SunFlair hot water test

[jimindenver]

At the request of a friend I am running a test with the SunFlair solar cooker and a 4 quart stew pot of water to see how well it can heat water. The test started at 11:15 am with full sun, the water was 72*f. I did not put the black plate into the cooker as I want all of the reflected sunlight onto the pot. Wunderland is reporting the outside temperature as 67*f. I'll check the temperature of the pot hourly with a IR thermometer.

I may rerun the test tomorrow with a 3 quart roasting pan that is wider to see if the results differ.

I have done this with the Global sun oven with good results. It easily produced water hot enough for getting washed up, dishes, even coffee.

 

[jimindenver]

One hour in and the cookers thermometer shows 175*. The pot shows 118* and a finger test of the water tells me it is certainly warm enough for washing up and even doing dishes. I need to pick up a new meat thermometer as I forgot mine at the house.

 

[jimindenver]

Two hours in and the cookers thermometer shows 195* and the pot shows 145*.

 

[jimindenver]

Three hours in and the cookers thermometer shows 200*, the pot shows 167* and I'm not sticking my finger in the water. We are getting some occasional clouds.

 

[abnorm]

Very impressive Jim...................

 

[Oneleggedcowboy]

Jim you need to try a half gallon canning jar painted black. I leave a strip unpainted to b able to see inside. I use a canning jar ring with old lid. It holds pressure and heats faster like a pressure cooker. Using a old lid dosent seal perfect so it wont pressure up to the bursting point mine is made from cardboard boxes and aluminum foil covered wings with a plexiglass sheet on the top of the box. Yours looks a lot faster and easier

 

[JT646]

Three hours in and the cookers thermometer shows 200*, the pot shows 167* and I'm not sticking my finger in the water. We are getting some occasional clouds.

Good data.  Some heat will be lost due to conductive air currents inside the oven--between the pot and the outside reflector & window.  You can minimize this by adding an oven roasting bag ( https://www.amazon.com/Reynolds-Ove...=1487626250&sr=8-2&keywords=oven+roasting+bag )  around the pot. This can add 10-20 degrees to your max temperature.

 

[highdesertranger]

that's cool certainly well within the range of pasteurization. highdesertranger

 

[Magicwolf]

Good data.  Some heat will be lost due to conductive air currents inside the oven--between the pot and the outside reflector & window.  You can minimize this by adding an oven roasting bag ( https://www.amazon.com/Reynolds-Ove...=1487626250&sr=8-2&keywords=oven+roasting+bag )  around the pot. This can add 10-20 degrees to your max temperature.

Thanks for that info, I didn't know you could do that. I have the little version of what Jim has. I think the mini is slightly less efficient so it'd be nice to boost the temp just a bit, though some of that could very well be operator error. I will try taking out the dark flat pan that usually sits on the chrome rack (if I'm using the collapsible black pot it came with) and see if that makes any difference as well.

I could get the oven up to 190-200, then that would decrease when I added something and I'd not be able to get it back up again to where it was. Watching Jim's data with interest.

 

[jimindenver]

Four hours in and cooker temp is still around 200*, pot temperature shows 178*.

I am using my black 4 quart stew pot. Adding another layer with a oven bag would likely help as possibly the wider 3 quart roasting pot with more flat surface to the sun above and the reflected light below. As I mentioned I am seeing intermittent clouds so that is also a factor. I really don't see a need to rerun the test tomorrow but I do intend on using it to cook some meat. I need to run into town but I'll check it when I get back.

 

[jimindenver]

I didn't get back in time to catch it before it was shaded but a little over 5 hours in the pot was registering 187* and the clear front was showing condensation. Certainly past the point of being scalding, close to hot enough for brewing coffee drip style.

 

[Oneleggedcowboy]

Great if and thresd! I need one ofvthese, my homemade solar oven is to large and fragile to go boondocking.

 

[29chico]

Nice test.   Pretty effective water heater.  That might be the best use for the Sunflair.

