Is heating with wood really that economical? Here are the - TopicsExpress

Is heating with wood really that economical? Here are the figures.... Wood heaters, even the best of them are less than 50 percent efficient at the best of times, usually more like 30 to 40%. That means if you spend $700.00 on wood, you are most likely throwing $400.00 or more up the chimney with no value to heating the home. How can this be? Wood heaters, the best airtights are rated 75 % efficient are they not? Yes they are, but what does that actually mean? This rating is done in a lab. The lab test models estimate 15% minimum as heat up the stack. So now you are down to 60%. The wood used is bone dry, eastern hardwood, usually elm or maple, stacked in a very particular way, small pieces, in layers, burned under ideal draft and chimney conditions. If you do not use hardwood, if the wood is not bone dry, or you do not use the configuration for piling wood in the fire box duplicating the test conditions, then you lose more. Wood at 20% moisture content is 15% less effecient than bone dry. Add these things together and you are in the 40% range. The test calculations do not take into account start up emissions or heat loss, the rating is for a specific time in mid burn, therefore skewing the rating even further, especially for particulate emission ratings. And all of this is for a new CSA approved airtight. If you achieve 35 to 45 % you are doing very well and a lot better than most. Of course older heaters and fireplaces are much, much worse. Open Fireplaces are in the 10 % category. So, you are in effect burning a stack of 20 $20.00 bills in the fire box. By contrast a heat pump is 400% efficient, that is 10 times better than the best wood heaters, I kW in , 4 kW out, and virtually pollution free..