# Forum Home Renovation Kitchens  heat shield behind underbench oven ?

## jetpatcher

I have just installed a pyrolitic oven (underbench) into our kitchen but i am worried that the rear of the oven is too close to the gyprock (approx 8mm). The installation instructions say the cut out requires 15 - 20mm. Can i screw a sheet of stainless steel to the wall to shield the gyprock or would this heat up just as much as the oven casing, or is there an alternative material i could use. Thanks in advance. 
Ash

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## jetpatcher

Tested temperature against gyprock with laser temp. The highest temp of the wall reached 35 degrees C when pyro cycle operating. I checked the Gyprock specifications and it says not to use above 52 degrees C so I'm hoping all will be good. I pulled the oven out and there were no visible signs or discolouration of the surface.

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## Godzilla73

G'day, 
Can you cut out that section of the plaster behind the oven to aid ventilation? Only reason i suggest it is because appliance mobs are great for rejecting repair claims due to incorrect installation.

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## cyclic

. Can i screw a sheet of stainless steel to the wall to shield the gyprock or would this heat up just as much as the oven casing, or is there an alternative material i could use. Thanks in advance. 
Ash[/QUOTE]   
Use Aluminium sheet not Stainless

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## jetpatcher

> G'day, 
> Can you cut out that section of the plaster behind the oven to aid ventilation? Only reason i suggest it is because appliance mobs are great for rejecting repair claims due to incorrect installation.

  Thanks Godzilla73, 
unfortunately I have a fair amount of electrical cabling, gas and water behind that section of wall so I would prefer not to open this up to the heat unless no other option.  
Thanks Cyclic, 
Will the aluminium sheet dissipate the heat better than the s/steel?

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## cyclic

Thanks Cyclic, 
Will the aluminium sheet dissipate the heat better than the s/steel?[/QUOTE]   
Aluminium is a far better heat shield than Stainless Steel eg every motor vehicle has a thin aluminium shield over exausts, starter motors etc.

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## jetpatcher

Thanks Cyclic, 
this is what I will use then :2thumbsup:

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## METRIX

A metal sheet will actually increase the temperature on the gyprock, AS 6501 states if you are to put a stainless back behind a gas cooktop then you must have fire resistant surface to attach it to. 
Gyprock is not classified as fire resistant, but Sheeting such as villaboard is, if you are really concerned about this then rip the gyprock off and replace that section with FC sheeting, a piece of metal won't do anything for you. 
I know this is not a gas cook top you are dealing with but the principals are the same.

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## jetpatcher

Thanks METRIX,
I've decided to wait until the bench tops go in and then run the pyro function again. The oven cabinet has about 40 mm space each side of the oven (installation instructions say 16 mm) and 40 mm above and below with a large cutout in the base 150mm off the back wall, so once the cleaning has finished I'll pull the oven out and check the gyprock again. If needed I will then cutout sheet and replace with villaboard.

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## Godzilla73

If you do go to the trouble of cutting out the plaster, replace it with proper fireproof board not just villaboard. You can get it at plumbing suppliers like Reece...

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## jetpatcher

Hi Godzilla73 
i did look at the gyprock fyrchek but i couldn't get any specific info on heat ratings etc...

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## DalfinaAlex

Aluminum is best option because it dissipates heat very quickly. .

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## grantbudd

given ali is such a good conductor of heat surely there needs to be some kind of heat sink attached to it? I know ali is used a lot but it usually has raised cooling fins like we see in down lighting. If a sheet of ali is used where is that heat going to go if the oven is built in? Id be worried about the wall cavity acting as a heat sink or is that the idea? just thinking aloud here.................

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## China

Metal is not suitable for a heat sheild in this situation one of the various fire resistant boards should be used, there should also be a suitable air gap,
around the oven, the instalation specs would cover this and should have taken into account

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## METRIX

> Aluminum is best option because it dissipates heat very quickly. .

  The idea is not to dissipate heat quickly, it is to stop heat being transferred to the wall studs potentially causing a fire. 
So dissipating heat quickly via Aluminium is the wrong approach, take a look at the AU standards and they clearly state you cannot have metal backing without some form of fire proof protection between the metal and the timber studs.

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## METRIX

> Hi Godzilla73 
> i did look at the gyprock fyrchek but i couldn't get any specific info on heat ratings etc...

  Hi Jetpatcher,  
There is no such data as specific heat ratings of the board, any structure that requires a fire rated wall is designed as a whole system not just a single component, Gyprock Fyrchek or Flamechek ar just the linings used for such systems. 
To design a resistant system you need to know what the FRL rating the wall or ceiling is required to withstand such as 60/60/60. 
FRL is quoted in figures like 60/30/90 what this means is that the structure behind the board will be protected for a certain amount of time as stated by the numbers.  
eg 60/30/90 means the structure being protected will be adequately protected for the times stated below 
The "Structural Adequacy" will be protected for 60 minutes
The "Integrity" will be protected for 30 minutes
 The "Insulation" will be protected for 90 minutes 
Fire protecting any structure is a science in it's own, this is why the Red Book was made, to help builders etc choose the right combination of boards / layouts to achieve the required FRL rating as designated by the designers, and is why there is no one such figure for the panels. 
For any situation like an enclosed oven the simple solution is to remove the standard gyprock and replace with Fyrchek, or cement fibre sheeting behind the enclosed oven section of the kitchen. 
Standard gyprock has minimal fire resistant properties does not have an opportunity to fail due to excessive heat from the oven.
We always put FC sheeting at any points in a kitchen where the oven will normally be, extending this out and up to around 600mm either side. 
With these new pyrolitic ovens, they get up to 450c inside to burn all the stuff off the oven walls, and they are sure to get a tad hot on the outside casings and rear of the oven during this process, after all, all that heat has to go somewhere.

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## grantbudd

you learn something new everyday  :Redface: ) Thanks for the education Metrix  :Redface: )

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