 

[JT646]

Thanks for that info, I didn't know you could do that. I have the little version of what Jim has. I think the mini is slightly less efficient so it'd be nice to boost the temp just a bit, though some of that could very well be operator error. I will try taking out the dark flat pan that usually sits on the chrome rack (if I'm using the collapsible black pot it came with) and see if that makes any difference as well.

I could get the oven up to 190-200, then that would decrease when I added something and I'd not be able to get it back up again to where it was. Watching Jim's data with interest.

MW another trick you can try is to place a reflector on the ground (flat) in front of the oven.  This could be mylar covered cardboard, reflectix or even a silver windshield shade.  When the sun is at a low angle--such as late afternoon, mornings and winter low-angle sun locations, this can greatly boost the solar gain the oven receives. You probably don't want to try this during Arizona summers at high noon....might melt your oven and spoil your dinner! 

 

[jimindenver]

You have to remember that this is a cooker not a oven. What is important is what happens inside the pot, not the temperature of the cooker around it. I use light colored pans to bake cakes in the ovens because I don't want the pan to act like a heat source, it cooks the outside too fast. That would never work in a cooker because the pan is the heat source. I would have to set the cake pan on a rack inside of a black pan to get the same results. a lot like baking in a dutch oven.

 

[Magicwolf]

You have to remember that this is a cooker not a oven. What is important is what happens inside the pot, not the temperature of the cooker around it. I use light colored pans to bake cakes in the ovens because I don't want the pan to act like a heat source, it cooks the outside too fast. That would never work in a cooker because the pan is the heat source. I would have to set the cake pan on a rack inside of a black pan to get the same results. a lot like baking in a dutch oven.

'Think like a cooker', have to keep reminding myself of that. Sunflair calls it an 'oven' - but I actually found myself kind of viewing it more like a solar-powered slow-cooker than an oven based on the experiences I've had with it already. Have you tried to bake in yours? Do you think the flat pan that came with these things (that sits on the rack) is more of a help or a hindrance if you're already using a black pot? I was keeping it in thinking 'heat absorption/conduction'.

 

[jimindenver]

I think the black plate is a attempt at getting the Sunflair to act like a oven by heating the interior instead of just the pot the food is in. To me it blocks the light from getting to the cooking vessel. The issues are it isn't a very big heating element for the space and a huge difference in the insulating abilities of the materials used to make it. It doesn't even completely seal like my ovens do. Add those things together and the ability to make and retain heat just isn't there to use it like a oven. The water test showed that has great potential at reflecting the light onto a black vessel and heating its contents.

On the other hand, everything inside of a solar oven is black giving a much larger heating element to space ratio. They are very well sealed, heavily insulated and can retain their heat as clouds pass over.

I have only used the Sunflair three times and only this last test was a success in my eyes. It's going to take time and effort to see what works and how to get the most out of it just like it did with the other two. I have had three years to figure them out and not every meal was a winner. Thinking cooker instead of oven will certainly help.

 

[Oneleggedcowboy]

I still like the fact it's lite weight and easily stored!

 

[Magicwolf]

Thanks for your .02 on that, I feel a little better since my success with this thing has been questionable as well. It's not marketed much differently than the All American Sun Oven, for example, but they are quite different. I went and looked at that style closer and now see what you were saying, with the Sunflair it has no black (or better insulated) interior, so the cooking container has to provide that function. I'm going to try changing up my techniques a little with it, perhaps make a few other modifications. You're right, an oven can retain heat better; this does not do that so well.

Cowboy - they certainly do; I got mine (the mini-version) for that reason. It packs into quite a small area and is very light. I would love to have a true sun oven-style but I'm not sure where on earth I'd keep something like that.

 

[highdesertranger]

has anyone tried heating water or cooking with a Fresnel lens? . it will cut the time down dramatically. I have one of the big lenses I have never tried to cook with it but just played around, it will light a 2x4 on fire almost instantly. highdesertranger