of the market. Mod/Con FHW boilers about 11% and steam boilers below that. Demand will drive the manufacturers not what is best for the actual operation and future of steam systems. 

TomM

thanks

ur the man Rod!  I haven't been around in awhile because I installed superior venting, and a new vaporstat.  No heating problems last season.  We left the thermostat at 66 degrees (sounds low but its not) with a .5 degree swing and never touched it the whole season.



I spent almost $2000 in oil two years ago, and last year I spent about $700.  I know, it was way warmer last winter, but i don't calculate degree days like JPF321 does...anyway it sounds good to me. 



My boiler is from 1984, and works ok, but the piping is horrendous!  copper, 2" bushed down to 1 1/2", deadheading or whatever its called.  The refractory material is totally breaking up, and the flame is probably at the cast iron by  now.  I'm going to rip it out and probably put in a wet based boiler with power gas burner.  Oil is just too steep right now, and looks like PA will have lots of gas for years to come.  Maybe not good water, but plenty of gas. 



Do we have any hard data on the efficiency of an oil boiler with a power gas burner? 



It seems like the power gas people say a drop of 1%.

The oil people say no way, its more like 10%.

Steamhead likes 'em, so that's a good testament.



i've seen anectodal evidence, but no real hard data.  you can measure the efficiency via the flue, but what about the latent heat from the flame to the boiler?  Thermal efficiency i guess.  does a power gas burner mimic the flame of an oil burner? 

TomM

thanks again

Tim ur the man also!  I guess you were typing the answer while I was typing the question. 



looks like economics 101. 



I guess we are making exceptionally efficient and elaborate horse drawn carriages while Henry Ford is across the street pumping out black Model T's.



Tim, can you please explain your two stage gas valve setup?  unless its proprietary, then don't worry about it. 



in the mean time, i'll be studying up on power gas burners. 

Tim McElwain

Two stage gas valves

can be fired on low fire or high fire. This is for the sake of efficiency, Not having to fire the burner at full input on every call for heat but firing first on high fire then as the pressure builds and the vaporstat would typically shut the burner off as it reaches its pressure setting it instead would power the low fire stage of the valve and reduce the input but still keep the boiler firing as long as the operating control is calling. Years ago we had a conversion burner the Republic Gyroscopic that did something similar to this.

Rod

Thanks!

Hi Tim-

    Thanks very much for your input!  One of the great things about the Wall is that every time you come on you learn something!   On the Megasteam- I was surprised at the gas test results, any idea why it didn't do better?

- Rod

Tim McElwain

Those numbers are pretty much what Burnham

quoted me as to testing that had been done. The one I tested recently I found that when I tried to lower O2 below 4% my CO started to climb. My readings were 4% O2, 9.8% net stack 400°F, excess air 20% CO air free 75 PPM this gives about 81% combustion efficiency. The plus on this boiler I believe is the transfer of thermal energy for better thermal efficiency.



My actual measure as far as efficiency is to look at the overall cost of operation one year after conversion with an average winter load and see how much the customer saved based on oil gallonage in the past as compared to cubic feet of gas usage on a degree basis. Typically I find as a conservative number about a 10% to 20% savings. The problem with some of these units which are already in place is they are over-sized for the heat loss now on the house. They match up to the EDR but work has been done on the house so the actual heat loss has been drastically reduced. TRV's become a good solution to that problem and that adds another 10 to 12% in some cases. Why heat it when you are not using it. I like to use a higher Cv rating when doing the TRV's. 

Steamhead

When we were e-mailing Burnham about that

whoever responded said they hadn't done any testing yet. I think I still have that e-mail somewhere. I've gotten a few other excuses as well. I'm sure they could get a gas MegaSteam to run at 85% AFUE if they really wanted to.



I think it's a political problem- someone high up at Burnham just doesn't want to do a gas MegaSteam, and is in a position to block it.



Since at least 70% of boiler replacements are gas these days, not offering the truly superior MegaSteam in gas is at best a questionable business decision.

Enreynolds

what model?

So I am ready to put in a mega steam with a Carlin ez gas Burner. Trouble is I can not find which model to order. Does anyone know what burner would be correct?

Tim McElwain

MegaSteam comes in four sizes

MST 288   92,000 BTU's



MST 396    120,000 BTU's



MST 513    164,000 BTU's



MST 629    201,000 BTU's



The Carlin EZ GAS is rated from 50,000 to 275,000 so it waill cover all four Models of MegaSteam.

