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 Hyprotherm FLRH-100, 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 FLRH-100 STORES 112,050 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 2,800 sq feet, (to use a FLRH-100) 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!

Which furnace do YOU need?

Our standard furnace, the FLRH-100 is 112,050 REAL BTU/hr* – no funny math here!

A smaller one, the FLRH-85 is 95,243 BTU/hr* for climates way South.

The FLRH-185 is 207,293 BTU/hr*

The FLRH-265 is 296,933 BTU/hr*

The FLRH-300 is 336,150 BTU/hr*

The FLRH-350 is 392,175 BTU/hr*

The FLRH-400 is 451,562 BTU/hr*

* = based on a 12 hour burn

hyprotherm hydronic furnace

Check out our furnace BTU calculator below: