To replace or not to replace

Bill Stocky

We have a 200 mBTU, welded steel, dry base, steam boiler
with an Economite gas conversion burner) that was old when
we moved in 32 years ago. See 4 attached pictures (it
says Standard Heater & Oil Equipment Co. on the heater
loop). It has worked fine all this time, but with gas
prices going up maybe it's time to update. I have
measured flue gas temp (570 degF) and oxygen (3.5%) so I
come up with about 76% combustion efficiency, which isn't
that far away from the conventional 82% that you get with
a new unit. I can add a flue damper and electronic
ignitor for better time-off efficiency. Should I stick
with this oldie but goodie or update to a new unit that
may not last as long as this one has?

Ken_8

Your numbers are suspect.

You are comparing the AFUE of a modern boiler with the "steady state" efficiency of your existing.

Apples to oranges.

Granted, you did think in the right direction of standby losses and a stack damper. But the standby radiation losses of THAT boiler would be huge compared to the stack loss you properly suggest can be upgraded.

A wild guess would place your current boiler at 60 percent - tops on an AFUE basis. I would suspect the actual to be closer to 50%.

With gas and oil prices going as wild as copper and steel, I'd replace the unit as soon as I could find a competent contractor.

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Ken_8

And remember...

Since it's steam, do NOT go by BTU's.

You must go by standing radiation, which is measured in square feet of EDR (equivelant direct radiation) - a number we derive through black magic and witchcraft.

Kidding.

We get EDR by determining three cahracteristics of each radiator, looking in a book, and adding all radiator outputs together - to match that number with the I=B=R rated output of the replacement boiler. All steam boiler makers provide the EDR rating (plus a small pick up factor) on their data sheets.

If you need more help, just ask.

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Weezbo

So shes got a new burner on er huh?

Somebody is probably just trying to get the thing away from you, cheap. I'd get a second opinon.

Bill Stocky

Yep, you're right

If the steady state is about 76% efficient, I can't do any better than that for AFUE - and I can only get up to that by installing a vent damper and electronic ignitor. The radiant coming off the boiler itself heats the basement nicely so I don't want to insulate it.

Bill Stocky

The burner is old also

but it has standing pilot, so I could upgrade the burner. A new version of the Economite with electronic ignition is available.

Weezbo

Bill....Intermittent VR-8304 kit?

honeywell. or something completely avant guard that starts off the glow from you warm face when you come down to visit your old friend:)

Christian Egli

Throw out the old?

Here is my take on your idea. If indeed what you want to do is save on heat bills, then invest first in better insulation for the house, after all there is nothing wrong with your current system.

The most immediate way to save on fuel is to simply crank down the thermostat, way down for instance when you are not home.

If you really want to get a new boiler, because boilers are cool, what I would do is install the new one in addition to the old one, keep both. Then, you could perform a realistic energy efficiency test on both. After that I would the best performer and keep the other one as a spare. I am not necessarily convinced that a new boiler would be truly more efficient other than on the label.

It is also an insurance in case the new system gives you all kinds of problems.

You seem attached to your faithful boiler, I would give it a good look over and a good clean-up and check for flue temperature efficiency again. Maybee a new paint job to make it look new. Painting it silver color will reduce heat loss to the basement.

Good luck, and if you do install a brand new boiler, I would be interested in knowing what numbers you get on your efficiency.

Mark Hunt

There is no way

that you wouldn't be doing yourself a favor by putting that boiler to rest.

The "combustion efficiency" number is not even close since that calculation is assuming a flame temp of 3600 degrees and 0% O2. It also assumes the caloric value of the gas you are burning.

I would take a close look at what your home actually needs in the way of heat. We would probably find that your radiators were oversized from the day they were installed, and so was the boiler.

Oversize is a huge energy hog.

You like that warm basement. Remember this, stack effect plays a HUGE roll in heat loss. It's also THE cause of dry home syndrome, NOT the heating system.

You are NOT getting "free" heat from that boiler for the basement, those BTU's were paid for by you, and the next time that boiler fires you have to pump all of the btus back into the mass of that beast before it will deliver btu 1 to the living area.

