Help - Is it time to replace my steam boiler

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Old 01-29-08, 10:16 AM
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Help - Is it time to replace my steam boiler

I need help, bad.

I have an older (not sure how old) American Standard A3 steam boiler with a newer (?) Beckett Burner in my home. I burn approx. 1400 gals. of oil annually and am looking at options to reduce that amount. At $2.70/gal its killing me.

My oil service company says that I'm getting approx. 80% efficiency from the existing boiler but this seems high to me. Is it possible??? I've done some research and everything points to a 40 year old boiler being about 60% efficient. Although I'm stuck with them for the rest of the season, I'm certainly not impressed - they can't even seem to keep my tank supplied - so I tend to doubt their competence.

What are the calculations for computing efficiency/AFUE so I can compare apples to apples?

Will upgrading to one of the energystar compliant steam boilers really reduce my fuel consumption or will I be chasing my tail? What other options are there?

Thanks.

Jeff
 

Last edited by Jeff9703; 01-29-08 at 10:48 AM.
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Old 01-29-08, 10:49 AM
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Well it may just be 80% efficient once all warmed up and firing. Now if a call for heat from the t-stat only lasts 6 minutes and it only reaches its maximum of 80% efficiency during the last minute or so and also if you factor in flue losses when it isn't even firing you can see how you may only be at 60% or even perhaps less for overall system efficiency.

The heating system's job is just to replace the heat that leaks out of your home. The best bet is always to reduce heat losses. You can do this by lowering the t-stat and or tightening up the structure so that it holds the heat better. You want to try and maximize insulation and minimize infiltration. Is there a energy audit outfit or utility in the area that does blower door testing and recommendations?

I think you'd get a far better bang from your buck tightening the house up before swapping in a newer boiler.
 
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Old 01-29-08, 12:03 PM
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Who:

Bare with me - I'm easily confused...

Thanks for that advice. I've got a company coming in on Friday for an energy audit with an insulation guy to follow as soon as I can get the time off from work.

I still can't get my mind around the efficiency thing... a local oil company rep told me that the upgraded burner could increase it to 80% or so and to hold off as well.

If I understand your post correctly that 80% may just be a snapshot in time and not an accurate depiction of overall efficiency.
My boiler service tech says its +/-80% efficient based on the tests they do when cleaning it.

How can I determine the overall efficiency so I can accurately compare it to a modern energystar compliant 84-86% efficient unit. I'm not confident in the existing unit estimates...

I've got a programable t'stat so in the am when I wake up the boiler fires for 30+ mins. By the time I walk downstairs to let the dog out the first or second radiator columns are just getting hot.

How long should it take to boil the water? Is 1/2 hour reasonable?

Oh, yeah I think I forgot to mention it is a 1 pipe steam system

Thanks.

Jeff
 
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Old 01-29-08, 12:57 PM
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The ONLY "efficiency" test that can be done in the field is a combustion test and it is indeed a snapshot in time rather than overall efficiency.

A 100% efficient system would be one where ALL of the heat released from the fuel combustion was utilized in keeping the structure warm. The only system that comes close is one that uses electricity as its "fuel" and that would be ignoring the losses between the fuel source at the power plant and your home.

Since a steam heating system must operate at a temperature in excess of 212 degrees Fahrenheit and the exhaust from a fuel-burning boiler must be higher than this temperature (to effect a heat transfer from the combustion gases to the water) there will always be some loss.

What you want is maximum efficiency of your environmental package. That includes the boiler AND the home. Increasing the insulation and decreasing the air infiltration (drafts) in the home will be a much better return for dollars spent than will a new boiler (or burner) without the improvements to the building envelope.

Ideally you want the least amount of "added" heat (from the boiler/heating system) as possible but at the same time you want that heating system to operate continuously for maximum efficiency. This is utterly impossible with a steam system and difficult with anything other than a modulating system.

You REALLY need to make the improvements to the building envelope FIRST and then re-evaluate the boiler/heating system. After the improvements to the envelope you will find that the additional heat needed for comfort will be less than it was before the improvements and the current boiler/heating system is oversized to the requirements. Oversized equipment is always less efficient.
 
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Old 01-29-08, 01:08 PM
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Insulate and air-seal until you can do no more. Then think about a new boiler.

From what I've heard, for oil-fired steam the new gold standard in design and efficiency is the Burnham Megasteam.

$2.70? Wow. Around here its 3.20+.
 
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Old 01-29-08, 01:52 PM
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How can I determine the overall efficiency so I can accurately compare it to a modern energystar compliant 84-86% efficient unit. I'm not confident in the existing unit estimates...
You can't - at least no easily. Every house is a unique system. You could measure oil burned against the number of heating degree days (65 - daily average temp), but that number wouldn't be useful until you installed another boiler to compare it with. You can do a heatloss calculation - slantfin web site has a good free package. Take maybe 70% of that number and compare it to what you're burning. That would give you a ball park overall efficiency. Who's to say what a new steam boiler would give you.


I've got a programable t'stat so in the am when I wake up the boiler fires for 30+ mins. By the time I walk downstairs to let the dog out the first or second radiator columns are just getting hot. How long should it take to boil the water? Is 1/2 hour reasonable?
Too many factors here to comment accurately but I can say this. If it recovers too fast then you system is way too big but steam boiler's are sized to the overall size of the radiators all combined...

***** ***** ***** ***** *****

The Megasteam does indeed sound like the ideal oil fired steam boiler. But insulate first... then do a heatloss calculation and better size your rads to the heatloss, then get the rightsized boiler for the reduces radiation capacity.
 
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Old 01-29-08, 06:38 PM
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All:

Thanks for all the great advice.

I will work on insulating the house to minimize heat loss but before I am able to move on would someone take a look at the energy savings calculator for boilers @ Energystar.gov and give me an honest opinion... link attached, the calculator is on the right hand side of the page. http://www.energystar.gov/index.cfm?...ers.pr_boilers

This is what got me thinking about boiler replacement in the firest place. With my numbers...

oil @ $2.70/Bridgeport, CT/2500sf/Pre 1940s House/<1960 Boiler/1400 gals. vs. energystar boiler was almost $2k/yr savings. Is this even remotely realistic or totally insane?

Thanks.

Jeff
 
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Old 01-29-08, 06:51 PM
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American Standard A3

That boiler is at least 40 & maybe 50 years old. In their day they were some of the best made. As Who said, your true AFUE would likely be somewhere in the 60-70% range. He and others have given you some excellent advice on tightening up the house to keep the heat in & cold out.
I doubt you can cut your heating bill in half but I don't think reducing it by 1/4 or 1/3 is unrealistic. Where else can you get that kind of return on investment?
 
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