my pizza oven / pool heater build

[tomds]

Step fifteen, closing off the top of the boiler, keeping some headspace, and insulating it.


 

Attachments:

[tomds]

Step sixteen, closing up the rear and connecting stainless tubing and PVC pool hoses, surrounding the top with some extra aluminum foil for good measure.

Attachments:

[tomds]

Step seventeen, I covered both the top of the dome and boiler compartment with vermiculite / portland cement mix, to insulate and make it gas tight. Then I bought and installed a second hand insulated stainless steel chimney, and bended some sheet metal and used some leftover insulation to produce two front covers for the oven and the batch box. Stainless steel handles were bought from IKEA. 

That's where I'm at now. I still need to cover the build with a stainless lid, or a bluestone slab, I'm undecided as of yet. 
I also have some grouting left to do.

(To avoid rantings about the dangers of heating water with fire, and possible pressure buildup and so on, I will mention that I consider this design as safe, since the boiler is connected to the pool and pump unit without any valves or obstructions. My pool filter pump is programmed to pump filtered water through the boiler for 15 minutes, every other 15 minutes. In case the power fails, I can always open up the pizza oven door, and close off the back window, to stop heating the water, and avoid melting my hoses with boiling hot water. )


Hope you enjoyed reading, and good luck to any and all who feel up to copying this design.  

Attachments:

[ericvw]

May I simply say.... "Sweet!" Nice work, tomds... Great detail too.

[wiscojames]

I second that. Sweet. Thanks for sharing the pictures and your thoughts on the project. I want one. What temperature is typical for the oven after such long firings?

[tomds]

Hi guys, thanks for the praise. That's just what I wanted to hear.

I've done loads of diy things when we built our house and afterwards, but none gave me such a sense of achievement as this silly oven

Regarding oven temperature, I have no means of measuring it (yet), but last Sunday evening, the dome and oven floor were absolutely clean, not a speck of soot, or spilled cheese remaining anywhere. I've been led to believe this starts to happen when the walls are between 370 and 400 degrees Celsius. 

When I started cooking, I did notice that the initial heat decreased more quickly than in the past firings, when the back window was closed off. I guess that's not too surprising, plus it's all relatively speaking, the 8th pizza was still ready in under 4 minutes

I should mention that, due to the heat, one crack formed in the outside brickwork during one of the first firings. The crack is slightly larger when the oven is hot, and reduces again when the oven is cold. It doesn't seem to get any worse, so I guess it just means it has created its own expansion joint. Better design on my part might have avoided that, If I would redo this, I would not rest the T bars on the outer wall, but on an inner wall, not touching the outer skin

But hey, it is what it is, I can live with the crack. (with fingers crossed)

[tomds]

Step eighteen, the brickwork was grouted, and I ended up putting together a sloped, painted hardwood cover for the oven, in order to agree more with the theme of the house. 

I had to make a modification to the burn chamber as well. After a few weeks of prolonged firings, my P channel had completely burned through. This caused the secondary burn to be inefficient, causing smoke. 

I've cut away all the remaining metal from the P channel in the burn chamber and created sort of an S channel around the port to the riser, using firebrick. Width of the slit is 4 mm all around. In order to provide enough secondary air, I've created two triangular channels below the tilted surfaces in the burn chamber to the back, and through the new extra firebrick, so it is a straight connection with the slit. I've also modified my burn chamber door with triangular holes, to allow this secondary air to pass to the channels.

(hope that's a bit readable)

The result is that due to the slower heating of the firebrick, I get about ten minutes of smoke when lighting the fire, then up to one hour into the burn, the air coming from the chimney is slightly blueish. After this period, you can't tell if the stove is running or not from looking at the chimney, even when adding a new log onto the fire. You can't even see heat escaping from the chimney (I have to pay some attention to adding logs. Best is to add logs one by one, with a minute or two in between, otherwise too much combustibles are released at once, and I get stinking black smoke) I can also add very large logs one by one, without any smoke. Even adding 20 cm diameter fresh cut wet logs do not cause any smoke, which I find remarkable.

