pconn171 wrote:I am trying to undestand how the BTUs of a particular stove is rated. My thought is that I have a furnace rated at 170,000 BTUs (I assume per hour input). Does that mean that it will effectively burn 170,000 BTUs of coal in one hour or does that mean it has the ability to feed 170,000 BTUs of coal per hour (approximately 27.2 lbs)? I know that if I have my stoker set to full stroke, it will push a significant amount of still burning coal off of the grate. My manual states to keep approximately 1 inch of ash at full burn, so I'm assuming that the 170,000 BTU value is calculated based on the 1" of ash. Thoughts?
To the best of my knowledge, there is no "standard" for rating or testing of output solid fuel appliances. It is up to each manufacturer to rate their appliance. How they do that is sometimes more optimism that science. Good companies will not mislead you.
Ratings in Btu are usually per hour.
Most ratings for solid fuel devices are rated at output. Therefore a 170,000 btu device would consume more than 170,000 btu of coal depending on it's combustion efficiency.
Coal stokers are more steady output than hand fired devices. Hand fired devices are usually rated at peak burn and will produce less btuh at either end of the firing cycle.
The stoker must be adjusted to match the appliance output. If you are pushing unburned ash off the grate, then the feed rate is too high.
Stokers are often designed to be used in more than one rating of appliance. Stokers that I have researched are rated at maximum pounds per hour of coal and are usually capable of moving more coal than the appliance can efficiently burn, hence the need for adjustment.