The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

External Steam Generator

DanAyo's picture
DanAyo

External Steam Generator


The following is what I did to fabricate an External Steam Generator for my home oven. Steam under pressure is a potential safety hazard. I am not endorsing, nor do I recommend this appliance for others. If another chooses to build a unit like this or similar to this, they do so at their own risk. If in doubt contact a professional. I don't want to see others burned, and I especially don't want to get myself burned. (If you know what I mean :D)

Use THIS LINK for best viewing or click the video below.

Here is a list of materials used for my project.

I used a 1/2" ball valve, but it was larger than necessary. Were I to do this again, I'd probably opt for a 1/4" needle valve instead. The needle valve would allow more precise control over the flow rate.

The steam is injected into the oven via the oven's exhast pipe. On my oven it was located underneath the front of the control panel. See image below.

By the way - I was inspired by Lance, aka Albacore. We’ve been pursuing high volume steam for some time. Here is his article. Lance tells me he got the original idea here.

I repeat. This is what I did to set my system up. This is not an endorsement or recommendation for others to do the same. Should anyone decide to build a Steam Generator, please make sure you know what you are doing. If in doubt, contact a professional. I would hate to see others get burnt, and I especially don't want to get burnt myself.

Updated 7-5-20 -
It seems that high pressure steam is not as efficient as low pressure. When the Pressure Cooker is injecting high pressure steam it appears that much of it is pushed through the oven and leaks out into the kitchen. Since the high pressure option is only used to inject steam for a short time (90sec) it is believed that the steam vents through the oven and it’s affects are not fully utilized. Also large volumes of steam will likely reduce the oven’s heating. By adjusting the heat under the Pressure Cooker and opening up the gate valve, steam pressure can be adjusted at will. The audible sound of the flowing steam as it passes through the silicone tubing is a good indicator of relative pressure. As of early testing it seems good to allow the steam to flow for many minutes during the initial part of the bake. The concern of over steaming is mitigated by the fact that my home electric oven is not tightly sealed and consequently leaks. For the first low pressure test it was allowed to flow for 8 minutes, with good baking results.

Here is a 5 second video showing low pressure steam slowly escaping the home oven,

For best viewing use THIS LINK

 

Danny

BrianShaw's picture
BrianShaw

Can’t wait for the details!

joe_n's picture
joe_n

where did you buy the tubing silicone food grade?

what a great idea!

DanAyo's picture
DanAyo

Joe, go back to the original post and click the High Heat Silicone tubing text. It is a hyper link to Amazon. All materials with the exception of the PC are linked to Amazon.

BreadLee's picture
BreadLee

You are hardcore, and you are my idol now.  Wow. 

Colin2's picture
Colin2

Very impressed by this!  Are there any concerns, though, about putting too much moisture into an electric oven?  I mean, clearly ovens are built to handle a certain amount of steam and vapor in normal use, but are there limits?

DanAyo's picture
DanAyo

I was also concerned about this. I asked Lance who has been using the for months and he told me that he didn’t have any issues. I think the super high heat will disburse the moisture quickly.

Crumb Control's picture
Crumb Control

It's like a steam engine firing its load!

For how long do you keep this amount of steam running when you bake now? 

DanAyo's picture
DanAyo

I inject 8- 10 oz of water, converted to steam. The valve is open for 1 1/2 minutes. The reason I would use a Needle valve instead of a ball valve if building again, is because you can more easily meter the amount of steam flow. As it is now, the valve is cracked open and an aluminum shim (0.125” thickness) is inserted in the gap and closed. This works well, but is not as graceful a solution than the above mentioned.

Crumb Control's picture
Crumb Control

So you created the required opening by "manually" opening the ball valve, it's a nice improvisation :-)
1.5 minutes of intense steam, then you turn it off and keep baking at the same temperature?

Not that have plans to build one (although this looks insane, in a good way), but I'm wondering about the seal around the oven door, I see that you have all the steam contained inside, mine is pretty crappy and that's part of the reason I'm using a dutch oven, the water tray didn't produce a steamy enough environment. 

I'm guessing this can be a useful solution, right? 

DanAyo's picture
DanAyo

Dutch ovens work very well,  since they are self contained.

