tertiary air on aga wood burner how to use?

tillycat123

My new Aga Much Wenlock has been installed today. They said to leave it for 3 days before using to let everything go off properly so I can't have a play yet.

I have primary, secondary air intakes that I understand and the instructions explain how to use, however I have another lever at the bottom on the right hand side that says tertiary air control and no guide of how you should use it.

How do you use this bit? I've googled it and I can't find when you are supposed to have it open or closed.

Thanks

crphillips

The following was copied and pasted straight from the Much Wenlock Manual......don't know if you missed it.

TERTIARY AIR / SYSTEM CONTROL
The stove has a Tertiary Air System located at the
top, under the roof baffle and connected to an air
feed ducting on the right hand side and controlled by
a push pull slider assembly, located at the bottom
right hand side.

OPERATION
To operate the Tertiary Air, push to open and pull to
close. Open tertiary air slider only when the fire is
established.

Note: Close off the tertiary air for overnight burn.

tillycat123

Thanks crphillips, I had read it, but still not clear on when I should be using it? Am I supposed to have it open all the time the fire is burning then, is it not something I need not worry about controlling? Just open it up when the fire is good and hot and leave it alone,

Sorry to sound dim.

grahamc2003

tillycat123 wrote: »

Thanks crphillips, I had read it, but still not clear on when I should be using it? Am I supposed to have it open all the time the fire is burning then, is it not something I need not worry about controlling? Just open it up when the fire is good and hot and leave it alone,

Sorry to sound dim.

While it's hard to work out how to operate it from the manual extract given above, it doesn't say to do what you suggested above. Looks like a pretty crap manual description to me.

So given the lack of guidence in the manual, you'll just have to work out yourself what works best, unless someone comes up with better information. But there are some general principles. When any air inflow control is open, you are taking in warmed air from the room, and that will cool the stove down if nothing else happens, so unless there's a reason to open any valves, I'd say keep them closed. (e.g. when you go to bed if you're not burning overnight)

The reason for opening some or all of them is to supply air for combustion (I don't think there are any other reasons at all). But you need just enough (i.e. stoichiomentric combustion, where all fuel and oxygen is reacted). Too much air and it's working less efficiently.

The best way of seeing if the air flow is correct is to look for smoke (once the fire/stove is going and hot). If there's smoke (i.e. unburnt fuel), then you need more air from somewhere. If the primary, and secondary valves are fully open, then I guess it's time to open the tertiery valve (but it may be a little more complicated than that).