Steel Boiler

Joe Brix

Stay away from the tankless coil. Have a look at the Burnham LE. Small, steel, and no tankless gasket to leak. Swing door for easy cleaning. Match it up with an indirect and outdoor reset , you can't go wrong. Just pipe it to spec.

Mike S_2

National Steel Boiler - two issues

Hi all,

I am running a National Steel Boiler for base board hot water 15 psi and domestic hot water. Model RO/V-2325 circa 1951 +/- 132,000 btu in a 1,700 sq foot two story cape design in Manchester NH. The boiler design has turbulator tubes and is pretty efficent. The setup is three zone with one circulator one thermostat, zone balacing was done via Base Board tuning (some double registers in areas)Domestic hot water is also genrateed bty this unit, and is pretty unlimited, the unit runs year round. The Beckeet burner runs at 1.2 gal/hour. Teh stack is 9 inch OD with a chimmny.

I have two issues.

A few years ago I had a leak in a capped fitting near the base, a commercial welding outfit cut out the fitting and welded in a window as filler. This has worked fine, and allowed me to determine the unit is made form 1/4" plate.

Issue 1: The domestic hot water is a bolt in unit to the case from the rear with studs, it is apparently leaking internally, as water pressure slowly builds (refill feed closed so this must be the source). Are these kinds of units servicable and by who? Do I need a plumber or welder or burn tech? I assume the burned will need to be drined the unit disconnected fromt he house pluming and removed for the bioler for rework. Since the domestic water pressure is 45 psi, and the boiler runs 15 psi, I am able to control this issue by drining cess water via the head tank. So is it worth servicing or replacing? The unit has been very low maintenance until now.

Issue 2: Recently along with Issue 1, durignt he heating cycle I have had the water pressure swing from 10 psi where the refill kicks in to to 32 psi where the saftey pops. The header tank has been draied and free flows. So I do not think the system is water bound. I have had no experience with swings of this type, any ideas what could be causing this? Also of note when this started we could hear water movment sounds in the second baseboards, which I assume means air in the system, none fo the nase boards are leaking.

Lastly, while this is a very good boiler, if I replace the unit I would favor another steel boiler, the local high end contactor recommended a iron boiler from Burnham PV-84WT-TBWF, 120,000 BTU with a tanless coil, while Burhams seals are published to be better, I am still wondering if a steel boiler is a better way to go. If so what would be the best steel unit in the 120,000+ BTU range for fuel econmy, and low maintenace. Inital cost of unit is not a big concern, I would rather have quality over inital cost saves, the problem is today quality seems to be less of a priorty with the industry.

Any comments including "whoa dude get a life" are appreciated.

Mike S

Steamhead (in transit)

Tankless coils

are inherently inefficient, since the boiler must be kept at full temperature for the coils to work. This results in a lot of standby loss. I'd forget the coil and use an indirect tank- this ties into your system much the same as a baseboard zone, and the boiler would not fire unless the tank called for heat. Most indirects are so well insulated that if there is no draw of hot water, they might only call for heat from the boiler once a day or less.

The "head tank" you refer to is actually an expansion tank. It is supposed to be partly filled with air so the water will have a place to expand into as it is heated. The air cushion in your tank is gone, that's why the pressure swings like it does. A modern boiler installation using this type of tank will have an air separator in the pipe leaving the boiler, which will route system air into the tank. Or, a different type of tank would be used, with a diaphragm to separate the water and air, and a float-type vent would be placed on the air separator. The circulator would be mounted after the air separator, pumping out toward the system, flushing the air back to the separator for removal. Ask me how I know this works so well!

Since your boiler has lasted so long, it really doesn't owe you anything. I think it's time for a new one, which will be more efficient than your National. The Burnham V-84 series you mention is a decent unit- assuming it was selected by doing a full heat-loss calculation on the house (NOT by just measuring the baseboard or matching the old boiler's rating!). There's really no excuse for not doing the heat-loss calculation, since all you need is a laptop computer and the right program.

Burnham also makes the MPO boiler which is noticeably more efficient than the V-8 series due to its 3-pass design. If I was going to put another Burnham in my house, that's what I would use. And Burnham still makes a steel boiler, the RS series. There's nothing really wrong with steel boilers, I see older ones all the time! You can use any of these boilers with an indirect- just have your contractor order it without the coil.

