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Old 08-11-2017, 08:13 PM   #1
Midwestdrifter
 
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Default Building a Toaster/Oven For Our Van

For a long time, we have wanted an oven in our van. It makes a larger variety of foods possible, and allows us to get that GBD (Golden Brown and Delicious) flavor with ease.

The challenge has always been size. Even the smallest ovens take up a lot of space. Many require propane, and even the compact diesel fired marine units cost over $3,000.

We have tried a number of stove top ovens, and they all have their downsides. With no insulation they heat the van like mad, and use lots of power. Others are terribly small, or have poor temperature control.

Recently we have made some space in our larger cabinet, so we checked out Amazon, to see if they had any countertop toaster ovens that would fit. Low and Behold, there were several options.

Obviously to use them in our van, they would need some modifications, but for 30$, the risk was worth it.


We decided on this unit as our base.
http://amzn.to/2vMuu0v

This is a pretty basic unit. No insulation, fully mechanical control, no door seals etc. I used it for some basic baking and toasting, and it worked acceptably.

You can see with the cover off, there is zero insulation. The back side has only one wall. This thing is basically a 1000w room heater.

IMG_20170810_134101 by J Luth, on Flickr

IMG_20170804_172147 by J Luth, on Flickr

I needed some materials to make this box Van compatible. So of course I start by browsing Amazon.

Here is my materials list.

I decided on some ceramic insulation. Fiberglass would work, but I hate dealing with the stuff. Mcmaster Carr has some good options as well. I could have used another 30% insulation.
http://amzn.to/2fxV5HY

I also needed some high temperature adhesive. This silicone has been doing well in my testing. There was some vapor/smell at the first use, but it has dissipated.
http://amzn.to/2fz3xXt

I also needed something to use as door seal material. These fiberglass wire sleeves fit the bill. 4mm diameter would probably be better than the 6mm I bought.
http://amzn.to/2fygyQY

I bought this high temp fiberglass tape, but it wasn't necessary.
http://amzn.to/2vN3lum

The thermostat in this unit does not have a probe, and relies on heat conducted into the space where its mounted. Insulating the oven would have made it inaccurate, so it had to go. I bought this 50-300C thermostat to replace it. It has a probe, so it will be much more responsive.
http://amzn.to/2fyTK3R
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Old 08-11-2017, 08:23 PM   #2
Midwestdrifter
 
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Default Re: Building a Toaster/Oven For Our Van

Let the hardware hacking begin!

First up is the thermostat. A couple of screws, and two spade connectors and its off. You can see the new thermostat and supplied knob at the bottom of the photo below.

IMG_20170810_135112 by J Luth, on Flickr

The new unit is a bit bigger, but its mounting provisions are pretty much the same. Drill out the mounting holes a bit larger, and use 2 M4x0.7x10mm screws to mount the new thermostat. A few washers for adjusting the back spacing will be needed. There is a small bracket that needs to be bent or trimmed to allow for clearance. The photo below has some sharpie marks where the trimming needs to happen.

IMG_20170810_135550 by J Luth, on Flickr

Here is the unit thermostat fitted. The original knob fits! And if you place the thermostat in the right orientation the marks will even line up! I will double check the temperature index, but it seems to be pretty close.

IMG_20170810_141441 by J Luth, on Flickr

Here it is wired up.

IMG_20170810_164742 by J Luth, on Flickr

The probe needs mounted inside the oven. A few holes and some stainless wire did the trick.

IMG_20170810_164737 by J Luth, on Flickr
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Old 08-11-2017, 08:30 PM   #3
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Default Re: Building a Toaster/Oven For Our Van

The next step is to insulate the unit as best we can. This ceramic insulation is a bit fragile, so the adhesive is applied to the metal first. Some coroplast provides abrasion protection on the outside.

IMG_20170811_083048 by J Luth, on Flickr

IMG_20170811_083054 by J Luth, on Flickr


The door has some serious gaps. I glued the sleeve to the metal frame, and clamped the door shut to compress the sleeves. It is curing currently.

IMG_20170811_093436 by J Luth, on Flickr
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Old 08-11-2017, 08:33 PM   #4
hein
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Default Re: Building a Toaster/Oven For Our Van

A toast to your ingenuity.
How many watts does it draw?
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Old 08-11-2017, 08:49 PM   #5
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Default Re: Building a Toaster/Oven For Our Van

Quote:
Originally Posted by hein View Post
A toast to your ingenuity.
How many watts does it draw?
Rated at 1000-1100 watts. It has 2 elements, and you can choose both, or the upper only for half the watts. For even lower power draw you could re-wire it to put the elements in series. (around 250W).

