Blower in door

[Gravel]

I have noticed new outdoor boilers are going to either one or two blowers in the door aimed down at the fire, any opinions on doing this to an arch?

[mapleack]

Check out the "air over fire" thread in the evaporator forum for tons of info on this subject. You dont want the air to be in the door itself I'd think because you'd have to shut it off to fire. That being said I know there are commercial arches that have air built into the door for combustion and cooling.

[Gravel]

Yes I have seen those threads this just seemed like the easiest way to do it plus I thought it would keep the heat from wanting escape threw the door as it would be blowing from the door?

[afretired]

I can't speak on the operaton of an evaporator yet, but I can on the outside wood furnace/boiler. I've built a few that have the blower in the door. Also to keep the door half way cool so you don't burn yourself and to conserve heat they have 4 inches of refractory cement in them for insulation. Without the insulation they would get extremely hot. There might be a difference in the door tempurature based on the direction of the blower but it wouldn't be much.

Dave

[Gravel]

So on an outdoor boiler what is the purpose of putting it in the door?

[xyz5150]

Its easy to do. I sell heatmor odwb's our blowers are in the auger tube under the grate/fire and our door is water cooled.Our blowers also blow over the fire if the grates are plugged. Quite a difference on water temp recovery time (efficiency) when the grates are full and not(air over vs air under).

[Gravel]

I have an older Aqua Therm furnace that has blower under grates, I have considered also putting a blower in the door of that but even if I do I am not sure I will gain any knowledge twords the arch!

[xyz5150]

A odwb is a different story the fire smolders for hours then it calls for heat the blower under the fire/coals is definitely the quickest way to get the fire going again. The odwb's with a blower in the door are usually smokers (takes a long time to get the fire going). A blower on the door is a cost effective way to equip them with one.

[afretired]

Having the blower in the door cancels the problem of having the grates fill with ashes and blocking the draft. Additionally, I beg to differ on it taking a long time to get the fire going, in a matter of minutes it will bring the fire up from a few coals to a rageing fire. On my stove and on some others, the door is the only surface of the fire box that isn't completly covered by the water jacket, even the bottom of the fire box is enveloped by the water jacket.

Dave

[xyz5150]

As i said on our stoves if the grates get plugged the air goes over the fire and its definitely not as efficient. But if you auger the ashes out once a week it doesn't happen. 99% of my service calls are new customers who are burning wet green wood and they don't auger out the ash pan the air goes over the fire and they notice a major difference in water temp recovery time. Now if everyone burned dry split wood you would not notice a difference but that's not why people want odwb's. Now as far what is and is not water jacketed is a whole different argument but is not the question.

[maple flats]

Don't take the easy route. Until you can do air over the fire just use the factory draft door. BUT then take the time to add air over the fire as discussed in another thread. Do not try to compare an arch with ant other wood heating unit except maybe an incinerator. The arch will always be run full speed ahead, you never slow until time to shut down at the end. An ODWB would not function with air over the fire until it was time to shut it down. These are 2 vastly different wood burning units doing vastly different tasks. If an ODWB could be burned hot enough to use over fire air there would never be any smoke at all, just a mirrage of heat out the stack.