Aga insulation, how it works and how to improve it

Making Agas more efficient is something everyone is interested in so I thought I’d write about the basic principles!

There are 3 areas of interest when talking about Aga insulation...

  1. Most crucial are the lids. These block heat from leaving your hotplate and simmering plate. If you leave the lids up you only need to feel how intense the radiated heat is to realise how much energy is contained in them and how important it is to conserve this energy for when you need it.
  2. Just behind the lids in importance is the insulation under the hob top of your Aga. When Agas are built the cavity is filled with loose insulation and then topped off with a ‘top blanket’. Very old Agas use diatomaceous earth as the loose insulation (looks like talcum powder), from the early 1960’s this changed to vermiculite (looks like tiny popcorn!). Until recently the ‘top blanket’ was usually simple rockwool identical to loft insulation.
  3. Finally the doors are crucial at containing the heat inside the ovens. Pre-1974 cookers (both ‘Standard’ and ‘Deluxe’ models) didn’t even have seals on the doors and only in the mid-1990’s did both doors use insulated liners. Only in the last 15 years or so has the rockwool door insulation been replaced with more modern types.

So now lets look at what you can do yourself to improve all these areas!

  1. There are two elements in your lids that govern how effective they are at preventing heat loss. The first is the seal that makes contact with the expansion ring around the hotplate. This is designed to cushion the lid and prevent ‘metal on metal’ contact that can damage things and will also transfer heat from the hotplate very effectively and bypass the insulation. This insulation is the other part of the lid working to prevent heat loss. Our DIY lid liner replacement kits (available in non stick finish or traditional aluminium) come with brand new rope seals reinforced with steel mesh to keep them nice and bouncy for a long time. The kits can also be supplied with replacement insulation. This is super modern ceramic wool with very low thermal conductivity. It is not harmful but we provide dust masks with all orders containing insulation as it can be irritating!
  2. To improve the insulation under the hob you need to do two things. The loose vermiculite needs to be topped up and the top blanket replaced with our modern ceramic wool. We have a DIY under Aga hob insulation upgrade kit that includes everything you need. Full instructions on how to do it are here. The loose insulation upgrade is always vermiculite; even if your cooker contains diatomaceous earth; there is no harm in mixing them and vermiculite is more effective.
  3. There are 3 elements that govern how effective the doors are at retaining heat. As with the lids new seals and insulation are crucial and both can be supplied as part of our DIY door liner replacement kits. We supply seals with all versions of the kit, every little helps even if pre-74 cookers didn't have them from new! Like the lid liners these are available in non-stick or traditional aluminium finishes. 
  4. One final item that can help are new plastic door washers. If your door pins are in direct contact with the body of the Aga then heat can be conducted into the outer part of the door easily. This bypasses your insulation no matter how good it is! Using new plastic door washers can improve this!

Aga insulation


Matthew Bates
Matthew Bates

Author

Matthew is from a farming family near Bath and a graduate of King's College London who decided not to follow the 'standard' path into banking or the law. He has been working with Aga's in some form or another since 2003. Matthew runs Blake and Bull from beautiful Bradford on Avon, near Bath. Alf the golden retriever makes sure the working day finishes at 6pm sharp - dog walk time!