NRC Boiler - was coal then diesel - can we convert to wood???

Tune Farm

Thank you, Steamhead!

Since you suggest leaving the bricks to "hold in the heat from the wood" and you are really familiar with this NRC-US boiler, it sounds as though you think it is possible to convert to wood - is that right?? Perry (in the thread above) suggested I would need to "get an appropriate set of grates and rebuild the ash pit and clean out". Is there anything else I need to know? Any advice is greatly appreciated!

Mauro

Tune Farm

NRC Boiler - was coal, then diesel - can we convert to wood???

We're in the process of trying to get our old single pipe steam heating system up and running. Is it possible to use wood, since it was originally fueled by coal? If possible, what are the pros and cons? Thank you! Mauro

Perry_5

It may be possible...

Do you know if it used chuck coal fed by shovels or did it use stoker coal that was fed through a burner pot.

Post pictures of the front of the boiler so we can see the door arrangement.

Also, any old pictures of how it was set up for coal.


If it was chuck coal - then you could probably convert to wood again: The key thing is that you would need to get an appropriate set of grates (which could be built) and rebuild the ash pit and cleanout.

Perry

Tune Farm

NRC Boiler photos (for coal to wood conversion)

Perry...thank you so much for your reply. I'm attaching photos of the front of the boiler as you requested. The original door to the ash pit was removed and replaced with the plate you see in the photo. Also, I'm wondering if the bricks are original or if they were added when it was converted to diesel? If I'm converting to solid fuel (wood, hopefully) do I leave or remove the bricks to increase the size of the firebox. Thank you, Perry!

Tune Farm

Hey Perry,
The answer to your question about whether it is chuck coal or stoker coal is I don't know. Are there clues I can look for? it was already retrofitted for diesel way before my time.
Mauro

Steamhead (in transit)

Those refractory fire bricks

were installed with the oil burner to form a firebox. That's probably a dry-base boiler, and the oil flame would have caused the base to buckle if it wasn't lined. It might not be a bad idea to leave them there to help hold in the heat from the wood.

Since that's a "NRC-US" boiler it was installed in the late 1950s to early 1960s. National Radiator Corp. and United States Radiator Corp. merged in the late 1950s, and in the early to mid 1960s were bought out by Crane. Crane later sold their boiler operation to Slant/Fin Corp. which is still making boilers today, though not coal-fired ones.

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ChrisK_2

Perry_5

I believe that was a Stoker Fired boiler

I believe that was a stoker fired boiler. It does not have the horizontal volume that I'd expect from a chunk coal/wood boiler.

The bottom access is not that large either (and I don't see the hinge pins & latch from an old ash door). Just so you know. It was always a plate. The original plate would have had a different sized access hole for the stoker feeder and air pipe.

As such, I do not see a practical way to convert this. Yes, there is a company that makes wood pellet burners - but they operate differently than the old stokers and burner pots that was in this boiler - and I doubt they would match the size required either.

I do note that unless you are in the middle of coal country I doubt you could get stoker coal anymore either (unless you are willing to buy it in about 100 ton lots). I do not know where you would get the parts for an old stoker system either (a couple years ago I went looking on the web for replacement firepots and did not find them).

As far as visual clues and differences of operation. I spent about 5 years as a teenage cleaning and repairing home/small business coal/wood fired furnaces and boilers with the local coal delivery guy. Louie passed away about 5 years ago and I do miss him (he was one of the adults who acted as a 2nd father for me).

All chunk coal units could also burn wood - and had large upper doors to allow you to add wood or shovel in chunk coal (typically 4" to 6" chunks) and wide lower doors for ash removal. You often had to add either wood or coal every 4 - 6 hours.

Stokers were a great improvement, in that you only needed to fill a stoker hopper typically once a day, and its fuel feeding rate could be adjusted for the weather: it feed some fuel at least every x minutes to keep a good live coal bed - but did it feed 1 minute or 3 minutes of coal, and in cold weather a house thermostat would reduce the interval between fuel feed - at least on the more modern systems.

Almost all coal boilers / furnaces built after WW II were stoker fired (and a lot after the late 30's). You could also build a smaller boiler or furnace as well.

Those sections that you can access by the top doors would often fill 1/2 up with ash and have to be cleaned out every summer. The duct pipe to the chimmney would also need cleaning every summer as well (and often had to be replaced every few years).

If you were going to retrofit back to coal or wood you would likely need to have your chimney redone as well - and not with a small modern flue or liner either. Wood needs a much larger flue than oil or gas.

