I use a covered charcoal grill (Weber 26") and can get the grilling temperature I want pretty reliably by setting the vents. The problem comes when I have a roast that wants 350F and I want to grill some vegetables at 400-450. The roast can come off and rest for the time the vegetables take, but I can't get the grill to heat up even if I open the vents all the way. Any suggestions?
I suspect what's happening is that you've depleted your fuel, charcoal's just wood at the end of the day, and after an hour or so it will have a lot less to give. If you want a hotter flame you can:
- Scrape the remaining coals together to concentrate the heat, this will give you high heat in say half your grill
- Replenish your fuel: there's two ways you can do this, a) you can use a chimney starter ahead of time and add the fresh hot coals or b) you can add unlit charcoal directly to the fuel bed say 10 minutes before you want to grill. Some webers have hinged side panels on the grill surface you can swing up to add fuel, personally I found this was a great way to singe my arm hair off so I would just lift the whole thing off and add it that way
- Use a long lasting charcoal: not all charcoal is created equally, some lasts much longer. I've found that Heat Beads or Weber brand charcoal lasts a lot longer than your standard supermarket stuff or lumpwood. It's more expensive, but if you don't want to have to add fuel it's the way to go