 Available with or without a burner cover. The EZ-Gas burner converts from propane to natural gas with just an orifice change - no conversion kit needed. Factory packed with combustion control and gas fuel train. Does not require a refractory liner - fires with or without a combustion chamber. Proven in extensive boiler and furnace testing, these burners will meet your needs for residential gas burning applications.   Input 50,000 to 275,000 BtuhFuels Natural Gas or Propane Gas

Maximum Supply Pressure: 14 inches w.c.

Minimum Supply Pressure: 5.0 inches w.c.

Manifold Pressure: 3.5 inches w.c. Control 

Carlin 60200FR Microprocessor Control

4 sec. Trial for Ignition (TFI)

1.3 Sec. FFRT

Pre-purge and post-purge

Serviceman Reset Protection

Latch-up after three consecutive lockouts

Interrupted Duty Ignition

Recyle on Flame FailureElectrical Power: 120 vac, 60Hz, 1-Phase

Current: Approximately 2.0 Amps

Limit Circuit Input: 120 vac, 60 Hz

Motor: 1/15 HP, 3450 RPM, 60 Hz

Motor Frame: 48 Frame, "M" Flange

Fuel Valve Power: 120 vac, 60 Hz Ignition 

Carlin Model 41800 Solid State Electronic Ignition

Ignition Voltage: 9,000 volts Orifice Selection Agencies UL Listed: US & Canada - US per ANSI Z21.17, Canada per CSA 2.7 

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Rod

MegaSteam?

Maybe I'm missing something here, but why are you considering a MegaSteam (with gas) if just a few posts above, Tim mentioned that the MegaSteam  WASN'T very efficient with gas?

- Rod

Enreynolds

My apologies

My question was rather poorly worded.  What I really meant to say was:

I am having some trouble finding the actual part number for the EZ-Gas burner that I need.

I have since had some help from Carlin on this.  This is what I have found out:

If you are going to use the burner cover, you should order an Air Tube 2" longer than you actually need.

The model number for the adustable flange models have an FR3 designation

So, for the MST288, I need a 9859212BFR3 burner.

I still have not figured out the cover model #, but is a work in progress

Enreynolds

Rod

The thermal efficiency of the three pass design is one factor.  Another is I am tired of replacing waterline-rotted boiler sections.  Finally, I need a pretty small boiler, and others in this size are all atmospheric, putting me at the ~%80 bracket anyway.  Steamhead feels that with some work, %85 is possible.  I am willing to experiment.

Rod

MegaSteam?

Good luck with your project. Please let us know how things turn out. Since Steamhead is involved, I would say you stand a reasonable chance of success as he is a steam expert who has a lot of experience with the MegaSteam.  I must say I was rather disappointed by the results Tim posted.  I have yet to figure out why there is such a great difference in MeagSteam's efficiency between oil and gas. The SlantFin and the Smith, with a gas power burner, supposedly matches/or exceeds the efficiency of oil so why not with the MegaSteam?

- Rod

Rod

Carlin Burner Cover

Hi- These are the notes from past posts that I saved on the Carlin burner cover.

Cover part numbers: CVRGKITS   (and /or)     50295K



You apparently need to replace the  "air tube also with one that has the cover mounting flange. The air tube will also be two inches longer, and so will the orifice nipple where the gas valve is mounted."

If I remember correctly these were from a post by Steamhead so you may want to ask him or check out his past Wall posts.

You might also want to check with Carlin as they should be able to give you the proper numbers for ordering. From what I can remember from other posts, if you purchase the cover separately (not ordered as part of the initial burner assembly), the cost is far more.

- Rod

  

Enreynolds

Sorry

I did not post my findings on the burner/cover:

From Carlin:

The original part# 9859210BFR1 - is EZGAS 10" Tube with B diffuser (B diffuser = BTU range which is 50,000 - 175,000)

With cover that part# turns in to a 9859212BFR3



Hope this helps someone else along the way

Eric

Enreynolds

Out with the old...

and in with the new.  I started this project near the end of summer, to give me plenty of time to get it done.  Nearing the end of the install so thought I would post some pictures and dialog.  We have a 1926 colonial in a suburb of Rochester NY.  As you can see from the pictures, it still had its original gravity hot air ("Octopus") furnace, probably originally coal fired, but converted to fuel oil somewhere along the line.  We have natural gas piped into the house, and fo was getting outrageous, so we decided to finally bite the bullet.  Ripped it all out.