Question: I have a pre-fab fireplace. I get the fires nice and hot (but not huge and roaring) with a good coal bed (1400 deg F as indicated by IR thermometer). I just noticed the back panel is scaling and the grate is thinning out. Are my fires too hot for the pre-fab unit? Unit is 10 years old, but is our new house - first season for us. Didn't notice the scaling and grate thinning prior to our usage. Are pre-fab units really that iffy when it comes to temperature? Answer: These grates are usually very cheap and thin, and should be expected to wear out every couple years. Also normal for the refractory to scale or crack. Any "normal" fire should be OK, just don't burn trash, particle board and construction lumber on a regular basis. Too hot a fire also makes for larger heat loss from the house due to too much air being sucked up the chimney.