I've managed to get my hands on 12 storage heater bricks that I was gonae place between insulation bricks and my hearth firebricks; however, they have been outside for a couple of years, does anybody think think there will be a problem?
A break in the weather has allowed me to start on the base. I laid a heavy plastic sheet for a DPC and then started placing large boulders of broken terracing from Yoker AFC for the walls, I filled in the void with smaller pieces and broken slabs.
They will take in water so it's easier to dry them out before use. Saying that.....I wouldn't use them. I think if you put them under your fire-brick hearth it will draw the main heat away from your fire-brick hearth. It will then take a lot more fuel to put (and keep) saturated heat in the hearth. I personally think that an imperial sized standard fire-brick ...laid flat (3") on top of an insulation layer of thermal blocks or vermecrete is ideal for a wood-fired oven that will be used primarily for pizza baking.
Even if your oven was to be used primarily for baking batches of bread, I would still only use fire-bricks on top of the insulation layer, except I would turn them on edge, thus having a 4 1/2" thick fire-brick hearth.
I would only use storage heater fire-bricks as an alternative to the 42% alumina content fire-bricks, which are said to give the best results in a wood-fired oven.
This is my own personal opinion....I warmly invite any contradiction to my views.
p.s.....your oven (base) is starting to take shape....
I've not idea if how I'm doing it will work well or not, or if the layers between fire brick and storage heater bricks will cause issues or not (I hope not). My storage heater bricks have also been outside for 1-2 years, I won't be drying them before laying the oven floor layer. I'm intending to dry lay (with wet sand though!) the oven floor though so hopefully the moisture will work its way out.
Another productive day today! I got the top of the base roughly leveled off with broken slabs, I then inserted another DPC between the slabs and a bed of sand for the insulation layer, then I laid the insulation of Celcon Aerated blocks. Which did cut to shape easily with a normal wood saw!
Possibly heading out to buy my firebricks this afternoon but before I do, should I have a thermal mass between insulation bricks and hearth bricks, I was going to put in a couple of inch of oven mud, is it required?
First time on the forum for 24hrs....whoops, I missed a critical question. I've looked back on your thread to refresh myself with your build. So...1st PM.....
NO....not in my opinion. The thermolite blocks will act as both insulation layer and a heat block for your fire-bricks. i.e......the thermal blocks will insulate your hearth fire-bricks plus they won't allow heat to "sink" through them.
Check your 2nd Pm reply from me...
And Terry's 2nd reply
Quote: Hi Terry,
Been on the phone to John Cameron's and they only have 50mm bricks in stock at the moment, they will get 70 mm bricks in on Friday what should I do? Are the smaller adequate or should I wait?
This response may be too late.....hope not.
As you are building a clay oven, I would say that 50mm fire-bricks on top of insulation blocks will give you the same thermal value as the clay, so the 50mm fire bricks will work. You can go for the 70mm fire-bricks ...they will keep more massed heat in the hearth floor, but 50mm will also work well.
So with this in mind I posted this today in the 'Jewsons Members discount' thread,
As promised here is the price of the 50mm/2" firebrick from
John Camerons Roofing and Plumbing Supplies 55 MacLellan St Glasgow Tel 0141 427 5353
Scone Firebrick 9"x 4.5" x 2" (230mm x 115mm x 50mm) Part No HEA60004
£1.78 including VAT or £1.49 excluding VAT
I purchased 18 so total cost including VAT £32.18
Before they confirmed the price they asked if I was also buying fireclay, so I think they would have given a discount if I had been.
All the staff were extremely helpful and dealt with all my requests, firstly worked out how many bricks I would require for a circular oven floor with a radius of 22.5" (15 bricks).
Staff were not sure of the Aluminium content so asked the manager, manager said she thought it was about 40%and when I asked if she could confirm this she went and phoned the supplier (central refractories) and confirmed it 40%.
As I have already stated was delighted with the service provided, and also very happy with the price.
Would recomend John Camerons to anyone thinking of building an oven in the Glasgow area.