Furnace size question

IGOTTAHEMI

My brother is planning an addition here in WI.
He would like to keep his existing furnace/AC.
His heat loss calcs are 59800 BTU
His existing furnace is 60000 BTU

Is this too close or is it OK since it is under the furnace rating (barely)?

Thanks

hvactech

That should be OK, just remember furnaces for some reason are rated by input not output for example a 80% efficient furnace, rated at 100K btus will only produce 80K btus of usable heat.

redline

Will the new addition have 2 x 4 or 2 x 6 walls?
Will he be using energy efficient windows?
How much insulation (R-value) will he be installing in the walls?
What R-value is he planning on using in the attic if the new addition?
Is the current space (walls and attic) properly insulated?

harleyrider

Wisconsin...........cold as he ..........your going to need supplimental heat for that room, how about a electric baseboard for that room. Its economical, runs off of its own t-stat and its quite, even heat.

IGOTTAHEMI

Redline,
2x6 walls
dbl pane windows
R19 in walls
R38 or more in ceiling
House is only 5 years old, so yes it's faily efficient
The new room will have an open concept, so plenty of air flow from existing house to new part. You won't be able to tell it's an addition, appearance wise.

Thanks for the thoughts

harleyrider

Wisconsin...........cold as he ..........your going to need supplimental heat for that room, how about a electric baseboard for that room. Its economical, runs off of its own t-stat and its quite, even heat.


Put it in.........if yopu need it its there...........if not then great but better to have it and not need it, then to need it and NOT have it.

pjpjpjpj

I agree with the above posts, you should be fine (especially in WI) for cooling needs, but definitely add supplemental heat in some form for those winters! Baseboard heat would be your best bet, and if you can't have them all around, definitely locate them below all windows.