Now if you decide to "tighten up" the house, and upgrade the thermal boundry, you will then have a system that is even MORE oversized than it was originally. In fact, I have seen cases where people insulated and their heating bills went up.

Take a good look around your home sir. Do you have a cordless phone? You obviously have a computer. Do you have a DVD player? CD player? Microwave oven? Are you driving a 40 year old car?

Why not bring your home comfort system into the 21st century? It's the most important appliance you will ever purchase for the home.


Mark H

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Weezbo

Bill:)

i noticed a telephone in the boiler room....does it like direct access the Brain Box on the boiler? see lotsa new boilers got lash ups to telephones to the computer or service man. you been had one and these guys think its some New type thing. I bet they are secretly envious you already got the telephone lash up.I wish i had kept the old cranker up telephone we had:) i could lash it up to one of the more Vintage boilers and Blow some minds:)))

Bill Stocky

You make some good points

However, there is more to it.

We have insulated and have removed about 20% of the EDR from what was originally installed - so at least that part of it is going the right direction and probably comes pretty close to balancing out. The heat is reasonably well distributed. However, I do need to do a heat loss calc for the home and compare that to the installed radiation (am waiting for the CD to arrive).

Like you mentioned, the boiler is oversized but I was thinking of downsizing the burner spud when I decided what it should be. (The current firing rate is 200,000 Btu/hr and we have about 70,000 Btu/hr of installed radiation)

If I insulated the boiler to reduce the off time heat loss, I would then have to install some radiation in the basement to keep it warm - which would not be elegant with this being steam.

Anther consideration is that a new installation will run $4000 - $6000 and if it lasts about 15 years that's $300 - $400 per year on the investment. The current boiler has no investment expense (other than installing a flue damper and intermittent pilot).

The combustion efficiency was gotten from the attached charts, which I believe to be accurate because I measured flue tem and O2 and am using natural gas.

Thanks for your comments

Mark Hunt

Efficiency


At the bottom of the combustion efficiency chart is the tell all.

"Assumes complete combustion with no water vapor in the combustion air".

The other chart mentions "stoichoimetric combustion", that is perfect combustion with a flame temperature of 3600 degrees. Not possible on earth.

Our industry perpetuates these numbers so you have done nothing out of the norm.

When you downfire that monster, keep this in mind. The unit was designed around the 200k or greater input model. LOTS of surface are for LOTS of btu laden flue gas. So if you remove the 200k btu blow torch and replace it with a 100k bic lighter, what do you think will happen? Sort of like putting a 4 cylinder engine in a Mack truck.

I will tell you this much, according to those charts your "efficiency" will jump off the scales! The flue temp will plummet and you will have a 90+% efficient boiler. But those numbers are wrong.

Treating the boiler as though it is a radiator for the basement is up to you, but consider how much time you actually spend there.

I mentioned "stack effect" before, and I would imagine that you have a good amount of that going on. The higher the amount of air leaking from the house, the higher the infiltration. Cold air from outside enters near the bottom of the structure and begins it's journey back out. That air leaking from the house is carrying moisture AND LOTS of your money.

Increasing the thermal and pressure boundries in your home is a great investment, but we ned to keep in mind that those changes affect the entire building system.

The return on your investment for a new boiler coupled with the other improvements you made would probably fall in the 5 to 7 year period. It might be lower, but without doing a real inspection of the home complete with a blower door test, I can't say for sure.

It's your money sir, and you're the boss.

If it were me, that boiler would be gone.

Best wishes!



Mark H

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Weezbo

Bill did you catch the Octopus steam heat..?

somewhere on our site is some flah on some vintage heat:) I am a nostalgist when it comes to some stuff. look around for it almost makes ya wanna yank the one you got out and lash up onea them puppies:) I have a Montgomery ward in the back yard i am weather tempering so i can sand blast it and bake some enamel on it put gertBig Gauges and dials and a whistle so it looks really jamming burn it in in chrome and brass .lash some Wrisbo and rehau to it and put it in the living room and let it "Radiate"