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Peter Parry
 
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Default Rayburn efficiency?

On Sun, 15 Jan 2006 18:53:02 +0000, Andy Hall
wrote:

On Sun, 15 Jan 2006 17:41:18 +0000, Peter Parry
wrote:


The maximum temperature you can achieve from the
oven roof is much lower than that of a normal grill.


This is irrelevant as well. I don't want to char things, and to the
extent needed to grill and brown things, the roasting oven does a
perfectly effective job.


I don't doubt that you find it adequate, I require a higher
temperature in a grill than an oven can achieve (and it doesn't
involve charring things either).

Those are Aga's recommended servicing times - twice yearly for oil
burners, annually for gas versions.


OK, so it's not 6 months across the board as you implied in the first
place. It makes sense to service or at least clean any gas appliance
annually.


From the Aga servicing list :-

* Check operation of all functional controls and components.
* Test safety devices.
* Confirm correct gas pressures.
* Clean burners and internal flue-ways.
* Inspect/Replace rope seals and gaskets.
* Adjust operation of insulating lids and doors.
* Verify level and if necessary top up insulation.
* Visual safety check of oil line and storage tank.
* Check for gas soundness.
* Check integrity and safety of electrical connections and
insulation.
* Ensure flue system and ventilation is correct.
* Clean circulation and/or oven venting fans.

Inspect the ropes and top up the insulation? It supposed to be a
cooker not the engine room of the Titanic!

Conventional cooker - "Put pan on hob, when water boils check level,
put lid on, reduce to simmer and boil for 1 hr".


This assumes that the hob can maintain a simmer at constant rate for
an hour without checking.


With one exception, a very aged Electrolux with bang bang control and
a minimum cycle time of about 5 minutes on the hob plates I've never
had one that can't.

We periodically do an overnight roast in the simmering oven and it
always works very well.


That's what I said - Haybox cooking, I've always said they are good
at that.


I've never used a haybox, but as far as the Aga is concerned, this is
a great way to cook a large piece of meat.


So is a haybox.

Why do so many people (other than yourself) have problems with heat
loss if the thermal mass alone is sufficiently great to compensate
for opening and closing the doors?


I have no idea. I am not sure that it is "so many" in the sense of
being a large proportion of owners of recent models.


"Recent" Aga? The last major revamp was about 1970. Most owners
won't have a problem because (in common with many overly expensive
cookers) most owners never cook anything in or on them.

What you have seems to differ considerably from all other Agas. Aga
put the quiescent heat loss from their ovens at 1kW, yours looses
700W.


Their specifications are generous.


They are? Why would they introduce an error of 20% when inefficiency
is something they mention many times and try to minimise the
significance of in all their literature?

Aga quote weekly gas consumption for a 4 oven model at 527kW
per week, yours seems to use much less.


That's a figure that they quote as "typical" without saying how it is
derived.


"An Aga is a heavily insulated, heat storage cooker, designed to
provide all the heat required for cooking operations, whilst
consuming the minimum of fuel. It is therefore possible to predict
the typical, weekly fuel consumption for each model, based on average
use."

It is difficult to understand why they would overstate this figure to
any extent, indeed it would make much more sense for them to try to
minimise it as much as they can. By any standard 75kW/hr a day every
day of the year for a cooker is dire.

(http://www.aga-web.co.uk/agatech/gen1.htm)

--
Peter Parry.
http://www.wpp.ltd.uk/