Furnace BTU Calculator for WoodMaster

Furnace BTU Calculator for WoodMaster

The easiest and best way to establish your BTU requirements is to look at your current furnace.
There is normally a label on the furnace that tells you the BTU output.
If your furnace is 90% efficient, you may have to multiply that amount by 0.90.
If not, call the manufacturer or go to their website with your
model number and they will tell you the rating.

Any furnace rated at 105,000 BTU NET output or less,
can be generally be replaced with our WM-4400,
assuming that it heats your home well now.
Of course if a furnace is oversized (e.g 100,000) and can really
heat your home with 80,000 BTU, then that should be considered.
Use square footage estimates below.

The WM-4400 STORES 125,000 BTU/hr, ready for use, unlike others who give you
phony numbers of what a furnace can do at maximum output, which may be 20 minutes.
Also remember, that the home should be no bigger than 4,000 sq feet, (to use a 4400)
unless in a southern climate like AR or in NC. See listings HERE

But remember, it’s more critical to have a heat exchanger with the correct output.
If the heat exchanger is too small, you will never get enough heat,
no matter how big the furnace is!


Check out our furnace BTU calculator below:

Select Insulation Type
Climate/Region
Square footage to heat x
Ceiling height (feet)
===>   BTU     (Watts)

Which furnace do YOU need?

Our standard furnace, the WM-4400 is 125,000 REAL BTU/hr* – no funny math here!

A smaller one, the WM-3300 is 75,000 BTU/hr* for climates way South.

The WM-5500 is 360,000 BTU/hr*

The WM-6500 is 650,000 BTU/hr*

* = based on a 12 hour burn