January 4, 2022 - 1:58pm
Steam injection
I am looking for a new or used full size single or double convection oven with steam injection. Webstaurant has steam ovens, but if I understand correctly it is a separate type of oven. Blodgett rep told me that they do not produce such ovens any longer... What I need is a regular oven where I can inject steam for a few minutes. The oven is to be used for breads and cakes. I would appreciate any advice regarding brands/models. My budget is 6-7k. Thank you!
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There are small combi ovens that you can buy for less than $7K. Don't even bother with the Anova as it is an underpowered toy. A used Rational might be in your price range but you will have to search to find one. Just make sure you understand what the installation requirements are. You will need a dedicated 60a/240vac 3-wire + ground circuit, a 1/2" water line that will deliver at least 7 gal per minute, with a 5 micron filter just before the oven connection, and a 2" drain line that will tolerate boiling water. A dedicated exhaust fan is also required, preferably one with a hood that extends out as far as the fully open door of the oven (i.e., big) but 700 cfm is probably all the capacity you need. Also check to make sure you have a service company that will come to a residence to do repairs. Some shops won't do that (for insurance reasons or just because it is too much trouble). Also see if you can buy authorized parts through the wholsaler so that you can get a third party repair technician to do the work if you break something. A repair guide and a parts list would also be helpful (perhaps essential).
I would checkout Miele ovens that have a steam injection function. I live in Australia, but I'm sure you can find more recent models in your own country. In April 2017 we renovated our kitchen and installed a Miele H6660 BP model that cost - $5,799 AUD. It is fantastic. I can inject up to three bursts of steam 5 minutes apart. Each burst uses about 100ml of water. When setting up the oven for baking, you can nominated how many bursts and hold a jug of water under a pipe to suck up into the oven for the bake. The steam is injected automatically or manually. Best investment ever. The oven has many other functions.
Cheers,
Gavin.
We recently installed Miele’s H 6780-2 double oven. It’s plumbed to a water supply so not necessarily a simple install. Steam injection (Moisture Plus in Miele-speak) works great as gavinc notes. Pretty sure this particular oven has been around for 3-5 years so possibly phasing out before long??? The only other steam injection ovens we saw when we were in design phase required manually filling a reservoir. I’m sure they could work, but the Miele has outperformed in my estimation.
Not that Miele has got everything right. Don’t get me started on modal dialogs and endless approvals (oks) of settings just made.
Gavin, are you baking in Bake mode, and then giving a burst of steam? I have a different combi, and while I like it, it is not all that great, IMO for bread. Mine does not have a separate bake element, only convection, and convection fan runs the entire time. I have a feeling that while cooking in combi mode ( steam plus heat ) should be an advantage over a regular oven with steaming towels, that having the fan blow air over the loaf the whole time detracts from the extra humidity.
Some combis have an intermittent fan mode (Rational does I know, also old Henny Pennys), and that seems to be better than running high fan all the time, but it is still not a deck oven. It might help to remember that the steam does it's job by condensing to water on the surface of the dough and thereby delivering a lot more heat than convection will at low fan speeds. I made a run at calculating the heat transfer rate for high fan speed relative to condensation of steam and could not convince myself that I had enough accuracy to make a pronouncement one way or the other. If the steam is too hot you have to cool it down to the local dewpoint before you can get it to condense which is why you see the description of steam injections as "low pressure steam" which means that it boiled at 100°C or very close.
For a few years I have been doing this gedankenexperiment where you build an oven that will allow you to pull a vacuum at high temperature and thus allow the trapped CO2 in the dough to expand without requiring that it heat up. I can simulate the result with a bell jar and a piece of proofed dough. And you can get an easy 2X to 3X volume expansion with a simple vacuum pump. But without a heat source to cook the dough it just collapses as soon as you re-pressurize the bell jar. So you need to pull the vacuum then let the dough fully cook to the point where the alveoli become connected and then slowly re-pressurize the oven. It is a great show in the bell jar and I imagine that the end product would be super light and airy.
My Miele oven has three main baking functions; Conventional, Fan Plus (convection), and Moisture Plus. The moisture plus function is what I use for bread requiring steam. I can set it up automatically or manually. I've found that manual steam is best as I can give it a burst about 5 minutes before I load the doughs, then I give two more burst about 5 minutes apart during the first part of the bake. The bake then finishes in a drying oven that is ideal.
Curious how many loads of bread you can fit in you Mile if you were to maximize the capacity?
