Mercury Thermometers and Aga Range Cookers

Almost all Aga range cookers come with a visual temperature guide on the outside that contains a 'L' shaped bulb of mercury. They are in a stainless steel housing and fronted with an aluminium scale plate. You'll know if you have an original mercury bulb as the liquid visible is silver. 

These temperature gauges are a visual guide only, they have no bearing on the successful operation of your cooker! 

The problem is that mercury thermometers have been very thoroughly banned so if yours breaks you cannot replace it 'like for like'. This is a very good idea as a whole but can create specific problems. They have been banned since April 2009 which is when European Union directive 2007/51/EC came into force in the UK. 

The replacements often don't fit the original housings, the bulbs in these units contain an alcohol mix that is bright blue for better visibility. Sadly this mixture is not as reliable as mercury, there is a reason everyone used it! It is not as accurate and prone to separating. Our advice would be to get the unit looking smart by replacing the plate or whole thing and then ignore it!

Instead use an 'in-oven' thermometer to get an accurate reading. Placed halfway back on the middle shelf it should read 235 degrees, simple!