do add on wood furnaces use gobs of wood?

huntingbuck101 said:

I have been looking at some post on the search forums and came across a few people saying add ons use tons of wood.
is this true? and if so compared to what? would it still be better then a OWB?

Click to expand...

Try reading this thread...
https://www.hearth.com/econtent/index.php/forums/viewthread/16653/

If you determine the heat load, and the manufacturers rated eff. of their unit , then dicount that number by 20-50% you will have a start.
I had a cast iron Sime ( wood - coal ) add on & it ate wood like crazy.

The equivalent of 1200 gallons of oil was 8-10 cords of wood, and 2000# of coal. When I bought it, I was anxious to burn wood free heat etc. that novelty wore off, I sold it after 6 years. Later sold that house, starting new I'm going for the most eff. equipment I can find. Stay tuned.

I have a woodchuck add on furnace rated for 1600 sq ft. Heating 1450 sq ft of newer construction. This last heating season used just under 5 cords(and 75 gals of propane for cooking and the furnace running for 10 days while on vacation in Dec.) from last week of Oct - 1st week of Apr. burning 24/7 . I think that is an average amount of wood for a heating season.

An add-on inside wood furnace is likely to be much more efficient than an OWB, mostly due to proper firebox sizing.

Here is an EPA rated furnace that is even better than that
http://www.woodstoves.net/psg/caddy.htm

Any indoor installation should use less wood than any comparably-sized (usable BTU) outdoor unit using comparable technology. Remember that an indoor boiler or furnace "loses" radiant from the unit and the chimney into living space, while anything outdoors essentially wastes any heat that escapes the insulation.

If by "furnace" you mean a hot-air blower, then it's really not comparable to an OWB (which produces hot water) in any event, but the same standby heat loss logic applies.