New Ovens Project

This project was prompted by our local food bank which we contribute so much of our surplus stock to in their basic form as fruit or veg and in prepared packs of foods such as our frozen stew packs to which you just add meat and gravy and them simmer.
More and more people have recently been asking for produce which doesn’t have to be cooked as they cannot afford to switch the cooker on; or foods which don’t need storing in the fridge as they are also switched theirs off.

This prompted me to put my engineering head on and I designed and built a cooker from scrap which is both easy to use and runs on waste wood which in my case was willow whips cut from our willow tree and dried for a couple of months and the leaves were left on and are now crisp and this is actually excellent fuel. I designed and made ours from scrap and the dimensions are those which suit us and anyone can make their own to their own dimensions.

Ours consist of a basic metal box which forms a basic oven and is surrounded by a larger metal box which is the burner and it is larger so there is a gap of 50mm around the inner box so it is equally heated to act as the oven and the front protrudes 50mm further than the heater box. At the bottom the outer box has a gap of 70mm as this is where the bulk if the burning wood will sit and it also has an adjustable air draught to increase the burn heat and on the top it has two smaller holes with caps to allow it to be filled with wood or other fuel.

This inner box is fitted with 25 X 25 X 3mm angle iron around the front to create a flange for the door hinges and catches and 50mm from the front flange we install 50 x 50 x 3mm angle iron along the top and both sides and we use 75 x 75 x 3mm for the bottom flange as this acts as the front for our outer box which contains the fire.
In this bottom flange we drill a series of holes and create air slots and a corresponding sliding plate to control the air and a small square with a bolt on plate as our cleaning port to remove any ashes from out burner and I made a little ash rake to do this.
With the outside of the inner cooking box done it was time to turn to the inside and 6 X lengths of 10mm square were welded in to form runners or supports for shelves or racks which we may install to allow the shelves or racks to be raised to different levels.

Our outer box was made with both sides, the bottom and the back and were tack welded together to form most of the box and this was slid over the inner cooking box and tack welded to the 50 and the 75 mm angle iron to solidify the sections and they were seam welded to form most of the outer box and the top plate was left because this needs additional work.

This top plate and the oven front door were made from 6mm plate as the top of the cooking box takes the most wear and it supports the chimney stub along with two slots for feeding the wood fuel in and welding a hot ring on top to stand saucepans on.
This plate was marked out and the two wood feed slots were cut and their covers made, the hole for the chimney was also cut and a piece of 80mm diameter pipe was welded on and a flange made for the top and a piece of 10mm thick plate was welded on to form the heating plate to stand saucepans on. Meanwhile the oven door was made from 6mm plate and the edges were flanged for strength and TIG welded and the hinges were made and welded onto the door and the flanged mounting frame and the door shut catch was made to hold the oven door closed and after rolling a 1metre long piece of 80mm diameter chimney it was ready for firing.

We fired it by screwing paper up and pushing them down through the feed slots until they were at the bottom of the burner and then covering them with wood shavings to help it fire and the paper was also lit through the air slots using an extended nose gas cooker lighter while small willow twigs were fed from the top and it lit instantly and within minutes it was alight and the air flues were adjusted accordingly.
With a nice burn going we timed the burn time and once lit it burned for about 2 hours with two handfuls of willow and willow whips make good fuel as they burn and they make excellent embers as once burned they glow for hours and these glowing embers make an excellent long term fuel for cooking on.

With everything completed it was time to clean and coat it and we shot blasted the unit inside and out and wiped it clean to remove any residue and we have spray on stove enamelling at work and the oven inside and the inside of the door was sprayed and the fire was lit and soon cured it. Once the oven was cured it was time to shut the door and fully cure this and it was filled with more wood and left to burn for several hours to ensure it was fully cured and then allowed time to cool overnight where heat resistant paint was applied to the outside of the cooker and it was fired again to cure it and this was now complete.

We had slight smoke from the two wood filling slots and to stop these leaking we had some heat resistant strip which is actually in a U section and this was applied to the wood filling doors and once tightened down it stopped all the smoking and it was fitted to the oven door to keep heat in and again this worked.
Our first prototype really needed testing for other modifications and this was done by installing it in a house and an ex Council property was chosen as the couple had bought it before he went wandering off with another woman and left his wife and three children. As this property has a small mortgage it means she cannot afford the heating either but it was originally built with two coal fireplaces and has a chimney and after investigating it we found the pot had been capped off and the stainless steel flue liner was still fitted and intact and originally the rear room had a log burner type fire originally installed.
Enter Babs the builder and Bob the plumber and the chimney was uncapped and all the concrete removed and the flue was smoke tested for leaks and cleaned by Bob who declared it fit for use and legs were fitted to the fire and concrete slabs were fitted to the floor for it to stand on and the flue was fitted and mated to the flue liner.

She has perfected her lighting technique and these is to screw newspaper into torpedoes and push through the filling hole and poke it to the front with the poker and push the next one in and overlap the first, this takes four pieces of paper and is repeated on the other side. Dried wood shavings are dropped onto the paper and spread the full length of the fire on either side and the willow whips are dropped on top of these and the air inlets are fully opened and each side is lit through the slots and the paper lights the shavings and the shavings light the willow which burns for ages.

They have found that shopping trolleys have chrome plated mesh and these make excellent shelves as they withstand the heat and they cut an old damaged shopping trolley for the mesh shelves and they can get three casserole dishes on the three shelves and they still have the top hotplate. Their stew takes 90 minutes to cook and this is within one fill of wood and she lights it at 12 o clock and again at 6 o clock so three of her neighbours can share it and get at least one hot meal a day and potentially two hot meals.

Another couple of options which i have are a stove made from a calor gas
bottle ,which serves as a heater and you can also use the top to cook on.
I also have a rocket stove which only requires a few twigs to boil a kettle
or a saucepan.

All of course require some welding / fabrication equipment.although it think
a rocket stove could be made without.
there are plenty of vids on youtube showing these.

Just building a thermal mass rocket heater for a neighbour to go in his shed and I have one which is stand by heat for one of my barns and it does heat it, his combined garage and shed are less than 1/4 the size of the barn.