350 EFM Coal Stoker Info

Teddy wrote:Thanks Don. By block off I simply meant to plug up some of the air holes so that it is incapable of burning above a certain lower burn rate because it can't get the air. So what would be the minimum fire rate for this pot? It's designed for 15#/hr. Would it still work well at lets say 6#/hr? Teddy

The air flow & coal feed rate are both adjustable. YOU CANNOT "BLOCK" PART OF THE STOKER TO MAKE IT DO WHAT YOU THINK YOU WANT. These stokers do not run constantly, even if set for a feed rate of 10#/hr doesn't mean that it will burn 10#/hr. Hourly usage will be determined by the heating load called for by the t-stat.

Mike, thanks for the info about the minimum fire rate of 4 teeth or 10 #/Hr. I know that it is designed for hard, small coal. I saw a U tube video about Mark's Supply burning soft coal in an EFM with some modifications. I am hoping to talk to him Monday. I am not very good at figuring out where to make these posts, but I did already respond to your concern about the heat rate that my house needs that you haven't seen yet I guess. Someone suggested that I shouldn't try to reinvent the wheel and find an old stoker to buy. Good advice but I really don't want an over sized burner that has to be shut down most of the time. That is why I am trying to understand the principles involved to build my own. Teddy

The youtube of the EFM from Mark's Supply is pretty old. I would like to know how that all worked out too. In the 3 videos it seemed to work very well.

Teddy I don't know why you are fixated on a 6 pound per hour stoker, especially burning bit coal. The EFM stoker in the video is an S-45 I think. The S-45 has a much higher firing rate than 6 pounds per hour.

-Don

Teddy,

Thanks for the further clarification.

I think you are overlooking the efficiency of a stoker that results from its small size relative to its output capability. It's sort of like having a turbocharger on a small displacement engine. When it idles it uses very little fuel, but when it runs it can produce multiples of the output of a hand-fired grate of comparable size. As a result output can be matched closely (and almost instantaneously) to variations in load without having a large coal volume lit at idle. Further efficiencies result from the ability of the stoker to provide tight control of the fuel-air mixture. Studies from back in the day estimated the overall efficiency of stoker operation relative to hand-firing at around 20 percent. Trying to make the stoker copy the performance of a hand-fired unit is selling short its advantages (sorry, hand-fired people, but this is a "stoker info" thread ).

I'll respond separately on heat rate issues when I find your other post.

Mike

Teddy,

Thanks for the further clarification.

I think you are overlooking the efficiency of a stoker that results from its small size relative to its output capability. It's sort of like having a turbocharger on a small displacement engine. When it idles it uses very little fuel, but when it runs it can produce multiples of the output of a hand-fired grate of comparable size. As a result output can be matched closely (and almost instantaneously) to variations in load without having a large coal volume lit at idle. Further efficiencies result from the ability of the stoker to provide tight control of the fuel-air mixture. Studies from back in the day estimated the overall efficiency of stoker operation relative to hand-firing at around 20 percent. Trying to make the stoker copy the performance of a hand-fired unit is selling short its advantages (sorry, hand-fired people, but this is a "stoker info" thread ).

I'll respond separately on heat rate issues when I find your other post.

Mike

StokerDon wrote:The youtube of the EFM from Mark's Supply is pretty old. I would like to know how that all worked out too. In the 3 videos it seemed to work very well.

Teddy I don't know why you are fixated on a 6 pound per hour stoker, especially burning bit coal. The EFM stoker in the video is an S-45 I think. The S-45 has a much higher firing rate than 6 pounds per hour.

-Don

Even if it is an S-30, the smallest of the EFM rotating pot stokers of that generation, its recommended firing rate would be 30 lb/hr. It would run at that rate as needed to carry the load(s), and idle the rest of the time.

Mike