Mine is the same model as Womble's.
Damper (flap on flue operated by side to side knob) is for when you want the fire right down, or if your chimney has insane draw and you're burning fuel at a stupid rate despite shutting everything else down. You would not normally be using the damper when you are wanting the rads hot and/or the oven hot.
Slidy thing that sits under the damper flap regulates the heat going up the chimney. Open for more draw to help the fuel burn, close to contain the heat and retain it in the device.
There's something in the manual about not using the damper if you're burning all wood, or else it's not if you're burning coal, I can't remember which, sorry. Do you have a manual for yours?
The thermostat, as Womble explained in more technical jargon, brings air into the back of the fire. Broadly, the setting here is about how hot you want the water in the tank and around the rads. Higher = hotter and burn more fuel. Lower for overnight. If your flue is clear and your draw good, you may find that 1 or 2 is fine for overnight, 2 or 3 if you want a bit of heat in the rads for morning.
Daytime I have ours on 4 or 5 if the weather's mild, up to 6 or 7 when really cold. Haven't needed 8 - yet
I need a higher setting and to renew the fuel more often if I have the pump on. Our pump only pumps when the water is at or above certain temperature; this was recommended by our installer.
According to the manual, the spinwheel at the front is for controlling the oven temperature. When starting the fire and when heating it up ready for heating the oven, have it three turns open. Once the fire is good and hot, close it down a little, but not a lot - so keep it maybe 2 turns open, close the slidy right down to stop the heat escaping up the chimney. H/C selector to C for Cook. All the heat goes into the oven and it heats up. In theory.
When the oven is nearly at the temp you want, close the spinwheel right down and use the thermostat if you need more air in the fire.
Sometimes, counter-intuitively, the oven temperature rises most the more everything is closed down, and with the H/C selector on H or partway between. (There's more air flow through the fire on C, less on H, as well as the routing being different.)
BH is good at making a hot fire that heats the oven. He doesn't fill the fire box and then try to get it all burning, he keeps adding a couple of logs and getting them burning well, then another couple. He likes to have the spinwheel right open and the slidy at about half open. Once he has the oven temperature starting to rise, and the fire is good and red-to-white right through, I take over, shut the slidy, reduce the spinwheel, select Cook.
I don't generally ask the oven to get up into the >200C zone. It's not worth the fuel, I use the electric oven if I need the very very high temperatures. The Rayburn oven heat is a deep all-encompassing heat and will cook more than you think from the temperature shown. If you want more heat, use the solid tray to reduce the oven volume and/or the supplied full-width-and-depth roasting tray as high up as it can go - the temperature at the top of the oven when the roasting tray is high up and the solid tray below it is much higher than the dial shows.
Having said that, anthracite does burn hotter than wood or our 'duck egg' coal cobs, so you maybe can get the higher oven temperatures.
You may well need to turn your central heating pump off to get the oven up to the highest temperatures, I would think. I don't find I need to reduce the thermostat, but you may find different.
Overnight if we have a good breeze and the flue and internals are all clear, I can close everything right down. Thermostat on 1, spinwheel closed or a quarter turn open, slidy fully shut or only 1/2" open.
If the chimney hasn't been swept recently and the internals haven't been cleaned in a few weeks, I probably need the thermostat on 2, spinwheel half or even a whole turn, slidy open about an inch.
You shouldn't get too much build-up of soot and so on as you are burning anthracite, but we get a lot build up here. I need to clean the internals once a month. More often would probably be better. (The manual says once a week
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You will need to experiment; every Rayburn is different, and they can behave very differently when the wind changes or drops too.
At first I'd think about it logically and make changes that were thought through; now it's more intuition and experience of our Rayburn and our weather. I 'just know' what settings to use. Usually