When I get it back to the van, I will post up some watt/hour numbers for baking/toasting.

Quote:
A toast to your ingenuity.
I see what you did there.
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Last edited by Midwestdrifter; 08-11-2017 at 08:58 PM.
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Old 08-11-2017, 09:24 PM   #6
sprint2freedom
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Default Re: Building a Toaster/Oven For Our Van

Pretty neat. Thanks for sharing your work as well as links the materials used!

I've written previously about the Panasonic Flashxpress toaster oven. The big advantage of this model over a resistive oven is that it doesn't need to preheat- which is both time-convenient and energy efficient.

The outer footprint is about 13"W x 10.5"H x 12"D. The inside fits 9"x9" cookware, and has a built in wire shelf attached to the door. The space above the shelf for cookware is only a couple inches tall.

It heats the inside of food evenly and browns the outside very nicely. Cook time is set in 30 second intervals (per button press). Melts cheese on a tortilla until it gets crispy with nice brown char marks in 2.5 minutes. Reheats a slice of pizza in 1.5 minutes, or bakes chocolate chip cookies in 7 minutes. Light brown toast is about 2 minutes.

While I'm very happy with the cooking performance, running it for longer than a few minutes at a time does start to heat up the metal case. Of course the first thing I did when it arrived was take it apart to see what's inside. It's just (three?) infrared lamps and a PCB for the control buttons with a relay that cycles the lamps on and off. No insulation to speak of, and a fair amount of empty space.

As I mentioned the lamp turns on and off to regulate temperature. Duty cycle varies but tends to be about 40-60%. With a power draw of 1300 watts, energy consumption is approx 1 Ah per minute of cook time. To date, around 90% of cooking has been below 3 minutes. I have yet to cook anything that needed even 10 minutes, although I imagine some things might. Due to the small volume and the intense brightness of the lamps, cook times seem to be quite a bit shorter than a conventional oven.

The toaster oven will live on a dedicated shelf under the counter. I had been planning on an air gap and a heat shield to protect the underside of the countertop, but your post gives me further ideas for how I might be able to insulate the inside of the oven to further mitigate heat buildup.
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Old 08-11-2017, 09:41 PM   #7
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Default Re: Building a Toaster/Oven For Our Van

Nice work as usual Mr. Drifter!



I have plans for a "stove top oven", but I'm still buried with the task of painting....
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Old 08-11-2017, 10:12 PM   #8
Midwestdrifter
 
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Default Re: Building a Toaster/Oven For Our Van

We looked at the Panasonic unit, and really liked it. But its a bit too large for our cabinet space. When we do some rework on the van we may make adjustments.

Rockwool would also make a good insulation material, and you can find it at many home stores.

The elements in this oven are of the IR type. There are shields around them though. It takes about 4-5 minutes to make toast. So it heats up fairly quickly.
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Last edited by Midwestdrifter; 08-11-2017 at 10:29 PM.
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Old 08-11-2017, 11:07 PM   #9
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Default Re: Building a Toaster/Oven For Our Van

<<<The thermostat in this unit does not have a probe, and relies on heat conducted into the space where its mounted. Insulating the oven would have made it inaccurate, so it had to go. I bought this 50-300C thermostat to replace it. It has a probe, so it will be much more responsive.
http://amzn.to/2fyTK3R>>>


Excellent mod. I noticed that replacement thermostat is rated 250V. Would it work at 110V? Answering my own question, it shouldn't matter since a thermostat is just an adjustable heat-activated switch.
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Old 08-12-2017, 12:48 AM   #10
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Default Re: Building a Toaster/Oven For Our Van

Quote:
Originally Posted by Thanasis View Post
<<<The thermostat in this unit does not have a probe, and relies on heat conducted into the space where its mounted. Insulating the oven would have made it inaccurate, so it had to go. I bought this 50-300C thermostat to replace it. It has a probe, so it will be much more responsive.
http://amzn.to/2fyTK3R>>>


Excellent mod. I noticed that replacement thermostat is rated 250V. Would it work at 110V? Answering my own question, it shouldn't matter since a thermostat is just an adjustable heat-activated switch.
Yep, it's a mechanical unit, so as long as I stay under the current limit it will work fine.
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