There are also some newer designs coming out, made possible in part by the move to low-sulfur fuel oil which is happening as we speak. Because some of these don't have a track record yet, it might be worth it to fix your system issues and install the indirect now, then install a really high-efficiency boiler later when the dust has settled. If the burner on the National has been upgraded to a "flame-retention" model such as a Beckett AF or AFG, Carlin CRD, EZ or FRD series, Wayne BA or MSR, or any Riello, it's probably running with reasonable efficiency so you could afford to wait.

I realize this is a lot to consider, but your inquiry comes at a time when we're seeing some exciting advances in oil-heating equipment. The most important thing to consider is the contractor who will install and service your equipment. Look at the Find a Professional page of this site to locate someone near you.

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Al Letellier_9

steel boiler

Mike, the very fact that your boiler is over fifty years old makes this a no-brainer......add in the fact that it has been patched (hopefully by an ASME qualified welder) makes your decision an easy one...replace it now.
When you say very efficient, it may seem that way by the combustion test and quantity of fuel burned, but by today's standards, it's most likey a dinosaur and should be replaced.
As to steel vs cast iron, I alway prefer cast for longevity and heat retention. In my opinion, the Burnham is no better or worse than a lot of boilers out there. Consider a quality cast boiler with an indirect water heater for max efficiency and loads of hot water. Buderus makes excellent equipment and the No. American distribution center is at the airport in your town....talk to a heating pro about it.

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Weezbo

many things to consider.

one is the cause of the over pressure. could be the coil. could also be a pressure regulating valve has accumulated various forms of debris that has it stuck open from time to time. i would valve off the coil. purge all the air from the system. check the pressure. open the fast fill feature make certain it increases to a couple pounds greater pressure and stops there when released. if so. it was either the air or the coil. now , when you open the valved off coil,if the pressure increases,then it is indeed the coil.

should it be the coil, may want to consider an indirect. pipe it in off a zone of its own ,with an eye to taking the existing boiler out in the future,at that time you would have more possibilities for some very modern equipment...and retain the indirect for DHW. I hope things work out for you.

Mike S_2

I agree the overpressure is probably from the leaking coil, however i only get the pressure spikes during active heating, kind of odd.

The underpressures are what are bugging me, the pressure swings occur in just a few minutes of firing.

I have manually drained the header (expansion) tank myself, I am sure it is not water logged.

I faver steel for reliability and repairability. Perhaps Cast Iron has the same attributes, but from reading it sounds like not.

If advancements are moving into oil units, I would hope to wait for and see some performance and maintance experience results for the new designs.

I will look into indirect tanks and adding a zone. Reguardless of boiler, the indirect tank should solve some problems.

Mike S

Steamhead (in transit)

Uhhhh, Mike

when you say "I have manually drained the header (expansion) tank myself, I am sure it is not water logged".... did you have a way of letting air back into the tank as the water drained out?

And if there is a valve between the system and the tank, is it open?

The pressure swings are a classic sign of a waterlogged tank or other cause of lack of room for expansion.

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Mike S_2

Steamhead,

Hmmm yes. I see. I failed to close the valve to the boiler when attempting to drain the expansion tank and watched the pressure drop on the boiler thinking the tank was taking air. My bad.

I closed the valve and drained the tank ...glorp glorp glorp, time passes so slowly... there is no air bleed to speed it along.

I re-fired the boiler and the pessure is solid at 15 psi. So the short term problem solved. Thanks for pointing this out, it had been so long since I drained that tank I had forgotten. Sigh.

About my comment on the unit being (to me) very good. CO2 runs 6.5 stack temp runs 200 and the effecency test gives back 85-87%. I know this is misleading as the stack is large, but still, I can't think this is a poor unit by any measure. It is two pass, and there are spiral fins down each tube to slow and turn the gases, the current designs look very much like this one in many ways. And steel is repairable, iron isn't. Anyway my 2 cents.

Steamhead (in transit)

Those numbers

aren't good. To me they show a lot of excess air coming into the firebox or flueways somewhere. The stack temp is too low as a result, and you could be getting condensation in your chimney which would make it deteriorate.

What type of burner is on that old beauty?

"Steamhead"

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Mike S_2

Beckett AF

Steamhead (in transit)

That should work efficiently

and without one bit of soot. If not there's something wrong. But you need to do something about all that excess air. It will take a real good oil tech to solve this but will be worth it, if you decide to wait for the next generation of equipment.

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