Woodburner burning coal?

I have a woodbirner insert for my fireplace, it has shaker grate in the bottom of it and is built pretty heavy duty. My question is can I add coal to my woodburner on top of a good bed of coal to help supplement my wood supply? I have a decent supply of wood this year so I'm just looking to burn some coal to help it last. If yes what type of coal can I add?

I bet you will warp your grate.

Most wood burners can't handle the higher heat that coal gives. Might try to look it up on the manufacturers website or even check reviews.
Here is somethinng to think about.
The diet of catalytics is restricted to wood—and nothing else. Just as a car's converter would be ruined by leaded gas, a wood-smoke combuster can be ruined if exposed to chemicals from coal, painted or treated wood, metals or plastics, and even some coated and colored papers. Mother earth

X3...coal burns hot.

I have a wood burning furnace that says wood/coal on the mfg tag on back...however when i look up a new model of the same furnace it mentions wood only. I contacted the mfg and they stated they changed it to just wood out of consumer confusion. Apparently people were not reading the user directions. Its wood AND coal not OR. The directions state after building a bed of wood coals you can add about ten pounds of coal at a time but only to a bed of wood coals. I was given an example where a guy filled one with coal and melted a hole right through the bottom. The bottom of my burn box is 1 inch plate. If theres any question id just forget about it..too dangerous imo.