The attached picture was taken this morning, 10 minutes after putting logs onto a few coals left after last nights fire. (I added some lamp oil to help the initial flaming)

Still happy with the stove after one month!

Attachments:

[satamax]

Hi Tomds.

Well, despite being somewhat complicated, i quite like your build.

But i have to ask, where do you live?

Well, detached houses in the uk are quite rare, as well as terrace rooves. That makes me think it's not in the UK. Tho, your english seems to be uk to me! Dormers aren't usualy built that way in uk as well.

But tiled roof doesn't fit the bill for the USA. But the chimney cowl looks very american to me.

Frankly it's hard to tell! Not northern france, the gutters wouldn't be that dark. Seems too brickey for germany. Again, tiles on a brick house, would it be in belgium or holland, are uncommon. Same in france actualy. Not southern't europe. Doesn't sem dry enough for australia.


Well, i'm puzzled by this house

[tomds]

Hi Satamax, let me just say that tiles on a brick house are not so uncommon in Belgium as you seem to believe... The saying goes that us Belgians are born with a brick in the stomach.

[satamax]

Thanks Tomds. I saw your email adress after typing my message. It's the modern'ish tiles which bugged me! But the wall type dormer is common in northern france, belgium and holland. So i should have guessed. The bay window bugged me too. It's not common on the French side of the border, that's for sure! I'm soo obsessed with old buildings, that you show me a brick house with slates and stepped type dormers faces, i straight away say, holland or belgium. My bad for not knowing more modern architecture.

[mkrepel]

That's a nice looking unit. Good work. I suspect that your wife has a big say in the asthetics around your place, so her approval is the one that matters.

This is a unique build. It looks like the heat riser dumps into the oven first and then the gases travel into the water heater chamber. It that right?

Mike

[tomds]

Hi Mkrepel, thanks. You hit the nail there, wife acceptance factor was a concern throughout the project :-) Last year has been a constant complaint about the garden looking like ground zero. (not entirely unfair of her I'll admit, it did take long...) Last week she said she couldn't stand to hear the word pizza oven anymore :-) But now in the end she's very happy with its performance and looks, and even helped with the grouting! (I let her do the back side :-) ). We still need to blend it into the surroundings with some well chosen plants and some hedges to hide some stash of wood, but we feel we'll get there.

Opinions do seem to differ; two weeks ago, a random guest at one of our bbq's had the guts to ask "what's that ugly thing you put in your garden?". He got only warm beer from me after that.

You got the internals right. The passage is at the top of the dome, so the hottest gases in the oven travel to the water heater, which is also what I want after the fire dies down. Having two compartments also enables me to close off the water heater chamber in winter, but continue to use the pizza oven.

[philpsy]

Hi Tom,

you may be the saviour i've been searching for, and also the man my wife will thank. I have been hooked on creating an outdoor rocket mass conception for a year or so, and love to make things. However, I wanted to created a combi water heater and pizza oven.) I had initially also wanted to include a bench warmer as well, but my wife's layout of the decking area doesnt suit that anymore)

So to find your posting has given me such a breath of optimism, and excitement.

I have dug out loads of clay from my garden (live on south coast of england, and garden has loads of it a metre down), as I had thought i would make mine using cob techniques.

Do you think I could use my clay to help build it. I have just put an extension on the house, so i dont need a nice brick finish. Plus i love some of the decorative patterns and animals that people do using cob, although as min is outside i'd need to put a finish coat, or cover it, due to the beautiful weather we have in UK.

Is there a way of contacting you directly, as almost a kind of mentor figure?

congrats on a brilliant effort, and I for one, would be proud to follow in your footsteps, and even call my finished pizza/heater the 'Smedt' in your honour

thanks

Philpsy
aka Richard

[kor]

Hi I would like to build a similar installation. and I'm wondering if it would be ok to use ytong blocks as the outside of the bell?

do u think ytong can be used ? or will the temperature get to high ?

[satamax]

Ytong blocks absorbs humidity. So it needs to be protected from the elements. Ans it lacks mass to store heat.