Do boilers produce less heat output as they age?

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Old 02-19-16, 08:45 PM
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Do boilers produce less heat output as they age?

I have a 1987 Vaillant gas boiler (80,000 BTU input) with cast iron heat exchanger. Would this boiler have used less gas than now to produce the same amount of hot water or heat (just house heating)? Recently, I attended the local home improvement show. At a heating contractor's booth, I was told that gas boilers lose about 1% efficiency each year. Can this be true, or is it "liar, liar, pants on fire"? Thanks for any response.
 
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Old 02-19-16, 10:24 PM
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When it comes to boilers...... efficiency isn't everything. Design build/quality is more important.

I'm not real familiar with your almost thirty year old wall mounted gas boiler. It would be nice to know how much life it has left. It doesn't appear that parts are easy to get for them as the company has been sold out.

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Old 02-20-16, 05:51 PM
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You could do your own little investigation by checking your annual gas usage and dividing by the degree days for that year. If its increasing by about 1 % each year, the contractor is correct. Also remember his job is to sell you a new boiler. Will he guarantee the new boiler will not have the same degradation and put it in writing?
 
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Old 02-20-16, 08:04 PM
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The 1% per year is b... s... Find the specified stack temp for your unit, may be on the label. Then measure it. If it is much higher than spec then cleaning will lower it.

The basic degrading issue with boilers is dirty chamber walls. One problem with new ones is that they are harder to clean.
 
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Old 02-21-16, 03:15 AM
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I agree with doug. The factors that will cause the loss of efficiency are the cleanliness of the firesides and water sides. Keep it clean and it will NOT drop off in efficiency.

Now it IS possible the combustion efficiency will change due to changers in the fuel make-up consistency but this is out of the user's control.
 
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