Boiler size..WOW!!! - Anyone looking to replace their boiler read this.


Old 11-19-08, 07:01 AM
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Boiler size..WOW!!! - Anyone looking to replace their boiler read this.

This is my experience with boiler sizing.

I bought a 6,000 sf house several years ago and last year I decided to add a 1,200 sf bedroom and 1000 sf kitchen.

The existing home before the additions was heated with 2 boilers. one 300,00 btu and another at 150,000 btu for a total of 450,000 in boilers.

After adding an additional almost 2,000 square feet to the home and needing to heat those areas, I decided to invest less than $100 in a heat loss program that I found online.

I was shocked at the difference in boiler sizing after doing the heat loss calculation. Even with the outside design temperature set lower than average and the inside design temperature higher than normal I calculated 250,000 btus. That is almost half of what I had without the additions.

I know its posted at the top of this board about boiler sizing but felt I needed to share my experience.
Anyone looking to replace boilers should spend a few dollars on a heat loss calculation.
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Old 11-19-08, 07:10 AM
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As you discovered a heat loss calculation is critical to sizing the boiler to the load. And BTW, you can get free heat loss software from
Old 11-19-08, 06:20 PM
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Thank you for giving us your unbiased & first hand experience. What you learned is what we've been preaching for I know not how long.

I would be very interested to see how the free Slant Fin program's figures compare to the program you had to pay for.
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