Meant to say loafs
I can fit 2 x 750-gram loaves, or 3 x 320-gram baguettes. I am restrained from adding a second tier due to height limits. I have a blog entry regarding this very topic here: I've hit the maximum capacity of my oven. | The Fresh Loaf
Cheers,
Gavin
I’ve done 2 800 g ciabatta, 3 300 g baguettes or 3 standard loaf pans of sandwich bread on my baking stone. Have also done 2 half-sheet pans of croissant on 2 racks simultaneously (no steam injection). Suspect I could get away with a second rack of ciabatta or other bread if I had a second pre-heated baking stone which I don’t. The steam feature works well as does the proof function.
Phil
I had read a blog that someone built a simple steam injection system for their regular home bought oven. Ive been using dutch ovens and had great results, but i was limited to 2 loaves at a time with a combined time of 40 mins per bake. So i built one for my whirlpool home oven and its a game changer!
Parts that i used were;
-A valu village pressure cooker
- compressor airline quick couplers
- a needle valve
- 1/4inch copper line
-fitting to attach everything
I found an area in my stove on the back wall and drilled a 5/16" hole thru it at the botton corner. Pushed the line thru it with about 2 in exposed in the oven, used straps to affix it to the screws along the back edge of the stove, looped the line overtop the stove to the placement of the pressure cooker and attached the valve and couplers. And thats it!
2 things i found was;
-the cooking time was cut almost in half. 21 mins ( burnt the first loaf)
-The spring and crust was amazing
The cost of supplies were around 40.00 and worth every penny :)
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Darryl: How do you control the amount of steam in your oven? Do you open and close a valve manually? You mention "needle" valve-what does that mean? I can't tell for sure, but it kinda looks like there's a knob that's turned to open and close the steam line. How long do you allow steam into the oven, and how many times do you steam your bake?
BTW, really clever solution. Jim
Well I built my self a similar steam injection system as the one Darryl has shown us. Now I need to know how long (or how much water should be converted to steam) to steam my loaves. I have a Bakers Pride Hearth series oven with a 55 lb granite deck. The oven chamber is probably about half the volume of a typical range oven.
To test the steam generator out, I opened the steam valve for 35 seconds. Lots of steam poured out of the oven (I had the door open to watch how the steam flowed). After the boiler cooled down I measured the water that remained, and found that the steam I released consumed 1/4 cup of water. Is that as much as I need, or do I need to steam longer? Should I steam multiple times, or all at once? Any advise anyone with steam injection experience can give me, is most appreciated. Thanks. Jim
I tried my steam injection system in a bake yesterday, and the results were encouraging. I baked two 850g loaves of Amy's Bread, Rustic Italian recipe. I injected steam into my Bakers Pride hearth oven 5 mi. before loading, then immediately after loading I injected steam for 60 sec., three min. later I injected steam for 30 sec. more, and finally 5 min. after loading I again injected steam another 30 sec. After the pressure cooker cooled, I measured the remaining water, and determined that I had used 1/2 cup of water. While I had some problems with over browning (I think starting the bake at 475 degrees is a little too hot for my set up), the loaves turned out very good. Nice open crumb, crisp chewy crust, and outstanding flavor.
My loaves had some shine, and showed about 1/2 to 3/4 in.oven spring. I was a little disapointed with this. BTW, the loaves were baked in 1 lb steel baking pans.
My questions: Is the oven spring similar to what others experience? Is 1/2 cup water enough steam to completely do the job? Finally, how long into the bake is steam beneficial?
Now I know when I used the boiling water into a hot cast iron pan, I used a lot more than 1/2 cup, but a lot of seam from that escaped before the oven door was closed. Steam injection is into a closed oven, so no steam immediately escapes through an open door. BTW, the Bakers Pride oven has about half the volume of a typical range oven. My steam injection was limited by the pressure cookers ability to produce steam.
Thanks for the help. Jim
Is the oven spring similar to what others experience?
Hard to tell without a photo. Linear measures of volume expansion miss two dimension and thus are hard to interpret. If you get decent ears on your baguettes you are OK.
Is 1/2 cup water enough steam to completely do the job?
That is not off by a lot, but also seems a bit low to me. As you point out, your oven is small and in this case size probably matters. I have no familiarity with the Bakers Pride oven so I don't know how tight the seals are. If the box is tight and the door has silicone wiping seals (or even tubular seals) I would not expect a lot of steam loss. The one factor that plays a role but for which I have no suggestion is how much superheat your steam has when it arrives in the oven. You want wet steam, not dry steam. And that means that the steam arrives at the oven as close to the local condensation temperature as you can arrange. Any superheat has to dissipate before the steam will condense on the dough. This works in a deck oven when the dough is baked largely by radiation rather than by convection and the local air temperature in the oven can be less than 100°C while the radiant temperature of the oven surfaces is high enough to do the cooking. This situation allows the steam to condense on the surface of the cool dough and deliver a very high heat transfer rate thus cooking the surface starch very quickly. I have seen no analysis of this so you are going to have to play with your setup to determine what works for you. The air in the oven is presumably heated by natural convection driven by the temperature differentials in the box and heat transfer is what baking is all about.