Anyway, glad to offer what I know. I'm actually not a heating professional - just an advanced homeowner who hangs on this site. I am probably one of the few who used to clean and repair this kind of furnace or boiler 30+ years ago when it operated on coal.

Perry

Steamhead (in transit)

With wood

even with that fairly large firebox, you might have to feed it more often than you'd like. Wood is not as concentrated a fuel as coal. You'd be a slave to the flame. Too much smoke might be an issue with the neighbors and the AHJ.

How were you planning to control the pressure?

The low water cut off won't shut off the flame anymore. I'd make sure the fusable plugs were intact and the Hartford loop was spot-on as well as making sure the return lines were up to snuff.

There is a reason why automatic flame is more common in smaller systems.

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Unknown

Perry - advanced?

Perry - advanced homeower? More like Advanced PhD in every thread that he's been in. Glad to have him back!

Tune Farm

regarding NRC boiler wood conversion


well, thanks all of you guys anyway.
But, I'll give it a try since on the front of the boiler says "37 series ALL FUELS" and I know for sure that this was not originally oil fired. The bottom plate was added on later, I can see the marks where the original hinge pins and latch were, they are exactly the same as the doors above. Also, the add-on plate is steal rather cast iron like the other three doors.
Underneath the cathedral I have, considering not removing the bricks, 24" x 24" x 24" of firebox. My guess is that it is enough to produce 1 1/2 psi of steam pressure to heat this 1919 farm house.
I'll build a grate and a new door for the ash pit.

I'll keep you all posted guys.

thanks a lot

Mauro

scrook_2

All Fuels...

"37 series ALL FUELS" = anthracite (hard) AND bituminous (soft) coal maybe?? Coal AND heating oil (w/ an appropriate burner)??

Be nice to find a copy of a sales flyer for it.

Perry_5

All Fuels = Coal, Oil, Gas

Steamhead dated this boiler to the late 50's early 60's based on who made it.

I interpret that to mean Stoker Coal (either anthracite or bituminous), oil, or gas.

All three of those are controllable based on steam pressure.

Gas was available in a number of large cities (even if it was only coal gas).

Perry

Perry_5

Something to think about

I admit I might be wrong. Afterall I havn't worked on coal & wood fired furnaces and boilers since 1975 when I went into the Navy.

Given the date that Steamhead dated the company I'd guess that "all fuel" is Stoker Coal, oil, or gas (see my other post on that).

However, before converting to wood please consider how are you going to control the steam pressure. That is not a minor item.

This is not about being able to build a head of steam. It is about having controllable steam pressure.

A stoker would have been tied to a pressure control unit. Oil and Gas the same way.

If you over-pressurize your boiler from over-firing it; you chance having things go bad - and it could be ugly.

Yes, there is supposed to be a relief valve. Will it work? I suggest a new relief valve if you do your conversion.

Are you planning to have someone spend a lot of time feeding and controlling the fire based on weather? Conventional chunk wood is not really that controllable. There is a lot more flexibility with a furnace than with a boiler on this issue.

Anyway, do have a great day.

Perry.

Tune Farm

NRC wood conversion


I just found covered in black dust the label of this beauty.

It says: STEAM 1100 sq ft oil fired or stoker fired
1100 sq ft hand fired (i guess it means shovel-in, does it not?

WATER 289,000 btu/hr oil fired or stoker fired
265,000 btu/hr hand fired

Max steam pressure: 15 psi
Max water pressure: 30 psi

Then it gives you the feeding rates:

oil fired : 3,.75 gal per hr
stoker fired: 42 lbs per hr

Also on the label says the boiler # 6-37

This is a farm house of my in-laws which I visit a couple of times a year. When we went to the basement I saw it and I totally fell in love with it. I said to my sister in-law it would be nice to put it back to work. She gave a book about boilers which I immediately went through to the last page. It turned out to be Dan's book that's how I got a bit familiar with the heating terminology

As for the boiler, it has the pressuretrol and burner cut-off wiring in place. It has two dry returns without a Hartford loop or drip/equalizer either. it seems that it was never a problem although I think it is a safety back-up device. The burner is gone cause it exploded 20 years ago when they run it on diesel. That was the very last time it was in service. Makes me sad. Now they use propane heaters all over the house while this piece of history is rusting down in the basement.

I do not know about you guys but I love the old fashion way of doing things even though I am only 30 years old. That's why I am pushing that way instead of trying to have everything on the boiler automatically controlled. I just want make it smile again while I visit my family, that's all.

