royall indoor boiler

jimmywoody said:

I have a royall indoor wood boiler and with the wright situation it back fires enough to blow my clean out door open anyone ever experience this

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I had the forerunner to the Royall, the Energy Mate. Mine would backfire too at times. Make sure you have dry wood & good draft. Try to keep the grate from plugging. Thats about all I can suggest, Randy

I have an energy mate and do experience the big POOF at times. I let the wood all catch and get going good before closing it up. If you can load when the fan wants to run that helps after closing it up to prevent the POOF. Mine is a draft issue because it's in the cellar with an outside ss chimney. There is a huge volume in these things for smoke to build then ignite or explode when enough air gets to it.

cheapsx said:

I have an energy mate and do experience the big POOF at times. I let the wood all catch and get going good before closing it up. If you can load when the fan wants to run that helps after closing it up to prevent the POOF. Mine is a draft issue because it's in the cellar with an outside ss chimney. There is a huge volume in these things for smoke to build then ignite or explode when enough air gets to it.

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If you think the poofing on wood is bad try soft coal, I almost blew the stovepipe off mine. Lucky I had a barometric on it to blast out the side. Do you get extremely high flue gas temps with yours? I talked to the engineer & he said 1400 degrees external was normal & that meant 2800 degrees internal in the flue pipe. He said glowing a dull red was normal, Randy

With those numbers, this is a smelter, not a boiler. Very dangerous. Class A is only rated for somewhat over 2000F short term emergency chimney fire protection.

jebatty said:

With those numbers, this is a smelter, not a boiler. Very dangerous. Class A is only rated for somewhat over 2000F short term emergency chimney fire protection.

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Yes, that is getting towards open hearth temps. The chimney really only saw the 1400 degrees though as the center stream was the part with the high temps, as they explained it to me, Randy

I have one of those magnet stick on thermometers and never see over 550* on it. I am sure I could see more on it but I don't leave it to do so. I am to concerned about it to walk away from it and allow it to burn to hot. I like the concept of royall's solenoid fan cover gizmo but my concern is that when you cut off the air as it does then shove all that air in there when the fan runs, you are asking for the big POOF. I was going to fabricate my own but I think it needs more air let in to it in the closed position. Has anyone out there tried this with the fan cover gizmo?

A possible explanation for the extreme backfires may relate to the presence of a large quantity of unburned combustible gases in the firebox with enough O2 to cause the explosion. Based on the info provided the unburned gases might be explained by the apparent low efficiency of the Royall, and for the backfire to occur the Royall must also be allowing sufficient O2 to cause an explosion.

There is about a 3% drop in efficiency for each 100F increase in flue temp. A typical gasification boiler might have 400F or less interior flue temp, and the OP says the Royall has 2800F. That corresponds to about a 21% reduction in efficiency of a boiler like the Royall from a gasification boiler. A gasification boiler operates in the 85%+/- efficiency range, and based on the info a boiler like the Royall might be about 64% efficiency. These numbers assume 20% MC wood.

Usually that will occur after a long "idle" that gives lots of time for wood gas to accumulate in the firebox. The gas builds up and then the aquastat brings on the draft fan and PRESTO instant pyrotechnics.
Make sure all vent pipe is screwed securely.
Try to use smaller loads of wood so as to lessen the amount of combustible gas buildup.
As for the 1400* surface temp........I'm calling hogwash on that one.

Mild steel reaches a dull read at 1200F, and at 1400F is quite bright red. As to 2800F interior, mild steel melts at 2690F, and stainless steel melts at 2550F. Blacksmith It's hard to imagine any metal surfaces being in contact with 2800F temperatures.

jebatty said:

Mild steel reaches a dull read at 1200F, and at 1400F is quite bright red. As to 2800F interior, mild steel melts at 2690F, and stainless steel melts at 2550F. Blacksmith It's hard to imagine any metal surfaces being in contact with 2800F temperatures.

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Just to clarify Jim, The engineer that I talked to in Franksville Wis at the factory said it was not unusual for the ones they were making to run 1400 degrees on the pipe out side & that the internal stream was around 2800 degrees. He said the pipe would glow at those temps & this wouldn't hurt anything. I didn't feel he was lying because he would have no reason to. The steel only saw the 1400 degrees. He also said this was necessary to "burn up the creosote". My Energy Mate didn't run those temps, that said the flue gas temps were off the chart for my gauge. My boiler was rated for 150,000 output, the owners manual stated that it was 50 percent efficient. So wood was being consumed at 300,000 btuh with this small boiler, fired hard I believe it was beyond this, approaching Garn territory from a small boiler. The ones made in Franksville had a grate area twice what mine was & straight sided chamber, they did that so it would burn anthracite & they put in standard shaker grates at that time. I know it seems preposterous that someone would make a "blast furnace" like this...... Randy

When I was a kid and ice skated on the river, the warming house had a pot bellied stove which glowed red too. And I even have to say that shortly after we bought the wood stove we still are using 21 years later, one of my first fires had the steel top glow dull red. So I'm not going to doubt what was said. Things have come a long way from simply burning as much wood as possible to get heat. And they still have a way to go. At the same time, having got used to low temperature, high efficiency wood burning, it's hard to get my head back around some of these high numbers.