Finally, how long into the bake is steam beneficial?
There is a diversity of views on how long is long enough. I leave the steam generator on for 8 min for an 18 min bake cycle. I suspect that the answer is probably dependent on how long it takes to throughly gelatinize the surface starch. A shiny crust is perhaps the signal but I have also seen non-shiny crusts that were beautiful, crisp, and fairly thick. A few experiments should put reasonable bounds on how long is long enough in your particular case.
It is probably not very useful to inject steam before loading the loaves since it serves to cool the oven and contributes nothing to gelatinizing the surface starch.
A big factor is that domestic ovens leak steam by design. This is for 2 reasons - 1) to stop the user getting a blast of steam in the face when opening the door and 2) to keep the oven atmosphere somewhat dry, so that pastry and the like is not soggy.
In a deck oven I believe the chamber is better sealed and is vented by the user when desired by opening the damper.
In my domestic oven I have built a little hinged plate that covers the vent. I can open this mid-bake to vent the oven. Note that this is only for an electric oven - of course gas ovens should not have the vent blocked for safety reasons.
My steaming process is to build up pressure in the pressure cooker (I use 5psi so the steam is soon wet). I give a quick blast of pre-steam, then put the loaves in, open steam valve full and once pressure has gone, throttle valve to keep steam trickling in for 3 mins total.
Close off steam and pressure cooker heating then steam stand phase of 20mins. Vent oven and proceed to vented phase - usually another 12mins.
If your oven leaks steam badly you may need to keep trickling in steam for most of the steam stand.
The more loaves in the oven the more "self generated" steam there will be, which helps (but not for the initial steam action).
Lance
Thanks for the replies.
My oven probably isn't very well sealed. No sealing strip, simply door leaning against the sides of the oven box. As far as I can determine, there is no vent (the oven is electric with upper and lower element, and a heavy granite deck) but the holes in the oven back where the electric elements exit, probably leak.
The pressure of the steam is what lifts the "jiggler" on the pressure cooker.. Don't know what that is, but have read that pressure cookers typically run at 15 psi. I haven't baked baguettes yet so I can't guage using them.
If the steam benefit lasts 8 to 10 min., I can probably apply steam multiple times early on to get more steam in the oven. Of course as long as the steam valve is open, the steam pressure continues to decline, and I could simply leave it open to allow whatever steam is in the cooker to enter the oven. With the heavy deck, the steam does not seem to lower oven temp much - maybe 10 degrees F.
I'd appreciate any additional suggestions anyone might have. BTW, the spring measurement I referenced was the loaf height growth from proofed raw loaf to baked loaf. Baked in a loaf pan. Thanks again. Jim
PS: The oven box is slanted rearward so the door is held closed by gravity. Anothe note: The pressure cooker is a self contained type with it own heating element and a temp control dial with settings from 200 degrees to 400, in case that helps understand the set up.
The needle valve is probably not helping as it will always be the choke point and induces a significant pressure drop; a ball valve would be a better choice if you can find one. And since you don't have a pressure gauge or a thermometer/thermocouple in the pressure cooker you really don't know what the temperature is. From what I have read, low pressure steam is typically 5psi or lower which you will get only after you have bled down the initial 15 psi that is the Presto standard. You may want to bring the pressure cooker to a boil without the weight on and your ball valve closed, and turn the heat down to low and just let it barely boil. When you load the bread on the deck and shut the door, immediately open the valve, put the weight on, and turn up the heat.
I would calibrate the pressure cooker by letting it get to that condition and weigh it, then turn up the heat and let it make steam for 10 minutes, then weigh it again. This will give you a number for grams of steam (water) per minute. With the oven set to 450°F, run the steam generator and you should see lots of steam escaping around the edge of the door. If not your steam is too hot or you have a vent you don't know about. You can calculate how much steam you should expect based on the power consumption of the pressure cooker assuming perhaps a 70±10% efficiency.