I'll watch the pressure all the time the same way you watch the fire in a fireplace. When you feel cold, you add another log in. That is, when pressures goes down I'll add another log in. Should it go up, I'll remove fire.

The safety valve which goes off at 15 psi can be changed for another one rated at 5 or 10 psi. I'll install another relief valve or some made-up device to release pressure when it goes above 2 or 2 1/2 psi. On top of that I'll be around the house all the time so I can keep an eye everything.

When I leave, "she" goes back to sleep until my next visit when she will be smiling again...


Thank you gentlemen for your kindness

Mauro

PS: sorry for any typo you might find.

Steamhead (in transit)

Some Things To Consider

What is the connected load to your boiler in EDR?

Your boiler is rated at 3.75gal/hr oil and 40 something lbs of coal per hour. That works out to over 500,000 BTU/hr. if we assume oil is 140,000 BTU/gal and anthracite is 13,000 BTU/lb. Wood is all over the place as to its heat value per lb., but let's say if wood is 5000 BTU/lb., you may need 100 lbs of wood per hour.

Of course, if your connected load is less, you'll need less wood. But that's still a lot of wood! There's a reason why they joke that wood is the fuel that heats you thrice.

Your low water cut off will not work with solid fuel. Your electric pressure control will most likely need extensive modifications, i.e. hook-up to a damper motor (such as a Honeywell M847) with a chain-link to dampers on your boiler.

I am sorry to say, but I would consider the use of relief valves to limit the pressure as unwise.

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scrook_2

So...

"ALL FUELS" meant: Coal (either stoker fed or hand fed) or Oil. Must have come w/ differant parts/accessories depending which fuel was to be used. 15psi steam / 30 psi water is pretty typical max rating.

Output: 1100 Sq Ft = 264,000 BTU/hr (240 BTU/hr per Sq.ft)

Input: 3.75 GPH or 42 lb/hr = 525,000 BTU/hr (140,000 BTU/gal or 12,500 BTU/lb)

Efficiency ~55% (assuming stoked or oil fired) ~50% hand fired.

Tune Farm

more details about NRC wood conversion


The house has 14 rooms all originally served by radiators. Total connected load, assuming we heat all the house, is 532 sq ft. Piping is not insulated, let's assume 700 sq ft, that is equal to 168,000 Btu/hr. Assuming 5000 Btu/lb for wood heat value. I'd need to stick in around 34 Lbs/hr of wood. Assuming 50% efficiency I'd need 68 lbs/hr instead. Am I right?

Now, there are 6 rooms that are not in use. We can gladly shut their supplies valves off. That would cut my heat need in about 236 sq ft. Therefore,I need to feed the boiler at a rate of 30 Lbs/hr of wood.

If all my measurements and math are correct I'd need to add 6-10 logs of wood per hour!!! How bad is that? That for sure is the worst it could get cause I bumped all the math up.

As for the pressure controlling issue, I meant I'd use a pressure relief valve meanwhile I figure how to hook up something to operate draft doors and dampers. I could use the same pressuretrol mercury switch to activate a damper motor or just buy a new whole kit of damper motor.

Ok guys any advice or comments on my plans will be highly appreciated.

Thank a lot
Mauro

Tune Farm

NRC wood conversion


All the radiators have hoffman 70A air vents. This kind of vents has a drop-away pressure of 6 psi. That means the max pressure against which they can still open. In order for them to shut, do they need also 6 psi of pressure in the radiator?

If I consider to keep the pressure somewhere between 1 1/2 and 2 psi. Would it be more convenient to use 1A vents instead?

Can anyone explain to me how to select a good air vent for the pressure above?

Thanks a lot

Perry_5

Hmmm...

I'm not sure the firebox is big enough to add 6 logs an hour and burn them, unless you add a forced draft system.

Even if it was - you'd likely need to be adding 1 log every 10 minutes. I don't know about you - but I can see better uses of my time.

The way coal works and the way wood works are very different.

Perry

Ashanti

How do I Convert my oil boiler back to coal

I have an old boiler it runs on oil,I wanted to know what would i need to convert it to coal. An how much coal would i need to run my house,right now 275 gals. of oil for 14 day. The house is 3,000square feet with an hot water system.

doctash

coal grate and parts for national heat exchanger model 100

I am wondering what parts I woudl need to convert back to "dual fuel" and cso add coal to this boiler.

Steamhead

You'd need

grates, shake-down mechanism, damper controls, a hold-fire control and much of this stuff isn't being made anymore. Plus maybe some other items. It's been a LONG time since I've seen a boiler in coal-fired trim......