Newmac oil/coal/wood furnace, how to make wood burn longer

Hello all.
I just got a Newmac combination, oil/coal/wood furnace around November 2012. Works great with coal. I've started to burn wood now about a few weeks ago since it is getting a little warmer here in south west pa. Man but the wood gos fast in my furnace. Now, the company gives a thin metal plate to lay on the shaker grates when burning wood. The plate has several rows of holes the size of a 50 cent coin. That of course leaves the wood ash fall down into the ash pan and for air to rise up to the wood.
I've put some times 3 to 4 layers of wood in the furnace and the burn will only last for maybe only 2 and a half hours. I keep the ash door closed and the top feed door closed and I still get that quick burn.
Any suggestions on what i can do to make a much longer burn? The holes in the metal plate leaves a lot of wood ash fall down in to the ash pan. There for I can't get a good large layer of ash under the burning wood. Like a wood only furnace would. If I leave the furnace for over 2 hours all I see is the plate covered a little with black ash and I can see the plate and its holes. Meaning maybe if I could build a good layer of ash under the wood, it may burn longer. So could i safely cover over just a little of the plate with the holes with maybe a solid metal plate but still leve some air to penetrate and rake some ash down into the pan?? Would like your suggestions. I know my furnace is mainly for coal, but burning wood save on coal some time. Thanks all.

can you lay a row of bricks on the steel plate to cover the holes.Keep burning coal untill you only need a fire to take the night chill off or you loose draft with coal fire.

gweedow wrote: Meaning maybe if I could build a good layer of ash under the wood, it may burn longer. So could i safely cover over just a little of the plate with the holes with maybe a solid metal plate but still leve some air to penetrate and rake some ash down into the pan?? Would like your suggestions. I know my furnace is mainly for coal, but burning wood save on coal some time. Thanks all.

Your logic here is to slow down combustion air from going up thru the burning wood so fast. A manual pipe damper would have the same effect. IS there a manual pipe damper installed? The only thing I can think of to slow the burn would be to close the MPD some so that combustion air will come in slower.. Are the primary and secondary combustion air inlets closed while it burns the wood up that fast? Are the door seals in good condition and sealing well?

I'll be the devil's advocate..... I'm going to say that it's working perfectly. The manufacturer either accidentally did a good thing, or actually put a lot of thought into it. 2 1/2 hours isn't bad for wood in this type of appliance. IF you do find a way to slow the burn down the next time you post I'll bet you'll be saying "I get a lot of creosote. It drips out of the chimney, stinks like heck & if this keeps up I'm bound to have a chimney fire. How can I prevent this?"

I agree with that too Freddy. It's usually hot and fast or slow and creosote dealing with wood.

Agree with the above two posts. Wood is going to be hot, fast, and fairly clean, or slow and smoky.

Yes and thanks guys. I'm not going to mess around with the newmac. you make a great point on how that furnace should burn the wood. When I continue to burn wood threw the night Ill just get up every few hours and feed it a little. I'm an early riser anyway. LOL. Hey whats retirement for. Anyway, when the fire dose go out. The oil feed part of the furnace kicks in. Only had about a hundred twenty gallons of fuel oil last November in the tank. Fuel tank gauge is down to a little above one fourth low. Not bad for what 4 months. Of course i burned mostly coal during that time. Thanks again everyone. I really like this forum.

Well, here it is...Don't Laugh


Read here..The Upside Down Wood Fire

Top Down Fire Method

McGiever wrote:Well, here it is...Don't Laugh


Read here..The Upside Down Wood Fire

Top Down Fire Method

Still seems like too much work.

Although, I kind of like the Dakota Hole fire.

http://www.youtube.com/watch?v=yXDlSjZ5fgQ

It'd be cool to try next time I go camping.

Cover the grates right up.
There are 2 models of the newmac. Wood only and the wood/coal. The wood only is vastly better than the wood/coal for burning wood.The wood model has no grates, just a floor.
I've selling Newmac for over 20 years so I know the product.

2.5 hours isn't normal for a wood furnace. More than likely there's an overdraft with the chimney. Even standard furnaces should see at least 4 to 6 hours for a burn. On the other hand, our epa certified wood furnace can burn up to 12 hours or more depending on the weather without filling the chimney with creosote.