Tunnel Oven Thermal Insulation Issues – How to Find and Solve

Tunnel Oven Thermal Insulation Issues

We previously discussed problems which could be easily avoided with your tunnel oven, this post looks more in depth into the problem of inefficient thermal insulation and how you can improve the efficiency of your tunnel oven leading to lower costs and improved working conditions for employees.

How to detect inefficient thermal insulation?

There are many ways in which you can detect if your tunnel oven has inefficient thermal insulation, simply by touching the oven walls or if the working environment feels uncomfortably hot for employees this could be an indication that the oven isn’t efficiently insulated. Other ways to detect inefficient thermal insulation are:-

  • An energy audit is an in depth review into how energy efficient your oven is overall. This will involve looking into the efficiency of the thermal insulation.
  • Monitoring gas usage over a set period of time and compare to previous figures.
  • Recording temperature differences over periods of time. This way you can see if there are variations which would indicate that the insulation of the oven is becoming less effective.
  • The effectiveness of the thermal insulation is dependent on the environmental conditions that it is exposed to, for example heat and water will degrade it over a period of time.
  • The optimum temperature for the outer panel of the oven wall in our experience should be about 35°C, if it is more than 40°C it is inefficient and if it is over 60°C it is a dangerous working environment
  • If the insulation on your oven looks like the image below –

Tunnel Oven Insulation Issues Bad Insulation

What type of insulation is available?

Tunnel Oven Insulation Issues RockwoolMineral (Stone) Wool Insulation – made from volcanic rock which is heated to about 1500°C causing it to melt, the liquid volcanic rock is spun at high speeds to produce rock fibres which are then bound together with a resin and small amounts of oil, creating the mineral wool.


Tunnel Oven Insulation Issues GlaswoolGlass Wool Insulation – made by heating glass and sand to about 1500°C causing the mixture to melt. This is then spun at high speed to form fibres, which are then stuck together using a resin binder, creating a thick web of fibres that is highly flexible and resembles sheep’s wool. It is recommended that glass wool insulation is laid to a thickness of 270mm to maximise its insulating properties.

Mineral Wool Insulation Glass Wool Insulation
Made by heating volcanic rock Made by heating glass and sand
Excellent Thermal Insulation Good insulating properties
Superior fire resistance compared to Glass Wool Resistant to fire
4 times denser than glass wool During manufacture 70-80% of glass wool is produced from recycled glass
Short Fibre Length Long fibre length
High pressure resistance Lower pressure resistance than Rockwool
Cheapest of all insulation products


How can you replace the insulation on your tunnel oven?

You can replace the insulation on the oven yourself; this can be the most cost effective way with regards to direct cost. We have created a DIY Guide for replacing tunnel oven thermal insulation.

The supplier of your oven should be able to help you replace the insulation.

SpoonerPlus’ experienced engineers can do the job for you quickly and efficiently saving you money in the long term by reducing down time. This example illustrates our approach and savings when solving tunnel oven insulation issues.

Final note

Don’t just concentrate on the largest part of the tunnel oven – the walls – a lot of heat can also be lost from the terminal ends. It is common for the insulation in the terminal ends to fail if disturbed and as this is not always visible can be overlooked but over time becomes an unnecessary cost to running your oven. Spooner Industries have developed their ovens to have integrated terminal ends which help improve the oven’s overall efficiency.


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