Replies

1. 
   walta100 | Feb 19, 2018 12:23am | #1

   Find a good local installer and follow his advice. In most cases a 92% + furnace makes sense.

   Walta

2. GBA Editor
   Martin Holladay | Feb 19, 2018 06:58am | #2

   Vissu,
   Step one to designing a heating system -- or specifying a furnace -- is to perform a heating load calculation. Here are links to articles you should read:

   Who Can Perform My Load Calculations?

   Saving Energy With Manual J and Manual D

   How to Perform a Heat-Loss Calculation — Part 1

   How to Perform a Heat-Loss Calculation — Part 2

3. 
   Reid Baldwin | Feb 19, 2018 08:21am | #3

   There are at least three aspects of selecting a furnace: brand, features, and size.

   Regarding features, my prioritized list would be condensing (first digit of efficiency is 9), ECM-type blower motor, and two stages.

   Regarding brand, my advise would be to select a contractor you trust and use whatever that contractor prefers. The hard part is finding a contractor you trust. After you read the articles Martin mentioned, you will know what question a good contractor should be asking you. If you call a contractor, and the only question they ask is square footage, or the label on the existing furnace, keep calling others. If this is a replacement and they ask about recent natural gas bills, that would be a good sign.

   Regarding size, even if the contractor asks the right questions to calculate it properly, you cannot necessarily trust the recommendation. Contractors typically have a "make sure you don't undersize" mindset rather than a "size it right" mindset. If this is a replacement, use the method described by Dana Dorsett at https://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/out-old-new to cross check the recommendation.