Keep playing with it until you can predict how much steam you will make during the first 8-10 min of your bake cycle. The granite slab will hold heat well so you might want to consider a cycle that loads the bread, turns off the oven heaters and injects steam for ~2 min, then turn the heaters back on to 450° or whatever it takes to get the crust/browning that you want (which may require more or less heat from the upper element) and continue steam for another few minutes. When you are done with the steam, shut off the pressure cooker, shut the steam valve, open the oven door for 5 sec to flush out any residual steam and continue crust browning until you get where you want to be.
Another alternative: J Kenji Lopez Alt had demonstrated a neat trick that eliminates the Dutch oven and uses a lightweight aluminum cover for the loaves. The cover contains the steam given off by the dough and yields a very pretty loaf. The trick works fine with long loaves but you have or make a cover to contain the steam for the first 15 min. The better the cover seals against the deck, the better the result. Warping will probably be your limiting factor.
This cat is skinable, you just have to figure out what works for you.
Thanks Doc. My system has a ball valve rather than a needle valve, so no restriction there. It also has 1/4" silicone tubing as the transfer media.
I'll follow your suggestions regarding pressure, open the valve with the jiggler off, and let it run. I'll adjust the pressure cooker temp control so it stays on during the bake. After everything is cooled down I'll measure the water use to get some idea how much steam has been used. Jim
Sometimes jigglers come in different weights to give different pressures. It depends on the pressure cooker model in question.
I used to have a Prestige (UK) pressure cooker and the weight comprised 3 concentric screwed sections. the inner section was used for 5, 2 sections for 10 and all 3 for 15psi.
European pressure cookers tend not to have jigglers anymore. It stops the kitchen steaming up but makes pressure control slightly more difficult.
Lance
I have not done the calculation but you can expect the silicone tubing to give you a pressure drop, and in the process it will remove some heat from the steam. The line is not long but the tube will rapidly reach the temperature of the steam and you will lose a little superheat to free convection. If you run a test with a cold oven and see water droplets spraying out of the injection port you will know that you are where you want to be. If the steam turns to fog and deposits water on a piece of glass that you put in front of the exit (a pint Mason jar would be a good way to see it) you will have a good sense of what the steam quality is at that point. If the glass quickly clears up you still have a fair amount of superheat when the steam gets into the oven. The question that is running through my head is whether you will have enough flow to do what you need to do in the oven. Sylvia's towels produce a lot of suitable steam but take heat from the oven and take up space in the box and you need to produce a comparable amount of steam by augmenting the oven power with your electric pressure cooker.
You can get an inexpensive and highly accurate power sensor to measure the energy you use to generate the steam which will help you determine the pressure cooker heat transfer efficiency. I find it useful for answering questions about small appliance power consumption so it has a high level of reuse (like how much does it cost to make a pot of coffee and what is the value of putting the coffee into a vacuum caraffe rather than letting it sit on the coffee-maker to stay warm). I have a foam box equipped with a small muffin fan, a 20W seed starter heating mat, and a temperature controller, and I use it as a fermentation chamber. It was interesting to see that two quarts of yogurt would ferment at 113°F for 14 hours while consuming only 0.23 KWH.
I did another test of my system, this time with a cold (68F) oven, and an 8 min.steam interval. I brought the pressure cooker to jiggler temp/pressure, then opened the ball valve and let steam from the cooker flow into the oven for the entire 8 mins. Of course instantly upon opening the valve the pressure was reduced to whavever the cooker's heating element can produce and was well below jiggler pressure.
I had loaded 1000 g (1 L) of distilled water in the cooker, brought it to temp, then flowed steam for 8 min. After the system cooled, I weighed the water that was left. The water used by the generator was 330 g. which I think is about 11.5 oz. Remembering that my oven has a 55 lb stone deck, the inside of the cold oven was saturated with water. I had also put a temp probe in the oven before I started, and the steam delivered to the oven, raised it's temp by about 35 F. A bit of water vapor was seen escaping the oven door, and water was dripping off the bottom of the door so the oven obviously leaks steam.
I was a pleased by the weight figures. I did not expect that much water to be converted to steam and delivered to the oven. BTW, my silicone steam line is about 30" long. My pressure cooker is 4 qt, and rated at 1410 w. I think the heating element was on the entire time. Considering that my oven is only about 2 cu. ft. in volume, what is your opinion of my steam generator's ability to steam my bakes?
Is this enough steam? If not, how much longer can I deliver steam (remember this was 8 mins with the valve open) to the oven before it becomes worthless? How long does bread benefit from steam at the beginning of a bake?