JohnAka's picture
JohnAka

This is a brilliant idea. I like how you used the existing infrastructure. And while there are work arounds like pans of water, squirt guns, rags, this beats them all. 

Dausone's picture
Dausone

Firstly thanks DanAyo for the post and to those before that have been working on this idea. Really cool! Some years back I had to ditch my trusty gas oven for a countertop electric convection oven. It is a great little beast and I have been surprised with the bread I can make using this! I saw your post and was wondering if I could possibly make it work for me. As I looked at my oven I noticed my Gaggia espresso machine with a steam wand sitting right beside my oven! Viola!

It is not pretty as I just jammed the tubing in the opening for the drip tray, but it does produce a good steady amount of steam for a few minutes!! This little oven is tight on space so I couldn’t do the usual cast iron / water pan. It gets up to 500 degrees and the thick baking tiles hold the heat amazingly well. The convection fan, when working, gives an even brown crust without having to turn the loaf around which is handy. The top does need to be rented with foil halfway through. Will update with pics on my next loaf with my new DIY steam machine!

barryvabeach's picture
barryvabeach

Looks nice -  how big is the oven cavity?  

Dausone's picture
Dausone

Product dimensions from the website:

0.8 cubic feet
Interior: 13.25"(W) x 11.25"(D) x 5.25"(H)

With my baking tiles on the bottom rack I get a height of: 4.75”. It is tight!

barryvabeach's picture
barryvabeach

I had considered a countertop model, though always worried that there would be an upper element too close to the top of the bread to make it work. 

Dausone's picture
Dausone

Yes it is an issue. I tend to make my loafs around 750grams or smaller because of this.  A boule will get uncomfortably close to the top but with a sheet of foil it is ok. Here is the latest loaf I just made for reference. I noticed a significant improvement on the ear (which isn’t much of an ear) and the overall crust and expansion with the added steam injection. Will wait for it to cool and check the crumb. This is a 10% whole meal rye, 67% hydration dough.



Dausone's picture
Dausone

barryvabeach's picture
barryvabeach

Great looking loaf, and I don't see any issue with browning of the top. 

Dausone's picture
Dausone

Thanks! I haven’t had any issues as long as I use a piece of foil on top. Not a big deal

Dausone's picture
Dausone

The boule is always a challenge as it touches the top of the heating element.

 

DanAyo's picture
DanAyo

Dausone, your breads are beautiful! When I look at them I think, “wow, and he baked those in that tiny oven”. But I wonder if you baked those because of that tiny oven.

Barry, aka BarryVaBeach believes that breads that are baked inside a vessel that closely fits the dimensions of the final dough produce the best results. The arrangement of the heating coils in proximity to your final loaf may lend credence to his concept.

Your free formed loaves are unique, so the following may not interest you. Have you considered baking some bread in a covered pullman?

Danny

Dausone's picture
Dausone

Thanks Danny! I definitely think that the small space helps. The new steam injection is also doing some good things for the crust and rise no question. I haven’t tried the pullman pans but I have considering trying a cast iron dutch oven. I have some friends using the dutch oven and they are getting some great loaves... the rise isn’t as prominent as with steam but still beautiful.

DanAyo's picture
DanAyo

I really like the profiles of the round slices that are produced from Chevron Scores. It is a great way to get sandwich bread from free formed loaves. No ears but a great slice. Thanks for reminding me!

Danny

Dausone's picture
Dausone

Ah I am still struggling with ears using this little oven. I had no problems with my old gas oven. I have been baking for a little over 15 years and I have to say I changed the way I do things after reading your post about putting faith in under proofing and oven spring. Wow. What a difference that has made! It only took me 15 years to figure that out with your help so thanks for making that post.

DanAyo's picture
DanAyo

I think baguettes might be your ticket for ears. Ears on baguettes are known to be difficult, but you may have the perfect oven setup for them. The relatively small circumference of the baguette will allow the dough to fully rise and still have room for ears. The close proximity of the heat to the crust may prove beneficial. Consider commercial deck ovens and how they are setup.

Like you, I over-fermented my dough for years before I got it right. I thought the dough needed more and larger bubbles, but failed to have faith in the power of oven spring.

Dausone's picture
Dausone

Ah yeah I need to try some short baguettes. It’s a great idea. I have always been hesitant because of the length restriction but there is no reason why they can’t be as short as I need them to be!