Thanks again for your thoughts. Jim
I've used my steam injection system for three bakes so far. I baked the same two 800g pan loaves of Amy's rustic Italian bread, and I must say the steam system has worked very well. It takes about 30 min. for the bread to bake in my Bakers Pride Hearth series oven. I spritz the loaves with water just before loading, load, turn on the steam, (it takes the pressure cooker about 10 min to come to pressure, which I do in advance of the bake) turn off the upper element (actually both elements because there are no individual element controls) and allow the heavy granite deck to bake the bread while steam is being injected. I run the steam generator (electric pressure cooker) for 8 minutes. Turn it off, turn on the oven elements, and let it bake for the remainder of the session.
The results are very nice. I get nice oven spring, nice crust shine, even browning, and an open crumb. The crust is crispy and tastey.
The steam generator running the entire first portion of the bake, deals with the leaky oven.(there are no seals on this oven's door) Steam can be observed flowing out the oven door the entire time the oven is steamed. After the steam session, I open the oven to purge any left over steam, but I don't think that's really necesssary because of how the oven vents it.
For anyone considering a steam injection system, I can highly recommend it. It seems to have completely solved my steaming issues. No more messy sprayers or boiling cups of water. No messy towels or iron pans taking up room on the oven deck. Easy steam introduction, controlled by however long the steam valve is open. Building the system wasn't particularly difficult and only cost me about $80-$90 for parts. Jim
I'm very excited to have found this forum. Yesterday I completed my steam injector for a wood-fired brick oven that I built during the pandemic (what else was I going to be doing?). I baked three batches of bread in it that first day (all of which had been fermenting and proofing for a few days). They probably came out better than they would have with a spray bottle and a pan of hot water, but with practice, I expect the quality will continue to improve. I posted a picture of the setup and a video of its first trial here: https://drive.google.com/drive/folders/1lf7O5QyJ8eOp7AsrWfBPTiZ9t3PVggZ0
I really appreciate all of Doc Dough's suggestions, and I guess one thing I need to is to reduce the temperature of the steam. Maybe I should get the pressure cooker up to 15-20 lbs and then blast it until the pressure drops to 5 lbs, so presumably the temp would drop as well, and then maintain that lower flow and lower temp for another 6- 8 minutes.
It's a pretty McGiver setup, but it does address some of the issues discussed here by using a ball valve coming off of a T, with the jiggler repositioned at the top of the T. (I had to fabricate a T to get one that would take the standard threads of the tube that the jiggler sits on top of.). I'd love to hear any other experiences people have had with steam injection in wood-fired ovens, but also just about how to manage steam in any steam-injection system.
My experience with steaming a wood-fired oven is based on one that was built at a local church by some very talented local amateur bread bakers using local materials (including some clay that came from a deposit in Culver City. The oven gets fired up about once a month when the weather is cooperative and the air quality is good enough that we don't make it too much worse. The fire is started about 0800 and tended by some of the old hands until about noon when the fire is pushed to the side and the deck is mopped. After a short wait we can bake pizza for an hour or so, then the door is put in place to let the oven settle down. Then we can run four or five bread baking cycles that are successively longer after which people can load bread like pumpernickel and pots that will braise for longer periods at lower temperatures.
The steam for each bake cycle is injected through a seal-able 1/2" hole in the plug door using a very clean hand pumped pressure sprayer. We calibrated the sprayer so that 30 sec of injection loads 1.5X enough water to completely fill the oven assuming that all of the water turns to steam and the remainder pushes out the dry air and leaks out around the door seal (there is no vent). The first bake cycle is about 10 minutes and the last one is about 25 min. The oven master has a good sense of where we are in terms of remaining residual heat and his guidance has been spot on. The point is that each oven is unique, that the oven will boil the water at local atmospheric pressure, and some of the steam will leak but enough stays in the oven to accomplish its mission of cooking the surface starch. And there is a LOT of skill required to manage the process. I don't think there is any set-it-and-forget-it methodology.
In my expierence, a pressure cooker can't produce enough steam, or steam at a high enough temp to worry about hot steam/cold steam. Now I'm using a four quart electric pressure cooker, and if you're using a much bigger and more powerful (mine's 1400w) pressure cooker, maybe there would be an issue, In my case with the 15 lb "jiggler" dancing, as soon as I open the ball valve (1/4"), the pressure drops to probably less than 5 lbs. The pressure cooker will keep the oven full of steam, but it adds minimal atomspheric pressure to it. I checked my oven temp with a therometer when steaming, and I could detect no temp. change due to the steam. I do have a two cubic foot electric deck oven with a 1.25" thick granite deck so it modulates heat pretty well. With your wood fired oven, I think temp movement would be even slower than mine.
I hope my experience and thoughts are helpful. Jim